Arahan Teknik (Jalan) 8-86 - A Guide on Geometric Design of Roads

8/3/2019 Arahan Teknik (Jalan) 8-86 - A Guide on Geometric Design of Roads

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Roads BranchPublic Works Department Malaysia

Jalan Sultan Salahuddin50582 Kuala Lumpur

Arahan Teknik (Jalan) 8/86

5.0m0m

7.0m0m

A Guide on

Geometric Design of Roads


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Page 2ARAHAN TEKNIK ( JALAN ) 8/86


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ADDENDUM NO. 1

This Addendum to the 'ArahanTeknik Galan) 8/86 - A Guide on

Geometric Design of Roads' shall bemade part of this Arahan Teknik and

users shall incorporate thisAddendum into the Arahan Teknik(jalan) 8/86.

1.0 TABLE 3-2A DESIGN SPEED

(RURAL) and

TABLE 3-2B : DESIGNSPEED (URBAN), page 25

Tables 3-2A and 3-?~B shouldread as table 3-2A : DESIGN

SPEED (RURAL) (AMENDEDSEPT. 1989) and table 3-2B :DESIGN SPEED (URBAN)(AMENDED SEPT. 1989)respectively, herewith asattached to this Addendum.

2.0 GENERAL SUMMARY -GEOMETRIC DESIGN CRITE-RIA FOR ROADS INRURAL AREAS (METRIC),page 103

The above mentioned table issuperceeded by table 'GEN-ERAL SUMMARY - GEOMETRIC DESIGN CRITERIA FORROADS IN RURAL AREAS

(METRIC) (AMENDED SEPT.1989)' herewith attached tothis Addendum.

3.0 GENERAL SUMMARY -

GEOMETRIC DESIGN CRITE-RIA FOR ROADS IN URBANAREAS (METRIC),t4Age 104

The above mentioned table is

superceeded by table 'GEN-ERAL SUMMARY - GEOMET-RIC DESIGNED CRITERIAFOR ROADS IN URBANAREAS (METRIC) (AMENDED SEPT. 1989)' herewithattached to this Addendum.


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TABLE 3-2A : DESIGN SPEED (RURAL) (AMENDED SEPT. 1989)

TABLE 3-213:DESIGN SPEED (URBAN) (AMENDED SEPT. 1989)

DesignStandard

Design Speed ( km / hr )

Terrain

Flat Rolling Mountainous

R6

R5

R4

R3

R2

R1

R1a

120

100

90

70

60

40

40

100

80

70

60

50

30

30

80

60

60

50

40

20

20

DesignStandard

Design Speed ( km / hr )

Area Type

I II III

U6

U5

U4

U3

U2

U1

U1a

100

80

70

60

50

40

40

80

60

60

50

40

30

30

60

50

50

40

30

30

20


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Note :

Type I - Relatively free iri road location with verylittle problems ns regards land acquisition, affected buildings or

other socially sensitive areas.Type II - Intermediate between I and II.

Type III - Very restrictive in road location with problems as regards landacquisition, affected buildings and other sonsiltive areas.


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GENERAL SUMMARY - GEOMETRIC DESIGN CRITERIA FOR ROADS IN RURAL AREAS ( METRIC) x 4

0 1 DESIGN STANDARD - R 6 R 5 R 4 R 3 R 2 R 1 R 1A

2 ACCESS CONTROL - FULL PARTIAL PARTIAL PARTIAL NIL NIL NIL

3 TERRAIN - F R M F R M F R M F R M F R M F R M F R M

0 4 DESIGN SPEED Km/hr 120 100 80 100 80 60 90 70 60 70 60 50 60 50 40 40 30 20 40 30 20

5 I LANE WIDTH m 3.50 ! 3.50 ( 3.15 3.00 I 2.75 I (5.00)0 (4.50)0I 6 1 SHOULDER WIDTH I m 13.00 3.00 2.50 13.00 3.00 1.50 13.00 3.00 2.00 12.50 2.50 2.00 12.00 1.00 1.50 1.50 1.50 1.50 ; 1.Y 1.50 I N I

1;HOULOrE~R~ allRI~trIVRLJ m 1:00 1.00 1: 00 0.50 0.50 0_50 0.50

z 8 I MEDIAN WIDTH (MINIMUM) m'

6.0 5.0 4.0 1 4.0 3.5 3.0 ! 3.0 2.5 2.0 1 N/A N/A N/A j N/A

N 9 MEDIAN WIDTH (DESIRABLE) m 18.0 12.5 8.0 12.0 9.0 6.0 9.0 6.5 4.0 N/A N/A N/A N/A

N 10 MARGINAL STRIP (WIDTH) m 0.50 0.50 0.25 0.25 0.00 0.00 0.00

11 MINIMUM RESERVE WIDTH m 60 60(50)b

40(30)b

20 20 12 12

12 STOPPING SIGHT DISTANCE m 185 205 140 205 140 85 180 120 85 120 85 65 85 65 45 45 30 20 45 30 20

13 PASSING SIGHT DISTANCE m N/A 700 550 450 625 500 450 500 450 350 450 350 300 300 250 200 300 250 200

z 14 MINIMUM RADIUS m 570 375 230 375 230 125 300 175 125 175 125 85 125 85 50 50 30 15 50 30 15

15 MINIMUM LENGTH OF SPIRAL m SEE TABLE 4 - 4A N/A N/A

0 16 MAXIMUM SUPERELEVATION RATIO 0.10 0.10 0.10 0.10 0.10 0.10 0.10

17 MAXIMUM GRADE (DESIRABLE) % 2 3 4 3 4 5 4 5 6 5 6 7 6 7 8 7 8 9 10

W

W18 MAXIMUM GRADE % 5 6 7 6 7 8 7 8 9 8 9 10 9 10 12 10 12 15 25

19 CREST VERTICAL CURVE (K) - 120 60 30 60 30 15 45 22 15 22 15 10 15 10 10 10 5 5 10 5 5

20 SAG. VERTICAL CURVE (K) - 60 40 28 40 28 15 35 20 15 20 15 12 -15 --12- 10 -I- 8 8 10 8 8 I


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GENERAL SUMMARY - GEOMETRIC DESIGN CRITERIA FOR ROADS IN URBAN AREAS ( METRIC )

s I DESIGN STANDARD - U 6 U 5 U 4 U 3 U 2 U i U la

o ~ 2 ACCESS CONTROL - FULL PARTIAL PARTIAL PARTIAL/NIL NIL NIL NIL

uN 3 AREA TYPE - I II III i II Itl I II III i il III I II III I II III I 11 III

0 4 DESIGN SPEED Km/hr 100 80 60 80 60 50 70 60 50 60 50 40 50 40 30 40 30 20 40 30 10

1~~, ;

6 1;

1 A\1

uvE 1 zI 1Z

J.5u J.uu IJ . L J I a.uu I L.ia irn i

-

(4.50;n I

-

6 !7

SHOULDER WIDTH !?SHOULDER WIDTH

STRUCTURES >1Wm

mm

3.003.001.00

2.50 3.003.001.00

2.503.00 2.501.00

2.00 2.502.000.50

1.501

2.001.500.50

1.501

1.501.500.50

0.50~

1.501.500.50

1.501

8 MEDIAN WIDTH (MINIMUM!) m 14.0 3.50 3.00 3.00 2.50 2.00 2.50 2.00 1.50 2.00 1.50 1.00 N/A N/A N/A

9 MEDIAN WIDTH (DESIRABLE) m 112-009- 6.00 9.00 6.50 4.00 7.50 5.00 3.00 6.00 4.00 2.00 N/A N/A N/A

v 10 MARGINAL STRIP (WIDTH) m 0.50 0.50 0.25 0.25 0.00 0.00 0.00

11 MINIMUM RESERVE WIDTH m 60 50 40(30) b 30(20) b 20 11 12

12 STOPPING SIGHT DISTANCE m 205 140 85 140 85 65 115 85 65 85 65 45 65 45 30 45 30 20 45~ 30 20

13 PASSING SIGHT DISTANCE m N/A 550 450 350 500 450 350 450 350 300 350 300 250 300 250 200 300 250 200Z 14 MINIMUM RADIUS m 465 280 150 280 150 100 210 150 100 150 100 60 100 60 35 60 35 15 60 35 15

15 MINIMUM LENGTH OF SPIRAL m SEE TABLE 4 - 4B N/A N/A N/A0

0 16 MAXIMUM SUPERELEVATION RATIO 0.060.06 0.06 0.06 0.06 0.06 0.06

17 MAXIMUM GRADE (DESIRABLE) % 3 4 5 4 5 6 5 6 7 6 7 8 7 8 9 7 8 9 7 8 9

W 18 MAXIMUM GRADE % 6 7 8 7 8 9 8 9 10 9 10 12 10 12 15 10 12 15 10 12 15

W 19 CREST VERTICAL CURVE (K) - 60 30 15 30 15 10 22 15 10 15 10 10 10 10 5 10 5 5 10 5 5

20 SAG. VERTICAL CURVE (K) 1 - 40 28 15 28 15 12 120 15 12 15 12 10 12 10 8 10 8 8 10 8 8


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ERRATA

Replace section 5.14.2(c) (i) on pages 92 and 94 with the following :

Section 5.14.2 (c) Horizontal Alignment

(i) Minimum Radius

The following formula is used in determining the required. minimumradius for the curves.

R = V2.............127(e+f)

Where R = Minimum radius of curve in meters V = Designspeed, in km/hr

e = Maximum rate of superelevationJ- = Maximum allowable side friction factor.

Table 5-11 gives the minimum radius that are to be used in design. Flatter-curves should always be used wherever possible. There is no necessity toprovide any transition (spiral) curves.

Table 5-11: MINIMUM RADIUS FOR DESIGN

Design Speed (km/hr)Minimum Radius

e = 0.06 e = 0.10

203040506080100

120

153560100150280465

710

15305085

125230375

570


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CONTENTS

CHAPTER 1 - INTRODUCTION AND SUMMARY

1.1 Introduction

CHAPTER 2 - DESIGN STANDARDS AND ROAD CLASSIFICATION

2.1. Road Standards

2.1.1 Standardisation2.1.2 Rural and Urban Areas2.1.3 Application of Standards

2.2 Road Classification

2.2.1 Function of Road

2.3 Road Administration

2.4 Access Control

2.4.1 Degree of Control2.4.2 Application

2.5 Design Standards

2.5.1 Selection of Design Standard

CHAPTER 3 - DESIGN CONTROLS AND CRITERIA

3.1 Topography

3.2 Traffic

3.2.1 Average Daily Traffic (ADT)3.2.2 Design Hourly Volume (DHV)3.2.3 Design Hourly Volume Ratio (K)3.2.4 Directional Distribution Ratio (D)3.2.5 Traffic Composition

3.2.6 Projection of Traffic


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3.3 Design Vehicles and Characteristics

3.3.1 Design Vehicles3.3.2 Summary of Dimension of Design

Vehicle

3.4 Speed

3.4.1 Operating Speed3.4.2 Design Speed3.4.3 Design Section

3.5 Capacity

3.5.1 Capacity Under Ideal Conditions

3.5.2 Design Volume3.5.3 Service Volume3.5.4 Design level of service and

Volume/Capacity Ratio

CHAPTER 4 - ELEMENTS OF DESIGN

4.1 Sight Distance

4.1.1 General4.1.2. Stopping Sight Distance4.1.3 Passing Sight Distance4.1.4 Criteria For Measuring Sight

Distance

4.2 Horizontal Alignment

4.2.1 General4.2.2 Superelevation Rates4.2.3 Minimum Radius

4.2.4 Transition (Spiral) Curves

4.2.5 Methods of Attaining Superelevation4.2.6 Superelevation Runoff with Medians4.2.7 Pavement Widening on Curves4.2.8 Sight Distance on Horizontal Curves4.2.9 General Controls For Horizontal

Alignment


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4.3 Vertical Alignment

4.3.1 Maximum Grades4.3.2 Minimum Grades4.3.3 Critical Grade Length

4.3.4 Climbing Lanes for Two Lane Roads4.3.5 Passsing Lane Section on Two Lane

Road4.3.6 Climbing Lanes on Multi lane Roads4.3.7 Vertical Curves4.3.8 General Controls for Vertical

Alignment

4.4 Combination of Horizontal and Vertical Alignment

CHAPTER 5 - CROSS SECTION ELEMENTS

5.1 Pavement

5.1.1 Surface Types5.1.2 Normal Cross Slope

5.2 Lane Widths and Marginal Strip

5.3 Shoulders

5.3.1 General Characteristics5.3.2 Width of Shoulders5.3.3 Shoulder Cross Slope5.3.4 Shoulder Structure

5.4 Kerbs

5.4.1 General Considerations5.4.2 Types of Kerbs

5.5 Sidewalks

5.6 Traffic Barriers


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5.7 Medians

5.7.1 General5.7.2 Median Types and Width

5.8 Service Roads

5.8.1 General

5.8.2 Design Requirements

5.9 Pedestrian Crossings

5.9.1 General Considerations5.9.2 School Level Crossings

5.10 U-Turns

5.10.1 General Considerations5.10.2 Design Considerations

5.11 Bridge and Structure Cross Sections

5.11.1 Width of Shoulders5.11.2 Required Clearances

5.12 Bias Laybyes

5.13 Minimum Reserve Width

5.14 Exclusive Cycle Lanes

5.14.1 General Considerations .5.14.2 Elements of Design5.14.3 Cross-Section Elements5.14.4 Intersection Treatment


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CHAPTER 6 - OTHER ELEMENTS AFFECTING. GEOMETRICDESIGN

6.1 Road Safety

6.2 Drainage

6.3 Lighting

6.4 Utilities

6.5 Signing and markings

6.6 Traffic Signals

6.7 Erosion Control, Landscape Development andEnvironmental Impacts


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CHAPTER 1

INTRODUCTION AND SUMMARY

1.1 INTRODUCTION

This Arahan Teknik. is limitedto the geometric features of roaddesign as distinguished from struc-

tural design. It is intended as a com-prehensive manual on the geometricdesign of road, inclusive both in ruralas well as in urban conditions. Thegeometric design of road isonly applicable to Rural or Urban

areas as specifically indicated in thisArahan Teknik.

This Arahan Teknik is to beapplied to all new construction andimprovements of roads for vehiculartraffic undertaken by JKR.

Modifications and updating will becarried out from time to time. In thisrespect, comments from users will bemost welcomed.

This Arahan Teknik is to beused in conjunction with other

Arahan Tekniks that have been orwill be produced by CawanganJalan.

The design of at-grade inter-sections and interchanges are pre-

sented individually in separate

Companion Arahan Tekniks.


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CHAPTER 2.

DESIGN STANDARDS AND ROADCLASSIFICATIONS

2.1 ROAD STANDARDS

2.1.1 Standardisation

The geometric design of allroads need to be standardisedfor the following; reasons:

(a) to provide a uniformitythe design of roadsaccording to their per

formance requirements.(b) to provide a consistent,

safe and reliable roadfacilities for movementof traffic.

(c) to provide. a guide forless subjective deci

sions on road design.

2.1.2 Rural and Urban Areas

Urban areas are defined asareas having a population ofat least 1,000 where buildings

and houses are gathered andbusiness activity is prevalent.It covers all areas within thegazetted Municipality limitsand also includes areasexpected to becomeurbanised within the design

period. Rural areas can beregarded as areas other thanurban areas.

There is no fundamental difference in the principles ofdesign for rural and urban

roads. Roads in urban areas,however,are characterised bybusy pedestrian activities and

frequent stopping of vehicles

owing to short intersectionspacings and congested built-up areas. Lower designspeeds are usually adopted

for urban roads and differentcross-sectional elements are

applied to take into accountthe nature of traffic andadjoining land use. It is forthese reasons that variationsin certain aspects of geometric design are incorporated forthese two broad groups of

roads.

2.1.3 Application of Standards

The design standard is classi-fied into seven groups(R6,R5, R4,R3,R2,:R1 & R1a)

for rural areas and into sevengroups(U6,U5,U4,it3,U'2,U1,& Uta)for urban areas. These are indescending order of hierarchy.

Roads which function to provide long distance travel, willrequire higher, design speedswhilst road which serve localtraffic, where the effect ofspeed is less significant canhave a lower design speed.

Also roads with heavier trafficwill be provided with a higher

standard.


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DESIGN STANDARDS AND ROADCLASSFICATIONS

ARAHAN TEKNIK ( JALAN ) 8/86

(h) Srandard U1a :

Applied to local accessto low cost housingareas.

2.2 ROAD CLASSIFICATION

2.2.1 Function of Road

Each road has its functionaccording to its role either in

the National Network,Regional Network, StateNetwork or City/TownNetwork. The most basic function of a road is transportation. This can be further divid-

ed into two sub-functions;namely mobility and accessibility. However, these two sub-functions are in trade-off. Toenhance one, the other mustbe limited. In rural areas,roadsare divided into five cate

gories, namely, EXPRESSWAY, HIGHWAY, PRIMARYROAD, SECONDARY ROADand MINOR ROAD and inurban areas, roads are divid-ed into four categories, name-ly, EXPRESSWAY, ARTERI-

AL, COLLECTOR AND

LOCAL STREET. They are inascending order of accessibili-ty and thus in descendingorder of mobility.

2.2.2 Categories of Road

Roads are divided into twogroups by area, i.e. rural andurban. Roads in rural areas

are further classified into fivecategories by function namely

Expressway, Highway,Primary Road, SecondaryRoad and Minor Road andinto four categories in urbanarea, namely, Expressway,Arterial, Collector and LocalStreet. Their general. appli-

cations are as follows.

CHAPTER 2


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Page 18



(a) Expressway

An Expressway is adivided highway forthrough traffic with full

control of access andalways with grade sep

arations at all intersections.

In rural, areas, theyapply to the interstatehighways for through

traffic and make the

basic framework ofNational road transportation for fast travelling. They serve longtrips and provide higherspeed of travelling and

comfort. To maintainthis, they are fullyaccess-controlled andare designed to thehighest standards.

In urban areas, theyform the basic framework of road trans portation system inurbanised area forthrough traffic. Theyalso serve relatively

long trips and smoothtraffic flow and with full

access control andcomplements the RuralExpressway.

(b) Highways

They constitute theinterstate national network and complementsthe expressway net

work. They usually link

up directly or indirectlythe Federal Capitals,State capitals andpoints of entry/exit to

the country. They serveong to intermediate trip

lengths. Speed serviceis not so important asin an Expressway butrelatively high to medium speed is necessary.Smooth traffic is provid-ed with partial access

control.

(c) Primary Roads

They constitute themajor roads formingthe basic network of

the road transportationsystem within a state.They serve intermedi-ate trip lengths andmedium travellingspeeds. Smooth traffic

is provided with partialaccess control Theyusually link up theState! Capitals andDistrict Capitals orother Major Towns.

(d) Secondary Roads

They constitute themajor roads formingthe basic network ofthe road transportationsystem within a District

or RegionalDevelopment Areas.They serve intermedi-ate trip lengths withpartial access control.

CHAPTER 2


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Page 19



They usually link up the

raajor towns within theDistrict or RegionalDevelopment Areas.

(e) Minor Roads

They apply to all roadsother than thosedescribed above in therural areas. They formthe basic road networkwithin a Land Schemeor other inhabited

areas in a rural area.

They also includeroads with special func-tions such as holidayresort roads, securityroads or access roadsto microwave stations.

They serve mainly localtraffic with short triplengths and are usuallywith partial or noaccess control.

(f) Arterials

An arterial is a conti-nous road with partialaccess control forthrough traffic withinurban areas. Basically

it conveys traffic fromresidential areas to the

vicinity of the centralbusiness district orfrom one part of a cityto another which doesnot intend to penetrate

the city centre .Arterials do not pene-trate identifiable neighbourhoods. Smoothtraffic flow is essential

since it carries large

traffic volume.

(g) Collectors

A collector road is aroad with partial access

control designed toserve on a collector ordistributor of trafficbetween the arterialand the local road sys-tems. Collectors arethe major roads which

penetrate and serve

identifiable neighbourhoods, commercialareas and industrialareas.

(h) Local Streets

The local street systemis the basic road net-work within a neighbourhood and servesprimarily to offer directaccess to abutting land.

They are links to thecollector road and thusserve short trip lengths.Through traffic shouldbe discouraged.

CHAPTER 2


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2.3 ROAD ADMINISTRATION

For the purposes of roadadministration, roads are clas-sified as Federal, State, Local

Authority (City Hall, Municipalor Local Council) or Kampong(District Office) Roads

depending upon their jurisdic-tion.

(a) Federal Roads areroads that are gazettedunder the FederalRoad ordinance and

are usually roads link-ing the State Capitals,Airports, RailwayStations and Ports.Roads within theFELDA Land Schemes

and those in otherRegional LandSchemes constructedwith Federal Fundsalso fall under this cat-egory. The maintnanceof these roads are the

responsibility of theFederal Governmentand is done through theState JKR with fundsfrom the FederalGovernment.

(b) State Roads are all the

other roads within theState outside the jurisdiction of the LocalAuthority or DistrictOffice, built to JKR

standards. They arenormally constructedwith State Funds. Themaintenance of theseroads are the responsi-

bility of the State

Government and isdone through the StateJKR.

(c) Local Authority Roadsare all those roads

within the limits of theLocal Authority and arenormally maintained bythe responsible localauthority.

(d) Kampong (District

Office) Roads are all

those roads directlyunder the jurisdiction ofthe District Office. Theyare usually earth roadswith no right of way.The maintenance of

these roads are theresponsibility of theDistrict Office.

2.4 ACCESS CONTROL

2.4.1 Degree of Control

Access control is the conditionwhere the right of owners oroccupants of abutting land orother persons to access, in

connection with a road is fully

or partially controlled by thepublic authority.

Control of access is usuallyclassified into three types forits degree of control, namely

full control, partial control andnon-control of access

CHAPTER 2


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Full Control of Access mean

that preference is given tothrough traffic by providingaccess connecting with selected public roads only and by

prohibiting crossings at gradeor direct private driveway con

nections.

Partial Control of Accessmeans that preference isgiven to through traffic to adegree that in addition toaccess connection with select-

ed public roads, there may be

some crossings traffickedroads, at grade intersectionsshould be limited and onlyallowed at selected locations.To compensate for the limitedaccess to fully or partially

access controlled roads,frontage or service roads aresometimes attached to thesides of the main roads.

In Non Control Access, thereis basically no limitations of

access.

2.4.2 Application

The selection of the degree ofcontrol required is important

so as to preserve the as builtcapacity of the road as well as

improved safety to all roadusers. Two aspects pertainingto the degree of control is tobe noted.

(a) during the time ofdesign in the consider-ation of accesses toexisting developments.

(b) after the completion of

the road in the controlof accesses to futuredevelopments.

The selection of degree ofaccess control depends on

traffic volumes, function of theroad and the road networkaround the areas. Table 2-2Aand 2-2B is general guide forthe selection of degree ofaccess control.

CHAPTER 2


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CHAPTER 2

TABLE 2--2A: ACCESS CONTROL (RURAL)

TABLE 2-2B: ACCESS CONTROL (URBAN)

NOTE :

F = Full Control of AccessP = Partial Control of AccessN = No Control of Access

Road CatagoryDesign Standard

R6 R5 R4 R3 R2 R1 / R1a

Expressway

HighwayPrimary RoadSecondry RoadMinor Road

F

----

-

PP--

-

-PP-

-

--P-

-

---N

-

---N

Road CatagoryDesign Standard

U6 U5 U4 U3 U2 U1 / U1a

ExpresswayArterial

CollectorLocal Street

F-

--

-P

--

-P

P-

--

PN

--

-N

--

-N


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Page 23



CHAPTER 2

2.5 DESIGN STANDARDS

The design standards used for various categories of roads are asshown in Table 2-3

TABLE 2-3: DESIGN STANDARDS

2.5.1 Selection of :Design Standard

The selection of the required design standard should begin with the assessment ofthe function of the proposed road and the area it traverses. This should generally bedone in conjunction with the Highway Planning Unit of the Ministry of Works. If there

is an overlapping of function, the ultimate function of the road shall be used for theselection criteria. The projected ADT at the end of the design life should then be calculated and from Table 2-3, the required design standard can be obtained. From thecapacity analysis (as in Chapter 3) the required number of lanes can then be calculat-ed.Figure 2--1 gives a flow chart indicating the processes for the selection of the,requireddesign standard.

Area Road Catagory

Projected ADT

AllTraffic

Volume

>100,00

10,000to

3,000

3,000to

1,000

1,000to

150

180 R-1- 230 R'-' 1100 R 2 880 Rar 680 R2510 R R'100 R' 68 R> 52 M39 39 MORE

M- 340- 20- 2309 1100>n 880- 670} 520;*- 68~ 52=- 39>

~-8U R-Ir

11-- R 1 30 R=340 R - 2 8 0 0 R ~ Z% R ICU I t - 4u R al.iI f -

a

180~' 150s- 130- 340- 280- 230y 190- J7~'

R~t150 R~-100 8286 R ~180 R~150 R'130 R'110 R'`24 1

86' 180' 150- 130=- 110=- 24 , . y

R264 R;!'150 R y100 R286 8274 4'-16

Note:64~8260

86aR265

74~R251

16~R' 15

1.25

is

65'R260

578245

154

45:

R238

1.75

35>

R2-- 35 2, 4

e


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Page 57

ELEMENTS OF DESIGN


attained owner the

superelavation runofflength with most of all,of' the wideningattained at the start of

circular curve point.

4.2.8 Sight Distance on HorizontalCurves

Another element of horizontallignment is the sight distanceacross the inside of curves.Where there are sight oba-

tructions (such as walls, cut

slopes, buildings andguardrails),a design to provideadequate sight distance mayrequire adjustment in the nor-mal road cross-section orchange) in alignment if the

obstruction cannot beremoved. Using the designspeed and a selected sightdistance as a control, thedesigner should check theactual condition and make the

necessary adjustments in themanner most fitting to provideadequate sight distance

4.2.9 General Controls forHorizontal Alignment

In addition to the specificdesign elements for horicontal

alignment, a number of gener-al controls are recognised andshould be used. These con-trols are not subject to empiri-cal or formula derivation but

are important for the attain-ment of safe and smooth-flow-ing roads. These are:

(a) The horizontal align-

ment should,be consis-tent with the topogra-phy and with preserv-ing developed proper

ties and community val-ues. Winding alignment

composed of shortcurves should beavoided. On the otherhand too long a straightshould also be avoided.

(b) The use of the mini-

mum radius for the par-

ticular design speedshould be avoidedwherever possible.Generally flat curvesshould be used, retain-ing the maximum for

the most critical condi-tions.

(c) Consistent alignmentshould always besought. Sharp curves

should not be intro-duced at the end oflong tangent. Wheresharp curves must beintroduced, it should beapproached, wherepossaible, by succes-

sively sharper curvesfrom the generally flat

curvature.

(d) For small deflectionangles, curves shouldbe sufficiently long to

avoid the appearanceof a kink. Curvesshould be at least150m long for a centralangle of` 50 and the

CHAPTER 4


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Page 58

ELEMENTS OF DESIGN


length should be

increased 30 m foreach 10 decrease inthe central angle

(e) Any abrupt. reversal inalignment should be

avoided. The distancebetween reversecurves should be thesum of the supreleva-tion runoff lengths andthe tangent runoutlengths.

(f) The 'broken back'arrangement of curvesshould be avoided. Ilseof spiral transitions or acompound curve align-ment is preferable for

such conditions if it. isunavoidable.

4.3 VERTICAL ALIGNMENT

4.3.1 Maximum Grades

The vertical profile of roadaffect the performance of

vehicles. The effect of gradeson trucks which have weight

power ratio of about 300lb/hp, is considered. Themaximum grade controls interms of design speed is sum-marised in Table 4-6

CHAPTER 4


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ELEMENTS OF DESIGN


4.3.2 Minimum grades

A desirable minimum grade or0.5 percent should be used. Agrade of 0.35 percent may beallowable where a high typepavement. accurately crownedis used. On straight stretchestraversing across wide areas

of low lying swamp use ofeven flatter grades may beallowable with prior approval.

4.3.3 Critical Grade Length

The term " critical grade

length" indicate the maximumlength of a designated

upgrade upon which a loadedtruck can operate without an

unreasonable reduction inspeed.

To establish the design vlauesfor critical grade lengths" forwhich gradeability of trucks is

the determining factor, the following assumptions are made:

(i) The weight-power ratioof a loaded truck is about 300 lb /hp .

(ii) The average runningspeed as related todesign speed is used to

CHAPTER 4

TABLE 4-6 : MAXIMUM GRADES

The desirable maximum should be aimed at in most cases. The maximumgrades should be used infrequently. The total upgrade for any section of roadshould not exceed 3000m, unless the grade is less than 4%.

Design Speed( km/hr )

Desirable MaximumGrade ( % )

Maximum Grade( % )

120100806050

4030

20

23456

78

9

56789

1012

15

Road StandardR1a

10 25


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ELEMENTS OF DESIGN


approximate the speed

of vehicles beginningand uphill climb.

(iii) A maximum reduction

in speed to half thedesign speed is

allowed for designspeeds of 80km/hr orabove except fordesign speeds of 50and 40km/hr where theallowable minimumspeeds are 30 and

25km/hr respectively.

The critical gradelengths for the variousspeeds are as shodmin Table 4-7.

Where a particular section ismade up of a combination ofupgrades, the length of criticalgrade should take into consid-eration, the entire section ofthe combination. A speed

reduction/recovery curveshould be plotted to determinethe critical grade length baseon the assumptions usedabove. Figure 4-2 gives theacceleration and decelerationcurves that can be used for

this purpose.

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ELEMENTS OF DESIGN


CHAPTER 4

Design Speed Gradient ( % ) Critical Grade

Length ( m )

120 345

500400300

100 456

500400300

80 567

500400300

60 678

300250200

50 789

250200170

40 8

910

200

170150

30 - Not defined - decisionleft to designer

20 - Not defined - decisionleft to designer


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ELEMENTS OF DESIGN


CHAPTER 4


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ELEMENTS OF DESIGN


Where the length of critical

grade is exceeded and espe-cially where grades exceed5%, consideration should begiven to providing an added

uphill lane, that is, the climb-ing lane, for slow moving vehi-

cles, particularly where thevolume is at or near capacityand the truck volume is high.

4.3.4 Climbing Lanes for Two LanedRoads

Climbing lanes are desirable

and should be consideredwhere the critical gradelengths are exceeded andprovided the volume of trafficand percentage of trucks justi-fy the additional cost. An

exception to the above wouldbe where overidding safetyconsiderations dictate theaddition of the climbing laneregardless of grade or trafficvolume. Where climbing lanes

are provided, the followingrequirements are to be fol-lowed.

(a) the climbing laneshould begin rear thefoot of the grade and

should be preceded bya tapered section of at

least. 50m long.

(b) the width of the -lirn-bing lane should be thesame as the main car-

riageway lane widthand in any case shouldnot be less than 3.25m.

(c) the section of the road

must be separated by aNew Jersey TypeConcrete Median withadequate signing and

markings and theopposing lane widened

also to 2 lanes to makeit a four-lane dividedcarriageway.

(d) the climbing laneshould end at least60m beyond the crest

and in particular should

be at a point where thesight- distance is suffi-cient to permit passingwith safety. In addition,a corresponding taperlength as in (a) of

100m should be provid-ed.

(e) the shoulder on theouter edge of the climb-ing lane should N a5

wide as the shoulderon the normal twolaved section, Whereconditions dictate oth-erwise, a usable stsulder widtn of 1.25m isacceptable.

4.3.5 Passing Lane Sections andLaybyes on Two-Lane Roads

Where a sufficient numberand length of safe passing

section cannot be obtained inthe design of horizontal andvertical alignment alone, anoccasional section of fourlanes may be introduced to

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ELEMENTS OF DESIGN


provide more sections and

length safe for passing. Suchsection are particularly advan-tageous in rolling terrain,especially where the align-

ment is winding or where thevertical profile includes critical

lengths of grade. Four lanesections should be sufficientlylong to permit its effectiveusage.

The sections of four lanesintroduced need not be divid-

ed. The use of a median,

however is advantageous andshoed be considered on roadscarrying 500 vehicles per houror more.

The transitions between the

two lane and four lane pave-ments should be locatedwhere the change in width isin full view of the driver.Sections of four-lane road,particularly divided sections

should not be longer than 3km so as to ensure that triedriver, does not lose hisawareness that the road isbasically a two lane facility.

Where four lane sections are

riot practical, passing laybyesmay be introduced at regular

intervals. This passing laybyemust be at least 1'000rri longand of full lane width and pre-ceded by a taper of 50m atthe beginning and 100m at

the end.

4.3.6 Climbing Lanes on Multilane

Roads

Multilane roats more frequent-ly have sufficient capacity to

handle their traffic load,including the normal percent-

age of slow-moving vehicleswithout becoming congested.However where the volume isat or neat, capacity and thetruck volume is high so as tointerfere with the normal flowof traffic, climbing lanes

should be considered.

4.3.1 Vertical Curves

Vertical curves are used toeffect a gradual charge

between tangent grades. Theyshould be simple in applica-tion and should result in adesign that is safe, comfort-able in operation, pleasing inappearance and adequate for

drainage. For simplicity, theparabolic curve with an equiv-alen-G vertical axis centeredon the vertical point of inter-section is used.

The rate of change of grade to

successive points on thecurve is a constant amount for

equal increments of horizontaldistance, and equals the alge-braic difference between theintersecting tangent gradesdivided by the length of curve

or A/L in percent per metere.The reciprocal L/A is the hori-zontal distance in metrerequired to ef:fec;t a 1 percentchange in gradient and is

CHAPTER 4


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ELEMENTS OF DESIGN


a measure of curvature. This

quantity (L/A), termed k, isused in determining the hori-zontal distance from thebegining of the vertical curve

to the apex or low point of thecurve. The k value is also

useful in determining the mini-mum lengths of vertical curvesfor the various des isanspeeds.

The lengths of vertical curvesused should be as long as

possible and above the mini-

mum values for the designspeeds where economicallyfeasible.

(a) Crest vertical curves

Minimum lengths ofcrest vertical curvesare determined by thesight distance require-ments. The Stoppingsight distance is the

major control for thesafe operation at thedesign speed chosen.Passing sight distancesare not used as it pro-vides for an. uneco-nomical design. An

exception may be atdecision. areas such as

sight distance to rampexit gores where longerlengths are necessary.

The basic formulas for length

of a parabclic vertical curve interms of algebraic differencein grade and sight distance(using an eye height of 0.92m

and object height of 0.15m)are as follows:

Where S is less than L,

L = AS2....................

405

Where S is greater than L,

L = 2S - 405........

A

Where :

L = length of verticalcurve(m)

S = sight distance (m)

A = algebraic difference ingrades (percent)

Table 4-8 indicates the mini-mum k values that are to beused design for the variousdesign speeds.

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ELEMENTS OF DESIGN


(b) Sag Vertical curves

At least four different criteria forestablishing lengths of snagvertical curves are recognised.These are (1) headlight sightdistance, (2) rider comfort, (3)

drainage control and (4) a ruleof thumb for general appear-ance. However, the headlightsight distance basis appears tobe the most logical for generaluse and this criterion is used to

establish the design values fora range of lengths of sag verti-cal curves. It is again conven-ient to express the design con-trol in terms of the k value.

Table 4-9 indicates the minimutr, kvalues that are to be used.

Longer curves are desired whereverfeasible and should be used butwhere k values in excess of 55 art-USF:d, special attention to drainage

must be exercised. Shorter sag verti-cal curves may be justified for eco-nomic reasons, in cases where anexisting element, such as a. structurewhich is not ready for rei)lace:mentcontrols the vertical profile.

Drainage of curbed pavements areespecially important on sag verticalcurves where a grade line of not lessthan 0.3 percent ;within 15m of thelevel point must be maintained.

CHAPTER 4

TABLE 4-8 CREST VERTICAL CURVE (k values)

Design Speed

( km/hr )

120 100 80 60 50 40 30 20

Minimum k value 120 60 30 15 10 10 5 5

TABLE 4-9 SAG VERTICAL CURVE (k values)

Design Speed( km/hr )

120 100 80 60 50 40 30 20

Minimum k value 60 40 28 15 12 10 8 8


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ELEMENTS OF DESIGN


4.3. 8 General Controls For Vertical

Alignment

In addition to the specific con-trols, there are several gener-

al. controls that should beconsidered.

(a) A smooth gradelinewith gradual changesshould be strived for inpreference to a linewith numerous breaksand short lengths of

grade. While the maxi-

mum grade and thecritcal length are con-trols, the manner inwhich they are appliedand fitted to the terrainon a. continous line

determines the suitabili-ty and appearance ofthe finished product.

(b) The 'roller coaster' orthe 'hidden-dip' type of

profile should be avoid-ed. They are avoidedby use of horizontalcurves or by moregradual grades.

(c) A broken back grade-

line should be avoiled,particularly in sags

where the full view, ofboth vertical curves isnot pleasing. This effectis very notice able endivided roadways with

open median sections

(d) On long grades, it is

preferable to place thesteepest grade at thebottom and lighten thegrades near the top of

the ascent or to breakthe sustained grade

by short intervals oflighter grade instead ofa uniformed sustainedgrade that might beonly slightly below theallowable minimum.

(e) Where intersections at

grad occur on sectionswith moderate to steepgrades, it is desirableto reduce the gradientthrough the intersec-tion.

4.4 COMBINATION OF HORIZON-TAL AND VERTICAL ALIGN-MENT

Horizontal and vertical align-ment should not be designedindepeni-Jilently. They com-plement each other.Excellence in their design and

in the design of their combina-tion increase utility and safety,

encourage uniform speed,and improve appeararce,almost always without addi-tional cost.

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ELEMENTS OF DESIGN


Proper combination of hori-

zontal alignment and profile isobtained by engineering studyand consideration of the fol-lowing general controls.

(a) Curvature and grades

should be in proper bal-ance. Tangent align-ment or flat curvatureat the expense of steepor long grades, andexcessive curvaturewith flat grades, are

both poor design. A log-

ical design is a compro-mise between the two,which offers the most insafety, capacity, easeand uniformity of oper-ation, and pleasing

appearance within thepractical limits of terrainand area traversed.

(b) Vertical curvaturesuperimposed upon

horizontal curvature, orvice versa, generallyresults in a more pleas-ing facility but it shouldbe analyzed for effectupon traffic. Successivechanges in profile rot in

combination with hori-zontal curvature may,

result in a series ofhumps visible to thedriver for some dis-tance, a hazardouscondition.

(c) Sharp horizontal curva-ture should not beintroduced at or nearthe top of a pro-

nounced crest vertical

curve. This condition ishazardous in that thedriver carinot perceivethe horizontal change

in alignment, especiallyat night when the head-

light beams go straightahead into space. Thehazard of this arrange-merit is avoided if thehorizontal curvatureleads the vertical cur-vature, i.e. the horizon-

tal curve is made

longer than the verticalcurve. Also, suitabledesign can be made byusing design valueswell above the mini-mums for the design

speed.

(d) Somewhat allied to theabove, sharp horizontalcurvature should not beintroduced at or near

the low point of a pro-nounced sag verticalcurve. Because theroad ahead is fore-shortened any but flathorizontal curvatureassumes an undesir-

able distorted appear-ance. Further, vehicular

speeds, particularly oftrucks, often are high atthe bottom of gradesand erratic operationmay result, especially

at night.

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ELEMENTS OF DESIGN


(e) On 2-lane roads the

need for safe passingsections at frequentintervals and for, anappreciable percentage

of the length of theroad often supersedes

the general desirabilityfor combination of hori-zontal and verticalalignment. In thesecases it is necessary towork toward long tan-gent sections to secure

sufficient passing sight

distance in design.

(f) Horizontal curvatureand profile should bemade as Qat as feasi-

ble at intersectionswhere sight distancea1mg both roads isimportant and vehiclesmay have to slowdown or stop.

(g) On divided roads, vari-ation in the width ofmedian, and the use ofseparate profiles andhorizontal alignmentsshould be considered

to derive design andoperational advantages

of one-way roadways.Where traffic justifiesprovision of 4 lanes, asuperior design withoutadditional cost general-

ly results from the con-cept and logical designbasis of oneway road-ways

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CHAPTER 5

CROSS SECTION ELEMENTS

5.1. PAVEMENT

5.1.1 Surface Type

The selection of the pavement

type is determined by the vol-

ume and composition of traf-fic, soil characteristics, weath-er, availability of materials, theinitial cost and the overallannual maintenance and serv-ice life cost.

Pavements may be consid-ered as three general types -high, intermediate and low.High type pavements are justi-fied for high volume traffic for

which it is fitting that the sur-face have smooth riding quali-ties and good nonskid proper-ties in all weather.Intermediate type pavementvary from those only slightlyless costly and with somewhat

less strength than high typepavements to surface treat-

ments. Low type pavementsrange from surface treatedearth roads and stabilized,materials to loose surfacesuch as earth and gravel.

The important characteristics

of surface type in relation togeometric design are the abili-ty of a surface to retain theshape and dimensions, the

ability to drain, and the effecton driver's behavior. Table 5-1

gives the general selection ofthe pavement surface typesfor the various road stan-dards. For minor roads ofgrades exceeding 8%, thesurface and shoulder shouldbe sealed to prevent erosion.

The structural design of thepavement should be in accor-dance to Arahan Teknik(Jalan) - 5/85 "Manual OnPavement Design''.


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CHAPTER 5

TABLE 5-1 : PAVEMENT SURFACE TYPE

Where : H : High Type Pavement

I : Intermediate Type Pavemant

L : Low Type Pavement

Design Standard PavementType

Description

R6 / U6 H / H Asphaltic Concrete / Concrete

R5 / U5 H / H Asphaltic Concrete / Concrete

R4 / U4 I / H Dense Bituminous Macadam / Asphaltic Concrete / Concrete

R3 / U3 I / I Bitumenous Macadam / Concrete

R2 / U2 I / I Surface Treatment / Semigrout

R1 / U1 L / I Earth Gravel / Semigrout

R1a / U1a L Surface Treatment / Semigrout


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5.2 LANE WIDTHS AND MARGINALSTRIPS

Lane widtlis and the conditionof the pavement surface arethe most important features ofa road pertaining to the safetyand comfort of driving, The

capacity of a highway ismarkedly affected by the 'lane

width and in a capacity sense,the effective width of a trav-elled way, is further reducedwhen adjacent obstructions

such as retaining walls, bridgepiers and parked cars restrictthe lateral clearance.

Marginal strip is a narrowpavement strip attached to

both edges of a carriageway.It is paved to the same stan-dard as the pavement struc-tures. For divided roads, themarginal strips are providedon both sides of the carriage-

way in both directions. Themarginal strip is included aspart of the shoulder width andis demarcated from the

through lane by lane edgemarkings on the marginalstrip.

Table 5-3 indicates the laneand marginal strip widths thatare to be used for the variousroad standards.

CHAPTER 5

5.1.2 Normal Cross Slope

Cross slopes are an important element in the cross-section designand a reasonably steep lateral slope is desirable to minimise waterponding on flat sections of uncurbed pavements due to pavement

imperfections or unequal settlements and to control the flow of wateradjacent to the curb on curbed pavements. Table 5-2 indicates the

range of cross slopes for various pavement types.

TABLE 5-2: NORMAL PAVEMENTS CROSS SLOPE

Surface Type Cross Slope Rate ( percent )

High

Intermediate

Low

2.5

2.5 - 3.5

2.5 - 6.0


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On 6-lane: divided highways,

the middle lane of the threelanes on each direction shouldhave a wider lane of 3.75m

when the commercial vehiclevolume exceeds 20% of thetotal traffic.

Figure 5-10A and 15-10Bshows examples of the usageof the above wider lama of3.75m and the usage of themarginal strips.

CHAPTER 5

TABLE 5-3 : LANE AND MARGINAL STRIP WIDTH

NOTE : ( ) denotes the total two-way lane width

Design Standard Lane Width ( m ) Marginal StripWidth ( m )

R6 / U6

R5 / U5

R4 / U4

R3 / U3

R2 / U2

R1 / U1

R1a / U1a

3.50

3.50

3.25

3.00

2.75

( 5.00 )

( 5.40 )

0.50

0.50

0.25

0.25

0.00

0.00

0.00


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5.3 SHOULDERS

5.3.1 General Characteristics

A shoulder is the portion ofthe roadway continuous with

the travelled way for accomo-dation of stopped vehicle, foremergency use and forLateral support of the pave-ment.

Their main functions are :

(a) space is provided foremergency stoppingfree of the traffic lane.

(b) space is provided forthe occasional motorist

who desires 'to stop forvarious reasons.

(c) space is provided toescape potential acci-dents or reduce their

severity.

(d) the sense of opennesscreated by shoulders ofadequate width con-tributes to driving easeand comfort.

(e) sight distances is

improved in cut sec-tions, thereby improv-ing safety.

(f) highway capacity is

improved and uniformspeed is encouraged.

(g) lateral clearance is pro-

vided for signs andguardrails.

(h) structural support is

given to the pavement.

5.3.2 Width of Shoulders

The normal. usable shoulderwidth that should be providedalong high type facilities is3m. However, in difficult ter-

rain and on lout volume roads,

usable shoulders of this widthmay not be feasible. A mini-mum usable shoulder width of0.6m should be considered insuch cases.Table 5--4A and 5--4B gives

the widths of shoulders for thevarious road standards in ruraland urban areas.

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CHAPTER 5

TABLE 5-4 : SHOULDER WIDTH ( RURAL )

TABLE 5-4Ba SHOULDER WIDTH (URBAN)

( * ) For Area Type see Table 3-2B

DesignStandard Usable Shoulder Width ( M )

Terrain


R6R5R4

R3R2R1R1a

3.003.003.00

2.502.001.501.50

3.003.003.00

2.502.001.501.50

2.502.502.00

2.001.501.501.50

DesignStandard

Usable Shoulder Width ( M )

Area Type *

I II III

U6U5

U4U3U2U1

U1a

3.003.00

3.002.502.001.50

1.50

3.003.00

2.502.001.501.50

1.50

2.502.50

2.001.501.501.50

1.50


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5.3.3 Shoulder Cross Slope

All shoulders should, besloped sufficiently to rapidlydrain surface water but not to

the extend that vehicular usewould be hazardous. Because

the type of shoulder construc-tion has a bearing on thecross-slope, the two should bedetermined jointly.

Bituminous and concrete sur-faced shoulders should be

sloped from 2, to 6 percent,

gravel or crushed rock shoulders from 4 to 6 percent andturf shoulders 6 percent.Where kerbs are used on theoutside of the shoulders, theminimum cross-slope shoud

not be less char 4 percent toprevent ponding on the road-way.

At supereleiated areas, theshoulder cross-slopes should

be adjusted to ensure that themaximum "roll over" does notexceed 8 percent.

5,3.4 Shoulder Structure

For shoulders to functioneffectively, they must be suffi-

ciently stable to support occa-sional vehicle loads , in allkinds of weather without rut-ting. Paved or stabilisedshoulders offers many advan-

tages in this aspect, Pavedshoulders of the samestrength and standard as thepavement should be consid-ered for road standards R6,

R5 and U6, U5 while sta-

bilised shoulders designed tocater for 50% of the designtraffic should be consideredfor road standards R4, R3 and

U4, U3. For road standardsR2, R1, U7,, U1 and R1a, the

normal earth type shouldercan be used. However, wheregradients exceed 8% theshoulders should also bepaved to prevent erosion.

5.4 KERBS

5.4.1 General Consideration

The type and location of kerbs

appreciably affect driver'sbehaviour and in turn thesafety and usage of a road.Kerbs are used for drainagecontrol, pavement edge delin-eation, aesthetics, delineationof pedestrian walkways and to

assist in the orderly develop-ment of the roadside.

Kerbs are needed mostly onroads in urban areas. In ruralareas, the use of kerbs shouldbe avoided as far as possible

except in localised areas

which has predominantaspects of an urban condition.

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5.4.2 Types of Kerbs

The two general classes ofkerbs are BARRIER KERBSand MOUNTABLE KERBS

and each has numerous typesand detail design. Each may

be designed as a separateunit or integrally with thepavement. They may also bedesigned with a gutter te, forma combination kerb and guttersection.

Barrier kerb are relatively high

and steep faced and aredesigned to inhibit or discour-age vehicles from leaving theroadway. They should not beused on expressways. Theyshould alsc not be used

where the design speedsexceed 70 km/hr. or in combi-nation with traffic barriers.They are recommended foruse in built-up areas adjacentto footpaths with considerable

pedestrian traffic, wherepedestrian traffic is light, asemibarrier type may be used.

Mountable kerbs are used todefine pavement edges ofthrough carriageways. For

channelisation islands, medi-ans, outer separators or any

other required delineationwithin the roadway, a ,semi-mountable type may be used.

Figure 5-1 shows the various

standard types of kerbs thatare to be used.

The width of kerbs are con

sidered as cross section elements entirely outside the traf-fic lane width. However, fordrainage kerbs, the gutter

section may be considered aspart of the marginal strip.

Where roadways do not haveany marginal strip, an offset of0.3 to 01.6m is desirable.

5.5 SIDEWALKS

Sidewalks are accepted asintegral parts of urban roadsand should be providedexcept on Urban Expresswaysor Major Arterials where the

presence of pedestrians areminimal. However, the needfor sidewalks in many ruralareas is great because of thehigh speed and general lackof adequate lighting and due

consideration must be givenfor it especially at points ofcommunity development suchas schools, local business andindustrial plants that results inhigh pedestrian concentra-tions. While there are no

numerical warrants, the justifi-cation for a sidewalk depends

on the vehicle-pedestrian haz-ard which is

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governed by the volumes of

padestrian and vehicular. traf-fic, their relative timiag andthe speed of the vehiculartraffic.

In urban areas, sidewalks can

be placed adjacent to the curband raised above the pave-ment. In the absence of curbs,a strip of a minimum width of1.0m must be providedbetween the sidewalk and thetravelled way to allow for

planting of trees or safety bar-

riers.

In rural areas, sidewalks mustbe placed well away from thetravelled way and separatedfrom the shoulder by at least

1.0m.

A desriable minimum width of2.Om is to be provided for allsidewalks. Where there arerestrictions on right of way, a

minimum of 1.25m can beconsidered. When provided,sidewalks must have allweather surfaces.

5.6 TRAFFIC BARRIERS

Traffic barriers are used tominimise the severity ofpotential accidents involvingvehicles leaving the travelledway. Because barriers are a

hazard in themselves, empha-sis should be on minimisingthe number of such installa-tions. Arahan Teknik (Jalan)1/8.5 "A2anual On Design

Guidelines of Longitudinal

Traffic Barrier" (May, 1984)should be used for the designof longitudinal traffic barriers.

5.7 MEDIANS

5.7.1 General

A median is a highly desirableelement on all roads carryingfour or more lanes and should

be provided wherever possi-

ble. The principal functions ofa median are to provide thedesired freedom front theinterference of opposing traf-fic, to provide a recovery areafor out-of-control vehicles, to

provide for speed changesand storage of right-turningand U-turning vehicles and toprovide for future lanes.

For maximum efficiency, a

medium should be highly visi-ble both night and day and indefinite contrast to the throughtraffic lanes.

5.7.2 Median Types and Width

Medians may be depressed

raised or flush with the pave-ment surface. They should beas wide as feasible but of adimension in balanced withother components of the

cross-section. The generalrange of median width variesfrom a minimum of 1.0 m in aType III urban situation to adesirable width of 18m on

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a rural expressway. On wide medi-

ans, it is essential to have adepressed centre or swale to providefor drainage.

Figure 5-2 gives examples of kerbedand unkerbed medians while Table 5-

5A and 5-5B gives the minimum anddesirable widths and types of medi-ans that are to be applied to the vari-ous road standards. The medianwidths as expressed are the dimen-sions between the through laneedges and includes the right shoul-

ders if any.

CHAPTER 5

TABLE5-5A : MEDIAN WIDTH AND TYPES (RURAL)

Note : Min. - MinimumDes. - Desirable (for consideration of landscaping)

DesignStandard

Median Width ( M )

MedianTypeTerrain


Min. Des. Min. Des. Min. Des.

R6

R5

R4

6.0

4.0

3.0

18.0

12.0

9.0

5.0

3.5

2.5

12.5

9.0

6.5

4.0

3.0

2.0

8.0

6.0

4.0

B, C, E, F

E, F

E, F


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5.8 SERVICE ROADS

5.8.1 General

Service roads are generallyfound in urban areas and theycan have numerous functions,depending on the type of road

they serve and the characterof the surrounding area. Theymay be used to controlaccess or function'as a streetfacility serving adjoining prop-erty. They segregate local traf-

fic from the higher speedthrough traffic and interceptdriveways of residences andcommercial establishmentsalong the road. Service roadsalso not only provide morefavourable access for com-

mercial and residential devel-ovment than the faster movingarterials but also helps to pre-serve the safety and capacity

of the latter.

5.8.2 Design Requirements

From an operational. andsafety standpoint, one wayservice roads are nuch prei-ferred to two-way and should

be considered. One-way oper-

ation inconveniences localtraffic to some degree, but theadvantages in reduction invehicular and pedestrian con-flicts at intersecting streetsoften fully compensate for this

inconvenience.

Two-way service roads may

be considered for partiallydeveloped urban areas wherethe adjoining road system isso irregular and disconnected

that. one-way operation wouldintroduce considerable added

travel distance and causeundue inconvenience. Two-way service roads may alsobe necessary for suburban orrural areas where points ofaccess to the through facilityare infrequent; where only one

service road is provided,

where roads connecting withthe service roads are widelyspaced or where there is noparallel street within reason-able distance of the serviceroads in urban areas that are

developed or likely to b edeveloped.

The design of a service roadis affected by the type of serv-ice it is intended to provide.

When provided, they shouldalways cater or at least oneside on-street parking. Theyshould be at least: 7.25mwide for one-way operationand 9.25m for two-way opera-tion. Figure 5-3 gives the rec-

ommended layout for a tw-o-way operation service road

fronting an urban arterialwhere the distance betweenjunctions is greater than 0.5km. The minimum reservewidth for a service road is

12m.

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5. 9 PEDESTRIAN CROSSINGS

5. 9.1 General Considerations

Pedestrian crossings (whetherlevel, overpass or underpass)

should be provided wherepedestrian volumes, traffic vol-umes, intersection capacityand other conditions favourtheir use. They may be war-ranted in areas of heavy peakpedestrian movements such

as factories, schools, athletic

fields or control business dis-tricts or where abnormal haz-ards or inconveniences topedestrians would otherwiseresult.

Table 5-6 gives the general

guidelines for determining thetype of crossing that isrequired. Where the pedestri-an and vehicle volumes does

not fit into any of the categoryshown, judgement is needed

in the assessment of the typeof crossing required.

CHAPTER 5

TABLE 5-6 : GUIDELINE FOR TYPE OF CROSSING REQUIRED

Pedestrian Volume atpeak hour

Traffic Volume ( 1 way )at peak hour

Type of Crossing

< 50

50 - 100

> 100

< 1000

100 - 2000

> 2000

Ordinary level crossing

Signalised level srossing

Overhead crossing /underpass


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For roads with dual 3-lanes or

more, an overhead crossingor underpass hcali aI.wz!ys heconsidered if a pedestriancrossing is justified so as not

to impede the smooth flow oftraffic unduly.

Where justified, the locationand design of the pedestriancrossing would require anindividual study. Where over-head pedestrian crossings areprovided, side barriers must

be installed. to prevent jay-

walking. Such barriers shallbe installed for a distance of75m on both sides of the loca-tion of the crossing. The mini-mum spacing between cross-ings is 400m.

For overhead pedestriancrossings, standard JKRdesigns shall be used as faras possible. These are avail-able from the Road Design

Unit.

5.9.2 School Level Crossing

The installation of a full trafficsignal school level crossing

should be considered whenthe following warrants are

met:

Either (a) 500 vehicles /hour on the roadand 100 school

children/hourcrossing duringthe peak hours.

Or (b) 500 vehicles /

hour on the roadduring the peakhour and a mini-mum of 500

school childrenduring the entire

day.

Where the above warrant fora full traffic signal school levelcrossing is not met, anunsignalised crossing mustalways be provided.

5.10 U-TURNS

5.10.1 General Considerations

Divided highways requiremedian openings to accomo-date vehicles making U turnsin addition to right turning andcross traffic. Separate U-turnmedian openings may be

required at the following loca-tions :

a. Locations beyond inter-sections to accomodate

minor turuing move-nente not otherwise

provided in the inter-section or interchangearea. The major inter-section area is keptfree for the important

turning movements, insome cases obviatingexpensive ramps oradditional structures.

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b. Locations just ahead of

an intersection to acco-modate U-turn move-ments that would inter-fere with through and

other turning movements at the intersec-

tion. Where a fairlywide median on theapproach roadway hasfew openings, 1U-turn-ing is necessary toreach roadside areas.Advance separate

openings to accomo-

date them outside theintersection proper willreduce interference.

c. Locations occurring inconjunction with minor

crossroads where traf-fic is not permitted tocross the major roadbut instead is requiredto turn left, enter thethrough traffic stream,

weave to the right, U-turn, then return. Onhigh-speed or high-vol-ume roads,the difficultyand long lengthsrequired for weavingwith safety usually

make this design pat-tern undesirable unless

the volumes intercept-ed are light and themedian is of adequatewidth. This conditionmay occur where a

crossroad with highvolurne traffic, a shop-ping area, or other traf-fic generator thatrequires a median

opening nearby and

additional medianopenings would not bepractical.

d Locations occurringwhere regularly spaced

openings facilitatemaintenance opera-tions, policing, repairservice of stalled vehi-cles, or other highway-related activities.Openings for this pur-

pose may be needed

on controlled-accessroads and on dividedroads through undevel-oped areas.

e. Locations occurring on

roads without control ofaccess where medianopenings at optimumspacing are provided toserve existing frontagedevelopments and at

the same time minimizepressure for futuremedian openings.

5.10.2 Design Considerations

U-turning vehicles interferewith through traffic by

encroaching on part or all ofthe through traffic lanes. Theyare made at low speeds andthe required speed change isnormally made on the through

traffic lanes with weaving toand from the outer lanes. Assuch U-turn facilities arepotential hazard areas.Careful consideration should.

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be made not only on the need

for it but also on the type andlocation of the U-turns.

(a) Minimum Design four

Direct U-Turns

For direct U-Turns, thewidth of the highway,including the medianshould be sufficient topermit the turn to bemade withoutencroachment beyond

the outer edges of the

pavements. Figure 5-4gives the minimumwidth of the mediumrequired for the varioustypes of maneuvers fordirect U-turns.

For direct U-Turns, thelayout in Figure 5-5Aand B is suggestedWhere direct U-Turnswill not be feasiblebecause of median

restrictions, indirect U-Turns can be used.

(b) Indirect U-Turns

Indirect U--Turns can

take many forms, thesimpliest being to allow

traffic to use existinglocal streets or to goaround the block fortheir turning move-ments. Where medians

are narrow, the specialindirect U-turn asshown in Figure 5-6can be used. IndirectU-Turns are only to be

used for Road

Standards R4, U4 andU3 only.

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CHAPTER 5

TABLE 4-s P ~t Widening On Open Road Curves

PKNW Win (m ) 7 5.5 5-5 REU8iE0

DESM SPEED (Km/h) 80 50 50 l0 60 50 40 30 50 40 30 70 (M)

P--470 8-340 R> 180 R-1- 230 R'-' 1100 R 2 880 Rar 680 R2510 R R'100 R' 68 R> 52 M39 39 MORE

M- 340- 20- 2309 1100>n 880- 670} 520;*- 68~ 52=- 39>

~-8U R-Ir 11-- R 1 3 0 R=340 R - 2 8 0 0 R ~ Z% R ICU I t - 4u R al.i

I f - a

180~' 150s- 130- 340 - 280- 230y 1 90- J7~'

R~t150 R~-100 8286 R ~180 R~150 R'130 R'110 R'`24 1

86' 180' 150- 130=- 110=- 24 , . y

R264 R;!'150 R y100 R286 8274 4'-16

Note:64~8260

86aR265

74~R251

16~R' 15

1.25

s

65'R260

578245

154

45:

R238

1.75

35>

R2-- 35 2, 4

e


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DIMENSION MINIMUMDISTANCE ( m )

DIMENSION MINIMUMDISTANCE ( m )

m

1

a

4

8

20

R1

R2

b

50

100

60


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(c) Locations for U-Turns

The locations of U-Turns are very important and proper consid-eration should be given to it. As a general guide, Table 5-8 canbe used to determine the minimum distances between U-turns.

TABLE 5-8 : DISTANCES BETWEEN U-TURNS

5.11 BRIDGE AND STRUCTURE CROSS-SECTIONS

5.11.1 Width of Shoulders

For bridges that are less than 100m long, the width of the usableshoulders should follow that as indicated in Table 5-4A and 5-4B.Where bridges are longer than 100m, the values as shown inTable 5-9 should be used. Figure 5-7 shows the typical bridge cross-

section to be used.

Design

Standard

Distance between

U-turns

Design

Standard

Distance between

U-turns

R6

R5

R4

No. U-Turns allowed

3 km

2 km

U6

U5

U4

U3

No. U-Turns allowed

2 km

1 km

0.5 km


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TABLE 5-9 : USABLE SHOULDER WIDTH FOR BRIDGES > 100m

Design Standard Usable Shoulder Width ( m )

R6 / U6

R5 / U5

R4 / U4

R3 / U3

R2 / U2

R1 / R1a

R1a / U1a

1.5

1.5

1.0

1.0

0.5

0.5

0.5


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NOTE:1) ALL DIMENSIONS ARE. IN MILLIMETRES UNLESS STATED

OTHERWISE.

2) DESIRABLE WIDTH Of SIDEWALK I'' is 2- 0 m. A MINIMUM WIDTH TOBE USED IS 1.25 m.

3 ) WIDTH OF CYCLE LANE "C" 15 AS INDICATED IN TABLE 5 - 12.

4) MINIMUM WIDTH Of 'K' TO HE USED IS 300mm. FOR PROVISION OFSERVICE DUCTS THIS VALUE IS TO BE INCREASED.

5) KERBS FOR BRIDGES ARE LEFT TO DISCRETION.

DESIGNSTANDARD

CARRIAGEWAY( L )

SHOULDER ( S ) MARGINALSTRIP( M )

SPAN < 100m SAPN > 100m

R5 / U5

R4 / U4

R3 / U3

R2 / U2

R1 / U1

R1a / U1a

7000

6500

6000

6000

6000

6000

3000

3000

2500

2000

1500

1500

1500

1000

1000

500

500

500

500

250

250

0

0

0


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5.11.2 Required Warance

(a) The clear verticalheight of all structuresshould be at least 5.0m

over the entire width oftraffic lanes, auxiliamy

lanes and lateral clear-ance areas to kerbs,walls on piers includingshoulders. However, forstructures over railwaylines, the minimum ver-tical clearance above

the rail level should be

at least 6.5m to meetthe requirements ofKeretapi Tanah Melayu.For underpasses, anadditional clearance of300mm should be pro-

vided initially to allowfor one to two cycles offuture resurfacings.

(b) For minor roads andlocal streets or where

alternative routes withclearances above 5.Omwithin a reasonable dis-tance are available, theclear vertical clearancemay be reduced to aminimum of 4.6m.

(c) Figure 5-8 indicates the

clearance required atunderpasses for vari-ous types of cross-sec-tions.

5.12 BUS LAYBYES

Bus laybyes serve to removethe bus from the through traf-fic lanes. Its location and

design should therefore pro-vide ready access in the

safest and most efficient man-ner possible. The basicrequirenent is that the decel-eration, standing and acceler-ation of the buses be effectedon pavement areas clear ofand separated from the

through traffic lanes.

The locations of bus laybyesare important so as not toimpede the normal flow oftraffic. In this respect, bus lay-byes must not be located on

any interchange ramps orstructures, slip roads or within60m of any junction or inter-section. The distance betweenlaybyes too should not be lessthan 150m. Liason will need

to be made also with the rele-vant bus companies and therespective Local Authority.

For school areas, provision ofbus laybyes and parkingareas should be specifically

studied so as to ensure theunimpeded flow of traffic.

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F1gure 5-9 show the typical

layout and dimensions of buslaybyes that are to be use inboth rural and urban areas. Ifpossible dividing area

between the outer edge of theroadway shoulder rind the

edge of the bus laybye laneshould be provided. Thisdividing area should be aswide as possible but not lessthan 0.6m.

The pavement areas of the

laybyes Should be of concrete

for contrast in ce)lour and tex-ture with the through trafficlanes to discourage throughtraffic from encroaching on orentering the bus stop.

5.13 MINIMUM RESERVE WIDTH

An adequate road reservewidth is important to cater notonly for the present demandsof traffic but more so for the

future requirements as bythen,it may not be possible toacquire any more additionalland. Figure 5-2 OA and 5-108 show examples of thetypical cross-sections for vari-

ous road standard in rural andurban areas together with the

minimum reserve required,while Table 5-10 lists the mini-mum reserve widths for thevarious road standards. Thevalues as shown in Table 5-10

are for road standards in flatareas and will need to beincreased accordingly forareas involving deep cuts orfills.

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CHAPTER 5

TABLE 5-10 : MINIMUM RESERVE WIDTH

Area Road Category Design Standard Minimum Reservewidth ( m )

RURAL

Expressway R6 60

Highway R5 60

Primary Road R5R4

5040

Secondary Road R4R3

3020

Minor Road R2R1R1a

201212

URBAN

Expressway U6 60

Arterials U5U4

5040

Collector U4U3

4030

Local Street U3U2U1U1a

20201212


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5.14 EXCLUSIVE CYCLE LANES

5.14.1 General Considerations

In areas where there is usual-ly a high proportion of motor

cyclists, the volume may beso substantial as to affect thesmooth flow of traffic. In suchinstances, the provision ofseparate and exclusive cyclelanes should be considered.Figure 5-11 shows the various

types of cycle tracks used.

The general warrant for deter-mining the need for an exclu-sive cycle lane are:

(i) the total volume of traffic exceeds the provid-

ed lane cspacity

and

(ii) the volume of motorcy-cles exceeds 20% of

the total volume of traf-fic.

5.14.2 Elements of Design

(a) Design Speed

The design speed to beused is 60 km/hr.However, where thereare physical constraints, this may be

lowered.

(b) Sight Distance

The priciples as estab-lished in Section 4.1also applies.

(c) Horizontal Aligriment

(i) Minimum Radius

The followingformula is usedin determining

the required min-

imum radius forthe curves.

R = 0.24V + 0.43

where R = radius ofcurve in(m)

V = speed inkm/hr

Table 5-11 gives theminimum radius thatare to be used indesign. Flatter curvesshould always be used

wherever possible.There is no necessity

to provide any transi-tion ( spiral ) curves.

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CHAPTER 5

TABLE 5-11 : MINIMUM RADIUS FOR DESIGN

(ii) Curve Treatment

To allow for the motorcyclist to lean on curves, there is aneed to increase the width through the curve. A maxi-mum widening of 1.2m is to be allowed. Figure 5-12shows the curve treatment that is to be used.

(iii) Superelevation

The maximum superele-vation to be used is 0.06.Superelevation should be applied from the tangent pointto its required value at the point of maximum widening.This is as shown in Figure 5-13.

(d) Vertical Alignment

(i) Grades

The maximuin grade allot,7ed is 10% with a minimumgrade Df 0.5%. At very flat areas, the minimum gradecan be reduced further but with prior approval.

Design Speed ( km / hr ) Minimum Radius ( m )

30

40

50

60

70

80

8

10

13

15

18

20


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R - RADIUS OF CURVEW - WIDTHA - CENTRAL ANGLE OF IHE CURVE OF THE DEFLECrION BETWEEN TAN-

GENTS,

MAXIMUM WIDEWING SHALL BE LIMITED TO 1.2M.

WHEN WKNK WANES I- 2M. (A 2' 95 - 4.) THAI WITH SHALL BE CAN G ON A MIS OF R-4 THROUGH THE CENTRAL PORITION OF THE CURVE (A>96.4) ASSHOWN


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(ii) Vertical Curves

The minimum vertical curve length to be used is15m. On sag vert.ical curves, the design shouldbe such as to avoid any ponding of surface water.

5.14.3 Cross-Section Elements

(a) Lane Width

The required widths of the cycle lane is as shown inTable 5-12, The cycle lane must be separated from anypedestrian sidewalk and the width of separation must be

at Least 10-in.

TABLE 5-12 : WIDTH OF CYCLE LANE

(b) Pavement

The pavement structure will vary according to groundand sub-surface conditions, volume of motorcycles andand type of use. Two types of standard design havebeen selected and are to be used. They are as indicated

in Figure 5-14. The normal crossfall of the pavement is2 %.

Volume ofmotorcycle / hr

Width of Cycle Lane ( m )

Minimum Desirable

1000 - 1500

1500 - 2000

> 2000

2.0

2.5

3.0

2.5

3.0

3.5


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5.14.4 Intersection Treatment

At intersection or interchangex, some form of chan-nelisation with specific roaces

for rhe motor should be pro-vided to minimise conflicts

that will arise. Possible inter-section treatment typesinclude (i) at-grade or(ii) gzade-separated. The typeof intersection treatment willdepend on the volume of thetraffic and the volume of

motorcycles.

(a) An-Grade IntersectionTreatment

An at-grade intersec-tion treatment is suffi-

cient where the volumeof motorcycles dces notexceed 30 percent ofthe total volume of traf-fic at the particularintersection at. the

peak hour.An at-grade intersec-tion treatment is suffi-cient with propeyAgning, speed limitsand lane markings.

(b) Grade SeparatedIntersection Treatment

When the volume ofmotorcycles exceeds30 percent of the totalvolume of traffic at the

particular intersectionat the peak hour orwhen an at-grade inter-secricn treatment doesnot provide a smooth

flow or adequate safety

to the motorcyclistsgrace separated inter-section treatmentshould be considered.

These can be easily

incorporated at round-about and other inter-sections with the provi-sion of underpasses(box culvert type).

The type of the under-

pass must have a 2.5m

clearance with a maxi-mum slope of 10 per-cent. They should belighted to give bettervisibility and safety dur-ing the night Lime.

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CHAPTER 6

OTHER ELEMENTS AFFECTING

6.1 Road Safety

Road safety have been amuch neglected area in thedesign of roads. With anincreasing number, of acci-dents each year, attention to

road safety should be empha-

sised. While the road elementis only one of the three groupsof influences causing acci-dents, it is nonetheless theresponsibility of the designerto provide as safe a road envi-

ronment as possible.

In this aspect, the road designshould be one with uniformlyhigh standards applied consis-tently over a section. It should

avoid discontinuities such asabrupt maljior changes indesign speeds, trarisitions inroadway crass-section, theintroduction of a short-radiuscurve in a series of longerradius curves, a change from

full to partial control of access,constrictions in roadway width

by narrow bridges or otherstructures, intersections with-out adequate sight distances,or other fail

Arahan Teknik (Jalan) 8-86 - A Guide on Geometric Design of Roads

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