LTA Civil_standards- Civil Design Criteria
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Published by Land Transport Authority
Revision History Date
Revision
Sept 1999 Sept 2000 Sept 2001 Sept 2002
A1 A2 A3 A4
DC/0/1
CONTENTS Chapter 1
GENERAL
Chapter 2
MRT ALIGNMENT AND STRUCTURE GAUGE
Chapter 3
LOADS
Chapter 4
TRACKWORK
Chapter 5
GEOTECHNICAL PARAMETERS
Chapter 6
FOUNDATIONS, EARTHWORKS AND PERMANENT RETAINING STRUCTURES
Chapter 7
BORED TUNNELS AND RELATED WORKS
Chapter 8
UNDERGROUND STRUCTURES
Chapter 9
BRIDGES AND ABOVE-GROUND STRUCTURES
Chapter 10 ROADS Chapter 11 STATION AND TUNNEL SERVICES FOR RAIL PROJECTS Chapter 12 EXTERNAL WORKS Chapter 13 E&M INTERFACE Chapter 14 STRAY CURRENT CORROSION CONTROL FOR RAILWAYS Chapter 15 NOT USED Chapter 16 NOT USED Chapter 17 NOT USED Chapter 18 AUTOMATIC AND MANUAL IRRIGATION SYSTEM Chapter 19 INSTRUMENTATION Chapter 20 ASSESSMENT OF DAMAGE TO BUILDINGS AND UTILITIES Chapter 21 LIGHTING SYSTEM
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CHAPTER 1 GENERAL 1.1 1.1.1 1.1.2 1.1.3
INTRODUCTION Scope Definitions General Obligations
1.2 1.2.1 1.2.2 1.2.3 1.2.4
STANDARDS Use of Singapore and British Standards Use of British Standard BS 5400 Use of United Kingdom Highways Agency Design Manual for Roads and Bridges Partial Safety Factor for Strength of Reinforcement
1.3 1.3.1 1.3.2 1.3.3 1.3.4 1.3.5 1.3.6
DESIGN Responsibility for Design Design Objectives Design of Temporary Works Design For Removal of Temporary Works Oversite and Adjacent Developments Governing Criteria
1.4 1.4.1 1.4.2 1.4.3 1.4.4
CALCULATIONS Method of Calculations Use of Computer Programs SI Units Language
1.5 1.5.1 1.5.2
SURVEY & SETTING OUT Levels Co-ordinates
1.6 1.6.1 1.6.2 1.6.3 1.6.4 1.6.5
DURABILITY ASSURANCE Design Considerations Critical Elements Durability Assessment Life Cycle Cost Analysis Drawings
1.7
MATERIALS AND WORKMANSHIP SPECIFICATION
1.8
DIMENSIONS
1.9
BLINDING
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CHAPTER 2 MRT ALIGNMENT AND STRUCTURE GAUGE 2.1
INTRODUCTION
2.2 2.2.1 2.2.2 2.2.3 2.2.4 2.2.5 2.2.6
HORIZONTAL ALIGNMENT Definitions Horizontal Curves Cant and Speed Transition Curves Chainages Co-ordinates
2.3 2.3.1 2.3.2 2.3.3
VERTICAL ALIGNMENT Vertical Curves Gradients Levels
2.4 2.4.1 2.4.2 2.4.3
TURNOUTS AND CROSSOVERS (for heavy and medium rail systems only) Turnouts Closure Rails Diamond Crossings
2.5 2.5.1 2.5.2 2.5.3 2.5.4 2.5.5 2.5.6
STRUCTURE GAUGE AND CLEARANCES Definitions Train and Track Vehicles Structure Gauge Throw Clearance to Structure Gauge Clearances at Platform Edge
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CHAPTER 3 LOADS 3.1
GENERAL
3.2 3.2.1 3.2.2
LOADS FROM RAILWAY VEHICLES General Design for Protection of Structures against the Effects of Derailment
3.3 3.3.1 3.3.2 3.3.3
LOADS FROM ROAD VEHICLES General Loads on Underground Structures Load on Temporary Works including Temporary Decking
3.4
SURCHARGE LOADS
3.5 3.5.1 3.5.2
SOIL AND WATER LOADS Soil Unit Weights and Earth Pressure Coefficients Water
3.6 3.6.1 3.6.2 3.6.3 3.6.4
IMPOSED LOADS IN RAILWAY STATIONS Floor Loadings Escalators Lifts Cooling Tower/Water Tanks
3.7 3.7.1 3.7.2 3.7.3 3.7.4 3.7.5
WIND Wind on Viaducts, Bridges, Gantries and other Road Related Structures Wind on Stations and Other Structures Aerodynamic Effects Wind Load from Fans in Underground Railway Structures Wind Load from Trains in Below Ground Structures
3.8
PARAPETS AND HANDRAILING
3.9 3.9.1 3.9.2 3.9.3
LIFTING FACILITIES FOR EQUIPMENT Crane Gantry Girder Overhead Runway Beams Eyebolts
3.10
PARTIAL SAFETY FACTORS FOR LOADS
3.11
SEISMIC LOADING
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CHAPTER 4 TRACKWORK 4.1
INTRODUCTION
4.2
VEHICLE DATA
4.3 4.3.1 4.3.2
ELECTRICAL Power Return System Signalling System
4.4 4.4.2 4.4.3 4.4.4 4.4.5 4.4.6 4.4.7 4.4.8
TRACK SYSTEM Ballasted Track Slab Track Noise and Vibration attenuating track Level Crossing Noise and Vibration Space Constraints Trackwork Components
4.5
TRACK INSULATION
4.6 4.6.1 4.6.2 4.6.3 4.6.4 4.6.5 4.6.6 4.6.7 4.6.8
MISCELLANEOUS Cable Troughs Buffer Stops Over-Voltage Protection Devices (OVPDs) Reference Points and Distance Indicators Cross-Bonding and Jumper Cables Bonded Insulated Rail Joints Welding Trap Points
4.7 4.7.1 4.7.2 4.7.3 4.7.4 4.7.5 4.7.6
THIRD RAIL SYSTEM General Conductor Rail Joints in the Conductor Rail Ramps Conductor Rail Supports Protective Cover
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CHAPTER 5 GEOTECHNICAL PARAMETERS 5.1
GENERAL
5.2 5.2.1 5.2.2
HYDROGEOLOGY Rainfall Design Ground Water Levels
5.3
SOIL AND ROCK CLASSIFICATION
5.4
DESIGN PARAMETERS
5.5
SOIL AND GROUNDWATER CHEMISTRY
5.6
SITE INVESTIGATION
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CHAPTER 6 FOUNDATIONS, EARTHWORKS AND PERMANENT RETAINING STRUCTURES 6.1 6.1.1 6.1.2 6.1.3 6.1.4
INTRODUCTION General Ground Movements Deleterious Substances in Soils Combining Foundation Types in a Single Structure
6.2 6.2.1 6.2.2 6.2.3
DESIGN REQUIREMENTS FOR FOUNDATIONS Shallow Foundations Deep Raft Foundations Deep Foundation Elements (DFEs)
6.3 6.3.1
SETTLEMENT/HEAVE General
6.4
DEBONDING OF PILES AND DEEP FOUNDATIONS
6.5 6.5.1 6.5.2 6.5.3 6.5.4 6.5.5
LOAD TESTING General Preliminary Load Tests Working Load Tests Quantity of Testing Selection of DFEs for testing
6.6 6.6.1 6.6.2 6.6.3 6.6.4 6.6.5 6.6.7
PERMANENT GRAVITY AND CANTILEVER RETAINING WALLS Lateral Earth Pressures Water Pressure Factors of Safety Use of DFEs for Retaining Structure Foundations Settlement and Deflections Seepage
6.7 6.7.1 6.7.2 6.7.3 6.7.4 6.7.5 6.7.6
EARTHWORKS General Factor of Safety Embankment for Railway Tracks Soil Improvement Drainage Non-Suspended Apron Structures and Services
6.8 6.8.1 6.8.2 6.8.3
TRANSITION SLABS General Transition Slab for Roadways Transition Slab for Railways
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6.9 6.9.1 6.9.2 6.9.3 6.9.4
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USE OF FINITE ELEMENT OR FINITE DIFFERENCE MODELLING TECHNIQUES Design Requirements Modelling Requirements Sensitivity Analysis Submission of Results
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CHAPTER 7 BORED TUNNELS AND RELATED WORKS 7.1
GENERAL PRINCIPLES
7.2
TUNNEL SIZE
7.3 7.3.1 7.3.2 7.3.3 7.3.4
TUNNELS IN SOFT GROUND Definition of Soft Ground Design Method Flotation and Heave Longitudinal Stiffness
7.4 7.4.1 7.4.2
TUNNELS IN ROCK Definition of Rock Design Method
7.5 7.5.1 7.5.2 7.5.3 7.5.4 7.5.5 7.5.6
SEGMENTAL LINING DESIGN General Deflections Waterproofing Fixings Taper Rings Bolt Pockets
7.6 7.6.1 7.6.2 7.6.3
TEMPORARY TUNNEL LININGS Types of Lining Sprayed Concrete Lining (SCL) Ribs and Lagging
7.7 7.7.1 7.7.2 7.7.3 7.7.4
IN-SITU TUNNEL LINING General Analysis Waterproofing Fixings
7.8 7.8.1 7.8.2 7.8.3
CROSS PASSAGEWAYS BETWEEN RAILWAY RUNNING TUNNELS Location Dimensions and Layout Design
7.9
SUMPS IN RUNNING TUNNELS
7.10 7.10.1 7.10.2 7.10.3
EMERGENCY ESCAPE SHAFTS Location Dimensions and Layout Shaft Design
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7.11 7.11.1 7.11.2
TUNNEL WALKWAY IN RAILWAY TUNNELS Arrangement Details of Walkway
7.12
FIRST STAGE CONCRETE
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CHAPTER 8 UNDERGROUND STRUCTURES 8.1 8.1.1 8.1.2 8.1.3 8.1.4
GENERAL Scope General Principles General Requirements for Trainways in Cut-and-Cover Tunnels and Stations General Requirements for Vehicular Underpasses and Depressed Cariageways
8.2
DESIGN APPROACH
8.3 8.3.1 8.3.2
ULTIMATE LIMIT STATE Structural Stability Robustness
8.4 8.4.1 8.4.2
SERVICEABILITY LIMIT STATE Settlement Cracking
8.5 8.5.1 8.5.2 8.5.3 8.5.4
DURABILITY Exposure Conditions Minimum Cover Cement and Water Content Shrinkage and Thermal Cracking
8.6
FIRE RESISTANCE
8.7
INSPECTION OF CONSTRUCTION
8.8 8.8.1 8.8.2 8.8.3 8.8.4
LOADS Load Factors for Earth and Water Pressure Ground Loads Load Combinations Unbalanced Loads
8.9 8.9.3
ANALYSIS Locked-in Stress Resultants (moment, shear axial force, etc)
8.10 8.10.1
DETAILED DESIGN Redistribution of Moments (only applicable for structures designed to SS CP 65) Design Moments Bottom Loaded Structural Elements Internal facing of Diaphragm and Secant Pile Walls Fixings for E&M Equipment Post Fixed Reinforcement Connections between Bored Tunnels / Cut-and-Cover Structures
8.10.2 8.10.3 8.10.4 8.10.5 8.10.6 8.10.7
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8.10.8 8.10.9
Pile Foundations and Deep Foundation Elements Torsion (only applicable for structures designed to SS CP 65)
8.11 8.11.1 8.11.2 8.11.3 8.11.4 8.11.5 8.11.6 8.11.7
DETAILING Slabs and Walls Columns / Piers Beams (only applicable for structures designed to BS 5400) Corner Details Construction Joints Slab to Wall Connections Detailing of Shear Links
8.12
CIVIL DEFENCE DESIGN (where applicable)
8.13 8.13.1 8.13.2 8.13.3 8.13.4
PROVISION FOR FUTURE DEVELOPMENT Knockout Panels for Access to Future Developments Fire Separation for Railway Structures Future Development Loads, Structural Capacity and Settlement / Deflection Design Assumptions and Construction Constraints
8.14 8.14.1 8.14.2 8.14.3 8.14.4 8.14.5
FLOTATION General Factors and Safety Soil Friction Assessment Measures to Counteract Flotation
8.15
STABILITY OF THE EXCAVATION
8.16
WATERPROOFING
8.17 8.17.1 8.17.2 8.17.3 8.17.4 8.17.5 8.17.6
DESIGN OF TEMPORARY WORKS General Requirements Design of Temporary Excavation Support Design for Removal of Temporary Works Use of Finite Element or Finite Difference Modelling Techniques Minimum Unplanned Excavation Temporary Ground Anchorages
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CHAPTER 9 BRIDGES AND ABOVE-GROUND STRUCTURES 9.1
GENERAL
9.2
STANDARDS AND CODES OF PRACTICE
9.3
ANALYSIS
9.4 9.4.1 9.4.2
LOADING Temperature loads Aerodynamic Effects
9.5 9.5.1 9.5.2 9.5.3 9.5.4 9.5.5 9.5.6 9.5.7 9.5.8 9.5.9 9.5.10 9.5.11
DESIGN CONSIDERATIONS AND REQUIREMENTS General Reinforced Concrete Prestressed Concrete Reduction or Isolation of Vibration Design Surface Crack Width Member Shapes and Sizing Precast Segments Piled Foundation Piers Abutments Approach (Transition) Slab
9.6 9.6.1 9.6.2
BEARINGS General Bearing Replacement
9.7 9.7.1 9.7.2 9.7.3
MOVEMENT JOINTS FOR DECKING SLABS Definitions General Movement Joints
9.8
WATERPROOFING AND MECHANICAL IRRIGATION SYSTEM FOR FLOWER TROUGH IN ROAD VIADUCTS AND PEDESTRIAN OVERHEAD BRIDGES
9.9 9.9.1 9.9.2
PARAPET SYSTEM ON VEHICULAR BRIDGES AND PEDESTRIAN OVERHEAD BRIDGES General Additional Design Requirements on Vehicular Bridge Parapets
9.10
THERMAL RAIL FORCES
9.11
RAILWAY DECK FURNITURE, DRAINAGE AND WATERPROOFING
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9.12
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CHAPTER 10 ROADS 10.1
GENERAL
10.2
ROAD PAVEMENT
10.3 10.3.1 10.3.2 10.3.3 10.3.4 10.3.5 10.3.6 10.3.7 10.3.8 10.3.9 10.3.10 10.3.11 10.3.12 10.3.13 10.3.14 10.3.15
ROAD GEOMETRY Horizontal Alignment Horizontal Sight Distance Vertical Alignment Vertical Curves Compound Curves Reverse Curves and Broken-Back Curves Corner Radius Cross Slope Transition Curves Superelevation Combined Vertical and Horizontal Alignment Lane Width Traffic Island Road Cross-Section Element Exits and Entries at Interchanges
10.4
VEHICULAR IMPACT GUARDRAIL
10.5
CLEARANCE TO STRUCTURE
10.6
KERBS
10.7
WALL OPENING/VEHICULAR BREAKDOWN LAYBY/EMERGENCY STAIRCASES
10.8 10.8.1 10.8.2
ROAD MARKING AND SIGNAGE Carriageway Markings Road Signs
10.9 10.9.1 10.9.2 10.9.3 10.9.4 10.9.5 10.9.6 10.9.7
INFORMATION SIGNS Introduction Design Considerations Siting of Signs Materials for Sign Sign Support Blockage of Signs by trees Other Examples
10.10
SITING OF INFORMATION SIGNS
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CHAPTER 11 STATION AND TUNNEL SERVICES FOR RAIL PROJECTS 11.1 11.1.1 11.1.2 11.1.3
GENERAL REQUIREMENTS Standard Codes and Regulations Approvals Routing of Pipework and Services
11.2 11.2.1 11.2.2 11.2.3 11.2.4 11.2.5 11.2.6
DRAINAGE General Tunnel Drainage Station Drainage Station Pump Sumps Sump and Pump Design Directives Storm Water Drainage
11.3 11.3.1 11.3.2 11.3.3 11.3.4 11.3.5
SEWERAGE & SANITARY PLUMBING General Design Code Design Directives Sewage Pump Sumps Sewage Ejector
11.4 11.4.1 11.4.2 11.4.3 11.4.4
WATER SERVICES General Water Supply System Water System for Fire Fighting Civil Defence (CD) Water System
11.5 11.5.1 11.5.2 11.5.3
ACCESS LADDERS General Design Material
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CHAPTER 12 EXTERNAL WORKS 12.1
LAND BOUNDARIES
12.2
FLOOD PROTECTION
12.3
PAVED AREAS
12.4
IRRIGATION SYSTEMS AND LANDSCAPING
12.5
HANDRAILS AND RAILINGS
12.6
FENCING AND PROTECTION AGAINST UNAUTHORISED ACCESS
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CHAPTER 13 E&M INTERFACE 13.1
GENERAL
13.2 13.2.1 13.2.2
ELECTRICAL SUBSTATION Cable Chamber Others
13.3 13.3.1 13.3.2 13.3.3
PLATFORM TOUCH VOLTAGE PROTECTION General Minimum Insulation Level Insulation Details
13.4 13.4.1 13.4.2
WATER AND ELECTRICAL EQUIPMENT General Protection External Cable Manholes and Cable Ducts
13.5
E&M EQUIPMENT DELIVERY ROUTES
13.6
ELECTRICITY SUPPLY TO CIVIL EQUIPMENT
13.7 13.7.1 13.7.2 13.7.3 13.7.4
EARTHING SYSTEM General Earthing Mat Design Requirements Installation and Execution Testing
13.8
CABLE AND PIPE DUCTS
13.9
EQUIPOTENTIAL BONDING
13.10
CABLE BRACKETS AND OTHER E&M FIXINGS IN TUNNELS
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CHAPTER 14 STRAY CURRENT CORROSION CONTROL FOR RAILWAYS 14.1 14.1.1 14.1.2 14.1.3
INTRODUCTION General Design Considerations Operating Modes
14.2 14.2.1 14.2.2 14.2.3 14.2.4 14.2.5
SYSTEM REQUIREMENTS Trackwork Elevated MRT Stations and Viaducts (Fig. 14.1) Underground Structures (Fig. 14.2, Fig. 14.3, Fig. 14.4) At-Grade and Transition Sections (Fig. 14.5) Depots
14.3 14.3.1 14.3.2 14.3.3 14.3.4
SYSTEM COMPONENTS Cabling Drainage Panels Drainage Terminal Boxes Reference Electrodes
14.4 14.4.1 14.4.2 14.4.3 14.4.4
STRAY CURRENT LEAKAGE PATH CONTROL General Installations Elevated Stations and Viaducts Underground Structures and Tunnels
14.5
SYSTEM TESTING AND MONITORING (refer to Fig. 14.6 to Fig. 14.9 and Appendix 2) Track to Structure Earth and Water Earth Resistance Stray Voltage Level Monitoring Substation Drainage Current Measurements Other Tests Test Procedures
14.5.1 14.5.2 14.5.3 14.5.4 14.5.5
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CHAPTER 18 AUTOMATIC AND MANUAL IRRIGATION SYSTEM 18.1
REGULATIONS, CODES AND STANDARDS
18.2
AUTOMATIC IRRIGATION SYSTEM DESCRIPTION
18.3
DESIGN CRITERIA
18.4
MICROPROCESSOR BASED IRRIGATION CONTROLLER
18.5
RAIN SHUT-DOWN
18.6 18.6.1
PUMPSETS Submersible Pumpset
18.7
SUMP PUMP
18.8
OPERATION OF PUMPS
18.9
SPRINKLER HEAD AND STREAM BUBBLER
18.10
PIPES AND FITTINGS
18.11
MANUAL IRRIGATION SYSTEM DESCRIPTION
18.12
DESIGN CRITERIA
18.13
PIPES AND FITTINGS
18.14
PIPE INSTALLATION
18.15
OTHER ACCESSORIES
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CHAPTER 19 INSTRUMENTATION 19.1
INTRODUCTION
19.2
INSTRUMENTATION REQUIREMENTS
19.3 19.3.1 19.3.2 19.3.3
MONITORING PLANS AND RELATED DOCUMENTS Monitoring Drawings Instrumentation Tables Instrumentation Specifications
19.4 19.4.1 19.4.2 19.4.4. 19.4.5. 19.4.6. 19.4.7. 19.4.8. 19.4.9. 19.4.10.
MINIMUM MONITORING Minimum Monitoring for Excavations Minimum Monitoring for Tunnels Minimum Monitoring of Struts and Ground Anchors Minimum Monitoring of Buildings and Structures Minimum Monitoring of Utilities Minimum Monitoring for Areas of Ground Treatment Minimum Monitoring for Tunnelling Under Buildings Minimum Monitoring for Buildings Subject to Protective Measures Minimum Vibration Monitoring
19.5
ADDITIONAL MONITORING
19.6
READING FREQUENCY FOR MONITORING INSTRUMENTS
19.7
ACCURACY AND RANGE OF MONITORING INSTRUMENTS
19.8
REVIEW LEVELS
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CHAPTER 20 ASSESSMENT OF DAMAGE TO BUILDINGS AND UTILITIES 20.1
GENERAL
20.2 20.2.1 20.2.2 20.2.3
PREDICTION OF SETTLEMENTS Ground Movements due to Bored Tunnelling Ground Movements due to Excavations Combined effects
20.3
ASSESSMENT OF DAMAGE TO BUILDINGS
20.4
ASSESSMENT OF DAMAGE TO UTILITIES
20.5
PROTECTIVE WORKS
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CHAPTER 21 LIGHTING SYSTEM 21.1 21.1.1 21.1.2 21.1.3
PUBLIC STREET LIGHTING General Luminaires Requirements Works in Conjunction with Lighting
21.2 21.2.1 21.2.2 21.2.3
VEHICULAR UNDERPASS LIGHTING General Emergency Lighting Luminaires Requirements
21.3 21.3.1 21.3.2 21.3.3 21.3.4
TUNNEL LIGHTING General Design Parameters Glare Control Emergency Lighting
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CHAPTER 1 GENERAL 1.1
INTRODUCTION
1.1.1
Scope The Design Criteria give the requirements for the design and detailing of all Civil Engineering Works for the Land Transport Authority. Unless stated otherwise, the requirements of the Design Criteria are for Permanent Works.
1.1.2
Definitions The definitions of “Authority“, “Contractor“ and “Works“ etc. shall be those given in the Conditions of Contract. The term Engineer used in the Design Criteria refers to the Engineer appointed by the Authority for the purposes of the Contract. Where the Conditions of Contract require instead that a Superintending Officer be appointed for the purposes of the Contract, the term Engineer in this Specification shall refer to the Superintending Officer so appointed by the Authority. The use of the terms “railways”, “stations” etc, shall be taken to apply to all guided systems, whether MRT or LRT, whether steel on steel or rubber tyres on guideways etc, unless specifically stated otherwise or agreed otherwise with the Engineer. The definition of “nominal cover” shall be the design depth of concrete cover to all steel reinforcement, including links. It shall be the dimension used in design and indicated on the design drawings.
1.1.3
General Obligations
1.1.3.1.1
Compliance with Statutory Requirements and International Standards All designs shall be carried out and fully endorsed by Professional Engineers holding a valid practising certificate and registered under the Professional Engineers Act, Singapore in the civil and/or structural discipline and registered Accredited Checkers in accordance with the Building Control Act. All designs shall comply with all Building and Safety Regulations including the Building Control Act. Compliance with a Singapore Standard (SS) or British Standard (BS) or a standard approved by the Authority (or accepted by the Engineer) or the
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requirements of these Design Criteria shall not confer immunity from legal obligations. 1.1.3.2
Adjacent Works The design shall take into account any constraints or effects imposed by the existing and planned works and services in the surrounding areas, and works of other nearby contractors.
1.2
STANDARDS
1.2.1
Use of Singapore and British Standards The design of all Works shall comply with the appropriate current standards and/or Codes of Practice issued by the Productivity and Standards Board (PSB), or if such a standard and/or Code of Practice does not exist, then the appropriate current standard issued by the British Standards Institution (BSI). If an appropriate standard from PSB and BSI does not exist and no other standard is stated in the Contract Documents, then subject to the acceptance of the Engineer and the Commissioner of Building Control of The Building and Construction Authority, an appropriate current standard from a reputable institution may be used. Three English language copies of such proposed standards shall be submitted to the Engineer. Generally the requirements spelt out in the Particular Specification, General Specification, M&W Specification and the Design Criteria shall take precedence over any relevant Singapore or British Standards, UK Highways Agency Standards and advisory notes or other International Codes of Practices. Where metric unit and imperial unit version of the same standard exist, the metric version shall apply.
1.2.2
Use of British Standard BS 5400
1.2.2.1
Unless noted otherwise use of BS 5400 shall be as implemented by the United Kingdom Highways Agency Standards and Advisory notes and as further amended by the Design Criteria.
1.2.2.2
References made within the Design Criteria to BS 5400 Part 2 shall be to the composite version of BS 5400 Part 2 (which forms an appendix to the United Kingdom Highways Agency Departmental Standard BD 37/88) and as further amended by the Design Criteria.
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1.2.3
Use of United Kingdom Highways Agency Design Manual for Roads and Bridges The design shall also comply with the following Standards contained in the Design Manual for Roads and Bridges, except where explicitly stated otherwise in the Design Criteria: BD 15/92 BD 16/82 BD 20/92 BD 24/92 BD 27/86 BD 28/87 BD 30/87 BD 32/88 BD 33/94 BD 36/92 BD 37/88 BD 52/93 BD 60/94 BA 26/94 BD 49/93
1.2.4
General Principles for the Design & Construction of Bridges – Use of BS 5400: Pt 1 1988 Design of Composite Bridges – Use of BS 5400 Pt 5: 1979 Bridges Bearings – Use of BS 5400 Pt 9: 1983 Design of Concrete Highway Bridges and Structures – Use of BS 5400 Pt 4: 1990 Materials for the Repair of Concrete Highway Structures Early Thermal Cracking of Concrete Backfilled Retaining Walls and Bridges Abutments Piled Foundations Expansion Joints for Use in Highway Bridge Decks The Evaluation of Maintenance Costs in Comparing Alternative Designs for Highway Structures Loads for Highway Bridges The Design of Highway Bridge Parapets Design of Highway Bridges for Collision Loads Expansion Joints for Use in Highway Bridge Details Design Rules for Aerodynamic Effects on Bridges
Partial Safety Factor for Strength of Reinforcement The partial safety factor for strength of reinforcement shall be taken as 1.15 (and not 1.05 as given in BS 8110 table 2.2).
1.3
DESIGN
1.3.1
Responsibility for Design Staff with proven relevant experience shall be deployed to design and detail the Works using their skills to the best of their abilities to achieve the design objectives described in Clause 1.3.2 below.
1.3.2
Design Objectives The design of structures and civil engineering works shall meet the following objectives: they shall be safe, robust, economical, durable, with operation and maintenance costs reduced to a practicable minimum, and shall be fit for purpose. Simplicity of structural form and layout is to be preferred. All structures shall be designed to be aesthetically pleasing.
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The elements of all structures shall be designed and detailed to achieve the design objectives by, inter alia, the following: (a) (b) (c) (d) (e) (f)
appropriate selection of materials consideration of the long term deterioration of materials in the service environment due care in design and detailing so as to facilitate good workmanship in construction and the achievement of design intent consideration of access and other requirements for inspection and maintenance adoption of good engineering practice use of low risk construction methods and proven techniques
The durability objective of the project shall be to achieve a service life, with appropriate maintenance, of 120 years for all structures. The measure of achievement of durability shall be that all the criteria set in the design shall be maintained throughout the service life. Deterioration of materials shall be taken into account in the design and specification of the works. Due diligence and skills shall be applied in the design and detailing to ensure that the works can be constructed economically, practically and safely. All structural designs shall comply with all the ultimate and serviceability limit states. 1.3.3
Design of Temporary Works All Temporary Works shall be designed and detailed to be compatible with the Permanent Works. Temporary Works designs shall be carried out and endorsed by a Professional Engineer. Any part of the Permanent Works that performs a temporary function during construction shall be defined as Permanent Works and shall be analysed for both conditions (permanent and temporary) and designed using Permanent Works design criteria for the more onerous condition. The exception to this is crack width requirements for embedded walls, for which the appropriate clause should be consulted.
1.3.4
Design For Removal of Temporary Works
1.3.4.1
All Temporary Works outside the limits of the following shall be designed for removal: (a)
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(b)
1.3.4.2
For railway projects, the smaller of the Railway Area (as defined in the Rapid Transit Systems Act) and an area bounded by a line 3m from the footprint of the Permanent Works
Within the limits stated in the above clause, Temporary Works shall also be designed to be removed. Exceptionally, within these limits the Contractor may propose to leave Temporary Works in place, where it is impracticable to remove them. Prior to installation the Contractor shall gain the acceptance of the Engineer for any such proposal.
1.3.4.3
Temporary Works shall be designed such that there is no risk of damage to the Permanent Works during removal. Unless otherwise accepted by the Engineer, all voids left in the ground due to the extraction of temporary works shall be backfilled with grout. The grout mix and method of backfilling shall be submitted to the Engineer for acceptance.
1.3.4.4
Where it is agreed that Temporary Works may be left in the ground they shall be designed so that there will be no risk of ground settlement or other deleterious effects as a consequence of decay of timber or other materials. In all cases Temporary Works shall be designed to be removed to a depth of 2 metres below the finished ground level unless shown otherwise on the Authority’s Drawings. This shall also apply to all secant and diaphragm walls and the like. Details of the construction sequence assumed, identification of the Temporary Works that are not to be removed (if any) and provisions made in the design to satisfy the above requirements shall be detailed on the Temporary Works design drawings. Any Temporary Works not removed shall be shown on the as-built drawings.
1.3.5
Oversite and Adjacent Developments All structures are to be designed wholly independently of any benefit which might be obtained from oversite or adjacent development. For example, in consideration of stability against flotation or of any lateral loading, the design should allow for the development not being present if that gives a more onerous design case.
1.3.6
Governing Criteria Unless specifically stated otherwise in the Particular Specification, where there are different criteria for design stated in the Contract Documents,
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Standards and Codes of Practice or relevant statutory regulations, the most onerous shall apply. 1.4
CALCULATIONS
1.4.1
Method of Calculations Unless otherwise varied by the subsequent Chapters of the Design Criteria, all calculations shall be carried out in accordance with the requirements and recommendations of appropriate current Standards. The use of "State-of-the-Art" methods of calculations or methods that have not been extensively tried and proven within the industry will not be permitted unless prior acceptance for their use has been obtained from the Engineer. The design shall be in accordance with established good engineering practice and principles.
1.4.2
Use of Computer Programs The use of computers is permitted, provided the computer programs to be used are accepted by the Engineer. The programs to be used shall be those that are produced by reputable software houses and have undergone extensive testing. In this respect, the relevant documents and sample calculations to demonstrate the accuracy and reliability of the programs shall be submitted. Details of computer programs, including assumptions, limitations and the like, shall be clearly explained in the design statement. All input and output data of a computer program shall be clearly defined and the calculations shall include clear and unambiguous information of what each parameter means in the computer output forms. When in-house spreadsheets are used, the proposed version of the spreadsheet shall be clearly indicated and submitted together with hand calculations to verify the results of the spreadsheet for all possible calculation scenarios. A print-out of the spreadsheet showing the formulas normally hidden shall also be submitted with the cell references clearly labelled along the top and left hand margins of each page.
1.4.3
SI Units All calculations shall be carried out and presented in SI Units as specified in BS 3763. The units of stress shall be N/mm2 or kN/m2.
1.4.4
Language All calculations and other documents shall be submitted in the English Language.
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1.5
SURVEY & SETTING OUT
1.5.1
Levels All levels given on the design drawings shall refer to a Project datum 100m below Singapore Standard Datum.
1.5.2
Co-ordinates All co-ordinates given on the design drawings shall be based on the project co-ordinate system as defined in the Particular Specification. The project co-ordinate system shall be clearly defined and indicated on the design drawings.
1.6
DURABILITY ASSURANCE
1.6.1
Design Considerations The design shall address the durability of all elements of the structures. The design process shall incorporate an assessment of potential deterioration of materials in their exposure environments (e.g. exposure to ground water) throughout the service life, including but not limited to: (a) (b) (c) (d) (e)
durability of concrete, corrosion of metals, long term performance of sealants, waterproofing, coatings and other forms of protection, serviceability of embedded pipework, services etc. maintenance/replacement of architectural finishes.
Construction processes which are critical to the achievement of durability shall be identified. These include workability requirements for casting concrete around relatively congested reinforcement sections, and duration of placement in terms of delay in setting to avoid cold joints. 1.6.2
Critical Elements Particular attention shall be given to deterioration of elements which cannot practically be accessed for maintenance or repair during the service life. In the case of such critical elements, the design shall be premised on the element (including all its components) remaining durable throughout the service life without maintenance. Additional measures shall be incorporated in the design of such elements to address the eventuality of the primary protection failing to achieve the desired durability. Where normal methods of inspection are impossible, provision for monitoring material performance by instrumentation shall be implemented where practicable.
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1.6.3
Durability Assessment Based on the durability objectives of the project, performance criteria for materials shall be developed from an assessment of the following: (a) (b) (c) (d) (e) (f)
the micro-environment to which the element is exposed potential deterioration mechanisms in this micro-environment the likely material life the feasibility and cost of in situ monitoring, maintenance and/or repair the necessity and cost-effectiveness of providing additional protection the significance of deterioration.
In addition to the assessment of “the likely material life”, the quality control tests to monitor the quality of concrete for durability and the acceptance criteria shall also be provided. Any proposal to revise the Materials and Workmanship specifications shall be based on the performance criteria arising from such considerations. 1.6.4
Life Cycle Cost Analysis Where required by the following chapters, life cycle cost analysis shall be undertaken as a basis for selection of materials. Such analysis will require prediction of material performance and life of all components of the element (jointing and waterproofing materials, fixings etc.) and compare the total life costs of viable options, by summation of: (a) (b) (c)
initial capital cost, including any monitoring system that is to be installed during the construction phase, recurrent costs of inspection, maintenance/repair, replacement (where feasible)
Total life costs, shall be expressed in present day dollars by using discounted cash flow techniques based on 5% discount rate. The analysis is to be used as a decision making process and costs therefore need only be sufficiently accurate for the purposes of comparison of options. A sensitivity analysis shall be undertaken to reflect the uncertainties related to: (a) (b) (c) 1.6.5
predictions of material performance workmanship in construction unit rates for calculation of inspection, maintenance, repair and replacement costs.
Drawings The design characteristic strength, the maximum nominal aggregate size, the minimum cement content, maximum cement content, and
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maximum free water: cement ratio and permitted cement types shall be shown clearly on the design drawings for reinforced, precast and prestressed concrete works together with any other restrictions on materials or properties required. 1.7
MATERIALS AND WORKMANSHIP SPECIFICATION Attention is drawn to the obligation to review the Materials and Workmanship Specification. Attention shall be drawn to any provision of the Materials and Workmanship Specification which appears incompatible with the design basis, and appropriate modifications to the Materials and Workmanship Specification shall be proposed, and agreed with the Engineer. The Materials and Workmanship Specification should however be regarded as a minimum standard.
1.8
DIMENSIONS All dimensions given on the Authority’s Drawings or within the Authority’s documentation shall be taken to be minimum dimensions to be achieved on site after allowance for all construction tolerances, deflection of embedded walls, sagging of beams and floors, etc.
1.9
BLINDING Reinforced and/or prestressed concrete shall be cast against an adequate concrete blinding and not directly against the ground. The minimum concrete grade and thickness shall be C20 and 75mm respectively. The thickness and strength of blinding may need to be increased depending on the softness and irregularity of the ground and the thickness of the concrete pour. Where the ground beneath the blinding is to be removed at a later date (for example in top-down construction) a debonding membrane shall be used at the interface between the blinding and reinforced concrete. The blinding and membrane details shall be indicated on the design drawings.
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CHAPTER 2 MRT ALIGNMENT AND STRUCTURE GAUGE 2.1
INTRODUCTION The final alignment of the railway shall conform to the Design Criteria and shall take full account of the following:• • • • • • • • • • •
Operating requirements Signalling requirements Traction power requirements Rolling stock requirements Minimise traction power Minimise track maintenance Construction constraints and cost Minimise conflict with existing structures and utilities Geotechnical and tunnelling conditions Environmental conditions Land use considerations
The design shall be co-ordinated with all relevant designers, contractors and other authorities 2.2
HORIZONTAL ALIGNMENT
2.2.1
Definitions
2.2.1.1
Track gauge is the distance measured between the inside face of the two running rails at a point 14.1mm below the crown of the rails (gauge points). For heavy and medium rail systems track gauge shall be 1435mm.
2.2.1.2
Horizontal alignment – non-tunnel is the alignment based on a point midway between gauge points.
2.2.1.3
Horizontal alignment – in tunnel is the alignment based on a point on the track centre line at a height above the rail line co-incident with the centre of the train mass. (For definitions of rail line and track centre line see Clause 2.5.1.2)
2.2.1.4
Circular Curve is a curve of constant radius.
2.2.1.5
Compound Curve is a curve formed of two or more circular curves of differing radii curving in the same direction. The circular curves may or may not be linked by transition curves.
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2.2.1.6
Reverse Curve is a curve formed of two or more circular curves curving in alternate directions which may or may not be of the same radius and which may or may not be linked by transition curves. A reverse curve has no straight track between each circular curve but has abutting transition curves. For the purpose of the alignment, each part of a reverse curve shall be given a separate curve number.
2.2.1.7
Transition Curve is a curve of progressively varying radius used to link either a straight with a circular curve, or two circular curves of different radii.
2.2.1.8
Virtual Transition is a length over which a train car experiences a change from straight to circular curve when no transition curve occurs. Its length is equal to the spacing between the car’s bogies and is theoretically placed symmetrically about the tangent point.
2.2.1.9
Cant (Superelevation) is the vertical distance (in millimetres) by which one rail is raised above the other and measured between the crowns of the two running rails. Cant is positive when the outer rail on a curve is raised above the inner rail or negative when the inner rail is raised above the outer.
2.2.1.10
Equilibrium Cant is the cant required to enable a vehicle to negotiate a curve at a particular speed, known as the equilibrium speed, such that the resultant of the weight of the train and its centrifugal force is perpendicular to the plane of the rails.
2.2.1.11
Applied Cant in millimetres is the actual cant specified for the curve.
2.2.1.12
Cant Deficiency in millimetres is the amount by which the applied cant is less than the equilibrium cant for the speed being considered.
2.2.1.13
Excess Cant is the amount by which the applied cant is greater than the equilibrium cant for the speed being considered.
2.2.1.14
Cant Gradient expressed as a dimensionless ratio, is the gradient at which applied cant or cant deficiency is increased or reduced.
2.2.1.15
Rate of Change of Cant or of Cant Deficiency in millimetres per second is the rate at which cant or cant deficiency is increased or reduced relative to the speed of the vehicle.
2.2.1.16
Line Speed Limit (in km/h) is the maximum speed permitted for any train anywhere on the line.
2.2.1.17
Restricted Speed is the nominal maximum permissible speed for a section of track imposed by means of a permanent speed restriction and is determined by the comfort and safety condition criteria.
2.2.1.18
Design Speed at a particular point on the track is the average speed of the train at that point under average running conditions calculated from
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the coasting run speed profiles prepared by the signalling or rolling stock designer. 2.2.1.19
Flatout speed at a particular point on the track is the average speed of the train at that point using maximum accelerating and braking capacities on a run between two adjacent stations and is calculated from the flatout speed profiles prepared by the signalling or rolling stock designer.
2.2.1.20
Shift is the amount by which the centre of radius of a circular curve needs to move due to the placement of transition curves.
2.2.2
Horizontal Curves
2.2.2.1
The limits for radii for horizontal circular curves are shown below.
Mainline
Depot, Temporary & non - passenger Tracks
Absolute Minimum
Preferred Minimum
Absolute Minimum
Heavy Rail system
400m
500m
190m
Medium Rail system
300m
400m
190m
For light rail systems refer to the manufacturer’s recommendations. 2.2.2.2
The track shall preferably be straight throughout the length of stations. The presence of external constraints may necessitate limited encroachment of curves at station ends.
2.2.2.3
Track through platforms shall be straight. Transitions shall normally be positioned so as to avoid horizontal throw (see Clause 2.5.1.4) affecting platform nosing clearance. Where encroachment is unavoidable, this shall be limited such that the combined effects of vehicle throw and cant do not affect the location of the nosing at platform ends by more than 20 mm when compared to straight track.
2.2.2.4
Circular curve radii shall be selected to be the maximum practicable. The radius selected for any particular curve shall not be so large as to unnecessarily impose more severe curvature of the track at either end of that curve.
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2.2.2.5
The combination of circular curve and their related transition curves shall be chosen such that the length of pure circular arc between transitions is not less than the following: Preferred minimum Desirable minimum Absolute minimum
2.2.2.6
50 metres 25 metres 17 metres
For any two consecutive circular curves with the same direction of curvature, the length of straight track between the ends of the curves or of the transitions where these are required shall not be less than the following: Preferred minimum Desirable minimum Absolute minimum
50 metres 25 metres 17 metres
2.2.2.7
For any two consecutive circular curves with opposite direction of curvature other than reverse curves, the length of straight track between the ends of the curves or of the transitions where these are required shall not be less than the values given in Clause 2.2.2.6 above.
2.2.3
Cant and Speed
2.2.3.1
The curve-speed-cant relationship shall be based on the following equations :-
²
11.82 Ve Equilibrium cant E = ------------R
_________ Maximum permissible speed Vm = 0.29 √ R (Ea + D) where R = horizontal curve radius in metres Vm = maximum permissible speed in kilometres per hour Ve = equilibrium speed in kilometres per hour E
= equilibrium cant in millimetres
Ea = actual applied cant in millimetres D = maximum allowable deficiency of cant in millimetres Formulae are only applicable for a track gauge of 1435mm.
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2.2.3.2
The maximum allowable applied cant shall be: Absolute Maximum For concrete track For ballasted track
2.2.3.3
150mm 125mm
Desirable Maximum 125mm 110mm
The amount of cant deficiency or excess cant at any point on the line shall be limited to the following :Plain Line Desirable Maximum
90mm for comfort conditions
Absolute Maximum
100mm for comfort conditions
Maximum deficiency for trains not carrying passengers
230mm for safety conditions
Turnouts Maximum Maximum deficiency for trains not carrying passengers
90mm for comfort conditions 125mm for safety conditions
2.2.3.4
Cant shall be selected to suit the design speed (typically 70% of equilibrium cant). Cant deficiency shall be checked against flatout speed to suit comfort condition criteria and cant shall be adjusted upwards as necessary. Consideration for both cant and cant deficiency shall also take into account the requirements of Clauses 2.2.4.3. and 2.2.4.4
2.2.3.5
Where constraints on the alignment design are such that the requirements of Clause 2.2.3.4 cannot be met, a permanent speed restriction shall be imposed. Such restrictions shall be minimised as far as practicable.
2.2.3.6
Permanent speed restrictions shall also be imposed as necessary to prevent a train at line speed limit breaching the safety condition criteria.
2.2.3.7
Suitable cant values shall be estimated during the preliminary design. The cant shall be finally selected from a consideration of the design speed and flatout speed.
2.2.3.8
Applied cant shall be specified to the nearest millimetre for concrete track and to the nearest 5 mm for ballasted track.
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2.2.4
Transition Curves
2.2.4.1
In general for all mainline track, transition curves shall be provided wherever possible between a circular curve and adjoining straight track, between the different radii of a compound curves and at the adjoining ends of circular curves forming reverse curves.
2.2.4.2
Transition curves shall be clothoids.
2.2.4.3
The cant gradient (not cant deficiency) shall be subject to the following limits:Absolute maximum = 1 : 500 Preferred = 1 : 750 Minimum = 1 : 1000
2.2.4.4
The rate of change of cant or cant deficiency shall be limited as follows:Plain Line Desirable maximum
= 35mm/sec for comfort conditions.
Absolute maximum
= 55mm/sec for comfort conditions.
Maximum for trains not carrying passengers.
= 125mm/sec for safety conditions.
Turnouts Absolute maximum
= 80mm/sec for comfort conditions.
Maximum for trains not carrying passengers.
= 125mm/sec for safety conditions.
2.2.4.5.
In cases where the design speed of the train on part or all of a curve is considerably less than the line speed limit, it may be necessary to impose a permanent speed restriction to ensure that any excess cant at the design speed is kept to a practical minimum.
2.2.4.6
Transition curves will not normally be required between the different radii of a compound curve where the change of radius of curvature does not exceed 15% of the smaller radius. Change in cant is applied over an effective transition length centred on the point where radii change and of a length to satisfy the requirement of Clause 2.2.4.4 or car bogie centres whichever is greater .
2.2.4.7
Where a compound circular curve is employed with a change of radius greater than 15% of the smaller radius, a transition curve shall be interposed between the two parts of the curve. The length of such a
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transition shall be equal to the difference between the required transition lengths at each end of the curve. 2.2.4.8
When the shift of any calculated transition curve would be less than 10 mm, the actual transition curve may be omitted. In this case, the required change of cant shall be applied over a length to satisfy the requirement of Clause 2.2.4.4 or car bogie centres whichever is the greater, and in the same location as if the transition had been provided.
2.2.4.9
The length of transition curves shall wherever possible be based on the preferred cant gradient in accordance with Clause 2.2.4.3 above. In cases where it is necessary to exceed the preferred cant gradient, the rate of change of cant shall be limited in accordance with Clause 2.2.4.4 above.
2.2.4.10
Transitions between reverse curves shall wherever practicable have the same cant gradient for both transitions.
2.2.5
Chainages
2.2.5.1
The datum of chainages for new lines will be provided by the Authority.
2.2.5.2
Chainages shall be quoted in metres correct to four decimal places and shall be measured along the centre line of each individual track in plan with no correction for differences in elevation.
2.2.5.3
Initially a nominal 10m jump in chainage shall be provided on each track at each station centre line. Subsequent alignment revisions that results in changes to chainages shall be reflected by revising the jumps. The chainage at Contract boundaries shall not be changed.
2.2.6
Co-ordinates
2.2.6.1
Calculations for the setting out of the horizontal alignment for each track shall be based on co-ordinates of horizontal intersection points of the nominal track centre line.
2.2.6.2
Co-ordinates shall be quoted in metres correct to four places of decimals. Horizontal curve radii shall be quoted in metres correct to three places of decimals and shall be the actual required radii after shift has been taken into account. Deflection angles shall be quoted in degrees to the nearest one-tenth of a second.
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2.3
VERTICAL ALIGNMENT
2.3.1
Vertical Curves
2.3.1.1
Ideally vertical curves shall be positioned such that coincidence with horizontal curves and, in particular with horizontal transitions is avoided. Where such coincidence is necessary, the maximum desirable practicable vertical curve radius shall be employed except at station ends where a hump profile is used where a radius of 1600m shall be selected.
2.3.1.2
Vertical curves shall for each location be selected on the basis of the most suitable radius of the following: 3000 m radius (maximum desirable radius) 2500 m radius (preferred radius) 2000 m radius 1600 m radius (minimum allowable radius)
2.3.1.3
The length of the constant grade between consecutive vertical curves shall be as follows: Desirable minimum Absolute minimum
50 m 25 m
2.3.1.4
At switches and crossings, vertical curves shall not coincide with any part of the overall length of switches or crossings. In other areas of turnouts, vertical curves shall be avoided whenever possible. Where they cannot be avoided, the vertical curve radius shall be the maximum in accordance with Clause 2.3.1.2 above.
2.3.1.5
At station ends where vertical curves are provided in conjunction with acceleration/deceleration gradients, the tangent point of the vertical curve may be permitted only under severe constraints of the alignment to encroach within the length of the platform to a limited extent. This length of encroachment shall be such that the vertical offset of the curve from the station gradient at the platform end shall not exceed 15 mm.
2.3.2
Gradients
2.3.2.1
The maximum gradients are shown below. Down-hill Gradient
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Up-hill Gradient
Heavy Rail system
3%
2.5%
Medium Rail system
3%
3%
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For light rail systems maximum gradients shall be in accordance with the manufacturer’s recommendations. 2.3.2.2
At stations, the track shall be level throughout the platform length except for the limited lengths of vertical curves as specified in Clause 2.3.1.5 above.
2.3.2.3
A drainage gradient shall be provided for all underground tracks, other than at platforms and sidings, as follows: Desirable minimum 0.5% Absolute minimum 0.25% circumstances only)
(to
be
used
in
exceptional
2.3.2.4
On ballasted track, level tracks may be employed provided drainage is catered for below the ballast.
2.3.2.5
Siding tracks should either slope 0.25% towards the buffers, or be level.
2.3.2.6
Where practicable within the bored sections of tunnels, acceleration/deceleration gradients shall be provided in the form of a hump profile between stations. The nominal value of the hump shall be 8 m but no more than 10m. Where tunnels are constructed by cut-andcover methods, hump profiles need not be employed.
2.3.3
Levels
2.3.3.1
All levels shall be quoted in metres correct to four decimal places and referred to Project Datum.
2.3.3.2
Rail level on superelevated ballasted track refers to the level at the crown of the lower rail.
2.3.3.3
Rail level on superelevated concrete slab track refers to the mid point between the two running rails and is unaffected by the application of cant.
2.4
TURNOUTS AND CROSSOVERS (for heavy and medium rail systems only)
2.4.1
Turnouts
2.4.1.1
Turnouts shall comply with recognised international design practices and geometries.
2.4.1.2
Turnouts shall not coincide with transition curves. Turnouts should be avoided where possible on horizontal curves.
2.4.1.3
A minimum speed limit of 55 km/h shall be allowed for through turnouts where regular passenger trains would normally operate.
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2.4.1.4 2.4.1.5
Drawings should state co-ordinates of the intersection point of turnouts and the chainage of beginning (BC point) and end of turnout. The minimum radii of curves within turnouts shall be 190m.
2.4.2
Closure Rails Distance between adjacent turnouts shall be designed to consider factors such as electrical problems (third rail gapping), signalling future maintenance issues and track stability. As a guide, the minimum length of closure rails between adjacent turnouts on the same track are as follows: -
Turnouts switch toe to switch toe (BC to BC)
Turnout following another turnout (End of turnout to BC of next turnout)
Desirable minimum
Absolute minimum
Desirable minimum
Absolute minimum
21m*
4.9m
9.1m
4.9m
* Applicable only to third rail systems Note: BC = Geometrical tangent point (Beginning of curve) End of turnout is defined as the location where the minimum dimension (shown below) between the gauge points of the diverging crossing legs is achieved. 1:7.5 - 190m Radius
500mm
1:9 - 190m Radius
420mm
1:9 - 300m Radius
420mm
1:12 - 500m Radius
380mm
1:14 - 500m Radius
350mm
2.4.3
Diamond Crossings
2.4.3.1
Diamond crossings shall be avoided unless deemed necessary.
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2.5
STRUCTURE GAUGE AND CLEARANCES
2.5.1
Definitions
2.5.1.1
The normal co-ordinated axes of a vehicle are defined as those orthogonal axes, normal to the longitudinal centre line of the vehicle, where one axis called the wheel line is the line connecting the points of bearing of pairs of wheels on the rails and the second, perpendicular to the first, called the vehicle centre line, is central between the wheels.
2.5.1.2
The normal co-ordinated axes of the track are defined as those orthogonal axes, normal to the longitudinal centre line of the track, where one axis, called the rail line is the common tangent to the tops of the rails and the second perpendicular to the first, called the track centre line, is central between the rails.
2.5.1.3
The static load gauge is defined as the profile related to the theoretical normal co-ordinated axes of the passenger vehicle outside which no part of the vehicle shall protrude when the vehicle is stationary and unloaded and when all play in the axles and suspension are uniformly distributed either side. Building tolerances for the vehicle are included in the static load gauge.
2.5.1.4
Horizontal throw is the distance measured parallel to the rail line of the vehicle centre line from the track centre line when a vehicle is on a horizontal curved track, and all play in the axles and suspension are uniformly distributed either side. Horizontal throw reaches (arithmetic) maximum midway between bogies and at the ends of the vehicle. These throws are called centre throw and end throw respectively.
2.5.1.5
Vertical throw is defined in a similar manner when a vehicle is on vertically curved track.
2.5.1.6
The Kinematic Load Gauge is defined as the vehicle profile related to the designed normal co-ordinated axes of the vehicle which covers the maximum possible distances from the vehicle centre line to any part of the vehicle taking into account the most unfavourable positions for running, including tolerances and wear
2.5.1.7
The Kinematic Envelope is defined as the profile related to the designed normal co-ordinated axes of the track which covers the maximum possible distances from the track of any part of the vehicle taking into account the most unfavourable positions for running, including tolerances and wear of the track. When enlarged horizontally and vertically on curved track to allow for throw, it is referred to as the Swept Envelope.
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2.5.1.8
The Structure Gauge is defined as the profile related to the designed normal co-ordinated axes of the track into which no part of any structure or fixed equipment may penetrate, taking into account all deformations and movements.
2.5.1.9
The Service Vehicle Load Gauge is the Kinematic Load Gauge for those rail vehicles used for construction and maintenance
2.5.1.10
The Construction Gauge is the structure gauge, which shall apply during construction until the time that trial running commences.
2.5.2
Train and Track Vehicles
2.5.2.1
All rail vehicles used for construction and maintenance will conform to the service vehicle load and shall not influence the design of the civil works.
2.5.3
Structure Gauge
2.5.3.1
The Structure Gauge shall be based upon the Kinematic Envelope in such a way that each point on the perimeter of the Kinematic Envelope is enlarged vertically upwards by 50mm and horizontally by 100mm (two points to be constructed for each point on the Kinematic Envelope). The Structure Gauge is the largest envelope based on the points constructed as described above. Below the vehicle, the Kinematic Envelope is enlarged by 15mm to form the lower limit of the Structure Gauge. The shortest distance between the Kinematic Envelope and the Structure Gauge at any point is the Clearance at that point.
2.5.3.2
Special provisions will be made to permit the intrusion of the platform nosing, the platform screen doors and platform edge columns into the Structure Gauge.
2.5.3.3
The Structure Gauge for curved track shall in all cases include an allowance for the maximum vehicle throw, both horizontal and vertical at the location being considered in accordance with Clause 2.5.4.1.
2.5.4
Throw
2.5.4.1
Horizontal throw can take the form of either centre throw or end throw. They are inversely proportional to the curve radius. When a vehicle is fully on a circular curve throw may be calculated from the formulae.
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Centre throw (mm) =
B2 103 8R
End throw (mm) =
(T2-B2 )103 8R
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B= Distance between bogie centres (metres) R= Radius in metres T= Overall length of vehicle (metres) 2.5.4.2
On circular curves, throw may be calculated in accordance with Clause 2.5.4.1 above. On transitions and on straight track adjacent to transitions, throw shall be calculated based on the vehicle characteristics. A “swept envelope” method may be employed.
2.5.4.3
An allowance shall be made for horizontal throw throughout the length of points and crossing and on the straight track adjacent to these areas. Similarly a “swept envelope” method may be employed.
2.5.5
Clearance to Structure Gauge
2.5.5.1
All structure and equipment shall be designed to be clear of the Structure Gauge with adequate allowance made to take into account all tolerances of construction and fixing, and for all deflections and displacements.
2.5.5.2
All moveable equipment, hinged doors, windows, etc close to the track shall be positioned so that they are not within the Structure Gauge at every position of movement. All covers to sumps, pits, etc within the track slab shall not infringe the Structure Gauge when in the open position.
2.5.5.3
Where two tracks are side-by-side with each track capable, within the constraints of the signalling system, of passing trains at the same time, the minimum clearance between the two tracks shall be such that the Structure Gauges do not overlap.
2.5.6
Clearances at Platform Edge
2.5.6.1
Alongside the station platform limited intrusion into the Structure Gauge of the platform edge, platform edge columns and screen doors is permitted; see Structure Gauge Drawing.
2.5.6.2
The platform edge shall be set such that 75mm clearance is provided horizontally between the static load gauge and the platform edge. Where a curved and/or canted track is less than 20 m from the platform, the platform edge distance shall be increased to account for effect of cant and throw. The distance shall be calculated precisely, for the worst position of the train.
2.5.6.3
The screen doors shall be set at a distance of 115mm (+10 - 0 mm) from the static load gauge.
2.5.6.4
Intrusions into the Structure Gauge permitted in Clause 2.5.6.1 shall extend no further than the section of the station platform within the length of a train stopped in the centre of the platform.
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2.5.6.5
Passageway and staircases beyond the platform and end barriers near ends of platform shall be designed to be clear of Structure Gauge.
2.5.6.6
Alongside depot platforms, intrusions into the Structure Gauge are also permitted. The platform edge shall be set at 115mm (+20 - 0 mm) from the static load gauge where the curved track is at least 20 m beyond the platform.
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CHAPTER 3 LOADS 3.1
GENERAL Loads shall be determined from The Building Control Regulations 4th Schedule, BD 37/88 (see Design Criteria clause 1.2.2) and BS 6399 except where stated otherwise in this Chapter. In any circumstances where there is a discrepancy between the relevant standards and regulations the more onerous shall apply. The following loads and effects shall be considered in the design of all structures: (a) (b) (c) (d) (e) (f) (g) (h) (i) (j) (k) (l) (m) (n)
Dead Load Superimposed dead load Load from adjacent building foundations or other structures Surcharge load Live load (primary and secondary) or imposed load Earth Pressure Hydrostatic Pressure Temperature effects Effects of shrinkage and creep in concrete Erection forces and effects Differential settlement Wind Load Collision Load Any other forces and effects arising out of the special nature of any structure
This Chapter specifies the general loading requirements. For loading requirements specific to the type of structure being designed reference shall be made to the relevant Chapter. The loads given in these Design Criteria shall be treated as unfactored (nominal or characteristic) loads for design purposes unless specifically noted otherwise (Therefore partial safety factors shall be applied in accordance with the limit state methods of the relevant standard, for example BS 5400, SS CP 65, etc.). All unfactored (nominal or characteristic) live loads, imposed loads and superimposed dead loads shall be shown clearly on a comprehensive set of loading plans.
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3.2
LOADS FROM RAILWAY VEHICLES
3.2.1
General
3.2.1.1
MRT Notwithstanding the particular rolling stock to be used, the design live loading from MRT railway vehicles shall be not less than that as determined in accordance with BS 5400 Part 2 for RL loading, or such other loading as specified in the Particular Specification. Dynamic effects shall be allowed for in accordance with BS 5400 Part 2 unless indicated otherwise in the Particular Specification.
3.2.1.2
LRT The design live loading from LRT vehicles, unless indicated otherwise in the Particular Specification, shall be not less than the larger of the actual system requirement or one half of RL loading determined in accordance with BS 5400 Part 2. Dynamic effects shall be allowed for in accordance with BS 5400 Part 2 unless indicated otherwise in the Particular Specification.
3.2.2
Design for Protection of Structures against the Effects of Derailment
3.2.2.1
General Considerations The following design requirements apply to the supporting structures for new bridges or new buildings and any new structure carrying hazardous materials (e.g. gas) constructed over or alongside railway tracks. They do not apply to lineside railway infrastructure such as overhead line masts or signal gantries. Wherever possible, supports carrying any structure over or alongside railway tracks should be placed outside the “danger zone” (see below for definition). Where supports must be placed inside the danger zone they should preferably be monolithic piers rather than individual columns. Columns and piers located within embankments, or at the bottom of embankments, may require special consideration even if outside the danger zone because of the possibility of derailed vehicles rolling down the embankment (See Figure 3.2.2.1-A below). If it is not possible to arrange the design to avoid the situation then special measures will be necessary to safeguard such columns and piers. Consideration shall be given to the following: (a) (b) (c)
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DC/3/3
Danger Zone 5250mm
Track
5250mm
Columns Located Outside Danger Zone
Embankment Bottom of Embankment
Figure 3.2.2.1-A
Where isolated columns are used within the danger zone a solid ‘deflector’ plinth shall be provided to a minimum height of 900mm above the rail level or 1200mm above ground level whichever is the higher. The height of the plinth shall be constant and the ends of the plinth shall be suitably shaped in plan to deflect derailed vehicles away from the columns (See Figure 3.2.2.1-B below for typical plinth detail). For individual columns within station areas a solid platform construction shall be used to provide similar protection from derailed vehicles.
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Figure 3.2.2.1-B
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Where, exceptionally, the use of ground anchors are accepted as part of the Permanent Works by the Engineer and where they are situated within the danger zone, special measures shall be taken to protect the anchorages from potential damage by derailed vehicles. 3.2.2.2
Definition of “danger zone”
“danger zone” Non-Platform Side
Track Centreline
Within tunnels the danger zone is considered to be bounded by the tunnel walls. At stations, it is bounded on the platform side(s) by the platform structure below platform slab level, and above platform slab level by a zone up to 2500mm from track centre-line; at non-platform locations it is bounded by the nearest continuous wall or 5250mm from track centre-line whichever is less. See Figure 3.2.2.2-A below.
Nearest Continuous Wall (where applicable)
5250mm ( If there is no continuous wall within 5250mm from track centreline )
“danger zone” Platform Side
2500mm
Platform Slab Level Platform Structure
Figure 3.2.2.2-A “danger zone” within stations
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Within the Depot and outside of any tunnels or stations the danger zone is to be taken as 5250mm from track centre-line. See Figure 3.2.2.2-B below.
Rails 5250mm
Track 5250mm 5250mm Extent of Danger Zone 5250mm
PLAN VIEW
Figure 3.2.2.2-B “danger zone” within depot and outside of tunnels 3.2.2.3
Design for Train Impacts When the face of a loadbearing element lies outside or does not define the boundary of the danger zone, no special provisions apply. To provide robustness against the effects of light train impacts, all piers, columns or walls, whose nearest face defines the boundary of, or lies within, the danger zone, shall be designed to withstand two point loads without collapse. A single horizontal ultimate design load of P1 kN acting at a height of up to H1 mm above trackbed (or ground) level, and a single horizontal ultimate design load of P2 kN acting at a height of between H1 mm and H2 mm above trackbed (or ground) level. The two point loads need not be considered to act simultaneously. For designs to BS 5400, γf3 shall be applied in accordance with the code requirements. Within tunnels and underground stations, the two point loads can act in a direction parallel to or up to D1 degrees from the direction of the adjacent track. At crossovers within tunnels, the direction of the load within 1 metre of the ends of dividing walls is parallel to or up to D2 degrees from the direction of the adjacent main-line track. Within the Depot and outside of the tunnels, the two point loads can act in any direction, and the design shall cater for the most adverse direction(s). Refer to Appendix 1 of this Chapter for the values of P1, P2, H1, H2, D1 and D2.
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The above impact loads shall be considered in combination with permanent loads together with appropriate live loads (where inclusion of live load is more critical) as defined below: (a) Structures Designed to SS CP 65 or BS 5950 Irrespective of the number of storeys, structures designed to SS CP 65 or BS 5950 shall be checked in accordance with the requirements of those codes for the effects of exceptional loads or localised damage (refer SS CP 65 Clauses 2.4.3.2 and 2.4.4.2, or BS 5950 Clause 2.4.5.4 etc) (b) Structures Designed to BS 5400 Structures designed to BS 5400 shall be checked for this purpose in accordance with United Kingdom Highways Agency Departmental Standard BD 60/94 using the ultimate loads (equivalent to the partial load factor (γfL) multiplied by the nominal impact load) given in Appendix 1 of this Chapter. γf3 shall be applied in accordance with the code requirements. 3.2.2.4
Disproportionate Collapse For all buildings irrespective of the number of storeys, all loadbearing elements, whose nearest face defines the boundary of, or lies within the danger zone, shall be detailed in accordance with SS CP 65 Clause 2.2.2.2 including the provision of vertical ties, or BS 5950 Clause 2.4.5.3, as appropriate. For the purposes of this clause each level of a station shall count as one storey. Structures whose nearest face defines the boundary of, or lies within, the danger zone shall be designed as follows: (a) Where individual columns are used within the danger zone, the design of the structure above them shall incorporate such continuity that the removal of any one column will not lead to the collapse of more than a limited portion of the structure close to the element in question under permanent loads, together with the appropriate live loads. (b) Where however the load bearing element is required to act as a key element defined for the purposes of this clause as one whose removal would cause the collapse of more than a limited portion of the structure close to the element in question, the following shall apply: (i)
Tunnels and underground stations The key element shall be designed for a horizontal ultimate design load of P3 at a height of H3 above adjacent
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Table 5/4 - Summary of Soil and Groundwater Properties SOIL MATERIAL
Total Sulphates (% SO3)
Sulphates SO3 parts per 100,000
2.8
0.01
9
20
7.95
0.01
4
1
2.8
2.8
0
9
8.0
4.9
11
9
640
1
33
6
4500
65
Marine Clay (M)
57
8.8
3.4
7
48
1.59
0.4
4
8
4.3
0.02
0
8
3.9
0.26
38
15
11
6.8
0
15
85
1
0
11
9050
20
Fluvial Sand (F1)
5
7.4
5.1
0
-
-
-
-
4
0.08
0.02
0
1
2.3
2.3
0
6
7.7
6.0
0
6
29
1
0
5
376
14
6 6 1 0 0
Fluvial Clay (F2)
9
7.7
4.3
55
4
0.23
0.02
0
2
0.09
0.02
0
3
1.2
0.8
0
1
6.7
6.7
0
1
85
85
1
-
-
-
-
Jurong Formation (S/S3)
23
8.4
3.2
13
19
0.76
0
0
4
6.8
0.01
25
-
-
-
-
34
8.5
4.3
9
40
26
1
0
32
18,200
6
2 2
Bukit Timah Formation (G)
42
8.9
3.9
17
1.9
0.16
0
0
18
0.15
0.01
0
3
2.79
0.2
0
24
5.1
4.0
4
25
230
1
0
22
222
6
0
Max. Value
Min. Value
Max. Value
Min. Value
Max. Value
Min. Value
Number of Samples
Max. Value
Min. Value
Max. Value
Min. Value
Max. Value
Min. Value
Note 1: Due to sampling difficulties during the initial investigation groundwater samples are indicative only of the properties of the groundwater in the region of the borehole and these have been assigned to the predominant ground type. Note 2: Classification system makes no allowance for any concentration factors. Note 3: High Chloride concentrations and low resistivity of groundwaters were associated with local areas. Note 4: Low pH values may have been influenced by aerobic bacterial activity.
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% in Class 4 or 5
22
% in Class 4 or 5 Number of Samples
79
% in Class 4 or 5 Number of Samples
2.2
% in Class 4 or 5
7.7
% in Class 4 or 5 Number of Samples
39
% in Class 4 or 5 Number of Samples
Estuarine Clay (E)
Number of Samples
Chlorides, ppm
% in Class 4 or 5
pH
Min. Value
SO3 in 2:1 Extract (g/l)
Max. Value
SO3 in 1:1 Extract (g/l)
Number of Samples
pH
GROUNDWATER
DC/3/8
trackbed level (or ground level as appropriate). For designs to BS 5400, γf3 shall be applied in accordance with the code requirements. Within tunnels and underground stations, the point load can act in a direction parallel to or up to D1 degrees from the direction of the adjacent track. At crossovers within tunnels, the direction of the load within 1 metre of the ends of dividing walls is parallel to or up to D2 degrees from the direction of the adjacent main-line track. Refer to Appendix 1 of this Chapter for values of P3 and H3. The structures shall be checked for these loads in the same way as for loads P1 and P2 in clause 3.2.2.3 above. (ii)
Depot Alongside test track: (iii) below applies. Elsewhere at the Depot: provided train speeds are low (typically less than 20 kph) in the Depot, the design to clause 3.2.2.3 above constitutes a design as a key element. Otherwise (iii) below applies.
(iii)
Other Areas (e.g. Viaducts and At-Grade Structures) The key element shall be designed for a horizontal ultimate design load of P3 at a height of H3 above adjacent trackbed level (or ground level as appropriate). For designs to BS 5400, γf3 shall be applied in accordance with the code requirements. Within the Depot and outside of the tunnels, the point load can act in any direction, and the design shall cater for the most adverse direction(s). Refer to Appendix 1 of this Chapter for values of P3 and H3. The structures shall be checked for these loads in the same way as for loads P1 and P2 in clause 3.2.2.3 above.
3.3
LOADS FROM ROAD VEHICLES
3.3.1
General Vehicular live loads shall comply with BD 37/88 except where modified below:
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3.3.1.1
Carriageway (replaces BD 37/88 Clause 3.2.9.1) The definition of carriageway in Clause 3.2.9.1 of BD 37/88 shall be replaced by the following: ‘For the purposes of this standard, that part of the running surface which includes all traffic lanes, hard shoulders, hard strips and marker strips. The carriageway width is the width between parapets. The carriageway width shall be measured in a direction at right angle to the line of parapets, lane marks or edge marking.’
3.3.1.2
Vehicular Live Loads (modifies BD 37/88 Clause 6) Vehicular live loads shall comply with the requirements of Clause 6 of BD 37/88, subject to the following modifications: (a)
For HA Uniformly Distributed Load (UDL) a factor of 1.2 shall be applied to the uniformly distributed load specified in BD 37/88 Clause 6.2.1 as given below: (i)
For loaded lengths from 2 metres up to and including 50 metres W = 1.2x336 (1/L)0.67
(ii)
For loaded lengths in excess of 50 metres but less than 500 metres. W = 1.2x36 (1/L)0.1 Where L is the loaded length in metres and W is the load per metre of notional lane in kN. Table 13 of BD 37/88 is accordingly superseded by the above.
(iii)
For loaded lengths above 500 metres, the UDL shall be agreed with the Engineer.
(iv)
HA lane factors: Type HA UDL and Knife Edge Load shall be multiplied by the appropriate lane factors as follows: For application of type HA UDL and KEL, at least two lanes shall have a lane factor of 1.0 and the other lanes shall have lane factors of 0.6. Table 14 in BD 37/88 is accordingly superseded by the above.
(b)
HA Wheel Load
In addition to the single wheel load of 100 kN specified in BD 37/88 Clause 6.2.5, a separate load case of 2 nos. of 120 kN wheel loads Sept 2002
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placed transversely, 2m apart, shall also be considered in the design for local effects. (c)
HA Longitudinal Traction or Braking force
The nominal HA longitudinal traction and braking force shall be 10 kN/m applied to an area one notional lane wide multiplied by the loaded length plus 200 kN, subject to a maximum of 800 kN. (d)
HB Loading
All structures shall be designed for 45 units of HB loading (180 T). However, the HB loading shall be restricted to the centre 5m strip of the carriageway with all other lanes closed to traffic except for the following cases: (i)
45 units of HB is free to travel anywhere between the parapets along the slip roads or loops of the interchange or flyover with no other associated loadings on the structure.
(ii)
45 units of HB is free to travel anywhere between the parapets for 80 metres of the main structure prior to the approach to the slip road or loop with no other associated loading on the structure.
All structures shall also be designed for 30 units of HB loading (120T) in co-existence with the relevant HA loadings. The application of loading shall be in accordance with BD 37/88 Clause 6.4.2. Where two separate carriageways are supported on one structure, only one number of 45 units of HB loading needs to be considered at any one time. Type HA loading shall be applied to the other carriageway if the resultant load case is more onerous. (e)
Collision Loads (i) Road and railway bridge and viaduct structures: The minimum height clearance of any structure above all roads shall be 5.4 metres. However, any structure having a clear height less than 5.7 metres shall be designed for collision loads on superstructures in accordance with the requirements of the United Kingdom Highways Agency Departmental Standard BD 60/94. Substructural elements, such as columns, situated within the Road Reserve or less than 4.5m from the edge of the carriageway shall be designed to withstand vehicle collision loads as specified in BD 60/94. The collision load shall be considered even if there is provision of single or double vehicular impact guard rails to these
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elements or even when there is no vehicular access to column positions. (ii)
Pedestrians Overhead Bridges: The minimum height clearance of any structure above all roads shall be 5.4 metres. However, any structure having a clear height less than 5.7 metres shall be designed for collision loads on superstructures as follows: •
For bridge spans over expressways or semiexpressways, collision loads shall be in accordance with BD 60/94.
•
For bridge spans over roadways other than expressways or semi-expressways, collision loads shall be in accordance with BD 37/88 Clause 6.8.
Where Pedestrian Overhead Bridge piers are located less than 4.5m from the edge of expressway or semiexpressway carriageways, they shall be designed for collision loads on supports in accordance with BD 60/94. Where Pedestrian Overhead Bridge piers are located less than 4.5m from the edge of other roadway carriageways, they shall be designed for collision loads on supports in accordance with BD 37/88 Clause 6.8. BD 37/88 Clause 7.2 shall not be used. The collision loads on bridge support structures shall be considered even if double vehicular impact guardrails are provided to these elements. 3.3.1.3
Sept 2002
Pedestrian Bridge Loads (a)
Pedestrian Live Load (Modifies BD 37/88 Clause 7.1.1) The nominal pedestrian live load shall be 5kN/m2 unless otherwise stated.
(b)
Live load for roof structures Minimum provision of nominal live load of 0.5kN/m2 shall be provided for roof structures or future installation of roof structures over pedestrian bridges.
(c)
Dead load for roof structures Minimum provision of nominal dead load of 1.0kN/m2 shall be provided for roof structure or future installation of roof structures over pedestrian bridges.
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3.3.2
Loads on Underground Structures
3.3.2.1
Under roadways, structures shall be designed to resist the following vehicular live loads: (a)
(b)
Vehicular live load and partial surcharge as derived from the following as appropriate: (i)
For depths of cover less than or equal to 600mm above top of structural roof slab level, full vehicular live loads as specified in Clause 3.3.1 above in conjunction with a uniformly distributed load of 5kN/m2.
(ii)
For depths of cover above top of structural roof slab in excess of 600mm, the more critical of: • HA wheel load and HB loading (as specified in Clause 3.3.1 above and modified in Clauses 3.3.2.3 and 3.3.2.4 below) in conjunction with a uniformly distributed load of 5kN/m2. • HB loading (as specified in Clause 3.3.1 above and modified in Clauses 3.3.2.3 and 3.3.2.4 below) in conjunction with a uniformly distributed load of 5kN/m2. • HA wheel load in conjunction with a uniformly distributed load of 5kN/m2.
Surcharge load as specified in Clause 3.4. No other loads from road vehicles need to be applied with this surcharge.
These loads shall be placed anywhere above, straddling or to the side of the structure to the extent that will give the most onerous load effect for the element of structure under consideration. 3.3.2.2
In the case of Underground Structures serving road vehicles (e.g. Vehicular underpass), vehicular live loads inside and on top of the vehicular underpass shall be assumed to co-exist with the exception that only one type HB loading will be considered for any given loading combination.
3.3.2.3
Application of the HB vehicles shall be as follows: Only 45 units of type HB loading shall be considered for design of Underground Structures. The 45 units of type HB loading shall be placed anywhere inside or on top of the vehicular underpass with co-existing HA loading on that carriageway, where more onerous. HA loading shall be applied on all the other carriageways simultaneously, where more onerous.
3.3.2.4
Sept 2002
Dispersal of loads: (a) The HA Knife Edge Load may be dispersed through the surfacing
Civil Design Criteria – Revision A4
DC/3/13
and fill from the depth of 200mm below the finished road level at 1 horizontally to 2 vertically to the top of the structural slab of Underground Structures. (b)
3.3.3
Wheel loads may be dispersed through the surfacing and fill from the finished road level at 1 horizontally to 2 vertically to the top of the structural slab of the Underground Structures.
Load On Temporary Works including Temporary Decking The design loading for temporary decking shall be the most onerous of the following: (a)
HA Loading as given in BD 37/88. The 20% increase in HA uniformly distributed loading specified in Clause 3.3.1.2(a) is not required.
(b)
25 units of Type HB loading
(c)
Loading from construction vehicles. Any limits on construction vehicle loading shall be clearly indicated on the Temporary Works drawings.
No reduction in load factors or material factors shall be used. 3.4
SURCHARGE LOADS
3.4.1
For all structures in locations where loads from road or rail vehicles do not apply, a live load surcharge as given below applied at finished ground level (existing or proposed ground level, whichever is higher) shall be allowed for in the design unless indicated otherwise in the Particular Specification. No additional live load needs to be applied. The loading shall be applied above, straddling or to the side of the structure to the extent that will give the most onerous effect for the structural element under consideration. (a)
Temporary Works including Retaining Walls in the Temporary condition
20.0 kN/m2
(b)
Bored Tunnels
75.0 kN/m2
(c)
All other structures
25.0 kN/m2
3.4.2
Where loads from road or rail vehicles do apply, the total loading shall be not less than the loading in 3.4.1 above.
3.4.3
For structures influenced by load imposed from nearby building foundations or other structures, the self weight of the existing structure
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with appropriate allowance for live load shall be applied as a surcharge at the foundation level of the building. The design loads shall generally be assumed to be those for which the adjacent structure was designed; but, in the absence of this information, the actual weights and imposed loads determined from the most onerous occupancy class for which the building is suitable shall be used. Where the effect of this load is less than the surcharge given in Clause 3.4.1 above, Clause 3.4.1 requirements shall govern the design. 3.4.4
Any known future works by others which may increase the loads on the structure shall be taken into account (e.g. earth filling in flood prone areas, reclamation works etc.) selectively.
3.5
SOIL AND WATER LOADS
3.5.1
Soil Unit Weights and Earth Pressure Coefficients
3.5.1.1
Refer to Chapter 5 for the bulk densities to be used for the various types of soil.
3.5.1.2
Refer to Chapters 5, 6, 7 and 8 for the appropriate horizontal coefficients to be used.
3.5.2
Water
3.5.2.1
Load due to ground water pressure shall be calculated using a density of 10.00 kN/m3 and due to seawater using a density of 10.30 kN/m3.
3.5.2.2
Maximum Ground Water Load shall be determined from the Design Flood Level as defined in Chapter 12. Minimum Ground Water Load shall be determined from the lowest credible groundwater level unless indicated otherwise in the Design Criteria.
3.5.2.3
Maximum sea water load shall be determined based on a maximum high tide level of 102.35 RL.
3.6
IMPOSED LOADS IN RAILWAY STATIONS
3.6.1
Floor Loadings
3.6.1.1
Floors within a station structure shall have the following occupancy class index.
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FLOOR AREA USAGE
OCCUPANCY CLASS INDEX
(a) Floor used primarily for railway Public Assembly. purposes (e.g. platform and concourse levels) and areas accessible to public during emergency. (b) Floors used primarily for shopping or office purpose. 3.6.1.2
Retail or Offices as appropriate.
The following minimum floor live loads shall be used in the design. All floors shall be designed to carry the uniformly distributed or concentrated load, whichever produces the greatest stresses (or where critical deflection) in the part of the floor under consideration. FLOOR AREA USAGE
DISTRIBUTED LOAD kN/m2
CONCENTRATED LOAD* kN
Public Assembly Areas
5
15
Traction and Service Substations, Generator Room
16
25
or actual equipment weight plus 3
15
in space around equipment whichever is more onerous All Other Plant Rooms
7.5
15
or actual equipment weight plus 3
15
in space around equipment whichever is more onerous * Concentrated load shall be applied on a square area of 300mm side. Both the distributed load and the actual equipment weight shall be considered in the calculations to determine the more onerous case.
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Where the actual equipment weight is the more onerous the maximum allowable equipment weight, co-existing distributed load and loading arrangement shall be clearly indicated on the design drawings. The loading arrangement shall show the areas over which the equipment load is applied and over which the co-existing distributed load is applied. 3.6.1.3
3.6.2
Notwithstanding the requirements of the Building Control Regulations – 4th Schedule, BS 6399 Part 1 and Clause 3.6.1.2 above, all floors shall be designed to resist the following loads without distress or damage: (a)
The total dead load of a piece of equipment at any reasonable position on the structure likely to be experienced during or after installation including consideration of access routes and method of transportation of the equipment during installation and any subsequent removal for repair.
(b)
The dynamic effect due to the operation of the equipment in its designed location.
Escalators Approximate loads from escalators are given below. These loads shall be verified with the System-wide Contractor and adjusted accordingly before the Final Design.
3.6.2.1
Approximate size of maximum section Length6000 mm Width 1700 mm Height 2600 mm Weight 4500 kg
3.6.2.2
Loadings:
H is Rise in mm. REACTION (kg)
Sept 2002
C (intermediate support)
Escalator Rise (mm)
A (lower landing)
B (upper landing)
0.37 H + 2100
0.37 H + 3200
1.14 H + 5800
Above 8000
0.37 H + 2000
0.37 H + 3200
1.14 H + 5400
Up to 8000
0.91 H + 4500
0.91 H + 5100
-
Up to 6000
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3.6.3
Lifts Lifts may be different for each station. These loads shall be co-ordinated with the relevant System-wide Contractor.
3.6.4
Cooling Tower/Water Tanks Cooling tower and water tank requirements may vary at each station. These loads shall be co-ordinated with the relevant System-wide Contractor.
3.7
WIND
3.7.1
Wind on Viaducts, Bridges, Gantries and other Road Related Structures The mean hourly wind speed to be used in the design shall be 20 m/s. Other recommendations of BS 5400: Pt 2 or BD37/88 with regard to the computation of wind forces shall be closely adhered to.
3.7.2
Wind on Stations and Other Structures Wind forces on structures other than viaducts and bridges shall be determined in accordance with BS 6399 Part 2 using a basic wind speed of 20 m/s (based on hourly mean value). This shall be deemed to be that appropriate to a 120 year return period, and, accordingly, Sp in BS 6399 may be taken as 1.0.
3.7.3
Aerodynamic Effects For structures considered likely to be susceptible to aerodynamic effects, criteria for design against wind loading will be specially established, and where necessary, this behaviour shall be the subject of testing.
3.7.4
Wind Load from Fans in Underground Railway Structures
3.7.4.1
These loads shall be co-ordinated with the relevant System-wide Contractor. However, for the purposes of tendering and preliminary design the following loads shall be assumed:
3.7.4.2
A pressure of 3 kN/m2 shall be allowed for in the design for the operation of the tunnel ventilation fans and the underplatform exhaust fans. This pressure may be either positive or negative and shall be applied to ventilation duct ways, plenums and shafts (including fitted doors and/or access hatches).
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Civil Design Criteria – Revision A4
DC/3/18
3.7.4.3
A pressure drop of not less than plus or minus 0.1 kN/m2 shall be allowed for across all louvre openings.
3.7.4.4
In the design of underground stations, an internal differential pressure of plus or minus 0.3 kN/m2 shall be allowed for between one room and the next and between above and below close fitting false ceilings, except for rooms used as fan rooms or air plenums where 3.7.4.2 applies.
3.7.5
Wind Load from Trains in Below Ground Structures
3.7.5.1
These loads shall be co-ordinated with the relevant System-wide Contractor. However for the purposes of tendering and preliminary design the following loads shall be assumed:
3.7.5.2
Doors fitted to an air path which leads from atmosphere to a single running tunnel shall be designed using a load of plus or minus 1 kN/m2 and a cycle load of plus or minus 0.5 kN/m2 for six million cycles. The pressures are caused by the positive and negative pressures which occur when a train passes the door. The door opening/closing mechanism shall be designed to operate in the conditions stipulated in Clause 3.7.4.4.
3.7.5.3
An overall pressure differential of plus or minus 2 kN/m2 and a cycle load of plus or minus 1 kN/m2 for six million cycles shall be assumed for crosspassage doors between adjacent running tunnels. The pressures are caused by the combined positive and negative pressures which occur when trains pass the door in opposite running tunnels. The door opening/closing mechanism shall be designed to operate in the conditions stipulated in Clause 3.7.4.4.
3.7.5.4
An overall pressure differential of plus or minus 1 kN/m2 shall be assumed for the underground trainway including the screen door area.
3.8
PARAPETS AND HANDRAILING
3.8.1
Parapets and handrailing for road structures or for structures where road vehicle containment is appropriate shall be designed in accordance with the requirements in Chapter 9. Live loads on parapets and handrailing where vehicle containment is inappropriate shall be in accordance with the Building Control Regulations - 4th Schedule, BS 6399 Part 1, with loads as follows:
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Civil Design Criteria – Revision A4
DC/3/19
USE
Balustrades & handrailing in Public assembly occupancy class*. Balustrades, handrailing & parapets in areas accessible to maintenance staff only including those along edge of railway viaducts and railway platform end stairs
A HORIZONTAL UDL
A UDL APPLIED TO THE INFILL
kN/m run
kN/m2
A POINT LOAD APPLIED TO PART OF THE INFILL kN
3.0
1.5
1.5
0.75
1.0
0.5
* includes areas accessible to the public during emergency. 3.9
LIFTING FACILITIES FOR EQUIPMENT
3.9.1
Crane Gantry Girder Loading for crane gantry girder shall be in accordance with the requirements of BS 2573.
3.9.2
Overhead Runway Beams
3.9.2.1
The working load of runway beams should be determined from the maximum weight of equipment to be lifted. Design load (i.e. the nominal or characteristic load) shall be taken as 1.5x working load which includes an allowance for dynamic effects.
3.9.2.2
Fixings into concrete shall be designed to have an ultimate capacity of 3x design load.
3.9.3
Eyebolts Fixed lifting points whether for equipment installation or subsequent maintenance, or for any other lifting purposes shall be “eyebolts with link” or where greater capacity is required “collar eyebolts” as defined by BS 4278. Cast-in reinforcement bars are not acceptable for this purpose.
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Civil Design Criteria – Revision A4
DC/3/20
To give warning against impending failure, in the unlikely event of overload, eyebolts shall be designed using the following procedure to ensure that yielding would occur before brittle failure of the base material. 3.9.3.1
Eyebolt selection/design: The safe working load of eyebolts for lifting or hauling shall be determined from the maximum weight of equipment to be moved. Eyebolts shall be selected/designed in accordance with BS 4278 giving consideration to the effects of non axial loading. Proof loading, taken as 2x the safe working load, may be assumed to have included an allowance for dynamic effects.
3.9.3.2
The maximum angle between the eyebolt axis and the line of application of pull shall be co-ordinated with the System-wide Contractors and clearly shown on the design drawings.
3.9.3.3
Local anchorage design: The anchorage capacity (e.g. pullout or cone failure) of the eyebolt fixing into the supporting member shall be designed to resist an ultimate load of 3x safe working load. In the case of concrete beams or slabs, the fixing shall be effectively anchored to the top of the supporting members using reinforcement links designed for this ultimate load.
3.9.3.4
Supporting Member design: Supporting structural elements (for example slabs, walls, beams, etc) shall be designed for a service load equal to the test load and for an ultimate design load equal to the test load multiplied by a partial safety factor for load equal to at least 1.4. For the purpose of design, the test load shall be taken as not less than 1.5x safe working load.
3.10
PARTIAL SAFETY FACTORS FOR LOADS No reduction in partial safety factors from those recommended in the relevant standards shall be allowed, even where the relevant standard provides guidance on the use of reduced or alternative partial safety factors, without the explicit approval of the Authority prior to the award of tender, or unless specifically stated otherwise in the Design Criteria. For example, the reduced load factors in SS CP 65 Part 2 Table 2.1 shall not be used; rather those in Table 2.1 of SS CP 65 Part 1 shall be used.
3.11
SEISMIC LOADING No allowance for seismic loading is required.
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Civil Design Criteria – Revision A4
DC/3/21
Chapter 3, Appendix 1 Design Parameters for Derailment All design shall allow for the following minimum values of loads and design parameters due to derailment. The designer shall ascertain whether more onerous values are appropriate, and, if so, shall incorporate such values into the design.
Sept 2002
a)
MRT
P1 P2 H1 H2 D1 D2 P3 H3
(kN): (kN): (mm): (mm): (degrees): (degrees): (kN): (kN):
b)
LRT
P1 P2 H1 H2 D1 D2 P3 H3
(kN): (kN): (mm): (mm): (degrees): (degrees): (kN): (kN):
2000 1000 1100 3500 6 10 4000 1100
1000 500 1100 3500 6 10 2000 550
Civil Design Criteria – Revision A4
DC/4/1
CHAPTER 4 TRACKWORK 4.1
INTRODUCTION
4.1.1
In the design of the trackwork and selection of components for the Mass Transit Rail system, the following factors shall be taken into consideration: a) b) c) d) e) f) g) h)
reliability and riding quality including in-car noise; minimisation and ease of maintenance; availability and cost of track materials and components at present and in the future; successful use of similar components in other transit railways; compatibility with the rolling stock and electrical and signalling systems; noise and vibration propagation to adjacent property. space constraints; track alignment.
4.2
VEHICLE DATA
4.2.1
All information concerning the rolling stock to be used in the system will be provided by the Authority and/or the rolling stock designer.
4.3
ELECTRICAL
4.3.1
Power Return System The running rails shall serve as the return path to the rectifier unit.
4.3.2
Signalling System
4.3.3
The signalling system will consist of audio frequency track circuits applied to the running rails.
4.3.4
Stray Current Control System (see Chapter 14)
4.4
TRACK SYSTEM
4.4.1
Trackwork shall consist of three basic types i) ii) iii)
Sept 2002
Ballasted track on viaducts and at grade sections Slab track in tunnels and depot; Floating slab or an alternative noise and vibration attenuating track system, in tunnels. Civil Design Criteria – Revision A4
DC/4/2
4.4.2
Ballasted Track
4.4.2.1
The track system for ballasted track shall be made up of medium hardwood sleepers at 700mm spacing with a rail support which conforms to internationally recognised standards. Alternative sleeper types shall be subject to the acceptance of the Authority. The rail fastening system used may be of a non-insulated type if the insulation provided by the timber sleeper is adequate, to meet the requirement of 4.5.1.
4.4.3
Slab Track
4.4.3.1
The track fastening used for the slab track shall be of an accepted international standard with track support spacing at 700mm and shall be capable of delivering a static resilience of 30kN/mm/m. It will be insulated and able to meet the requirements of clause 4.5.1. In addition, the system will provide an incremental vertical height adjustment of 14mm at each rail support.
4.4.3.2
Slab track shall be selected throughout the tunnels and depot except where there is a need to protect buildings sensitive to excessive noise and vibration.
4.4.4
Noise and Vibration attenuating track
4.4.4.1
In specific areas of sensitivity to noise and vibration where the resilience characteristics of normal slab track are deemed to be insufficient a special track form shall be provided. This will be of an internationally recognised standard to the acceptance of the Authority.
4.4.5
Level Crossing
4.4.5.1
The rail fastening system used for level crossings in the depot area shall be of an insulated type in accordance with clause 4.4.3. The gap between the concrete and the rail shall be sealed with non-conductive, pre-formed elastomeric flangeway sealing section.
4.4.5.2
Alternatively the rail can be supported on a site installed elastomeric compound which provides resilience under the rail, lateral support and electrical insulation between the rail and the concrete channel.
4.4.6
Noise and Vibration
4.4.6.1
Noise and vibration in buildings adjacent to the tunnels shall be predicted. This prediction shall be based on the use of slab track and shall take into account: a) b) c) d)
Sept 2002
the details of the track design; the configuration and construction of the tunnel; the ground conditions; the structural arrangement of the building; Civil Design Criteria – Revision A4
DC/4/3
e) f) g)
the mass, suspension characteristics and arrangement of the rolling stock; the design speed of the rolling stock. the operating condition of the rolling stock and the tracks
4.4.6.2
Where the predicted noise from the passage of a single train exceeds 40 dB(A) peak, the use of the building shall be determined. Uses sensitive to noise and vibration (includes residential properties) shall be high-lighted and ambient conditions measured. Acceptable noise and vibration levels in sensitive use buildings shall be agreed between the Designer and the Authority. A noise and vibration analysis shall be conducted along the proposed railway route. Where the acceptable noise and vibration level is exceeded by the use of slab track, floating slab or an alternative track form shall be installed in the tunnels for sufficient length either side of the sensitive building to reduce noise and vibration to an acceptable level. The extent of floating slab track shall be rationalised to avoid an excessive number of changes from one type of track to another. Transition lengths shall be incorporated to avoid an abrupt change from slab track to floating slab track.
4.4.7
Space constraints
4.4.7.1
The track design shall be compatible with the space provided in both tunnels and on viaducts.
4.4.7.2
The civil works contractor will install a depth of concrete in the base of the tunnel (stage 1 concrete). The trackworks contractor will install all works above the stage 1 concrete. The depth of stage 2 concrete shall be determined by the Designer.
4.4.8
Trackwork components
4.4.8.1
Rail components (rails, turnouts, crossings) shall conform to UIC standards. Further details of these can be found in the Materials and Workmanship specification.
4.4.8.2
Rail shall be UIC 60. They shall be inclined at 1:40 to the vertical except at switch and crossing areas where the rail shall be vertical.
4.5
TRACK INSULATION
4.5.1
In general, adequate insulation is required to prevent current leakage to the track supporting structure and for proper functioning of the signalling system. The track system shall achieve a minimum of 10 ohm-km resistance between the track and the supporting structure measured in both dry and damp conditions, with newly laid track and without any other trackside equipment or cable installation attached. The maximum rail to rail resistance when the track is dry shall not exceed 2000 ohm-km.
Sept 2002
Civil Design Criteria – Revision A4
DC/4/4
4.6
MISCELLANEOUS
4.6.1
Cable Troughs
4.6.1.1
The size, length and location requirement of the pre-cast reinforced concrete cable trough shall be determined in co-ordination with the electrical & mechanical designers. Wherever possible, cables shall be placed in cable brackets installed on the walls of the tunnels or viaducts. The trackwork designer shall detail cable troughs mainly for the cables to cross the tracks. Owing to interference with ballast tamping, the installation of cable troughs parallel to the tracks or crossing the tracks within turnouts shall be avoided as far as possible.
4.6.1.2
Cable trough crossing the track shall be placed perpendicular to the track. The placing of troughs in the adjacent sleeper space is not permitted. The top surface of the trough shall be level with the top surface of the adjacent sleepers.
4.6.2
Buffer Stops
4.6.2.1
The buffer stops shall be of the sliding friction type and located at the end of the tracks. They shall be able to stop the train on impact at a deceleration rate of 0.15g for tracks where trains will be carrying passengers and 0.22g for tracks where trains will not carry passengers, with a maximum track occupancy of 12m. The considered speed for buffer stop design shall be the speed protected by the signalling system.
4.6.3
Over-Voltage Protection Devices (OVPDs)
4.6.3.1
The Over-Voltage Protection Devices shall be the self re-settable type and provided to avoid excessive contact voltages at insulated rails of track circuits and also across Insulated Rail Joint (IRJ) provided for sectionalising the traction return. The provision of these devices shall be determined in co-ordination with the signalling designer. The OVPD shall have an appropriate fusing voltage and be installed between negative return rail and signalling rail for the insulated rail section. The device provided shall be compatible with the return voltage.
4.6.4
Reference Points and Distance Indicators
4.6.4.1
Reference Points shall be placed at fixed points alongside the track and generally at 10m interval in plain line. They shall contain the following data: Distance (chainage value) Level Alignment point (BC, EC, etc) Offset (Distance to nearest gauge face of running rail) Cant Value
Sept 2002
Civil Design Criteria – Revision A4
DC/4/5
4.6.4.2
Distance Indicators are required at every 50 m in tunnel and at 100 m outside tunnels. These are to be manufactured from work-hardened aluminium sheets faced with high-intensity reflective film. The chainage values in black are to be superimposed on the reflective film. The plates are to be mounted on the tunnel walls and viaduct parapets.
4.6.5
Cross-Bonding and Jumper Cables
4.6.5.1
For bridging insulated sections of the running rail in order to ensure the flow of the negative return current, cross-bonding cables and jumper cables are required.
4.6.5.2
The installation locations shall be co-ordinated and determined in collaboration with the Signal and Power Designers. In general, jumper cables shall be installed at all turnouts and interrupted rails on either side of the insulated sections. The method of cable connection to the running rail shall be subject to the authorities approval.
4.6.6
Bonded Insulated Rail Joint
4.6.6.1
All bonded insulated rail joints shall be factory-made and welded into the track.
4.6.6.2
The insulated rail joint (IRJ) is to separate electrically two adjacent running rail sections and shall have minimum electric resistance of 1000 ohm for a thoroughly moistened joint. The location shall be determined by the Signal Designer.
4.6.6.3
The joint shall be of the glued synthetic-resin type with steel fishplates and high tensile bolts and successfully installed for UIC 60 rail with a major railway system for a minimum of 5 years.
4.6.7
Welding
4.6.7.1
Rail for all main line tracks outside the limits of turnouts shall be welded into continuous strings using the electric flash-butt welding process using an on-track machine
4.6.7.2
Rail within turnout limits may be welded using an accepted thermit welding process.
4.6.8
Trap points
4.6.8.1
Trap points shall be provided on all reception tracks with a downhill gradient from sidings to passenger carrying lines. They shall also be provided at all centre siding locations.
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Civil Design Criteria – Revision A4
DC/4/6
4.7
Third Rail System
4.7.1
General
4.7.1.1
The third rail system shall be of the bottom contact type in which vehiclemounted current collection shoes press upwards onto the underside of the conductor rail.
4.7.1.2
The third rail shall be provided with a continuous insulating cover to protect persons from accidental contact with the third rail and protect the third rail from foreign objects falling or being thrown onto it.
4.7.1.3
All fastenings shall be of stainless steel minimum grade A4-80 forging of stainless steel components shall be prohibited
4.7.2
Conductor Rail
4.7.2.1
The conductor rail shall be manufactured from a high-conductivity aluminium alloy with a stainless steel wearing face and shall be to the dimensions shown on the drawings. The stainless steel shall be joined to the aluminium by a molecular or welding process and not by mechanical means alone. The rail shall be supplied to site straight and in standard lengths.
4.7.3
Joints in the Conductor Rail
4.7.3.1
Individual lengths of conductor rail shall be rigidly connected to each other, both mechanically and electrically, using splice plates made from the same aluminium alloy as the rail.
4.7.4
Ramps
4.7.4.1
Entry and exit ramps shall be provided at turnouts and at other locations where a gap in the conductor rail is necessary. They shall also be provided at all electrical disconnecting points and changes of the third rail installation from one side of the track to the other. The ramp design should take into account the differing requirements of high and low speed train running.
4.7.5
Conductor Rail Supports
4.7.5.1
Conductor rails shall be supported at intervals which are sufficiently small to ensure that nowhere will the conductor rail deflection exceeds 6mm from the design level.
4.7.6
Protective Cover
4.7.6.1
The materials used for the protective cover shall be unplasticized polyvinyl chloride (UPVC) for use outside tunnels and glass fibre reinforced plastic (GF-RP) inside tunnels. Outside tunnels, the covers shall be resistant to degradation due to prolonged exposure to sunlight.
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Civil Design Criteria – Revision A4
DC/4/7
Exact materials specifications shall be proposed by the Contractor for acceptance by the Engineer.
Sept 2002
Civil Design Criteria – Revision A4
DC/5/1
CHAPTER 5 GEOTECHNICAL PARAMETERS 5.1
GENERAL The Geotechnical design parameters and other requirements/ information given in this chapter have been derived from various LTA projects. The Contractor shall use these together with the results of the soil investigation for the Project. For any relaxation of the minimum requirements given in this Chapter, the Contractor shall obtain the Engineer's prior approval by showing convincing data from soil investigations.
5.2
HYDROGEOLOGY
5.2.1
Rainfall Mean monthly rainfall values for Singapore are given below:
5.2.2
Month
Jan
Feb
Mar
Apr
May
Jun
Rainfall, mm
250
180
190
190
170
170
Month
Jul
Aug
Sept
Oct
Nov
Dec
Rainfall, mm
170
200
180
210
250
260
Design Ground Water Levels In the design of underground structures, Design Ground Water Level shall be assumed to be at existing ground level or at proposed final backfill level, whichever is higher. A further factor in the design for groundwater pressure is the flooding which occurs in the river valleys. Major floods in Singapore may persist for up to a day. Therefore, underground structures constructed by cut and cover techniques could be subject to hydrostatic pressure to flood level (please refer to Chapter 3 of the Design Criteria).
Sept 2002
Civil Design Criteria – Revision A4
DC/5/2
5.3
SOIL AND ROCK CLASSIFICATION Various soils and rocks likely to be encountered have been classified into a number of "Soil and Rock Types" relating to their geological origins as shown in Table 5/1. In general, distinction between soils and rocks is rather arbitrary, especially for deeply weathering profiles. Hence for LTA Projects, the "Soil and Rock Types" classification has been adopted for all strata encountered. For rocks and their associated weathering products, a weathering grade has been assigned in accordance with the classification system proposed by the Geological Society Engineering Group Working Party in 1970 (Anon. 1970). The relationship between this weathering grade and the Soil/and Rock Type classification of Table 5/1 is shown in Table 5/2.
5.4
DESIGN PARAMETERS The design parameters have been defined in accordance with the classification system described in Table 5/1. The Design Parameters (bulk density and the coefficient of earth pressure at rest) for each soil type as summarised in Table 5/3 shall be adopted for the design. The subgrade modulus for a given soil or rock depends on the length, width and the depth of the loaded area. These factors should be considered in establishing the design subgrade modulus for each type of foundation or retaining structure. Typically, the design modulus should be established based on the elastic modulus of the loaded soil/rock by establishing the relationship between the contact pressure and the resulting settlement or deflection, using an acceptable analytical or numerical modelling. The modulus obtained from plate load tests with appropriate modifications to the scale and depth effects is also acceptable. The selection of other Design Parameters which are not given in Table 5/3 shall be derived from the site investigation carried out for the Project and from other relevant geotechnical exploration, sampling and testing. Design Parameters must be justified and submitted to the Engineer for acceptance.
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Civil Design Criteria – Revision A4
DC/5/3
TABLE 5/1: DESCRIPTION OF SOIL AND ROCK TYPES REFERENCE
SOIL & ROCK TYPE
GENERAL DESCRIPTION
GEOLOGICAL FORMATION (PWD, 1976)
B
BEACH (Littoral)
Sandy, sometimes silty, KALLANG Littoral, with gravels, coral and possibly also part of all other members & shells. TEKONG
E
ESTUARINE (Transitional)
Peats, peaty and organic clays, organic sands.
KALLANG Transitional, possibly part of Alluvial and Marine.
F
FLUVIAL (Alluvial)
Sands, silty sands, silts and clays.
KALLANG Alluvial, possibly part of all other members and TEKONG.
F1
Predominantly granular soils including silty sands, clayey sands and sandy silts.
F2
Cohesive soils including silty clays, sandy clays and clayey silts.
M
MARINE
Very soft to soft blue or grey clay.
KALLANG Marine Member.
O
OLD ALLUVIUM
Silty sand to silty clay.
OLD ALLUVIUM
S3
BOULDER BED (Colluvial)
A colluvial deposit of boulders in a soil matrix. The matrix is typically a hard silty clay, but can be granular. The material is largely derived from the rocks and weathered rocks of the Jurong Formation.
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Civil Design Criteria – Revision A4
DC/5/4
Table 5.1 Cont’d REFERENCE
S
SOIL & ROCK TYPE
GENERAL DESCRIPTION
GEOLOGICAL FORMATION (PWD, 1976) JURONG Tengah, Rimau, Ayer Chawan and Queenstown Facies.
SEDIMENTARIES Sandstones, siltstones and mudstones. (Rocks & associated soils)
S1
Fresh to slightly weathered rock (Weathering Grades I and II)
S2
Moderately to highly weathered rock (Weathering Grades III & IV).
S4
Completely weathered rock or residual soil (Weathering Grades V & VI).
S4a
Silty, sandy weak rock or partially indurated, very dense, predominantly granular soils.
S4b
Fine grained weak rock or partially indurated, hard, cohesive soils.
G
G1
Sept 2002
GRANITE (Rock and associated Residual soils)
Fresh to slightly weathered rock (Weathering Grades I & II).
BUKIT TIMAH GRANITE
Moderately to highly weathered rock (Weathering Grades III & IV).
Civil Design Criteria – Revision A4
DC/5/5
Table 5.1 Cont’d REFERENCE
SOIL & ROCK TYPE
GENERAL DESCRIPTION
GEOLOGICAL FORMATION (PWD, 1976)
G2
Moderately to highly weathered rock (weathering Grades III & IV).
G3
Bouldery soil: Boulders of rock of variable weathering within its weathered by-product.
G4
Completely weathered rock or residual soil (Weathering Grades V & VI).
Sept 2002
Civil Design Criteria – Revision A4
DC/5/6
TABLE 5/2 : ROCK WEATHERING CLASSIFICATION (AFTER ANON, 1970)
GEOLOGICAL CLASSIFICATION
GRADE
DESIGNATION
SYMBOL
IA
Fresh
IB
Faintly Weathered
FW
Weathering limited to the surface of major discontinuities.
II
Slightly Weathered
SW
Penetrative weathering developed on open discontinuity surfaces but only slight weathering of rock material.
III
Moderately Weathered
MW
Weathering extends throughout the rock mass but the rock material is not friable.
IV
Highly Weathered
HW
Weathering extends throughout rock mass and the rock material is friable.
V
Completely Weathered
CW
Rock is wholly decomposed and in a friable condition but the rock texture and structure are preserved.
VI
Residual Soil
RS
A soil material with the original texture, structure and mineralogy of the rock completely destroyed.
S1 & G1
F
S2 & G2
S4 & G4
Sept 2002
DESCRIPTION No visible sign of weathering.
Civil Design Criteria – Revision A4
DC/5/7
Table 5/3 - Design Parameters
Design Parameters
Soil Type B
E
F1
F2
M
O
S3
S1
S2
S4
G1
G2
G3 & G4
Fill*
Bulk Density (kN/m3)
19
15
20
19
16
20
22
23
22
20
24
23
20
19
Coefficient of Earth Pressure at Rest (K0 )
0.5
1.0
0.7
1.0
1.0
1.0
1.0
0.8
0.8
0.8
0.8
0.8
0.8
0.5
* The ‘Fill’ here refers to both the top fill and the hydraulic fills.
Sept 2002
Civil Design Criteria – Revision A4
DC/5/8
5.5
SOIL AND GROUNDWATER CHEMISTRY A summary of soil and groundwater investigation results obtained from various LTA projects is given in Table 5/4 for guidance. These may be studied together with the chemical test results obtained during the soil investigation for the Project. The classification system to be adopted for the design, in relation to chemical properties of soil and groundwater, is given in Table 5/5. This shall be used in conjunction with the recommendations of BS 5328 and data from investigations at actual site locations.
5.6
SITE INVESTIGATION A site investigation may be conducted by the Contractor to justify any changes to the parameters given in Table 5/3 and Table 5/4 of this chapter as well as to obtain reliable information for an economic and safe design and to meet the tender and construction requirement. The data collected shall be of sufficient quantity and quality to enable the following analysis to be carried out where appropriate: a) Shallow and deep foundations •
ultimate and allowable bearing capacities of soils for shallow foundations;
•
ultimate and allowable vertical bearing capacities for deep foundations including the evaluation of negative skin friction;
•
ultimate and allowable lateral bearing capacities for deep foundations;
•
settlement estimates for shallow and deep foundations; and
•
settlement estimates for effects of dewatering.
b) Temporary and permanent retaining structures •
stability and deformation analyses; and
•
evaluation of bracing or anchoring system;
c) Underground structures
Sept 2002
•
settlement estimates for bored tunnelling, including NATM;
•
evaluation of methods of building protection; Civil Design Criteria – Revision A4
DC/5/9
•
evaluation of methods of ground treatment;
•
evaluation of tunnelling shield requirements;
•
evaluation of tunnel face stability and protection;
•
stability and deformation analyses during and after construction works;
•
identification of areas with potential problems; and
•
ground and structural deformation estimates for effects of dewatering, increase or decrease in stresses around the tunnels.
d) Earthworks and Soil Improvement Works •
effects of earthworks on ground water condition including, but not limiting to, water level, piezometric level and pore pressure changes; and
•
settlement and time estimates for improvement works.
e) Evaluation of the chemical corrosiveness of groundwater and soils and its effect on underground structures.
Sept 2002
Civil Design Criteria – Revision A4
DC/5/11
Table 5/5 - Classification of Soil and Groundwater Corrosion Properties
CLASS
CLASSIFICATION
TOTAL SO3 %
SOIL SULPHATES SO3 1:1 Extract g/l
GROUNDWATER SO3 2:1 Extract g/l
pH
SULPHATES SO3 parts per 100,000
pH
CHLORIDES ppm
SO3
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