REAM Guidelines On Geometric Design of Roads

F'OITEWORD Road Engineering Association of Malaysia (REAM), througlr the cooperation and support of various road authorities and engineering institutions in Malaysia, publishes a series of official

documents on STANDARD SPECIFICATIONS, GUIDELINES, MANUALS and TECHNICAL NOTES which are related to road engineering. The aim of such publications is to achieve quality and consistency in road and highway construction. The cooperating bodies are:-

Public Works Department, Malaysia Malaysian Highway Authority Institution of Engineers, Malaysia Institution of Highways & Transportation (Malaysian Branch)

The production of such documents are carried out through several stages. The documents are initially compiled/drafted by the relevant Technical Committee and subsequently scrutinised by the relevant Standing Committee of REAM. They are finally endorsed by road authorities and practitioners of road engineering at a conference/workshop before publication. REAM welcomes feedback and suggestions which can update and improve these documents.

This GUIDE ON GEOMETRIC DESIGN OF ROADS is the revision of the existing Arahan Teknik (Jalan) 8/86 "A Guide on Geometric Design of Roads" published by Jabatan Kerja Raya.

The revision was undertaken by the Standing Committee on Technology and Road Management of the Road Engineering Association of Malaysia (REAM) with the mandate given by the Director-General of Public Works Department, Malaysia.

The draft of this Arahan Teknik was presented and discussed at the Forum on Technology and Road Management in November 1997 and the 4th Maiaysian Road Conference in November 2000.

It is hoped that this Guide will will

address the shortcomings of Arahan Teknik (Jalan) 8/86 and be accepted by the highway engineering fraternity in the country.

ROAD ENGINEERING ASSOCIATION OF MALAYSIA 46-4, Jalan Bola Tarnpar 13114, Section 13,40100 Shah Alam, Selangor, Malaysia. Tel:603-55136521 Fax:603-55136523 e-mail:[email protected]

ROAD ENGINEERING ASSOCIATION OF MALAYSIA A GUIDE ON GEOMETRIC DESIGN OF ROADS TABLE OF CONTENTS PAGE NO.

INDEX

I.

INTRODUCTION

I

2.

ROAD CLASSIFICATIONS AND DESIGN STANDARDS

z

2.1

ROAD CLASSIFICATION / HIERARCHY

2

2.2

DESIGN STANDARDS FOR ROADS

5

2.3

ACCESS CONTROL

6

)4

SELECTION OF DESIGN STANDARDS

8

DESIGN CONTROL AND CRITERIA

A

11

J.l

TOPOGRAPHY AND LAND USE

ll

J.Z

TRAFFIC

12

3.3

DESIGN VEHICLES CHARACTERISTICS

l.+

J-+

SPEED

18

3.5

CAPACITY

20

ELEMENTS OF DESIGN

25

4.1

SIGHT DISTANCE

25

A'

HORIZONTAL ALIGNMENT

a1 J+

+.J

VERTICAL ALIGNMENT

44

4.4

COMBINATION OF HORIZONTAL AND VERTICAL

52

ALIGNMENT

5.

CROSS SECTION ELEMENTS

61

5.1

PAVEMENT

6l

5.2

LANE WIDTH & MARGINAL STRIPS

62

5.3

SHOULDERS

62

5.4

KERBS

66

5.5

SIDEWALKS

69

5.6

TRAFFIC BARRIERS

6q

5.7

MEDIANS

69

TABLE OF CONTENTS (Cont'd) INDEX

PAGE NO. 5.8

SERVICE ROADS

10

5.9

U-TURN

73

BRIDGE AND STRUCTURE CROSS SECTION

16

BUS LAYBYES

to

5.

l0

5.t

6.

I

OTHER ELEMENTS AFFECTING GEOMETRIC

DESIGN

6.I ROAD SAFETY 6.2 DRAINAGE 6.3 LIGHTING 6.4 UTILITIES 6.5 SIGNING AND MARKINGS 6.6 TRAFFIC SIGNALS 6.1 EROSION CONTROL, LANDSCAPE DEVELOPMENT AND ENVIRONMENTAL IMPACTS

80 80 80

8I 81

8I 8I 82

TABLE OF CONTENTS (Cont'd) TABLES

PAGE NO.

TABLE 2-I

CHARACTERISTICS OF ROAD CATEGORIES

A T

TABLE2-2A

SELECTION OF ACCESS CONTROL (RURAL)

8

TABLE2-28

SELECTION OF ACCESS CONTROL (URBAN)

8

TABLE 2-3

SELECTION OF DESIGN STANDARD

9

TABLE

DIMENSION OF DESIGN VEHICLES

14

TABLE 3-2A

DESIGN SPEED FOR RURAL ROADS

19

TABLE 3-2B

DESIGN SPEED FOR URBAN ROADS

1q

TABLE 3-3

CONVERSION FACTORS TO P.C.U.

2l

TABLE 3-4

LEVELS OF SERVICE

22

TABLE 3-5A

DESIGN LEVEL OF SERVICE AND VOLUME/

aA

3.1

CAPACITY RATIO (RURAL) TABLE 3-58

DESIGN LEVEL OF SERVICE AND VOLUME/

24

CAPACITY RATIO (URBAN) TABLE

4-1

TABLE4-2

MINIMUM STOPPING DISTANCE

zo

EFFECTS OF GRADES IN STOPPING SIGHT

2'7

DISTANCE _ WET CONDITIONS TABLE 4-3

DECISION SIGHT DISTANCE

28

TABLE 4-4

MINIMUM PASSING SIGHT DISTANCES

30

(2LANE-2WAY) TABLE 4-5

MINIMUM RADIUS

3s

TABLE 4-6

RELATIONSHIP OF DESIGN SPEED TO MAXIMUM

5l

RELATIVE PROFILE GRADIENTS

TABLE4.]A TABLE 4-78

TABLE 4-8 TABLE 4-9A

(RURAL) 38 DESIGN SUPERELEVATION TABLE (URBAN) 39 PAVEMENT WIDENING ON OPEN ROAD CURVES 43 MAXIMUM GRADES FOR RI. R2. Ul & U2 45 DESIGN SUPERELEVATION TABLE

STANDARD ROADS

TABLE 4-98

MAXIMUM GRADES FOR R3 AND R4 STANDARD 45 ROADS

TABLE 4-9C

MAXIMUM GRADES FOR U3 AND U4 STANDARD 45 ROADS

TABLE 4-9D

MAXIMUM GRADES FOR R5 STANDARD ROADS

TABLE 4-9E

MAXIMUM GRADES FOR U5 STANDARD ROADS

TABLE 4-9F

MAXIMUM GRADES FOR U6 AND R6 STANDARD ROADS

ul

A<

46

TABLE OF CONTENTS (Cont'd) TABLES

PAGE NO.

TABLE 4-1OA

CREST VERTICAL CURVE (K VALUES)

50

TABLE 4-IOB

SAG VERTICAL CURVE (K VALUES)

51

TABLE

TYPICAL PAVEMENT SURFACE TYPE

6l

TABLE 5-2

LANE & MARGINAL STRIP WIDTHS

6l

TABLE 5-3A

USABLE SHOULDER WiDTH (RURAL)

64

TABLE 5-3B

PAVED SHOULDER WIDTH (URBAN)

65

TABLE 5-4

PAVED SHOULDER WIDTH (RURAL)

65

TABLE 5-5A

MEDIAN WIDTH (RURAL)

70

TABLE 5-58

MEDIAN WrDTH (URBAN)

70

TABLE 5-6

DESIRABLE DISTANCE BETWEEN U-TURNS

74

5-1

TABLE OF CONTENTS (Cont'd) PAGES NO

FIGUR.ES

FIGURE 2-I

FLOW CHART FOR SELECION OFDESIGN STANDARDS IO

FIGURE

P DESIGN

FIGURE 3-3

VEHICLE SU DESIGN VEHICLE WB-15 DESIGN VEHICLE

FIGURE 3-4

RELATIONSHIP OF LEVEL OF SERVICE TO OPERATING 23

3-1

FIGURE 3-2

15

16

I1

SPEED AND VOLUME / CAPACITY RATIO FIGUR.E 4-1

MEASURING SIGHT DISTANCE ON PLAN

32

FIGURE 4-2

MEASURING SIGHT DISTANCE ON PROFILE

JJ

FIGURE 4-3

COMPARISON OF SIDE FRICTION FACTORS ASSUMED

35

FOR DESIGN OF DIFFERENT TYPES OF ROADS FIGURE 4-4

4]

DIAGRAMMATIC PROFILES SHOWING METHODS OF ATTAINiNG SUPERELEVATION

FIGURE 4-5

4't

CRITICAL LENGTHS OF GRADE FOR DESIGN FOR TYPICAL HEAVY TRUCK OF 180kg/kw.

-

|<

fr

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F

v)

a rI1

VE 1J i

33

A Guide on Geometric Design of Roads

4.2

HORIZONTAL ALIGNMENT

4.2.1

General In the design of horizontal curves, it is necessary to establish the proper relation between the design speed and curvature and also their joint relations with superelevation and side friction. From research and experience, limiting values have been established for the superelevation (e), and the coefficient of friction (fl.

4.2.2 Superelevation Rates The maximum rates of superelevation usable are controlled by several factors such as climatic conditions, terrain conditions and frequency of very slow moving vehicles that would be subjected to uncertain operation. While it is acknowledged that a range of values should be used, for practical purposes in establishing the design criteria for horizontal alignment, a maximum superelevation rate of 0.10 is used for roads in rural areas and 0.06 for roads in urban areas.

4.2.3 Minimum Radius The minimum radius is a limiting value of curvature for a given speed and is determined from the maximum rate of superelevation and the maximum allowable side friction factor. The minimum safe radius (Rmin) can be calculated from the standard curve formula.

Rmin =

v2 127 (e+f)

WhereRmin = minimum radius of circular curve (m)

V=

Design Speed (kph)

e = maximum superelevation

rate

f = maximum allowable side friction

34

factor

Design of Roads 4 Guile on Geometric

Figure 4-3 illustrates the range of side friction factors (0 that has been derived using imperial methods for the various types of roads. FIGURE 4-3 : COMPARISON OF SIDE FRICTION FACTORS ASSUMED FOR DESIGN OF DIFFERENT TYPES OF ROADS

ion between t ,ation and si

blished for

r,

0.5

f

Maximum side friclion ./ lactor tor new tyres on / wet concrete pavement

actors SUCh r g vehicles th 'ange of valu,

horizont areas and 0.( for

A ; H

E

0.4

1l concrete

Assum ed for design

lyres on s el

lvement

p

I

of turning roadways

I I

u'r

r..

5 E !

]-

Assumed for design of

f

1/ tow speed urban roads

f

O)

q)

f

(a

--t ruraland high speed urban highways

0.1

is determine kiction facto U

formula.

30

40

60

50

70

90

80

100

Speed (kph)

Table 4-5 lists the minimum radius to be used for the designated speed and maximum superelevation rates.

TABLE 4.5: MINIMUM RADIUS Minimum Radius (m)

Design Speed (kph) e

= 0.06

e

= 0.10

s60 465 335 284

s00 315

195 150 100

n5

4A

60

50

30

35

30

110 100

90 80 70 60 50

35

305

230 125 85

I

l0

A Guide on Geometric Design

of

Roads

While the values in Table 4-5 lists the minimum radius that can be used, it should be noted, that the above minimum radii will not provide the required stopping sight distance and passing site distance within typical cross-sections. Hence, all elforti should be made to design the horizontal curves with radii larger than the minimum values shown for greater comfort and safety.

4.2.4 Transition (Spirat) Curves Vehicles follow a transition path as it enters or leave a circular horizontal curye. To design with builrin safety, the alignment should be such that a driver travelling at the design speed will not only find it possible to confine his vehicle to the occupied lane but will be encouraged to do so. Spiral transition curves are used for this purpose. Generally, the Eulers spiral, also known as the clothoid is used. The degree of curve varies from zero at the tangent end of the spiral to the degree of the circular arc at the circular curve end. a road

a)

Length of Spiral The length of spirals to be used are normally calculated from the Spiral formula or from the empirical superelevation runoff lengths. The following formula is used by some for calculating the minimum length of a spiral:

, L= where

L = minimum

0.0702v' RC .,'

length of spiral;

V-

speed (kph);

R=

curvo radius; and

C=

rate of increase of centripetal accelerating (m/sec3)

The factor C is an imperial value and a range of lto 3 have been used for highways. Highways design does not normally require the level of precision achieved using this formula. A more practical control for determining the length of a spiral is that *fri.tt equal the length required for superelevation runoff. Superelevation runoff is the general term denoting the length of highway needed to accomplish the change in cross slope from a section with adverse crown removed to a fully superelevated sectjon or vice versa. Current practice indicates that the appearance aspect of superelevation runoff largely governs the length. The length of superelevation runoff should not exceed a longitudinal slope as indicated in Table 4-6.

36

A Guide on Geometric Design of Roads

TABLE 4.6: RELATIONSHIP OF DESIGN SPEED TO MAXIMUM RELATIVE PROFILE GRADIENTS Maximum Relative Gradients (and Equivalent Maximum Relative Slopes) for Profiles between the Edge of Two-Lane Travelled Way and the Centerline (Vo)

Design Speed v (kph)

0.75 (l:133) 0.70 (l:143) 0.65 (l:150) 0.60 (1:167) 0.55 (l:182) 0.50 (1:200) 0.48 (l:210) 0.45 (I:222) 0.42 (l:238)

30 40 50 60 70 80 90 100 110

Table 4-74 and 4-78 gives for the various design speeds and degree of curvature, the minimum lengths of spiral, the superelevation rates and the limiting curvature for which superelevation is not required.

For pavements with more than 2 lanes and standard lane width of 3.5m, the superelevation runoff lengths should be as follows.

(i)

3 lane pavements

(ii)

4?aneundivided pavements

-

(iii) 6 lane undivided

1.2 times the length

pavements

37

,i

-

for 2-lane roads.

1.5 times the length for 2 lane roads.

*

2.0 times the length for 2 lane

roads.

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v A Guide on Geometric Desigrr of Roads

5.9

U.TURN

5.9.1

General U-turns are categorised into two (2) types:

i)

Dedicated U-turn

- These U-turns are grade separated from the through

traffic.

This form of U-tum should be considered for high speed and high volume highway as the diverging and merging movements are on the slow lanes.

ii)

Median Opening U-turn.

5.9.2 Location of U-Turns U-turns may be required in the following circumstances:

a)

Beyond intersections to accommodate minor turning movements not otherwise provided in the intersection or interchange area.

b)

Just ahead of an intersection to accommodate U-turn movements that would interfere with through and other turning movements at the intersection. Where a fairly wide median on the approach roadway has few openings, U-turning is necessary to reach roadside areas. Advance separate openings for U-turn outside the intersection proper will reduce interference.

c)

In conjunction with minor crossroads where traffic is not permitted to cross the major road but instead is required to turn left, enter the through traffic stream, weave to the right, U-turn, then retum. On high-speed or high-volume roads, the difficulty and long lengths required for weaving with safety usually make this design pattern undesirable unless the volumes intercepted are light and the median is of adequate width. This condition may occur where a crossroad with high volume traffic, a shopping area, or other traffic generator that requires a median opening nearby.

d)

Locations occurring where regularly spaced openings facilitate maintenance operations, policing, repair service of stalled vehicles, or other highway-related activities. Openings for this purpose may be needed on controlled-access roads and on divided roads through undeveloped areas.

e)

Locations occuming on roads without control of access where median openings at optimum spacing are provided to serve existing frontage developments and at the sanre time minimize pressure for future ntedian openings.

The locations of U-turns are very important and traffic safety should be given due consideration. As a general guide, Table 5.6 can be used to detennine the desirable distances between U-turns.

13

A Guide on Geometric Design

TABLE 5.6 : DESIRABLE DISTANCE BETWEEN U.TURNS Distance Between U-Turns R6 R5 R4

No U-turns allowed

3km 2km

Design j Standard I U6 U5 U4 U3

Distance Between U-Turns No U-turns allowed

2km

lkm lkm

5.9.3 DesignConsideration u-turning vehicles interfere with through traffic by encroaching on part or all of the through traffic lanes. They are n11de uilo* speeds and the required speed change is normally mad^e the through traffic Ianes with weaving to and riom ttre outer lanes. As 91 such, U-turn facilities are potentialhazard areas. Careful consideration should be made to design and locate the u-turn that are safe for ail the road users. For direct u-turns, the width of the highway, including the median should be sufficient to permit the turn to be made without encroachment beyond the outer edges of the pavements' Figure 5'4 gives the minimum width of the median required for the various types of maneuvers for direct U_turns. The U-turn should be designed such that the through traffic approaching the U-turn are travelling at much lower than the highway desigipeed. Traffic signage and calming devices, etc. should be considered.

74

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A Guide on Geometric Design of Roads

5.10

5.10.1 Width of Shoulders The width of the usable shoulders should follow that as indicated in Table 5-3A and 5'38. The width of the shoulder of bridges and structures should be the same as that of the carriageway. Figures 5.5 show the typical bridge cross section.

5.10.2 Required Clearance (a)

(b)

The vertical height clearance of all structures above the roadway shall be a minimum of 5.3 meters over the entire width of traffic lanes, auxiliary Ianes and shoulders. It is recommended that an additional 0.1 meter be allowed for future pavement resurfacing. Whenever resurfacing will reduce the clearance to less than 5.3 meters, milling will be required to maintain the minimum clearance. For ciearance requirements over railways and waterways, reference should be

made to the relevant authorities. (cJ

5.11

Figure 5.6 indicates the clearance requirements for undemasses of various cross sections.

BUS LAYBYES Bus laybyes serve to remove the bus from the through traffic ianes. Its location and design should therefore provide ready access in the safest and most efficrent manner possible. The basic requirement is that the deceleration, standing and acceleration of the buses be effected on pavement areas clear of and separated fromihe through traffic lanes. The locations of bus laybyes are impoftant so as not to impede the normal flow of traffic. In this respect, bus laybyes must not be located on any interchange ramps or srmctures, slip roads or within 60 m of any junction or intersection. The distance between laybyes too should not be less than 150 m. Liaison will need to be made also with the relevant bus companies and the respective Local Authority.

For school areas, provision of bus laybyes and parkings areas should be specifically studied so as to ensure the unirnpederj flow of triffic. Figure 5.7 shows the typical layout and dimensions of bus laybyes that are to be used in both rural and urban areas. If possible, a dividing area between the outer edge of the roadway shoulder and the edge of the bus laybye lane should be provided. This dividing area should be as wide as possible but not less than 0.6 m. The pavement areas of the laybyes should be of concrete or other material fbr contrast in coiour and texture with the through traffic Ianes to discourage through traffic from encroaching on or entering the bus stop.

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