Guide on Geometric Design 886

8/12/2019 Guide on Geometric Design 886

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Roads BranchPublic Works Department Malaysia

Jalan Sultan Salahuddin50582 Kuala Lumpur

Arahan Teknik (Jalan) 8/86

5.0mm

7.0mm

A Guide on

Geometric Design of Roads


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Page 2 ARAHAN TEKNIK ( JALAN ) 8/86


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ADDENDUM NO. 1

This Addendum to the 'ArahanTeknik Galan) 8/86 - A Guide onGeometric Design of Roads' shall bemade part of this Arahan Teknik andusers shall incorporate this

Addendum 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 : DESIGNSPEED (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 issuperceeded by table 'GEN-ERAL SUMMARY - GEOMET-RIC DESIGNED CRITERIAFOR ROADS IN URBAN

AREAS (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 orother socially sensitive areas.

Type II - Intermediate between I and II.Type III - Very restrictive in road location with problems as regards land

acquisition, affected buildings and other sonsiltive areas.


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

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

2 ACCESS CONTROL - FULL PARTIAL PARTIAL PARTIAL NIL N

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

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

5 ILANE WIDTH m 3.50 ! 3.50 ( 3.15 3.00I 2.75I (5.00)0 (4.50)0 I 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 ;HOULOr E~R~ allRI~trIVRLJm 1:00 1.00 1:00 0.50 0.50 0_50 0.50

z 8 IMEDIAN WIDTH (MINIMUM)m'

6.0 5.0 4.014.0 3.53.0 ! 3.0 2.52.01N/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 10 MARGINAL STRIP (WIDTH) m 0.50 0.50 0.25 0.25 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 4513 PASSING SIGHT DISTANCE m N/A 700 550 450 625 500 450 500 450 350 450 350 300

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

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

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

17 MAXIMUM GRADE (DESIRABLE) % 2 3 4 3 4 5 4 5 6 5 6 7 6 7 8 7 8 WW 18 MAXIMUM GRADE % 5 6 7 6 7 8 7 8 9 8 9 10 9 10 12 10 12 15

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

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 8I


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GENERAL SUMMARY - GEOMETRIC DESIGN CRITERIA FOR ROADS IN

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

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

0 4 DESIGN SPEED Km/hr 100 80 6080 60 50 70 60 50 60 50 40 50 40 30 40 30 20 40 30 101~~, ;

6 1;

1 A\1

uvE1 zI1Z

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

-

(4.50;n I-

6 !7

SHOULDER WIDTH !?SHOULDER WIDTHSTRUCTURES>1Wm

mm 3.00

3.001.002.50 3.00

3.001.002.50

3.00 2.501.00 2.00 2.50

2.000.50

1.501 2.00

1.500.50

1.501 1.50

1.500.50

0.50~ 1.50

1.500.50

1.501

8 MEDIAN WIDTH (MINIMUM!) m14.03.50 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 2.00N/A N/A N/A

v 10 MARGINAL STRIP (WIDTH) m0.50 0.50 0.25 0.25 0.00 0.00 0.00

11 MINIMUM RESERVE WIDTH m60 50 40(30) b 30(20) b 20 11 12

12 STOPPING SIGHT DISTANCEm 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 550450 350 500 450 350 450 350 300 350 300 250 300 250 200 300 250 200Z 14 MINIMUM RADIUS m465 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

203040506080

100120

153560

100150280465710

15305085

125230375570


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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 Composition3.2.6 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 andVolume/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 Radius4.2.4 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 Length4.3.4 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 Medians5.7.1 General5.7.2 Median Types and Width

5.8 Service Roads

5.8.1 General5.8.2 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 this Arahan Teknik.

This Arahan Teknik is to beapplied to all new construction andimprovements of roads for vehicular traffic 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 or will 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 decisions on road design.

2.1.2 Rural and Urban AreasUrban areas are defined asareas having a population ofat least 1,000 where buildingsand 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 dif ference in the principles ofdesign for rural and urbanroads. Roads in urban areas,however,are characterised bybusy pedestrian activities and

frequent stopping of vehiclesowing to short intersectionspacings and congested built-up areas. Lower designspeeds are usually adoptedfor urban roads and differentcross-sectional elements areapplied to take into accountthe nature of traffic andadjoining land use. It is forthese reasons that variationsin certain aspects of geometric design are incorporated for these two broad groups ofroads.

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 higherstandard.


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Page 16

DESIGN STANDARDS AND ROADCLASSFICATIONS

ARAHAN TEKNIK ( JALAN ) 8/86

Each design standard is generally applicable to the roadtypes as follows:-

(a) Standard. R6/U6 :

Provides the highestgeometric design standard for rural or urbanareas. They usuallyserve long trips withhigh speed of travelling, comfort and safety.It is always designedwith divided carriage

way and with fullaccess control. TheRural and UrbanExpressway falls under this standard.

(b) Standard. R5/U5:

Provides also high geometric standard andusually serve long tointermediate triplengths with high tomedian travellingspeeds. It is usuallywith partial access control, The Highway,Piimary Road and

Arterial falls under thisstandard.

(c) Standard R4/U4:

Provides medium geometric standard andserve intermediate triplengths with mediumtravelling speeds. It isalso usually with partialaccess control. ThePrimary Road,

Secondary Road, Minor Arterial and Major collector falls under thisstandard.

(d) Standard R:3/U3:

Provides low geometricstandard and servesmainly local traffic.There is partial or noaccess control. TheSecondary Road,Collector or MajorLocal Streets falls

under this standard.

(e) Standard R2/U2:

Provides the lowestgeometric standard fortwo way flow. It isapplied only to localtraffic with low volumesof commercial traffic.The Minor Roads andLocal Streets fall underthis standard.

(f) Standard R1/U1:

Provides very low geometric standard and isapplied to very low traf fic where the chancesof two way flow is low.

(g) Standard R1a :

Applied to local accessto restricted areas suchas access tomicrowave stations andsecurity areas.

CHAPTER 2


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Page 17



(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 categories, 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 areasare further classified into fivecategories by function namelyExpressway, 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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(a) Expressway

An Expressway is adivided highway forthrough traffic with fullcontrol of access andalways with grade separations at all intersections.

In rural, areas, theyapply to the interstatehighways for throughtraffic and make the

basic framework ofNational road transportation for fast travelling. They serve longtrips and provide higher speed of travelling andcomfort. To maintainthis, they are fullyaccess-controlled andare designed to thehighest standards.

In urban areas, theyform the basic framework of road trans por tation system inur banised area forthrough traffic. Theyalso serve relativelylong trips and smoothtraffic flow and with fullaccess control andcomplements the RuralExpressway.

(b) Highways

They constitute theinterstate national network and complementsthe expressway net

work. They usually linkup directly or indirectlythe Federal Capitals,State capitals andpoints of entry/exit tothe country. They serveong to intermediate triplengths. Speed serviceis not so important asin an Expressway butrelatively high to medium speed is necessary.Smooth traffic is provid-ed with partial accesscontrol.

(c) Primary Roads

They constitute themajor roads formingthe basic network ofthe road transportationsystem within a state.They serve intermedi-ate trip lengths andmedium travellingspeeds. Smooth trafficis 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 Districtor RegionalDevelopment Areas.They serve intermedi-ate trip lengths withpartial access control.

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) Roadsdepending 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 Schemesand those in otherRegional LandSchemes constructedwith Federal Fundsalso fall under this cat-egory. The maintnanceof these roads are theresponsibility 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 Local

Authority or DistrictOffice, built to JKRstandards. They arenormally constructedwith State Funds. Themaintenance of theseroads are the responsi-

bility of the StateGovernment and isdone through the StateJKR.

(c) Local Authority Roadsare all those roadswithin the limits of theLocal Authority and arenormally maintained bythe responsible localauthority.

(d) Kampong (DistrictOffice) Roads are all

those roads directlyunder the jurisdiction of the District Office. Theyare usually earth roadswith no right of way.The maintenance ofthese 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, inconnection with a road is fully

or partially controlled by thepublic authority.

Control of access is usuallyclassified into three types forits degree of control, namelyfull control, partial control andnon-control of access

CHAPTER 2


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Full Control of Access meanthat preference is given tothrough traffic by providingaccess connecting with selected public roads only and byprohibiting crossings at gradeor direct private driveway connections.

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

In Non Control Access, thereis basically no limitations ofaccess.

2.4.2 Application

The selection of the degree of control required is importantso as to preserve the as builtcapacity of the road as well asimproved 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 ofthe road in the controlof accesses to futuredevelopments.

The selection of degree ofaccess control depends ontraffic 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

ExpresswayHighwayPrimary RoadSecondry RoadMinor Road

F----

-PP--

--PP-

---P-

----N

----N

Road CatagoryDesign Standard

U6 U5 U4 U3 U2 U1 / U1a

Expressway ArterialCollector Local Street

F---

-P--

-PP-

--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

aacs d

O ,~ l t i .' ~ l a.yl 'I-)

~lJ V b Q N

V V

'A '0 `0 `0 V a . a v'e

Y ~ C a . J 7C f . 7O ~ . N ~

~ ~\O V -0 Z tq '~ ~a{a b

ILI b b u u u n n u

er `

V ~~:11

,Ono

Q1 v2

2 v AC ~~ ~' . p a o 0 0 a

v

.S

8

J ro4O

~ ,

~

-1) '1

7 ro

V U V v~.

F0 O O b O O .

4

y! . . . r.

c

a8


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Page 52

ELEMENTS OF DESIGN


CHAPTER 4

TABLE: _,rE. BEe ~IC' SUPERELEVATIOM TABLE~~nax ~ ~. 06 D t.nax = O. /DD

V- d-6 / t ml l / c ,~6 A ~ 1 1

( m ) C C m ) t! (m~ e L ( / m

e _-o2- lame ~~ - lee e 02-lane of / acnei N G ' _ ~ l v ' C D HC D lq C D

a NC __D ~lC O NC D K C 0.7 a o NC __O _NC D NC O INCes '0.6 NC _d HC /.C NC O __ NC /,SS d 6 NC O A' r- /S' /VC D N C - u o o N G _ _ D / 2 / S ' N C O RC ' S

NC O_ &C /S NC O R C . S '~ 3 o D A / C O .G)OO /S NC 40- .A,),) Sd O NC D . ~"pllL / S NC D . 0016 /Sof D 45 NC / o . Do1d' S VC 16

/ 8 d _ 1-r RC /10/ 6 a RG /vo rsd / S R C / o , / S/ BCD RC. _/0 .e 6 /S oat /D .ouJ /73d ate! /o M7 /S .a~j /o .a" /8a __ .o.~ .et- /o .o0. / v a u /a .44o /,6 & -W /o aa _aooD .c0~6 _%o .a4,j /7 . '~")9 /a .aS6 0ta9D /d >ektt /7 ' .m3o /~ .061ao .ago _.o .4k /a, .Ms /a .od6 a6

.04? / . 04A / . 0 V o2 8o~fj a s . ouS /d - .67,P 3 i

4c a . O6!L a l - o S 3 730 04 /6 Rm~~=3S .n 6 ozS . ioa ~9

Rm"= /S


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Page 53

ELEMENTS OF DESIGN


pavement is made withless distortion than bythe other methods. Thecentreline profile is thebase line and one-halfof the required eleva-tion change is made ateach edge.

(b) Fig. 4-1B illustrates themethod where thepavement section isrevolved about theinside edge profile. Theinside edge profile is

determined as the lineparallel to the calculat-ed centreline profile.One half of the requiredchange in cross slopeis made by raising thecentre line profile withrespect to the insidepavement edge and theother half by raising theoutside pavement edgeand equal amount withrespect to the centre-line profile.

(c) Fig. 4-1C illustrates themethod where thepavement section isrevolved about outsideedge profile involvessimilar geometrics as(b), except that thechange is affectedbelow the upper controlprofile.

Except when site conditionspecifically requires , method(a) shall be adopted for undivided roads.

4.2.6 Superelevation Runoff withMedians

In the design of divided roads,the inclusion of a median inthe cross section alters some-what the superelevation runoff treatment. The three generalcases for superelevationrunoff design are as follows:

(a) The whole of the trav-elled way, including themedian, is superelevat-ed as a plane section.This case is limited tonarrow medians andmoderate supereleva-tion rates to avoid sub-stantial differences inelevation of theextreme pavementedges because of themedian tilt.Diagrammatic profilecontrols is similar toFig. 4-1A except thatthe two median

CHAPTER 4


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Page 54

ELEMENTS OF DESIGN


CHAPTER 4


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Page 55

ELEMENTS OF DESIGN


edges will appear asprofiles only slightlyremoved frog centre-line.

(b) The median is held in ahorizontal plane andthe two pavementsseparately are rotatedaround the medianedges. This case hasmost application withmedians of intermedi-ate width. Runoffdesign uses the medi-

an edge profile as thecontrol. One pavementis rotated about itslower edge and theother about its higheredge. The diagrammat-ic profile control is simi-lar to Fig. 4_1B andFig. 4T1C with the cen-treline grade control thesame for the two pave-ments.

(c) The two pavements areseparately treated forrunoff with a resultantvariable difference inelevation at the medianedges. The differencesin elevation of theextreme pavementedges are minimisedby a compensatingslope across the medi-an. A fairly wide sectionis necessary to developright shoulder areasand desired gentleslope between. Thusthis ease is more appli-cable to wide median of

9 m or more. The pave-ment rotation can bemade by any methodsin Fig. 4-1

4.2.7 Pavement Widening onCurves :

Pavements on curves arewidened to make operatingconditions on curve. compara-ble to those on tangents.Pavement widening on curvesis the difference in pavement

width required on a curve andthat use in a tangent. Table 4-5 give the widths of pavementwidening that are required onopen road curves.

Widening should be attainedgradually on the approachesto the curve to ensure a reasonable smooth alignment onthe edge of pavement and tofit the paths of vehicles enter-ing or leaving the curve.Preferably, widening shouldbe

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ELEMENTS OF DESIGN


CHAPTER 4

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

PKNW Win (m ) 7 5.5 5-5 REU8iE0

IDESM 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 R2 880 Rar 680 R2510R R'100 R' 68 R> 52 M39 39 MORE

4M- 340- 20- 2309 1100>n 880- 670}520;*- 68~ 52=- 39>

~-8U R-Ir 11-- R1 3 0 R=340 R- 2 8 0 0 R ~ Z% RICU 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: 64~826086aR265

74~R251

16~R' 15

1.25

s

65'R260

578245 154

45: R238

1.75

35>

R2-- 35 2, 4e


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ELEMENTS OF DESIGN


attained owner thesuperelavation runofflength with most of all,of' the wideningattained at the start ofcircular 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 theobstruction cannot beremoved. Using the designspeed and a selected sightdistance as a control, thedesigner should check theactual condition and make thenecessary adjustments in themanner most fitting to provideadequate sight distance

4.2.9 General Controls for Horizontal Alignment

In addition to the specificdesign elements for horicontalalignment, a number of gener-al controls are recognised andshould be used. These con-trols are not subject to empiri-cal or formula derivation butare 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 alignmentcomposed 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 forthe most critical condi-tions.

(c) Consistent alignmentshould always besought. Sharp curvesshould not be intro-duced at the end oflong tangent. Wheresharp curves must beintroduced, it should beapproached, wherepossaible, by succes-sively sharper curvesfrom the generally flatcurvature.

(d) For small deflectionangles, curves shouldbe sufficiently long toavoid the appearanceof a kink. Curvesshould be at least150m long for a centralangle of` 50 and the

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ELEMENTS OF DESIGN


length should beincreased 30 m foreach 10 decrease inthe central angle

(e) Any abrupt. reversal inalignment should beavoided. 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 forsuch conditions if it. isunavoidable.

4.3 VERTICAL ALIGNMENT

4.3.1 Maximum Grades

The vertical profile of roadaffect the performance ofvehicles. The effect of gradeson trucks which have weightpower ratio of about 300lb/hp, is considered. Themaximum grade controls interms of design speed is sum-marised in Table 4-6

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4.3.2 Minimum grades

A desirable minimum grade or 0.5 percent should be used. Agrade of 0.35 percent may beallowable where a high typepavement. accurately crownedis used. On straight stretchestraversing across wide areasof low lying swamp use ofeven flatter grades may beallowable with prior approval.

4.3.3 Critical Grade Length

The term " critical gradelength" indicate the maximumlength of a designated

upgrade upon which a loadedtruck can operate without anunreasonable 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( % )

1201008060504030

20

2345678

9

56789

1012

15

Road StandardR1a

10 25


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CHAPTER 4

Design Speed Gradient ( % ) Critical GradeLength ( m )

120 345

500400300

100 456

500400300

80 567

500400300

60 678

300250200

50 789

250200170

40 89

10

200170150

30 - Not defined - decisionleft to designer

20 - Not defined - decisionleft to designer


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ELEMENTS OF DESIGN


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ELEMENTS OF DESIGN


provide more sections andlength safe for passing. Suchsection are particularly advan-tageous in rolling terrain,especially where the align-ment is winding or where thevertical profile includes criticallengths 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 hour or more.

The transitions between thetwo 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 sectionsshould 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 areriot practical, passing laybyesmay be introduced at regularintervals. 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 atthe end.

4.3.6 Climbing Lanes on MultilaneRoads

Multilane roats more frequent-ly have sufficient capacity tohandle 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 lanesshould be considered.

4.3.1 Vertical Curves

Vertical curves are used toeffect a gradual chargebetween tangent grades. Theyshould be simple in applica-tion and should result in adesign that is safe, comfort-able in operation, pleasing inappearance and adequate fordrainage. 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 tosuccessive 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 curveor 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

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ELEMENTS OF DESIGN


a measure of curvature. Thisquantity (L/A), termed k, isused in determining the hori-zontal distance from thebegining of the vertical curveto the apex or low point of thecurve. The k value is alsouseful in determining the mini-mum lengths of vertical curvesfor the various des isanspeeds.

The lengths of vertical curvesused should be as long aspossible 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 themajor control for thesafe operation at thedesign speed chosen.Passing sight distancesare not used as it pro-vides for an. uneco-nomical design. Anexception may be atdecision. areas such assight distance to rampexit gores where longer lengths are necessary.

The basic formulas for lengthof a parabclic vertical curve interms of algebraic differencein grade and sight distance(using an eye height of 0.92mand 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 in

grades (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 for establishing 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 toestablish 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 drainagemust 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)


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)


120 100 80 60 50 40 30 20

Minimum k value 60 40 28 15 12 10 8 8


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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 ofgrade. While the maxi-

mum grade and thecritcal length are con-trols, the manner inwhich they are appliedand fitted to the terrainon a. continous linedetermines the suitabili-ty and appearance ofthe finished product.

(b) The 'roller coaster' orthe 'hidden-dip' type ofprofile 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 sagswhere the full view, ofboth vertical curves isnot pleasing. This effectis very notice able endivided roadways withopen median sections

(d) On long grades, it ispreferable to place thesteepest grade at thebottom and lighten thegrades near the top ofthe ascent or to breakthe sustained gradeby 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 andin 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 gradesshould be in proper bal-ance. Tangent align-ment or flat curvatureat the expense of steepor long grades, andexcessive curvaturewith flat grades, areboth 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 pleasingappearance within thepractical limits of terrainand area traversed.

(b) Vertical curvaturesuperimposed uponhorizontal curvature, orvice versa, generallyresults in a more pleas-ing facility but it shouldbe analyzed for effectupon traffic. Successivechanges in profile rot incombination 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 verticalcurve. This condition ishazardous in that thedriver carinot perceivethe horizontal changein 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 designspeed.

(d) Somewhat allied to theabove, sharp horizontalcurvature should not beintroduced at or nearthe 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, especiallyat night.

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ELEMENTS OF DESIGN


(e) On 2-lane roads theneed for safe passingsections at frequentintervals and for, anappreciable percentageof the length of theroad often supersedesthe general desirabilityfor combination of hori-zontal and verticalalignment. In thesecases it is necessary towork toward long tan-gent sections to securesufficient 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 consideredto derive design andoperational advantagesof 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 pavementtype 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 forwhich 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 somewhatless 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 characteristicsof surface type in relation togeometric design are the abili-ty of a surface to retain theshape and dimensions, theability to drain, and the effecton driver's behavior. Table 5-1gives 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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On 6-lane: divided highways,the middle lane of the threelanes on each direction shouldhave a wider lane of 3.75mwhen 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 withthe 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 motoristwho desires 'to stop for various reasons.

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

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

(e) sight distances isimproved in cut sec-tions, thereby improv-ing safety.

(f) highway capacity isimproved and uniformspeed is encouraged.

(g) lateral clearance is pro-vided for signs andguardrails.

(h) structural support isgiven 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 of 0.6m should be considered insuch cases.Table 5--4A and 5--4B givesthe 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


R6R5R4R3R2R1

R1a

3.003.003.002.502.001.501.50

3.003.003.002.502.001.501.50

2.502.502.002.001.501.501.50

DesignStandard

Usable Shoulder Width ( M )

Area Type *

I II III

U6U5

U4U3U2U1

U1a

3.003.00

3.002.502.001.501.50

3.003.00

2.502.001.501.501.50

2.502.50

2.001.501.501.501.50


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5.4.2 Types of Kerbs

The two general classes ofkerbs are BARRIER KERBSand MOUNTABLE KERBSand each has numerous typesand detail design. Each maybe designed as a separateunit or integrally with thepavement. They may also bedesigned with a gutter te, forma combination kerb and gutter section.

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 usedwhere the design speedsexceed 70 km/hr. or in combi-nation with traffic barriers.They are recommended foruse in built-up areas adjacentto footpaths with considerablepedestrian traffic, wherepedestrian traffic is light, asemibarrier type may be used.

Mountable kerbs are used todefine pavement edges ofthrough carriageways. Forchannelisation islands, medi-ans, outer separators or anyother required delineationwithin the roadway, a ,semi-mountable type may be used.

Figure 5-1 shows the variousstandard types of kerbs thatare to be used.

The width of kerbs are considered as cross section elements entirely outside the traf-fic lane width. However, fordrainage kerbs, the guttersection may be considered aspart of the marginal strip.Where roadways do not haveany marginal strip, an offset of 0.3 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 thepresence of pedestrians areminimal. However, the needfor sidewalks in many ruralareas is great because of thehigh speed and general lackof adequate lighting and dueconsideration must be givenfor it especially at points ofcommunity development suchas schools, local business andindustrial plants that results inhigh pedestrian concentra-tions. While there are nonumerical warrants, the justifi-cation for a sidewalk dependson the vehicle-pedestrian haz-ard which is

CHAPTER 5


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governed by the volumes ofpadestrian and vehicular. traf-fic, their relative timiag andthe speed of the vehiculartraffic.

In urban areas, sidewalks canbe 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 forplanting of trees or safety bar-

riers.

In rural areas, sidewalks mustbe placed well away from thetravelled way and separatedfrom the shoulder by at least1.0m.

A desriable minimum width of2.Om is to be provided for allsidewalks. Where there arerestrictions on right of way, aminimum 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 ahazard in themselves, empha-sis should be on minimisingthe number of such installa-tions. Arahan Teknik (Jalan)1/8.5 "A2anual On Design

Guidelines of LongitudinalTraffic 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 shouldbe 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, toprovide for speed changesand storage of right-turningand U-turning vehicles and toprovide for future lanes.

For maximum efficiency, amedium 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 depressedraised or flush with the pave-ment surface. They should beas wide as feasible but of adimension in balanced withother components of thecross-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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CHAPTER 5

TABLE 5--5B : DREDIAN WIDTH AND TYPES (URBAN)

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

DesignStandard

Medium Width ( M )

MedianType

Area Type

I II III

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

U6

U5

U4

U3

4.0

3.0

2.5

2.0

12.0

9.0

7.5

6.0

3.5

2.5

2.0

1.5

9.0

6.5

5.0

4.0

3.0

2.0

1.5

1.0

6.0

4.0

3.0

2.0

B, C, E, F

B, C, E

A, B, C, D

A, B, D


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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 roadthey 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 capacityof the latter.

5.8.2 Design Requirements

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

Two-way service roads maybe considered for partiallydeveloped urban areas wherethe adjoining road system isso irregular and disconnectedthat. one-way operation wouldintroduce considerable addedtravel 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 oneservice 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 aredeveloped 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 roadfronting an urban arterialwhere the distance between

junctions is greater than 0.5km. The minimum reservewidth for a service road is12m.

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5. 9 PEDESTRIAN CROSSINGS

5. 9.1 General Considerations

Pedestrian crossings (whether level, 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 suchas factories, schools, athletic

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

Table 5-6 gives the generalguidelines for determining thetype of crossing that isrequired. Where the pedestri-an and vehicle volumes doesnot fit into any of the categoryshown, judgement is neededin 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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CHAPTER 5


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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 notto 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 mustbe 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 DesignUnit.

5.9.2 School Level Crossing

The installation of a full trafficsignal school level crossingshould be considered whenthe following warrants aremet:

Either (a) 500 vehicles /hour on the roadand 100 schoolchildren/hourcrossing duringthe peak hours.

Or (b) 500 vehicles /hour on the roadduring the peakhour and a mini-mum of 500school childrenduring the entireday.

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 berequired at the following loca-tions :

a. Locations beyond inter-sections to accomodateminor turuing move-nente not otherwiseprovided in the inter-section or interchangearea. The major inter-section area is keptfree for the importantturning 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 andother turning movements at the intersec-tion. Where a fairlywide median on theapproach roadway hasfew openings, 1U-turn-ing is necessary toreach roadside areas.

Advance separateopenings to accomo-

date them outside theintersection proper willreduce interference.

c. Locations occurring inconjunction with minorcrossroads 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 usuallymake this design pat-tern undesirable unlessthe volumes intercept-ed are light and themedian is of adequatewidth. This conditionmay occur where acrossroad with highvolurne traffic, a shop-ping area, or other traf-fic generator thatrequires a median

opening nearby andadditional medianopenings would not bepractical.

d Locations occurringwhere regularly spacedopenings 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 onroads without control of access where medianopenings at optimumspacing are provided toserve existing frontagedevelopments and atthe same time minimizepressure for futuremedian openings.

5.10.2 Design Considerations

U-turning vehicles interferewith through traffic byencroaching on part or all ofthe through traffic lanes. Theyare made at low speeds andthe required speed change isnormally made on the throughtraffic 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 needfor it but also on the type andlocation of the U-turns.

(a) Minimum Design fourDirect U-Turns

For direct U-Turns, thewidth of the highway,including the medianshould be sufficient topermit the turn to bemade withoutencroachment beyondthe 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 medianrestrictions, indirect U-Turns can be used.

(b) Indirect U-Turns

Indirect U--Turns cantake many forms, thesimpliest being to allowtraffic to use existinglocal streets or to goaround the block fortheir turning move-ments. Where mediansare narrow, the specialindirect U-turn asshown in Figure 5-6can be used. IndirectU-Turns are only to be

used for RoadStandards 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

IDESM 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 R2 880 Rar 680 R2510R R'100 R' 68 R> 52 M39 39 MORE

4M- 340- 20- 2309 1100>n 880- 670} 520;*- 68~ 52=- 39>

~-8U R-Ir 11-- R1 3 0 R=340 R- 2 8 0 0 R ~ Z% RICU 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: 64~826086aR265

74~R251

16~R' 15

1.25

s

65'R260

578245 154

45: R238

1.75

35>

R2-- 35 2, 4e


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CHAPTER 5

DIMENSION MINIMUMDISTANCE ( m )

DIMENSION MINIMUMDISTANCE ( m )

m

1

a

4

8

20

R1

R2

b

50

100

60


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CHAPTER 5

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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CHAPTER 5

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 5.0mover the entire width oftraffic lanes, auxiliamylanes and lateral clear-ance areas to kerbs,walls on piers includingshoulders. However, for structures over railwaylines, the minimum ver-tical clearance abovethe 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 of future resurfacings.

(b) For minor roads andlocal streets or wherealternative 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 theclearance 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 anddesign should therefore pro-vide ready access in thesafest 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 thethrough 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 onany interchange ramps orstructures, slip roads or within60m of any junction or inter-section. The distance betweenlaybyes too should not be lessthan 150m. Liason will needto be made also with the rele-vant bus companies and therespective Local Authority.

For school areas, provision ofbus laybyes and parkingareas should be specificallystudied so as to ensure theunimpeded flow of traffic.

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F1gure 5-9 show the typicallayout and dimensions of buslaybyes that are to be use inboth rural and urban areas. Ifpossible dividing areabetween the outer edge of theroadway shoulder rind theedge of the bus laybye laneshould be provided. Thisdividing area should be aswide as possible but not lessthan 0.6m.

The pavement areas of thelaybyes 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 thefuture 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 theminimum reserve required,while Table 5-10 lists the mini-mum reserve widths for thevarious road standards. Thevalues as shown in Table 5-10are 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 R2R1

R1a

201212

URBAN

Expressway U6 60

Arterials U5U4

5040

Collector U4U3

4030

Local Street U3U2U1

U1a

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 motorcyclists, 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 varioustypes of cycle tracks used.

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

(i) the total volume of traf fic exceeds the provid-ed lane cspacity

and

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

(b) Sight Distance

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

(c) Horizontal Aligriment

(i) Minimum Radius

The followingformula is usedin determiningthe 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 usedwherever possible.There is no necessityto 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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CHAPTER 5

(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 beat 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 indicatedin 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 inter changex, some form of chan-nelisation with specific roacesfor rhe motor should be pro-vided to minimise conflictsthat 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 ofmotorcycles.

(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. thepeak hour.

An at-grade intersec-tion treatment is suffi-cient with propey

Agning, speed limitsand lane markings.

(b) Grade SeparatedIntersection Treatment

When the volume ofmotorcycles exceeds30 percent of the totalvolume of traffic at theparticular intersectionat the peak hour orwhen an at-grade inter-secricn treatment doesnot provide a smooth

flow or adequate safetyto the motorcyclistsgrace separated inter-section treatmentshould be considered.

These can be easilyincorporated 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 toroad 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 shouldavoid discontinuities such asabrupt maljior changes indesign speeds, trarisitions inroadway crass-section, theintroduction of a short-radiuscurve in a series of longerradius curves, a change fromfull to partial control of access,constrictions in roadway widthby narrow bridges or otherstructures, intersections with-out adequate sight distances,or other failures to inaintain.consistency in the roadwaydesign. The highway shouldoffer, no surprises to the driv-er, in terms of either geometrics or traffic controls.The tendency to base road

designs upon minimum, stan-dards rather than to adopt, anoptimum design is unfortunateand must be avoided. A moreliberal and optimi-mi designmust always be considered,and although it would cost alittle more in terms of capitalcost of the project it wouldincrease the road's level ofsafety substantially.

All too often, minimum designstandards attempt to rely, onthe use of warning signs or

other added roadside appurte-nances for the safe operationthat could have been built inby the use of higher designstandards, Often the safetydeficiencies generated byminimum design are impossi-ble to correct by any knowntraffic device or appurtenance.

A warning sign is a poor sub-stitute for adequate geometridesign.

6.2 Drainage

Road drainage Utilities pro-vide for carrying water acrossthe right of way and forremoval of storm water fromthe road itself. These facilitiesincluds bridges, culverts,channels, gutters and varioustypes cf drains. Drainagedesign considerations are anintegral part of geometricdesign and flood plainencroachments frequentlyaffect the highway alignmentand profile.


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The cost of drainage is neither incidental nor minor an mostreads, Careful attention torequirements for adequatedrainage and protectAn of thehighway from floods in allphase of location axed designwill prove to be effective inreducing costs in both con-struction and maintenance.

Reference should be made tothe relevant JKR manual onthis subject.

6.3 Lighting

Lighting may improve thesafety. of a road and the easeand comfort of operation thereon. Lighting of rural highwaysmay be desirable but the needis much less than on roads inurban areas. They are seldom

justified except on critical por-tions such as interchanges,intersections, railroad gradecrossaings, narron or longbridges, tunnels and areaswhere roadside interference isa factor.

Where lighting is being con-sidered for future installation,considerable savings can beeffected through design. andinstallation of necessary con-duits under the pavementsand kerbs as part of the initialconstruction and should beconsidered

Reference should be made tothe relevant JKR manual onthis subject.

6.4 Utilities

All road improvement,whether upgrade within theexisting right of way or entirelyon new right of way, generallyinvolves the shifting of utilityfacilities. Although utilitiesgenerally have little effect onthe geometric design of the

read, Full considerationshould be given to measuresnecessary to preserve andprotect the integrity and visualquality of the road, its mainte-nance efficiency arid the safe-ty of traffic.

Utilities relocation shoold formpart of design and the design-er should Wase closely withthe relevant service authori-ties in determining the existingutilities and their proposedrelocation.

6.5 Signing and Markings

Signing and marking aredirectly related to the designof the road and are features of traffic control and operationthat the engineer must, con-sider in the georretric layout of such a facility, The signingand marking should bedesigned concurrently with thegeometrics as an integral part,arid this will reduce signifi-cantly tne possibility of future

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operational problems. Thesigning and marking shouldfollow the standards that havebeen established. Feferenceshould be made to ArahapTeknik (Jalan) 2A, 2B, 2C and2D on the design, usage andapplication of signs an mark-ings.

6.6 Traffic Signal

Traffic control signals aredevice that control vehicular

and pedestrian traffic byassigning the right of way tovarious movements for certainpretimed or traffic actuatedintervals of time. They are oneof the key elements in thefunction of many urban roadsand should be integrated withthe geometric design so as toachieve optimum operationalefficiency.

6.7 Erosion Control LandscapeDevelopment andEnvironmental Impacts

Erosion prevention is one ofthe major factors in design,construction and maintenanceof highways. It should be con-sidered early in the locationand design stages. Somedegree of erosion control canbe incorporated into the geo-metric design, particulatly inthe cross-section elements.

Lanscape development shouldbe in keeping with the charac-ter of the road and its environ

ment. The general areas ofimprovement include the fol-lowing:

(a) preservation of existingvegetation

(b) transplanting of existingvegetation where feasi-ble

(c) planting of new vegeta-tion

(d) selective clearing and

thinning

(e) regeneration of naturalplant species andmaterial.

Landscaping of urban roadsassume an additional impor-tance in mitigating the manynuisances associated withurban traffic. Referenceshould be made to the rele-vant JKR manual on this sub-

ject.

The highway can and shouldbe located and designed tocomplement its environmentand serve as a catalyst toenvironmental improvement.The area surrounding a pro-posed highway is an interrelated system of natural, man-made and sociologic vari-ables. Changes in one vari-able within this system cannotbe made without some effecton other variable. Some ofthese consequences may benegligible, but others mayhave strong and lasting

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impact on the environmentincluding the sustenance andquality of human life. Becausehighway location and designdecisions have. an effect onadjacent area development, itis important that environmen-tal variables be given full consideration. Environmentalimpacts include social, eco-nomic and physical impacts.In geometric design, onlyphysical impacts areassessed, while the socialand economic impacts would

have been taken care of dur-ing the planning stage.

CHAPTER 6

Documents

Guide on Geometric Design 886