Final Thesis in PDF

A Thesis Submitted in partial fulfillment of the requirement for the award of the Degree of Master of Technology in TRANSPORTATION ENGINEERING on "RE-APPROPRIATION OF INTERSECTIONS: A CASE STUDY OF

BHOPAL CITY" Submitted by

M.M. TRIPATHI

Scholar No: PG/FT/092111502

Guided by: Prof. Siddhartha Rokade Assistant Professor

Prof. Kamal Singh Assistant Professor

Department of Civil Engineering MAULANA AZAD NATIONAL INSTITUTE OF TECHNOLOGY BHOPAL-462 051 June 2011

CERTIFICATE This is to certify that the Thesis titled “Re-Appropriation of Intersections: A Case Study of Bhopal City” submitted by M.M.Tripathi in partial fulfilment of the requirement for the award of the degree of Master of Technology in TRANSPORTATION ENGINEERING is a bonafide work carried out by him under our supervision and guidance.

Prof. Siddhartha Rokade Assistant Professor Department of Civil Engineering M.A.N.I.T., Bhopal

Prof. Kamal Singh Assistant Professor Department of Civil Engineering M.A.N.I.T., Bhopal

Countersigned by:

Dr. P. K. Jain Head Department of Civil Engineering M.A.N.I.T., Bhopal

i

CANDIDATE’S DECLARATION I hereby declare that the Thesis entitled “Re-Appropriation of Intersections: A Case Study of Bhopal City” submitted by me in partial fulfilment of the requirement for the award of the degree of Master of Technology in “Transportation Engineering” of Maulana Azad National Institute of Technology is an authentic record of my own work carried out under the guidance of Prof. Siddhartha Rokade, Assistant Professor and Prof. Kamal Singh, Assistant Professor, Department of Civil Engineering M.A.N.I.T. Bhopal.

(M.M. Tripathi)

ii

ACKNOWLEDGEMENT I express my deep sense of gratitude to my guides Prof. Siddhartha Rokade, Assistant Professor and Prof. Kamal Singh, Assistant Professor, Department of Civil Engineering, Maulana Azad National Institute of Technology for their invaluable help and guidance. I am highly thankful to them for their continuous support and encouragement in completing this work. I am thankful to Dr. R.P. Singh, Director, Maulana Azad National Institute of Technology, and Dr. P.K. Jain, Head of Department, Department of Civil Engineering, Maulana Azad National Institute of Technology, for their continuous support and encouragement in completing my M.Tech programme. I am also thankful to Dr. Anil Sharma, Professor and Coordinator, Post Graduate course, Maulana Azad National Institute of Technology. I especially thanks to Dr. P.K. Agarwal, Associate Professor, Department of Civil Engineering, Maulana Azad National Institute of Technology, for his guidance and support during my Post Graduation programme. Thanks is also extended to Mrs. Ranjana, Programmer, Computer Centre, Mr. Ramanuj Yadav, Assistant Grade III and Mr. Mahesh Verma, Office Assistant, Department of Civil Engineering, Maulana Azad National Institute of Technology, I also express deep sense of appreciation to the staff of Department of Civil Engineering, Maulana Azad National Institute of Technology, for their cooperation and support throughout the session. I am also thankful to Dr. M.S. Chouhan, Associate Professor, Department of Civil Engineering, Maulana Azad National Institute of Technology, for his overall support and valuable guidance during my Post Graduation Programme.

iii

ABSTRACT In the field of road transport, the intersections are road junctions where two or more roads either meet or cross at grade (i.e., they are at the same level). They include not only the pavement area but the adjacent sidewalks and pedestrian curb cut ramps also. All the modes of travel e.g., pedestrian, bicycle, motor vehicle and transit are there at a typical intersection. They are very important elements of road and at grade intersections are very common on Indian roads. They are generally a major construction for smooth flow of traffic. It is observed that well over half of the fatal and serious road accidents occur at junctions. Since an intersection involves conflicts between traffic in different directions, its scientific design can control accidents and delay and can lead to orderly movement of traffic. The importance of design of the intersection stems from the fact that efficiency of operation, safety, speed, cost of operation and capacity are direct governed by the design. Thus there is a great need to properly study and subsequently design intersection on the road networks. The safe and efficient design of the intersection depends on many factors which include human factors, traffic considerations, road and environmental considerations, economic factors. Bhopal, capital city of Madhya Pradesh, like all the major cities of India has very heterogeneous kind of traffic. There are large numbers of light commercial vehicles such as motorcycles and cars as well as heavy vehicles like buses, trucks, trailers and dumpers running across the city According to Regional Transport Office, Bhopal, out of 100% of road traffic, approximately 80 % are two wheelers, 10 % are cars, and rest 10 % are other commercial vehicles including truck, tractor, trailer, bus and other goods vehicle. Hence due to such vastness of traffic, it is also prone to large number of accidents. According to the traffic data of Bhopal of year 2009, there is steep increase in road accidents in this decade. It can be seen from the fact that in year 2002, total numbers of road accidents were 2001, while in the year 2009, these total step-ups to massive 3719. Thus, there is an urgent need to reduce the rate of road accidents in Bhopal city by identifying the significant causes of accidents. Out of them one of the major cause is improper intersection design, which, in this project, is studied and subsequent suggestions are being accounted.

iv

In this thesis, five main intersection of Bhopal city, having different traffic situation, conditions, and type of vehicles are taken. The intersections and their prevailing situations are (i) J. K. road Junction: A three legged intersection situated on a National Highway and one leg connects the J.K. Road which is having many residential and commercial establishment and joins Ayodhya bypass. (ii) Piplani Junction: It consists of two 3-legged intersections, one connects Raisen road to BHEL side and other connection goes towards the Sonagiri side, both having high volume of traffic flow. (iii) Jyoti Talkies intersection: A four legged intersection situated in major commercial area of Bhopal i.e., M.P. Nagar (iv) MANIT Junction; A four legged intersection of which three legs are having high volume of traffic including lots of motorcycles, cars, trucks and dumpers. (v) Mangalwara junction: A five legged intersections surrounded by commercial as well as residential establishment in old Bhopal area. It has high intensity of traffic due to transport business nearby. To find out real existing situations at the junctions, total station and traffic volume surveys had been done at all the intersections and the data thus obtained is analyzed and then in accordance with relevant IRC codal provisions, redesigning of the intersection is done.

v

CONTENTS Certificate

i

Candidate declaration

ii

Acknowledgement

iii

Abstract

iv

Contents

vi

List of Tables

viii

List of Figures

ix

CHAPTER 1 INTRODUCTION

1

1.1

General

1.2

Objective of the Study

1.3

Need of the Study

1.4

Scope of the Study

1.5

Thesis organisation

CHAPTER 2 LITERATURE REVIEW

10

2.1

Review of Research Papers

2.2

Review of IRC Codal Provisions

CHAPTER 3 METHODOLOGY

44

3.1

Review of Relevant Literature

3.2

Selection of Study Area

3.3

Conducting Surveys

3.4

Analysis of Surveyed data and design of Intersections

CHAPTER 4 DEVELOPMENT OF MODIFIED INTERSECTION 4.1

Design of J.K. Road Intersection

4.2

Design of Piplani Intersection

4.3

Design of Jyoti Talkies Intersection

4.4

Design of MANIT Intersection

4.5

Design of Mangalwara Intersection vi

45

CHAPTER 5 CONCLUSION & RECOMMENDATIONS 5.1

65

Conclusions and Recommendations

REFERENCES

67

vii

LIST OF TABLES

Table No.

Name of Table

Page No.

1.1

Rate of road accidental deaths in India during 2004 to 2008

7

1.2

Motor Vehicle Population in Bhopal

8

2.1

Intersection Design Data

25

2.2

Design Speed in Urban Areas

27

2.3

Conditions for Design of Intersection according to their situation

28

2.4

Dimensions and Turning Radii of Some of the Typical Indian

29

Vehicles 2.5

Dimensions and Turning Radii of Design Vehicles

29

2.6

Length of Right Turning Lane

34

viii

LIST OF FIGURES Figure No.

Name of Figure

Page No.

1.1

A Typical Four Legged Intersection

4

1.2

Various Types of Intersection

6

2.1

General Type of At-Grade Intersection

19

2.2

Potential Conflict Point at Different Types of

21

intersection 2.3

Channelisation Technique Illustrating Basic Intersection

22

Design Principle 2.4

Staggering of the Intersections

23

2.5

Analysis of Accident at Three armed Intersections

24

2.6

Method of Transition Curves at points of Additional

30

Lane 2.7

Provisions of Turning Lanes at Intersections

31

2.8

Method of Widening of Intersections

32

2.9

Method of Widening for Turning Lanes at Intersections

33

2.10

Typical Dimension of Road Intersections

34

2.11

General Types and Shapes of Islands

36

2.12

Details of Triangular Island Design

37

2.13

Progressive Layouts of T-Intersections for use on main Highways

38

2.14

Rotary Elements

39

2.15

Circular Shaped Rotary

40

ix

2.16

Squarish rotary with rounded edge

41

2.17

Elliptical Rotary

42

2.18

Rectangular shape

42

2.19

Layout of Complex Rotary

43

4.1

Existing Details of J.K. Road Intersection

47

4.2

Overlap of Existing and Proposed Details of J.K. Road

48

Intersection 4.3

Details of Proposed J.K. Road Intersection

49

4.4

Details of Existing Piplani Intersection

51

4.5

Overlap of Details of Existing and Proposed Piplani

52

Intersection 4.6

Details of Proposed Piplani Intersection

53

4.7

Details of Existing Jyoti Talkies Intersection

55

4.8

Overlap of Details of Existing and Proposed Jyoti Talkies

56

Intersection 4.9

Details of Proposed Jyoti Talkies Intersection

57

4.10

Existing Details of Manit Intersection

59

4.11

Proposed details of Manit Intersection

60

4.12

Existing Details of Mangalwara Intersection

62

4.13

Overlap of Existing and Proposed Mangalwara

63

Intersection 4.14

Details of Proposed Mangalwara Intersection

x

64

CHAPTER 1: INTRODUCTION 1.1. General An intersection is the area where two or more streets join or cross at-grade. The intersection includes the areas needed for all modes of travel: pedestrian, bicycle, motor vehicle, and transit. Thus, the intersection includes not only the pavement area, but typically the adjacent sidewalks and pedestrian ramps. The intersection is defined as encompassing all alterations (for example, turning lanes) to the otherwise typical cross sections of the intersecting streets. Intersections are a key feature of street design in four respects: i.

Focus of activity The land near intersections often contains a concentration of travel destinations.

ii.

Conflicting movements Pedestrian crossings and motor vehicle and bicycle turning and crossing movements concentrated at intersections.

iii.

Traffic control At intersections, movement of users is assigned, through traffic control devices such as yield signs, stop signs, and traffic signals. Traffic control often results in delay to users travelling along the intersecting roadways.

iv.

Capacity In many cases, traffic control at intersections limits the capacity of the intersecting roadways, defined as number of users that can be accommodated within a given time period.

1.1.1. Intersection Users All roadway users are affected by intersection design such as: i.

Pedestrians. Key elements affecting intersection performance for pedestrians are: (a) the amount of right-of-way provided for the pedestrian including both sidewalk and crosswalk width; (b) the crossing distance and resulting duration of exposure to motor vehicle

1

and bicycle traffic; (c) the volume of conflicting traffic; and (d) the speed and visibility of approaching traffic. ii.

Bicyclists. Key elements affecting intersection performance for bicycles are: (a) the degree to which pavement is shared or used exclusively by bicycles; (b) the relationship between turning and through movements for motor vehicles and bicycles, (c) traffic control for bicycles; and (d) the differential in speed between motor vehicle and bicycle traffic.

iii.

Motor vehicles. Key elements affecting intersection performance for motor vehicles are: (a) the type of traffic control, (b) the vehicular capacity of the intersection, determined primarily from the number of lanes and traffic control; (c) the ability to make turning movements; (d) the visibility of approaching and crossing pedestrians and bicycles; and (e) the speed and visibility of approaching and crossing motor vehicles.

iv.

Transit. Transit operations usually involve the operation of motor vehicles (buses), and therefore share the same key characteristics as vehicles as outlined above. In addition, transit operations may sometimes involve a transit stop in an intersection area, thereby influencing pedestrian, bicycle, and motor vehicle flow and safety. Additionally, in some cases, the unique characteristics of light-rail transit must be taken into account.

In addition to the users of the street and intersections, owners and users of adjacent land often have a direct interest in intersection design. This interest can be particularly sensitive where the intersection is surrounded by retail, commercial, historic or institutional land uses. The primary concerns include: maintenance of vehicular access to private property; turn restrictions; consumption of private property for right-of-way; and provision of safe, convenient pedestrian access.

1.1.2. Definitions and Key Elements The major street is typically the intersecting street with greater traffic volume, larger cross section, and higher functional class. The minor street is the intersecting street likely to have less traffic volume, smaller cross section and lower functional classification than the major street. 2

The term intersection encompasses not only the area of pavement jointly used by the intersecting streets, but also those segments of the intersecting streets affected by the design. Thus, those segments of streets adjacent to the intersection for which the cross section or grade has been modified from their typical design are considered part of the intersection. Definitions, summarizes the extent and terminology used to define an intersection. Two geometric features are common to all intersections, regardless of their level of complexity. The angle of intersection is formed by the intersecting streets’ centrelines. Where the angle of intersection departs significantly (more than approximately 20 degrees) from right angles, the intersection is referred to as a skewed intersection. Intersection legs are those segments of roadway adjacent to the intersection. The side of the leg used by traffic approaching the intersection is the approach leg, or simply approach, and the side used by traffic leaving is referenced to as the departure leg. Sidewalks, crosswalks and wheelchair ramps are considered to be within the intersection. The pavement corner is the curve connecting the edges of pavement of the intersecting streets. Auxiliary lanes are lanes of traffic added at the intersection. These lanes are added accommodate left-turning motor vehicles. Less often, they are added for right-turning motor vehicles. They may also be used to add through lanes through an intersection. Channelizing islands may be added to an intersection, to help delineate the area in which vehicles can operate. Islands can also provide for pedestrian refuge. A turning roadway is a short segment of roadway accommodating a right turn, delineated by channelizing islands. Turning roadways are used where right-turn volumes are very high, and where skewed intersections would otherwise create a very large pavement area. Traffic control devices assign right-of-way, to both motorized and non-motorized traffic and include traffic signals, STOP signs, and YIELD signs.

3

Fig 1.1: A Typical Four legged intersection 1.1.3. Intersection Types and Configurations Intersections can be categorized into four major types, depending on their basic configuration: i.

Simple Intersections Simple intersections maintain the street’s typical cross section and number of lanes throughout the intersection, on both the main and minor streets. Simple intersections are best-suited to locations auxiliary (turning) lanes are not necessary to achieve the desired level-of-service, or are infeasible due to nearby constraints.

ii.

Flared Intersections The characteristic feature of flared intersections is an expansion of the typical cross section of the street (main, cross or both). The flaring is often done to accommodate a 4

left-turn lane, so that left-turning bicycles and motor vehicles are removed from the through-traffic stream for reasons of capacity at high-volume locations, and safety on higher speed streets. Right-turn lanes, less frequently used than left-turn lanes, are usually a response to large volumes of right turns. iii.

Channelized Intersections Channelized intersections use raised islands to designate the intended vehicle path. The most frequent use is for right turns, particularly when accompanied by an auxiliary right-turn lane. At skewed intersections, channelization islands are often used to delineate right turns, even in the absence of auxiliary right turn lanes. At intersections located on a curve, channelization islands can help direct drivers to and through the intersection. At large intersections, short median islands can be used effectively for pedestrian refuge.

iv.

Roundabouts The roundabout is a channelized intersection with one-way traffic flow circulating around a central island. All traffic through as well as turning enters this one-way flow. Although usually circular in shape, the central island of a roundabout can be oval, or irregularly shaped. Roundabouts can be an appropriate design alternative to both stopcontrolled and signal-controlled intersections. At intersections of two-lane streets, roundabouts can usually function with a single circulating lane, making it possible to fit them into most settings.

5

1.1.4. Intersection Types

Fig 1.2: Various Types of Intersections

6

1.2. Objective of the study The objectives of the study are as follow: (i)

Study of relevant literature.

(ii)

Study of the existing scenario of the intersections in Bhopal City.

(iii)

Re-appropriation of intersections in Bhopal City.

1.3. Need of the Study Rapid growth rate (GDP) of India from the past 2 decades had lead to increase in per capita income henceforth increasing their capacity to buy more vehicle or to use the intermediate transport systems like taxies etc. But, on the other hand, the design of the Indian roads and intersection had not been improved up to such extent to bear such a huge traffic. This has placed a great stress on the road traffic particularly in the cities and urban areas, as compared to the rural areas. And along with this rapid increase in traffic, number of accidents and the number of people killed and injured in traffic crashes has been steadily increasing. The severeness of the problem can be seen from the accident data provided by National Crime Bureau, from the year 2004 to 2008. Table 1.1 Rate of road accidental deaths in India during 2004 to 2008 S.No.

Year

Total no. of

Estimated mid- year

Rate of accidental deaths

deaths

population (in

(col.3/col.4)

lakhs) (1)

(2)

(3)

(4)

(5)

1.

2004

277263

10856

25.5

2.

2005

294175

11028

26.7

3.

2006

314704

11197.75

28.1

4.

2007

340794

11365.53

30.0

5.

2008

342309

11531.3

29.7

(Source: National Crime Records Bureau, 2008)

7

In the Bhopal city, the traffic scenario can be observed from the table provided by the Regional Transport Office (RTO), Bhopal. The table presents the motor vehicle population from the year 1999 to 2009. Table 1.2 Motor vehicle population in Bhopal Year

1999

2003

2006

2009

Truck

3489

4241

4889

5435

Other goods vehicle

1967

4109

6147

8170

Bus

2325

2637

2939

3233

Taxi

3206

6107

8998

11,918

Auto-rickshaw

8582

9566

10,954

12,451

Two-wheeler

2,10,218

2,92,522

3,87,308

4,50,291

Car

15,945

24,916

37,015

45,370

Jeep

2621

3044

3417

3949

Tractor

8993

9512

10,132

10,765

Trailer

2829

3548

4110

4720

Others

710

651

396

415

Total

2,60,885

3,60,853

4,76,305

5,56,717

(Source: Regional Transport Office, Bhopal, 2009) From the above table, it can be seen that the overall motor vehicle population is increased by more than 2 times in this decade. Hence by considering the future perspective too, it becomes very important to design the roads and intersections in according to the future needs. It is observed that well over half of the fatal and serious road accidents occur at intersection. The intersections in these roads are the bottleneck for them because the efficiency safety, speed, cost of operation and capacity of the facility depends on the intersection design to a great extent. Each intersection involves through or cross traffic movement on one or more of the highways and may involve turning movements between these highways. Such movements can be facilitates by various geometric design and traffic controls, depending on the type of intersection. Hence there is an urgent need for the proper designing of the various important intersections on the basis of current real time information as well as future predictions and also satisfying various codal provisions setup by IRC. 8

1.4. Scope of the Study The Scope of this study is limited to re-appropriation of five intersections of the Bhopal city which are chosen according to variance in their traffic and their situation in the Bhopal area, viz Mangalwara Junction is located in old Bhopal city, where there are large number of pedestrians as well as 2-wheelers, and also heavy commercial vehicles due to transport business near, while on the other hand Jyoti Talkies Intersection is situated in New Bhopal city in commercial area of M P Nagar which has a huge number of 2-wheelers as well cars and small buses of city transport. The Piplani Junction and J.K, Road Junction are having large numbers of heavy commercial vehicles like trucks and dumpers flowing through them, MANIT Intersection has large number of 2-wheelers due to its connection with MANIT college, and also it has huge traffic flowing from the kolar road to new market and Nehru nagar and vice-versa. 1.5. Thesis Organisation This thesis is divided in to 6 different chapters. Chapter 1 provides the general introduction of intersections, objective of this thesis, its need as well as scope of work done in this thesis. In chapter 2, literature review of various research papers has been done, as well as the analysis of the codal provisions in this regard has been exercised. Chapter 3 gives the brief idea of the methodology followed for designing the intersections in Bhopal city. In chapter 4 the improved design of the junctions under consideration is rendered and at last in chapter 5 the conclusion of the whole operation is given and future recommendation are furnished for the intersection design.

9

CHAPTER 2: LITERATURE REVIEW 2.1. Review of Research Papers Study of the various research papers in this arena is done and some of important findings are summarised below:

NCHRP Report 650 (2010), describes common safety issues at median intersections on rural divided highways and presents innovative geometric and operational treatments for addressing those issues. It includes recommendations for modifications to the AASHTO A Policy on Geometric Design of Highways and Streets (Green Book) and the Manual on Uniform Traffic Control Devices (MUTCD). According to this report, Median-separated highways provide distinct benefits over undivided roadways (two-lane or multilane roads without medians). Medians separate opposing traffic, provide a recovery area for out-ofcontrol vehicles, provide a stopping area in case of emergencies, allow space for speed changes and storage of left-turning and U-turning vehicles, minimize headlight glare, and provide width for future lanes. Research has shown that the percentage of total expressway crashes which occur at two-way stop-controlled (TWSC) intersections increases as the mainline traffic volumes increase and that all intersection crashes increase and become more severe as minor roadway volumes increase. The majority of crashes at TWSC expressway intersections tend to be right-angle crashes. The most problematic of these (with respect to severity) tend to be those occurring in the far-side intersection (i.e., after the minor road driver has travelled through the median). After addressing potential design issues such as insufficient sight distance, the traditional approach to addressing safety problems at expressway intersections is to improve the trafficcontrol devices, implement traffic signal control, and eventually construct an overpass or interchange. However, traffic signals do not always improve safety: they may only change the crash type distribution. In general, traffic signals in rural areas are discouraged for several reasons including violation of driver expectations and difficulty in servicing and maintaining signals in remote locations. The final alternative is to build an interchange at the intersection. The construction of an reduces the cost advantage of building an expressway as compared with building a freeway, and the mix of at-grade intersections and interchanges tends to violate driver expectations.

10

Although this report identifies many issues, most must be solved by others in the future. For example, although thorough reviews of the Green Book and the MUTCD were conducted with many resulting recommendations, these are meant for the consideration for groups themselves, and it is ultimately their responsibility to actually modify the contents of those manuals. Furthermore, the safety effectiveness of the rural expressway intersection treatments examined in the case studies can only be determined if state transporting agencies (STAs) are willing to deploy and to evaluate them rigorously. While the recommendations that follow are specific, others must implement them to positively impact rural expressway inter-section design and safety. Kent J. Fugal et al (2008), emphasis on the Design for Single-Lane to Dual-Lane Roundabout Expandability. Roundabout planners and designers are often faced with situations where a multi-lane roundabout will be required to handle the design-year traffic volumes, but where a single-lane roundabout would be sufficient for a number of years. Due to issues of safety, complexity, driver familiarity, and sometimes cost, it may be desirable to construct a single-lane roundabout that can be expanded in the future. Two alternatives for the initial single-lane layout are presented, including advantages and disadvantages of each. One alternative involves building the full outside footprint and widening inward, while the other involves building the central island and splitter islands in the ultimate configuration and widening outward. The paper also includes a case study of the Amity Avenue/Happy Valley Road Roundabout in Nampa, Idaho. According to author, an expandable design should always begin with a good dual-lane layout. Dual-lane operation and design are much more complex than single-lane. While single-lane roundabout operations can be forgiving, to an extent, of shortfalls in the design, the safety and efficiency of dual-lane roundabouts generally suffer significantly from even “small” design problems. Expanding a “good” single-lane design does not necessarily result in a “good” dual-lane design. However, a good single-lane, initial-build layout can often be readily developed as a first phase of the development of a dual-lane roundabout. The designer must fully check the dual-lane layout to ensure that it will function with the intended safety and efficiency as he or she would do if a dual-lane roundabout were being constructed right from the start.

For example, the geometry should be checked for proper entering and

circulating speed control (fastest path analysis). It should also be checked for potential entering and exiting lane path overlap issues and proper handling of pedestrians and bicycles.

11

This paper explores the characteristics of a good expandable roundabout design, including basic procedures that should be followed. However, it does not discuss roundabout design in its entirety.

Rather, it focuses on the additional steps that are required to design an

expandable roundabout. Those steps include: 1.

Development of the proposed dual-lane roundabout geometry,

2.

Development of an initial-build, single-lane layout consistent with the proposed duallane geometry, and

3.

Development of the detailed construction drawings for the initial-build layout.

The author accentuated the fact that it would be undesirable to construct a dual-lane roundabout initially when a single-lane roundabout would adequately handle the traffic for many years. Roundabouts should not be overbuilt for a number of reasons. These include concerns with operational simplicity, safety, and cost. Ragnhild Davidse (2007) is concerned with the possibilities offered by road design and driver assistance systems to improve older adults’ safe and independent mobility by compensating for their age-related functional limitations. The author’s aim is to identify those characteristics of intersections that may contribute to the over-representation of crashes that older drivers are considered legally responsible for. These characteristics were traced by looking at the functional limitations of older people and the demands they make on intersection design. It was assumed that if the design elements of an intersection allow for the functional limitations of older people, the crash involvement of older drivers will be low and vice-versa. The validity of these assumptions was tested by the inspections of the intersections that have different shares of crashes involving older drivers. The intersection inspections indicated that priority regulation is a predator of the crash involvement of older drivers. Crashes involving older drivers occur more often at yieldingcontrolled intersections than at the intersections with traffic lights. It reveals that the following intersection design elements appear to allow for the older drivers functional limitations: a positive offset of opposite left-turn lanes, roundabouts, and a high in service contrast level for road markings, background plates for traffic lights, long sight distances, advance warning signs, and protected-only operations of traffic lights. However, the actual effect that they have on the safety of older drivers has hardly been tested yet. In this research paper, two strategies were followed to look for intersection design elements that play a role in the difficulties that older drivers encounter in traffic: 1) inspections of 12

intersections that have different shares of crashes involving older drivers, and 2) a review of the literature on intersection design elements that appear to take the functional limitations of older drivers into account. The intersection inspections were guided by the concept of task difficulty. It was expected that the crash risk of older drivers would increase with the complexity of the traffic situation, provided that drivers have to make decisions with regard to road users that are about to cross their path, and provided that drivers cannot use their experience to make these decisions. These expectations were only confirmed for one of the intersection characteristics that were expected to determine the need for decision making with regard to other road users: implementation of right of way. It turned out that at intersections at which no crashes occurred in which older drivers were involved, traffic was more often regulated by means of traffic lights than it was at intersections at which relatively many crashes occurred in which older drivers were involved. At the latter intersections, traffic was more often regulated by means of yield signs. The intersection inspections that were carried out within the scope of this thesis had a rather exploratory character and the number of intersections that were inspected was relatively small. However, the concept of task difficulty and its application to the difficulty of passing intersections deserve it to be studied in a more systematic way. They evaluated the effects of a positive offset of opposite left-turn lanes and protected only operations of lights on driving behaviour in a driving simulator and instrumented car respectively. Neither of the adjustments had a significant effect on driving behaviour. Kay Fitzpatrick et al (2002) emphasizes on the issues to be considered in developing an Intersection design guide. He throws light on the fact that safe and efficient operation of an intersection is directly related to its design, and decisions made during the design of an intersection occur after examining a series of tradeoffs. The resources available to designers can limit effective intersection design. The wealth of information published in the past years demonstrates that there are several new ideas on how to better design intersections. Unfortunately, if these ideas are not readily available or included in the reference materials used by designers, they will not become generally accepted or used. So he accentuated on the importance of the use of past data for the design purpose. The prime objective of author is to produce a reference document for the Texas Department of Transportation (TxDOT), that

13

provides information on each of the design elements associated with an intersection and discusses related geometric and operational issues involved in urban intersection design. The project is a three-year effort and is structured into two phases. The first phase (Phase I) took place during the initial 12 months of the project, and this report summarizes the firstyear activities. A wide variety of issues were raised in the discussions. Issues that received repeated interest among the engineers and designers interviewed included: o Pedestrian issues: curb cuts, crosswalks, and protrusions. o Drainage: ponding and flow across the intersection. o ROW: conflicting or unknown locations for utilities, utility access, utilities clearance, obtaining ROW, establishing requirements, and customary practice. o Traffic control device issues: wide medians, islands and pedestrians, mast arm length, number of signal heads, internally illuminated street signs, protected/permissive operations, marked crosswalks, illumination, and use of span wire. o Intersection layout: dual lefts, turn bays, turn priorities, bicycles, sight distance, skew angle, traffic counts, cost estimates, driveways, pavement design, and acceleration lanes. This research is designed to provide TxDOT and other interested parties with useful and practical information on operations and design for intersections. This includes chapters on Intersection Function, Design Control and Criteria, Design Elements, Cross Section, Roadside, Drainage, Street Crossing, Signals, Marking, Signs, Influences from Other Intersections. Synthesis of Highway Practice 264 (1998), provides information on current practices with respect to the planning, design, and operation of modern roundabouts in the United States. Administrators, engineers, and researchers are continually faced with highway problems on which much information exists, either in the form of reports or in terms of undocumented experience and practice. In an effort to correct this situation, a continuing NCHRP project, carried out by the Transportation Research Board as the research agency, has the objective of reporting on common highway problems and synthesizing available information. The synthesis reports from this endeavour constitute an NCHRP publication series in which various forms of relevant information are assembled into single, concise documents pertaining to specific highway problems or sets of closely related problems.

14

The concept of the modern roundabout to move traffic more efficiently through un-signalized intersections has evolved from conventional traffic circles. This report of the Transportation Research Board presents a discussion of modern roundabout applications in the United States, based on a survey of state and local transportation agencies, which provided information on 38 individual roundabouts. The synthesis demos information on the design guidelines used in the United States as well as those of other countries. Other major areas of interest with regard to roundabouts include safety issues; traffic capacities and delays; issues related to pedestrians, bicyclists, and the visually impaired; costs; and location criteria to be considered for roundabouts. Modern roundabouts have become a subject of great interest and attention over the last few years in the United States. This interest is partially based on the great success of roundabouts in Europe and Australia, where intersection design practice has changed substantially as the result of the good performance of roundabouts and their acceptance by the public. The public reaction to roundabouts has been positive in general. This is substantiated by the survey respondents, by opinion surveys, and by reporting in the press. Some concerns were raised regarding pedestrians at roundabouts, especially with regard to the absence of clear right-of-way control. This perceived problem is related to some degree to the belief by the general public that signalized intersections bring the greatest safety to pedestrians. These concerns tend to disappear after the pedestrians have an opportunity to use the roundabout. For bicyclists, the preferred arrangement in the case of single-lane and low-speed roundabouts is to stop bicycle lanes before they reach the roundabout and to let bicycles circulate in mixed traffic through the circle. For larger, multi-lane roundabouts, it appears preferable to provide separate bike paths, or to provide for mixed bicycle/pedestrian paths, or reroute bicyclists. To conclude, roundabouts can have significant benefits in terms of safety, delays, and capacity. Another major new benefit is related to the aesthetic and urban design improvements resulting from the landscaping and sculptural elements in the central island. This synthesis has portrayed the roundabouts starting from its history and evolution to the modern use in United States. It has summarized the design guidelines that are being used in

15

the United States and in other countries. It also throws light on the safety of roundabouts. It also talks about the issues related to pedestrians, bicyclist, and the visually impaired. Bruce Hellinga et al had given Signalized Intersection Analysis and Design and its implications of day-to-day variability in Peak. This paper presents findings of a study that quantifies the impact of day-to-day variability of intersection peak hour approach volumes on intersection delay and demonstrates that this impact is not insignificant and therefore should not be ignored. Finally, the study explores the number of days for which intersection approach volumes should be counted in order to establish intersection delay within a desired level of confidence. Intersection performance as measured by delay is a function of many factors including, signal timing plan, turning movement traffic demands, traffic stream composition, pedestrian volumes, intersection geometry, temporal variation in traffic demands, the headway distribution of each traffic stream, driver characteristics, weather and road surface conditions and visibility. Some of these factors are invariant for a given intersection operating under a defined signal control strategy (e.g. geometry and signal timing plan) while others vary (e.g. weather, traffic demands, etc.). This paper seeks to address the following specific questions: 1. What degree of day to day variability exists in the peak hour traffic volume and to what extent are traffic volumes on different intersection approaches statistically correlated? 2. What impact does the day to day variation in the peak hour volume have on intersection performance as measured by delay? 3. For how many days are turning movement counts required in order to estimate the intersection performance with a given level of confidence? In this paper the answers of these questions were given using empirical data to quantify the distribution of day-to-day peak hour traffic volumes and the degree of statistical correlation between approach volumes. On the basis of these observations and conclusions, the following recommendations are made: 1. Additional field data should be obtained from another region to confirm the findings

of

this study. 2. The impact on intersection performance of day-to-day variability of other factors such as the PHF and turning movement proportions should be examined.

16

3. The presence of significant auto-correlation in the intersection peak hour traffic volumes could impact the number of observations required to estimate intersection performance within a specified tolerance. Consequently, an analysis should be conducted to quantify the extent of auto-correlation and the impact that this has. 4. Criteria should be established to incorporate the day-to-day variability of volume within existing signalized intersection evaluation and analysis methodologies. 2.2. Review of IRC Codal Provisions IRC-SP-41, ‘Guidelines for the Design of At-grade Intersection in Rural and Urban Areas’ and IRC-SP-65, ‘Recommended Practice for Traffic Rotaries’ has been reviewed in this regard and some main codal provisions are depicted below: 2.2.1. Factors covering design Road intersections are critical element of a road section. They are normally a major bottleneck to smooth flow of traffic and a major accident spot. The general principles off design in both rural and urban areas are the same. The basic difference lies in the design speeds, restriction on available land, sight distance available and the presence of larger volume of pedestrians and cyclists in urban areas. Design of a safe intersection depends on many factors. The major factors can be classified as under. A. Human Factors. a) Driving habits, b) Ability to make decisions, c) Driver expectancy, d) Decision and reaction time, e) Conformance to natural paths of movement, f) Pedestrian use and habits. B. Traffic considerations a) Design and actual capacities, b) Design hour turning movements, c) Size and operating characteristics of vehicle, d) Type of movement (diverging, merging weaving, and crossing), e) Vehicle speeds, 17

f) Transit involvement, g) Accident experience, h) Traffic Mix i.e., proportion of heavy and light vehicles, slow moving vehicles, cyclists etc. C. Road and Environmental considerations a) Character and use of abutting property, b) Vertical and horizontal alignment at the intersection, c) Sight distance, d) Angle of the intersection e) Conflict area, f) Speed-change lanes, g) Geometric features, h) Traffic control devices, i) Lighting equipment, j) Safety features, k) Environmental features, l) Need for future upgrading of the at-grade intersection to a grade separated intersection. D. Economic factors a) Cost of Improvements, b) An effect of controlling of limiting right-of-way on abutting residential or commercial properties where channelization restricts of prohibits vehicular movements.

2.2.2. Basic Design Principles In the design of an intersection the primary considerations are safety, smooth and efficient flow of traffic. To achieve this, the following basic principles must be followed. 2.2.3. Uniformity and Simplicity Intersections must be designed and operated for simplicity and uniformity. The design must keep the capabilities and limitation of drivers, pedestrians and vehicles using intersection. It should be based on the knowledge of what a driver will do rather than what he should do. 18

Further all the traffic information on road signs and markings should be considered in the design stage, prior to taking up construction work. All the intersection movements should be obvious to the drivers, even if he is a unfamiliar to the area. Complex design which required complicated decision-making by drivers should be avoided. There should be no confusion and the path to be taken by the drivers should be obvious. Undesirable short cuts should be blocked. Further, on an average trip route, all the intersections should have uniform design standards so that even a newcomer to the area anticipates what to expect at an intersection. Some of the major design elements in which uniformity is required are design speed, intersection curves, vehicle turning paths, super-elevations, level shoulder width, speed change lane lengths, channelization, types of curves and type of signs and markings.

Fig 2.1: general types of At-grade Intersections

19

2.2.4. Minimise Conflict Points Any location having merging, diverging or crossing manoeuvres of two vehicles is a potential conflict point. Fig. 2.2 shows the potential conflict points for different types of intersections. The main objective of the intersection design is to minimise the number and severity of potential conflicts between cars, buses, trucks, bicycles and pedestrians and whenever possible, these should be separated. This can be done by: i.

Space separation

:

by access control islands through channelising

ii.

Time separation

:

by traffic signals on waiting lanes.

Some of the common methods used to reduce conflict points are: a) Convert a 4-armed intersection having 32 conflict points to a roundabout having only 12 conflict points. Round-about treatment may not, however, be warranted at most of rural locations except those close to the urban areas. b) Signalise intersection. As Fig. 2.2 shows introduction of a two-phase signal reduces the conflict points at 4 armed intersections from 32 to 16. If more phases are introduced and separate lanes provided for turning traffic, conflict points can be virtually eliminated. (Provisions of signals may however, be justified only at a few rural locations carrying heavy traffic). Research abroad has shown that signals increase accidents at simple intersections with low volumes but reduce them at complex and/or high volume intersections. c) Channelising the directional traffic by selective use of channelising islands and medians. Some of these techniques are shown in Fig. 2.3 shows how the conflict points can be reduced on a 3-armed intersection by introducing combinations of channelising islands. d) Changing priority of crossing by introducing the GIVE WAY or STOP signs for traffic entering the junctions from minor road, By this, traffic causing the conflict is restrained. e) Staggering a 4-armed junction by flexing the two opposing arms of the side road to create two T-junctions. When staggering is employed, it should be ensured that minimum distance between two junctions is 45 m and desirably right-left staggers are created. (Fig. 2.4).

20

Fig 2.2: Potential Conflict Points at Different Types of Intersection

21

Fig 2.3: Channelisation Technique Illustrating Basic Intersection Design Principles

22

Fig 2.4: Staggering of the Intersections

A study of conflict points and accidents records by classifying accidents according to the types of conflicts would greatly help in adopting appropriate engineering measures for intersection design. For illustration, an example of a 3-armed intersection as shown in Fig. 2.5 may be considered. The Figures (a) to (i) show the various left turning & right turning movements, and the percentage of accidents classified according to types of collision. Following measures can be considered for improving safety:

23

i.

The accident situations in Figs. 2.5 (c), (d) and (h) involving right turning vehicles in high percentage of accidents can be prevented by controlling traffic movement either manually or by traffic signals.

ii.

Provisions of acceleration lane on the major road for the left turning traffic flow from the minor road could prevent traffic situation, Fig. 2.5 (f).

iii.

A separate right turning lane on the major road could minimise or prevent rear and collision at Fig. 2.5 (g).

Fig 2.5: Analysis of Accident types at Three-armed Intersections

iv.

Channelizing islands at the minor road could be useful in situation at Fig. 2.5 (i).

v.

Deceleration lanes for left turning traffic from major road would also ensure better safety for situations at Fig. 2.5 (e).

24

Table 2.1 Intersection Design Data Intersection Design Data

Peak Hour _____________ Hrs. To ____________ Hrs.

Peak Hour Design Traffic Name & Location of Intersection __________________________________________ Entering Type

Nos

1

From Leg B* PCU PCU Equivalency 2 3=1x2

Leg A* Leg C* Leg D* Nos PCU Nos PCU Equi Equi valency valency 1 2 1 2

Remarks

Fast Vehicles 1.

Passenger cars, tempos, auto rickshaw, tractors, pickup vans Motor cycle. scooters Agricultural tractor Light Commercial Vehicles Trucks, Buses

2. 3.

4. 5.

Tractor-Trailer, Truck Trailer Units TOTAL FAST

1.00

0.50 1.50

3.00 4.50

Slow Vehicles 6.

Cycles

0.50

7.

1.50

8.

Cycle Rickshaws Hand Cart

3.00

9.

Horse Drawn

4.00

10.

Bullock-Carts

8.00

TOTAL SLOW PEDESTIAN NOS. * Specify the name of an important place or land on this leg such as Market leg, Temple leg, etc. 25

Separate report sheets will be needed for the other legs of the intersection. The volume of the above traffic in terms of number of vehicles and in PCU should then be reflected in the diagrams. If the numbers of legs in the intersection are 3 or more than 4, these figures should be suitably modified. vi.

In the urban/sub-urban areas and intersection near villages with substantial pedestrian movements, the peak hour data on persons crossing the intersecting road arms should be collected for the design of a well planned pedestrian crossing facility at the intersection.

2.2.5. Parameters of Intersection Design 2.2.5.1. General Intersections are designed having regarded to flow speed, composition, distribution and future growth of traffic. Design has to be specified for each site with due regard to physical conditions of the site, the amount and cost of land, cost of construction and the effect of proposal on the neighbourhood. Allowances have to be made for space needed for traffic signs, lighting columns, drainage, public utilities etc. The preparations of alternative designs and comparison of their cost and benefits is desirable for all major intersections. 2.2.5.2. Design Speed Three types of design speeds are relevant for intersection element design: i.

Open highway or "approach" speeds.

ii.

Design speed for various intersection elements. This is generally 40 percent of approach speed in built up areas and 60 percent in open areas.

iii.

Transition speeds for design of speed change elements i.e. changing from entry/exit speed at the intersection to merging/diverging speed.

In rural areas ruling design speed should be used, but minimum can be adopted in sections where site conditions and costs dictate lower speeds. In urban areas a lower or higher value of design speed can be adopted depending on the pressure of physical controls, road side developments and other related factors. A lower value is appropriate for central business areas and higher in sub-urban areas.

26

2.2.5.3. Design Traffic Volumes Intersections are normally designed for peak hour flows. Estimation of future traffic and its distribution at peak hours is done on the basis of past trends and by accounting for factors like new development of land, socio-economic changes etc. Where it is not possible to predict traffic for longer period, intersection should be designed for stage development for design period in steps of 10 years. Where peak hour flows are not available they may be assumed to be 8 to 10 percent of the daily flow allocated in the ratio of 60:40 directionally. 2.2.5.4. Radius of Curves of Intersection The radii of intersections curves depend on the turning characteristics of design vehicles their numbers and the speed at which vehicles enter to exit the intersection area. The design curve is developed by plotting the path of the design vehicles on the sharpest turn and fitting curves or combination of curves to the path of inner rear wheels. Generally four types of curves are possible to fit in with the wheel paths of a turning vehicle. Table 2.2 Design Speeds in Urban Areas

S.No.

Road Classifications

Design Speed (Km/h) 80

1.

Arterial

2.

Sub-arterial

60

3.

Collection street

50

4.

Local street

30

2.2.5.5. Design Vehicle IRC: 3 – 1983 recognises three types of roads design vehicles namely single unit truck, semi trailer and truck trailer combination. Passenger cars are not considered as design vehicles in rural areas as savings in construction using this vehicle cannot be justified on economic basis. As such nearly all intersection curves in rural areas should be designed for either single unit trucks/buses of 11/12 m length, or semi-trailer combination of 16 m length or truck trailer combination of 18m length. On most rural highways semi trailer combination would be used for design, whereas in non arterial urban areas a single unit truck or bus can form the basis for design. In purely residential areas, alone a car forms the basis of design. 27

There are five common situations in design of intersections and each one has to be generally designed for following conditions:

Table 2.3 Conditions for Design of Intersection according to their Situation S.No. 1.

Location of Intersection Rural Section

2.

Suburban Arterial Section

3.

Urban Arterial & sub Arterials Urban Central Business District

4.

5.

Residential area

Curve Design Design for single unit truck is preferred for intersection with local minor roads. Semi-trailer design is preferred for major road intersection where large paved areas result, channelization also becomes essential. Designed for semi-trailer with speed change lanes and channelisation. Three-centred compound curves are preferred. Designed for single unit truck. Designed for single unit trucks for minimum curve radii with allowance for turning vehicles encroaching on other lances. Designed for cars only with encroachment of tracks into other lanes.

Table 2.4 Dimensions and Turning Radii of Some of the Typical Indian Vehicles S.No.

Make of Vehicle

Length

Width

Turning

(m)

(m)

Radius (m)

1.

Ambassador

4.343

1.651

-

2.

Maruti Car

3.300

1.405

4.400

3.

TATA (LPT 2416)

9.010

2.440

-

9.885

2.434

10.030

11.170

2.450

-

3-axled truck 4.

TATA (LPO 1210) Full forward control Bus Chassis

5.

TATA (LPO 1616) Bus Chassis

6.

Leyland Hippo Haulage

9.128

2.434

10.925

7.

Leyland (18746)

8.614

2.394

11.202

Taurus 28

8.

Leyland

12.000

2.500

-

5.895

1.870

6.608

Beaver Multi Drive 9.

Mahindra Nissan Allwyn Cabstar

10.

Swaraj Mazda Truck (WT 49)

5.974

2.170

6.400

11.

DCM Toyota (Bus)

6.440

1.995

6.900

Table 2.5 Dimensions & Turning Radii of Design Vehicles

S.No. 1.

Vehicle Type Passenger Car (P)

Overall Width (m) 1.4 – 2.1

Overall Length (m) 3–

Overhang

Minimum Turning

Front (m)

Rear (m)

Radius (m)

0.9

1.5

7.3

5.74 2.

Single Unit Truck

2.58

9

1.2

1.8

12.8

2.58

15.0

1.2

1.8

12.2

2.58

16.7

0.9

0.6

13.71

2.58

19.7

0.6

0.9

18.2

(S.U.) 3.

Semi Trailer and Single unit Bus (WB-12m)

4.

Large Semi-Trailer (WB 15m)

5.

Large Semi-Truck Trailer (WB-18m)

29

2.2.5.6. Auxiliary Lanes Three types of auxiliary lanes are provided at intersections. These are storage lanes, right turning lanes, acceleration lanes and deceleration lanes. The last two together are also called speed change lanes. Provision of these increases the capacity of intersection and improves safety. The length of these lanes depends on the volume of traffic entering or leaving the side road. The shape of these can be either parallel lane with sharp taper or a direct taper or with a transition curve. Fig. 2.6 shows the method of introducing addition lane using transition curves.

2.2.5.6.1. Storage lanes/right turning lanes Storage lines are generally more important in urban areas where volume of right turning traffic is high and if not catered for, blocks the through traffic. Normal design procedure provides for storage length based on 1.5 times the average number of vehicles (by vehicle type) that would store in turning lane at peak hour. At the same time the concurrent through lane storage must also be kept in view, as it may occur that the entry to turning lane may become inaccessible due to queued vehicles in through lane. Fig. 2.7 shows several methods of introducing turning lane at intersections. Figs. 2.8 and 2.9 show satisfactory method of widening at intersections and widening for turning lanes at intersections.

Fig 2.6: Method of Transition Curves at Points of Additional Lane

30

Fig 2.7: Provisions of Turning Lanes at Intersections

31

Fig 2.8: Method of Widening of Intersections

32

Fig 2.9: Method of Widening for Turning Lanes at Intersections

33

In places where not more than one or two vehicles are expected to wait for right turn, such as in rural areas, the storage lane may be provided as per Table 2.7. Table 2.6 Length of Right Turning Lane Design Speed (km/h)

Length of storage lane including 30 – 45 m taper

120

200

100

160

80

130

60

110

50

90

2.2.5.6.2. Speed Change Lanes Speed change lanes are more important in rural areas. In urban areas such lanes are rarely required but provision of short lanes to assist merging and diverging manoeuvres are provided in conjunction with channelising islands. Speed change lanes should are uniformly tapered and have a setback of 5.4m at the tangent point of curve leading into or out of minor road. The turning lane should be reduced in width to 4.25m by carriageway marking etc. as shown in Fig. 2.10.

Fig 2.10: Typical Dimension of Road Intersections

34

2.2.5.7. Channelising Island The objectives of providing channelising island are to i.

Control speed and path of vehicles at the intersection;

ii.

Control angle of conflict;

iii.

Separate conflicting traffic streams;

iv.

Provide shelter to vehicles waiting to carry out certain manoeuvres;

v.

Assist pedestrians to cross;

vi.

reduce excessive carriageway areas and thus limit vehicle paths; and

vii.

Locate traffic control devices.

The general types of island and their shapes are shown in Fig. 2.10. To ensure proper functioning of each type of islands, principles given below for each should be adhered to. 2.2.5.7.2. Corner or directed islands Figures 2.12 illustrate the design features of corner islands and the considerations which govern their sizes and shapes. Corner or Directional Islands (normally triangular) should meet the following requirements: a) Is should be of sufficient size to be readily identified and visible. For an island to be clearly seen it must have an area of at least 4.5m2 in urban areas and 7m2 in rural areas and should usually be bordered with painted raised kerbs. Smaller areas may be defined by pavement marking Accordingly triangular islands should not be less than 3.5m and preferably 4.5m on a side after rounding of curves. b) It should be offset from normal vehicle path by 0.3m to 0.6m. The layout should be tested using the track diagram for all turning movements. c) Is should be provided with illuminated sign or a bollard at suitable places e.g. apexes of islands. It should be of sufficient size to enable placement of such traffic control devices. d) It should be accompanied by suitable carriageway marking to show actual vehicle paths. Marking should be made conspicuous by use of refectories materials. e) Is should be properly marked for night visibility.

35

2.5.7.3. Centre or divisional islands Centre islands require careful location and designing. They require careful alignment and are invariably accompanied by widening of right-of-way. Centre or divisional islands should meet the following requirements. a) It should be preceded by a clearly marked or constructed natural area of not less than 1.5 sec. travel time at approach speed.

Fig 2.11: General Types and Shapes of Islands

36

Fig 2.12: Details of Triangular Island Design (kerbed island, no shoulder)

37

Fig 2.13: Progressive Layouts of T-Intersections for use on main Highways.

38

2.2.6. Definitions (1) At grade intersection

An intersection where all roadways join or cross at the same level.

(2) Diverging

The dividing of single stream traffic into separate streams.

(3) Intersection angles

The angle between two intersection legs.

(4) Merging

The converging of separate streams of traffic into a single stream.

Fig 2.14: Rotary Elements

(5) Rotary Intersection

A road junction laid out for movement of traffic in one direction round a central island.

(6) Rotary Island

A traffic island located in the centre of an intersection to compel movement in a clock-wise direction and thus substitute weaving of traffic around the island instead of direct crossing of vehicle pathways.

39

(7) Weaving

The combined movement of merging and diverging of traffic streams moving in the same general direction.

(8) Weaving length

The length of a section of a rotary in which weaving occurs.

2.2.7. Shape of Rotary Island The shape of the rotary island depends upon various factors such as the number and disposition of the intersecting roads and the traffic flow pattern. While finalising the shape of the rotary island, traffic streams within the rotary should be given dominance over the streams of traffic entering from different roads. Asymmetric shapes either wholly curved or with a combination of straight and curves may often provide the only satisfactory solution. Some of the more common shapes and disposition of the rotary islands are discussed below 2.2.7.1. Circular A circular shape is suited where roads of equal importance intersect at nearly equal angles and carry nearly equal volume of traffic, Fig.2.15, under these conditions, with a circular shape, a constant and regular flow is achieved.

Fig 2.15: Circular Shaped Rotary

40

2.2.7.2. Squarish with rounded edges This is a modification of the circular shape and is composed of four straights or four large radii curves roughly forming four sides of a square, Fig 2.16 and four small radii curves at the corners. The advantage of this layout is that it is suitable for predominantly straight ahead flows.

Fig 2.16: Squarish rotary with rounded edge

2.2.7.3. Elliptical, elongated, oval or rectangular shapes The above shapes are provided to favour through traffic, to suit the geometry of the intersecting legs, or to provide a longer weaving length. Fig 2.17 and 2.18 are illustrative.

41

Fig 2.17: Elliptical Rotary

Fig 2.18: Rectangular shape

42

2.2.7.4. Complex intersection with many approaches Fig 2.19 gives a layout of a complex intersection whose shape is dictated by the existence of a large number of approaches.

Fig 2.19: Layout of complex Rotary Intersection

43

CHAPTER 3: METHODOLOGY Major steps of the proposed methodology are as follows: 3.1 Review of relevant literature The research paper given by various researchers in this arena are reviewed and the relevant codal provisions in the IRC are being analyzed and their brief summary is being described in this thesis. 3.2 Selection of study area a) The study area includes old and new Bhopal, for satisfying heterogeneity of the problem as different conditions prevails in different junction areas. b) Following are the junctions that are taken under the scope of this study: i. J.K. road Intersection ii. Piplani Intersection iii. Jyoti Talkies Intersection iv. MANIT Intersection v. Mangalwara Intersection 3.3 Conducting Surveys For the understanding of the existing situations at the site and for getting the required true data, following surveys are being done: a) Total Station survey of the Intersections, to find out the existing or available cross section of all legs of Intersection, existing surroundings structures at that Intersection, space available and possibilities for modification and construction of all members of Intersection for future expansion. b) Traffic volume survey at all legs of Intersection. 3.4 Analysis of the surveyed data and design of intersections Then the analysis of the surveyed data is done in order to design the junction on the basis of the real time data and in accordance with the relevant IRC codal provisions.

44

CHAPTER 4: DEVELOPMENT OF MODIFIED INTERSECTIONS 4.1 Design of J.K. Road Intersection The intersection under consideration is a three legged intersection. The two legs are of Raisen road which is National Highway. This through route carries high intensity of traffic including heavy commercial vehicles. The third leg leads to JK Road which passes through many residential and commercial establishments and joins the Ayodhya By-Pass. At present the intersection is uncontrolled intersection as there are no pavement markings, physical dividers like median on through route, channelizing islands, traffic signals and no pedestrian crossing facilities. The situation is worsened by the encroachments on all three legs of the intersection. Visibility at night is very poor leading to possibility of conflicts. Therefore to design the Intersection for the safe and efficient functioning, peak hour traffic volume surveys at the intersection are carried out. The observations and recommendations for the intersection are as follows:1. The peak hour traffic volume of the three legged Intersection is found out as 6800 PCU per hour. This traffic intensity at the intersection is very high for the safe operation of traffic at the intersection in its present situation. 2. The intersection in its present situation is unable to handle the high volume of crossing and turning traffic especially during peak hours. The junction has become completely incapacitated and present traffic management measures are inadequate to deal with such a high intensity traffic volume. 3. At present there is no traffic signal at the intersection. It is suggested to provide traffic signals. This signalization should also have pedestrian timings. (IRC:93-1985). Traffic signal at the intersection needs to be designed based on real time data. 4. The junction should be signalized with necessary widening on all the legs of the intersection as shown in the drawing sheet. 5. Encroachment on all the three legs should be removed to enhance the capacity of the junction. 6. To streamline the vehicular traffic and to provide refuge to the pedestrians crossing the road channelizing islands are proposed as shown in the drawing sheet. 7. Necessary traffic signs and pavement markings need to be provided at the intersection. (IRC: 35-1997 and IRC: 67-2001).

45

8. No bus stops should be located within the 75 meter length from the junction. Therefore all the existing bus stops at the junction which lie within the 75 meter should be removed. Also the location of the bus stops should be at the farther side of the junction. 9. To enhance the visibility of the junction at night, it is recommended to provide High Mast light to lighten the junction area.

46

Fig 4.1: Existing Details of J.K. Road Intersection

47

Fig 4.2: Overlap of Existing and Proposed Details of J.K. Road Intersection

48

Fig 4.3: Details of Proposed J.K. Road Intersection

49

4.2 Design of Piplani Intersection The peak hour traffic volume survey at the Piplani Petrol Pump intersection was carried out. The observations and recommendations for the intersection are as follows:1. The peak hour traffic volume at the first three legged Intersection Sonagiri side i.e. considering the three legs is found out as 6000 PCU per hour. The peak hour traffic volume at the BHEL side i.e. considering the three legs is found out as 6500 PCU per hour. This traffic intensity at the intersection is very high for the safe operation of traffic at the intersection. 2. An at grade intersection having traffic volume in excess of 10000 PCU per hour, warrants for a grade separated intersection (IRC: 92-1985). In this case the total traffic volume at the staggered junction is 12500 PCU per hour which is very high and it warrants for a grade separated intersection. 3. The maximum volume that a traffic rotary can handle efficiently is about 3000 vehicles per hour entering from all intersection legs and rotaries are most adaptable where the volumes entering the different intersection legs are approximately equal. (IRC: 65-1976, Recommended Practice for Traffic Rotaries) 4. At present intersection gets locked frequently because of high volume of crossing and turning traffic especially during peak hours. The staggered junction has become completely incapacitated and present traffic management measures are inadequate to deal with such a high intensity traffic volume. 5. At present there is no traffic signal at both the intersections. It is suggested to provide traffic signals. 6. The junction should be signalized with necessary widening on all the legs of the intersection as shown in the drawing sheet. 7. Encroachment on all the four legs should be removed to enhance the capacity of the junction. 8. As traffic volume is very high, the available width of carriageway is insufficient to accommodate the vehicles. 9. To streamline the vehicular traffic and to provide refuge to the pedestrians channelizing islands are proposed as shown in the drawing sheet. 10. Necessary traffic signs and pavement markings need to be provided at the intersection. 11. Traffic signal at the intersection needs to be designed based on real time data.

50

Fig 4.4: Details of Existing Piplani Intersection

51

Fig 4.5: Overlap of Details of Existing and Proposed Piplani Intersection

52

Fig 4.6: Details of Proposed Piplani Intersection

53

4.3 Design of Jyoti Talkies Intersection The Jyoti Talkies intersection is a four legged intersection. The Board office leg & leg towards Chetak Bridge are the part of major road; this through route carries very high intensity of traffic. The third leg goes toward M.P. Nagar Zone-I and fourth leg towards M.P. Nagar Zone-II which are highly dense commercial areas, so both of these two legs also having high volume of Domestic Vehicles. At present the intersection is a Rotary intersection and is not having pavement marking, channelizing islands, traffic signals, medians for through route and no pedestrian crossing facilities. Therefore to design to intersection peak hour traffic volume surveys at the intersection has been carried out. The observations and recommendations are as follows: 1. The peak hour traffic volume of the four legged Intersection is found out as 5500 PCU/hour. The present situation is not fulfilling the safe and efficient operation of traffic due to high intensity of traffic volume. 2. An at grade Intersection having traffic volume in excess of 10000 PCU per hour, warrants for a grade separated Intersection (IRC: 92-1985). In this case the total traffic volume at the rotary Intersection is 5500 PCU per hour which is very high and it warrants for a grade separated Intersection. 3. The maximum volume that a traffic rotary can handle efficiently is about 3000 vehicles per hour entering from all Intersection legs (IRC: 65-1976). 4. The present Intersection gets locked frequently because of high volume of crossing and turning traffic especially during peak hours. The rotary junction has become completely incapacitated and present traffic management measures are inadequate to deal with such a high intensity traffic volume. 5. The junction should be signalized with necessary widening on all the legs of the Intersection as shown in the drawing sheet. 6. The channelizing islands should be provided to streamline the vehicular traffic and refuge for pedestrians crossing the road according to drawings. 7. The pavement marking & traffic signs should be provided at the intersection. (IRC: 35-1997 & IRC: 67-2001)

54

Fig 4.7: Details of Existing Jyoti Talkies Intersection

55

Fig 4.8: Overlap of Details of Existing and Proposed Jyoti Talkies Intersection

56

Fig 4.9: Details of Proposed Jyoti Talkies Intersection

57

4.4 Design of MANIT Intersection The intersection which is under consideration is a four legged intersection; one is towards Bittan Market, second is towards New Market, third is towards Nehru Nagar and fourth is towards MANIT. In this intersection three legs are having (Except MANIT Leg) high volume of traffic, all these three legs having residential and commercial establishments nearby. The Nehru Nagar leg is connected to Bhadbhada Road, which is have number of quarries, the Nehru Nagar leg and Bittan Market leg have traffic including heavy vehicles like trucks and dumpers. The Intersection is presently uncontrolled Intersection not having channelizing islands, traffic signals, pedestrian crossing facilities, pavement marking, visibility at night etc. The observations and recommendations for safe and efficient functioning of that intersection are as follows: 1. The peak hour traffic volume of the four legged Intersection is found out as 4800 PCU/Hr. The present situation is not fulfilling the safe operation of traffic. 2. Presently the Intersection is unable to handle the crossing and turning traffic at high volume during peak hours. 3. The capacity of Intersection is inefficient and traffic management measures are inadequate to deal with such high traffic volume intensity. 4. The existing Rotary diameter is inadequate so minimize the Rotary diameter according to given drawing, therefore heavy volume of traffic can be accommodate at the intersection. 5. All the legs should widened according to given drawings with providing channelizing islands at three major roads to streamline the traffic and provide refuge for pedestrians crossing the road. 6. The pavement marking & traffic signs should be provided at the intersection. (IRC 835-1997 & IRC: 67-2001) 7. The high mask light should be provided at junction area for better visibility at night. 8. Existing bus stops should be removed and locate it 75 meter away from intersection that too on the further side of the Intersection.

58

Fig 4.10: Existing Details of Manit Intersection

59

Fig 4.11: Proposed details of Manit Intersection

60

4.5 Design of Mangalwara Intersection Mangalwara junction is a five legged intersection and all the legs having high volume of traffic intensity. The intersection is surrounded by dense commercial as well as residential establishments. One of the leg which is Itwara road carries high intensity of traffic including heavy commercial vehicles due to transport business nearby, so that lot of commercial vehicles stand here and there for loading and unloading work, and create congestion of traffic every time. Presently the intersection is uncontrolled intersection and not having channelizing islands, traffic signals, pedestrian crossing facilities, pavement markings and high mask lights for proper night vision. Therefore to design the intersection for the safe and efficient functioning, three days peak hour traffic volume survey at the intersection was conducted. The observations & recommendation for the intersection are as follows: 1. The peak hour traffic volume of the five legged intersection is found out as 5200 PCU/hour. This traffic intensity is very high for the safe and efficient operation of traffic at the intersection in its present situation. 2. The cross section of intersection legs is unable to handle the high volume of crossing and turning traffic during peak hours. The junction become completely in capacitated such a high volume of traffic intensity. 3. Signals should be provided at the intersection. This signalization should also have pedestrian timings (IRC: 93-1985). The traffic signals should be designed based on real time data at that intersection. 4. All the five legs should be widened according to given drawings with providing channelizing islands to streamline the traffic and provide refuge for pedestrians crossing the road. 5. The pavement marking & traffic signs should be provided at the intersection (IRC: 35-1997 & IRC: 67-2001). 6. High mask light should be provided at junction area for better visibility at night.

61

Fig 4.12: Existing Details of Mangalwara Intersection

62

Fig 4.13: Overlap of Existing and Proposed Mangalwara Intersection

63

Fig 4.14: Details of Proposed Mangalwara Intersection

64

CHAPTER 5: CONCLUSIONS AND RECOMMENDATIONS 5.1 Conclusions and Recommendations 1. The increase in road accidents at intersections is one of the burning issues in the present situation as rapid growth of population coupled with increasing economical activities, particularly in the urban area play an important role for the tremendous growth in motor vehicle. 2. The number of fatalities and injuries as a result of accidents at intersection in Bhopal is serious enough to demand attention of responsible administrative authority. The total number of fatal accidents as well as related fatality at intersections in the city is increasing over the year. Persons killed per 100 accidents as high as 33 during the year 2009. 3. The buses are the most risky, as far as vehicle-wise accidents are concerned. Truck and three wheelers are the second and third most risky vehicles, respectively. 4. The intersections are redesigned according to IRC recommendations. 5. The intersection is the most important part of the roads and highways to give prime attention for their proper planning and designing. 6. If the traffic volume will exceeds the 10000 PCU per hour at an at-grade intersection, a separate grade intersection is suggested. 7. The junction should be free from encroachment on all the legs to enhance the capacity and proper visibility. 8. To streamline the vehicular traffic and to provide refuge to the pedestrians, channelising islands should be provided. 9. The necessary traffic signs and pavement markings need to be provided at the intersections 10. Traffic signals should be provided whenever required and their design should be based on real time data. 11. A road safety audit at intersections must be carried out by road professionals to compare existing characteristics of the intersections, that may be related to congestion 65

and accidents (width of carriageway, obstacles at the intersection, signalized or not, design of signal, visibility, channelising islands, quality of surfacing, traffic sign and marking etc) to standard characteristics meeting safety requirements. 12. On heavily trafficked intersections, more account should be taken of the needs of the pedestrians and cyclists.

66

REFERENCES 1) Indian Roads Congress, Guidelines for the Design of At-Grade Intersections in Rural and Urban Areas, IRC : SP-41-1994. 2) Indian Roads Congress, Recommended Practice for the Traffic Rotaries, IRC : 651976. 3) Indian Roads Congress, Geometric Design Standards for Urban Roads in Plains, IRC : 86-1983. 4) Indian Roads Congress, Space Standards for Roads in Urban Areas, IRC : 69-1977. 5) Indian Roads Congress, Guidelines for Pedestrian Facilities, IRC : 103-1988. 6) Indian Roads Congress, Dimensions and Weights of Road Design Vehicles, IRC : 31983. 7) National Crime Records Bureau, Accidental Deaths and Suicides in India, Ministry of Home Affairs, Government of India, New Delhi, 2008. 8) Vehicular Population Data, Regional Transport Office, Bhopal, 2009. 9) Kent J. Fugal, Mayor Tom Dale and Stephen J. Lewis, “Design for Single-Lane to Dual-Lane Roundabout Expandability”, May 2008, National Roundabout Conference 2008, Kansas City, Missouri. 10) Kay Fitzpatrick, Angelia H. Parham, and Mark D. Wooldridge, “Issues to consider in developing an Intersection Design Guide”, September 2002, Texas Transportation Institute. 11) Report on “Median Intersection Design for Rural High-Speed Divided Highways”, National Cooperative Highway Research Program report 650, 2010. 12) A synthesis of Highway Practice, “Modern Roundabouts

Practice in the United

States”, National Cooperative Highway Research Program Synthesis 264, 1998. 13) Bruce Hellinga “Signalized Intersection Analysis and Design – Implications of Dayto-Day Variability in Peak”. 14) Ragnhild Davidse, “Assisting the Older Driver”, 2007. 15) Kadiyali L.R., “Traffic Engineering and Transport Planning”, Khanna Publications, New Delhi 2008. 16) Khanna S.K. and Justo C.E.G., “Highway Engineering”, Nemchand Brothers, Roorkee, 2005.

67