A

Thesis

Submitted in partial fulfillment of the requirement for the award of the

Degree of

Master of Technology

in

TRANSPORTATION ENGINEERING

on

"RE-APPROPRIATION OF INTERSECTIONS: A CASE STUDY OF

BHOPAL CITY"

Submitted by

M.M. TRIPATHI

Scholar No: PG/FT/092111502

Guided by:

Prof. Siddhartha Rokade Prof. Kamal Singh

Assistant Professor Assistant Professor

Department of Civil Engineering

MAULANA AZAD NATIONAL INSTITUTE OF TECHNOLOGY

BHOPAL-462 051

June 2011

i

CERTIFICATE

This is to certify that the Thesis titled “Re-Appropriation of Intersections: A Case Study

of Bhopal City” submitted by M.M.Tripathi in partial fulfilment of the requirement for

the award of the degree of Master of Technology in TRANSPORTATION ENGINEERING

is a bonafide work carried out by him under our supervision and guidance.

Prof. Siddhartha Rokade Prof. Kamal Singh

Assistant Professor Assistant Professor

Department of Civil Engineering Department of Civil Engineering

M.A.N.I.T., Bhopal M.A.N.I.T., Bhopal

Countersigned by:

Dr. P. K. Jain

Head

Department of Civil Engineering

M.A.N.I.T., Bhopal

ii

CANDIDATE’S DECLARATION

I hereby declare that the Thesis entitled “Re-Appropriation of Intersections: A Case

Study of Bhopal City” submitted by me in partial fulfilment of the requirement for the

award of the degree of Master of Technology in “Transportation Engineering” of

Maulana Azad National Institute of Technology is an authentic record of my own work

carried out under the guidance of Prof. Siddhartha Rokade, Assistant Professor and Prof.

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

(M.M. Tripathi)

iii

ACKNOWLEDGEMENT

I express my deep sense of gratitude to my guides Prof. Siddhartha Rokade, Assistant

Professor and Prof. Kamal Singh, Assistant Professor, Department of Civil Engineering,

Maulana Azad National Institute of Technology for their invaluable help and guidance. I am

highly thankful to them for their continuous support and encouragement in completing this

work.

I am thankful to Dr. R.P. Singh, Director, Maulana Azad National Institute of Technology,

and Dr. P.K. Jain, Head of Department, Department of Civil Engineering, Maulana Azad

National Institute of Technology, for their continuous support and encouragement in

completing my M.Tech programme. I am also thankful to Dr. Anil Sharma, Professor and

Coordinator, Post Graduate course, Maulana Azad National Institute of Technology.

I especially thanks to Dr. P.K. Agarwal, Associate Professor, Department of Civil

Engineering, Maulana Azad National Institute of Technology, for his guidance and support

during my Post Graduation programme.

Thanks is also extended to Mrs. Ranjana, Programmer, Computer Centre, Mr. Ramanuj

Yadav, Assistant Grade III and Mr. Mahesh Verma, Office Assistant, Department of Civil

Engineering, Maulana Azad National Institute of Technology, I also express deep sense of

appreciation to the staff of Department of Civil Engineering, Maulana Azad National

Institute of Technology, for their cooperation and support throughout the session.

I am also thankful to Dr. M.S. Chouhan, Associate Professor, Department of Civil

Engineering, Maulana Azad National Institute of Technology, for his overall support and

valuable guidance during my Post Graduation Programme.

iv

ABSTRACT

In the field of road transport, the intersections are road junctions where two or more

roads either meet or cross at grade (i.e., they are at the same level). They include not

only the pavement area but the adjacent sidewalks and pedestrian curb cut ramps also.

All the modes of travel e.g., pedestrian, bicycle, motor vehicle and transit are there at a

typical intersection. They are very important elements of road and at grade

intersections are very common on Indian roads. They are generally a major

construction for smooth flow of traffic. It is observed that well over half of the fatal and

serious road accidents occur at junctions. Since an intersection involves conflicts

between traffic in different directions, its scientific design can control accidents and

delay and can lead to orderly movement of traffic. The importance of design of the

intersection stems from the fact that efficiency of operation, safety, speed, cost of

operation and capacity are direct governed by the design. Thus there is a great need to

properly study and subsequently design intersection on the road networks. The safe

and efficient design of the intersection depends on many factors which include human

factors, traffic considerations, road and environmental considerations, economic

factors.

Bhopal, capital city of Madhya Pradesh, like all the major cities of India has very

heterogeneous kind of traffic. There are large numbers of light commercial vehicles

such as motorcycles and cars as well as heavy vehicles like buses, trucks, trailers and

dumpers running across the city According to Regional Transport Office, Bhopal, out of

100% of road traffic, approximately 80 % are two wheelers, 10 % are cars, and rest 10

% are other commercial vehicles including truck, tractor, trailer, bus and other goods

vehicle. Hence due to such vastness of traffic, it is also prone to large number of

accidents. According to the traffic data of Bhopal of year 2009, there is steep increase in

road accidents in this decade. It can be seen from the fact that in year 2002, total

numbers of road accidents were 2001, while in the year 2009, these total step-ups to

massive 3719. Thus, there is an urgent need to reduce the rate of road accidents in

Bhopal city by identifying the significant causes of accidents. Out of them one of the

major cause is improper intersection design, which, in this project, is studied and

subsequent suggestions are being accounted.

v

In this thesis, five main intersection of Bhopal city, having different traffic situation,

conditions, and type of vehicles are taken. The intersections and their prevailing

situations are (i) J. K. road Junction: A three legged intersection situated on a National

Highway and one leg connects the J.K. Road which is having many residential and

commercial establishment and joins Ayodhya bypass. (ii) Piplani Junction: It consists of

two 3-legged intersections, one connects Raisen road to BHEL side and other

connection goes towards the Sonagiri side, both having high volume of traffic flow. (iii)

Jyoti Talkies intersection: A four legged intersection situated in major commercial area

of Bhopal i.e., M.P. Nagar (iv) MANIT Junction; A four legged intersection of which three

legs are having high volume of traffic including lots of motorcycles, cars, trucks and

dumpers. (v) Mangalwara junction: A five legged intersections surrounded by

commercial as well as residential establishment in old Bhopal area. It has high intensity

of traffic due to transport business nearby. To find out real existing situations at the

junctions, total station and traffic volume surveys had been done at all the intersections

and the data thus obtained is analyzed and then in accordance with relevant IRC codal

provisions, redesigning of the intersection is done.

vi

CONTENTS

Certificate i

Candidate declaration ii

Acknowledgement iii

Abstract iv

Contents vi

List of Tables viii

List of Figures ix

CHAPTER 1 INTRODUCTION 1

1.1 General

1.2 Objective of the Study

1.3 Need of the Study

1.4 Scope of the Study

1.5 Thesis organisation

CHAPTER 2 LITERATURE REVIEW 10

2.1 Review of Research Papers

2.2 Review of IRC Codal Provisions

CHAPTER 3 METHODOLOGY 44

3.1 Review of Relevant Literature

3.2 Selection of Study Area

3.3 Conducting Surveys

3.4 Analysis of Surveyed data and design of Intersections

CHAPTER 4 DEVELOPMENT OF MODIFIED INTERSECTION 45

4.1 Design of J.K. Road Intersection

4.2 Design of Piplani Intersection

4.3 Design of Jyoti Talkies Intersection

4.4 Design of MANIT Intersection

4.5 Design of Mangalwara Intersection

vii

CHAPTER 5 CONCLUSION & RECOMMENDATIONS 65

5.1 Conclusions and Recommendations

REFERENCES 67

viii

LIST OF TABLES

Table No. Name of Table Page No.

1.1 Rate of road accidental deaths in India during 2004 to 2008 7

1.2 Motor Vehicle Population in Bhopal 8

2.1 Intersection Design Data 25

2.2 Design Speed in Urban Areas 27

2.3 Conditions for Design of Intersection according to their situation 28

2.4 Dimensions and Turning Radii of Some of the Typical Indian

Vehicles

29

2.5 Dimensions and Turning Radii of Design Vehicles 29

2.6 Length of Right Turning Lane 34

ix

LIST OF FIGURES

Figure No. Name of Figure Page No.

1.1 A Typical Four Legged Intersection 4

1.2 Various Types of Intersection 6

2.1 General Type of At-Grade Intersection 19

2.2 Potential Conflict Point at Different Types of

intersection

21

2.3 Channelisation Technique Illustrating Basic Intersection

Design Principle

22

2.4 Staggering of the Intersections 23

2.5 Analysis of Accident at Three armed Intersections 24

2.6 Method of Transition Curves at points of Additional

Lane

30

2.7 Provisions of Turning Lanes at Intersections 31

2.8 Method of Widening of Intersections 32

2.9 Method of Widening for Turning Lanes at Intersections 33

2.10 Typical Dimension of Road Intersections 34

2.11 General Types and Shapes of Islands 36

2.12 Details of Triangular Island Design 37

2.13 Progressive Layouts of T-Intersections for use on main

Highways

38

2.14 Rotary Elements 39

2.15 Circular Shaped Rotary 40

x

2.16 Squarish rotary with rounded edge 41

2.17 Elliptical Rotary 42

2.18 Rectangular shape 42

2.19 Layout of Complex Rotary 43

4.1 Existing Details of J.K. Road Intersection 47

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

Intersection

48

4.3 Details of Proposed J.K. Road Intersection 49

4.4 Details of Existing Piplani Intersection 51

4.5 Overlap of Details of Existing and Proposed Piplani

Intersection

52

4.6 Details of Proposed Piplani Intersection 53

4.7 Details of Existing Jyoti Talkies Intersection 55

4.8 Overlap of Details of Existing and Proposed Jyoti Talkies

Intersection

56

4.9 Details of Proposed Jyoti Talkies Intersection 57

4.10 Existing Details of Manit Intersection 59

4.11 Proposed details of Manit Intersection 60

4.12 Existing Details of Mangalwara Intersection 62

4.13 Overlap of Existing and Proposed Mangalwara

Intersection

63

4.14 Details of Proposed Mangalwara Intersection 64

1

CHAPTER 1: INTRODUCTION

1.1. General

An intersection is the area where two or more streets join or cross at-grade. The intersection

includes the areas needed for all modes of travel: pedestrian, bicycle, motor vehicle, and

transit. Thus, the intersection includes not only the pavement area, but typically the adjacent

sidewalks and pedestrian ramps. The intersection is defined as encompassing all alterations

(for example, turning lanes) to the otherwise typical cross sections of the intersecting streets.

Intersections are a key feature of street design in four respects:

i. Focus of activity

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

ii. Conflicting movements

Pedestrian crossings and motor vehicle and bicycle turning and crossing movements

concentrated at intersections.

iii. Traffic control

At intersections, movement of users is assigned, through traffic control devices such

as yield signs, stop signs, and traffic signals. Traffic control often results in delay to

users travelling along the intersecting roadways.

iv. Capacity

In many cases, traffic control at intersections limits the capacity of the intersecting

roadways, defined as number of users that can be accommodated within a given time

period.

1.1.1. Intersection Users

All roadway users are affected by intersection design such as:

i. Pedestrians.

Key elements affecting intersection performance for pedestrians are: (a) the amount of

right-of-way provided for the pedestrian including both sidewalk and crosswalk

width; (b) the crossing distance and resulting duration of exposure to motor vehicle

2

and bicycle traffic; (c) the volume of conflicting traffic; and (d) the speed and

visibility of approaching traffic.

ii. Bicyclists.

Key elements affecting intersection performance for bicycles are: (a) the degree to

which pavement is shared or used exclusively by bicycles; (b) the relationship

between turning and through movements for motor vehicles and bicycles, (c) traffic

control for bicycles; and (d) the differential in speed between motor vehicle and

bicycle traffic.

iii. Motor vehicles.

Key elements affecting intersection performance for motor vehicles are: (a) the type

of traffic control, (b) the vehicular capacity of the intersection, determined primarily

from the number of lanes and traffic control; (c) the ability to make turning

movements; (d) the visibility of approaching and crossing pedestrians and bicycles;

and (e) the speed and visibility of approaching and crossing motor vehicles.

iv. Transit.

Transit operations usually involve the operation of motor vehicles (buses), and

therefore share the same key characteristics as vehicles as outlined above. In addition,

transit operations may sometimes involve a transit stop in an intersection area, thereby

influencing pedestrian, bicycle, and motor vehicle flow and safety. Additionally, in

some cases, the unique characteristics of light-rail transit must be taken into account.

In addition to the users of the street and intersections, owners and users of adjacent land often

have a direct interest in intersection design. This interest can be particularly sensitive where

the intersection is surrounded by retail, commercial, historic or institutional land uses. The

primary concerns include: maintenance of vehicular access to private property; turn

restrictions; consumption of private property for right-of-way; and provision of safe,

convenient pedestrian access.

1.1.2. Definitions and Key Elements

The major street is typically the intersecting street with greater traffic volume, larger cross

section, and higher functional class. The minor street is the intersecting street likely to have

less traffic volume, smaller cross section and lower functional classification than the major

street.

3

The term intersection encompasses not only the area of pavement jointly used by the

intersecting streets, but also those segments of the intersecting streets affected by the design.

Thus, those segments of streets adjacent to the intersection for which the cross section or

grade has been modified from their typical design are considered part of the intersection.

Definitions, summarizes the extent and terminology used to define an intersection.

Two geometric features are common to all intersections, regardless of their level of

complexity. The angle of intersection is formed by the intersecting streets’ centrelines. Where

the angle of intersection departs significantly (more than approximately 20 degrees) from

right angles, the intersection is referred to as a skewed intersection.

Intersection legs are those segments of roadway adjacent to the intersection. The side of the

leg used by traffic approaching the intersection is the approach leg, or simply approach, and

the side used by traffic leaving is referenced to as the departure leg.

Sidewalks, crosswalks and wheelchair ramps are considered to be within the intersection. The

pavement corner is the curve connecting the edges of pavement of the intersecting streets.

Auxiliary lanes are lanes of traffic added at the intersection. These lanes are added

accommodate left-turning motor vehicles. Less often, they are added for right-turning motor

vehicles. They may also be used to add through lanes through an intersection.

Channelizing islands may be added to an intersection, to help delineate the area in which

vehicles can operate. Islands can also provide for pedestrian refuge.

A turning roadway is a short segment of roadway accommodating a right turn, delineated by

channelizing islands. Turning roadways are used where right-turn volumes are very high, and

where skewed intersections would otherwise create a very large pavement area.

Traffic control devices assign right-of-way, to both motorized and non-motorized traffic and

include traffic signals, STOP signs, and YIELD signs.

4

Fig 1.1: A Typical Four legged intersection

1.1.3. Intersection Types and Configurations

Intersections can be categorized into four major types, depending on their basic

configuration:

i. Simple Intersections

Simple intersections maintain the street’s typical cross section and number of lanes

throughout the intersection, on both the main and minor streets. Simple intersections

are best-suited to locations auxiliary (turning) lanes are not necessary to achieve the

desired level-of-service, or are infeasible due to nearby constraints.

ii. Flared Intersections

The characteristic feature of flared intersections is an expansion of the typical cross

section of the street (main, cross or both). The flaring is often done to accommodate a

5

left-turn lane, so that left-turning bicycles and motor vehicles are removed from the

through-traffic stream for reasons of capacity at high-volume locations, and safety on

higher speed streets. Right-turn lanes, less frequently used than left-turn lanes, are

usually a response to large volumes of right turns.

iii. Channelized Intersections

Channelized intersections use raised islands to designate the intended vehicle path.

The most frequent use is for right turns, particularly when accompanied by an

auxiliary right-turn lane. At skewed intersections, channelization islands are often

used to delineate right turns, even in the absence of auxiliary right turn lanes. At

intersections located on a curve, channelization islands can help direct drivers to and

through the intersection. At large intersections, short median islands can be used

effectively for pedestrian refuge.

iv. Roundabouts

The roundabout is a channelized intersection with one-way traffic flow circulating

around a central island. All traffic through as well as turning enters this one-way flow.

Although usually circular in shape, the central island of a roundabout can be oval, or

irregularly shaped. Roundabouts can be an appropriate design alternative to both stop-

controlled and signal-controlled intersections. At intersections of two-lane streets,

roundabouts can usually function with a single circulating lane, making it possible to

fit them into most settings.

6

1.1.4. Intersection Types

Fig 1.2: Various Types of Intersections

7

1.2. Objective of the study

The objectives of the study are as follow:

(i) Study of relevant literature.

(ii) Study of the existing scenario of the intersections in Bhopal City.

(iii) Re-appropriation of intersections in Bhopal City.

1.3. Need of the Study

Rapid growth rate (GDP) of India from the past 2 decades had lead to increase in per capita

income henceforth increasing their capacity to buy more vehicle or to use the intermediate

transport systems like taxies etc. But, on the other hand, the design of the Indian roads and

intersection had not been improved up to such extent to bear such a huge traffic. This has

placed a great stress on the road traffic particularly in the cities and urban areas, as compared

to the rural areas. And along with this rapid increase in traffic, number of accidents and the

number of people killed and injured in traffic crashes has been steadily increasing.

The severeness of the problem can be seen from the accident data provided by National

Crime Bureau, from the year 2004 to 2008.

Table 1.1 Rate of road accidental deaths in India during 2004 to 2008

S.No. Year Total no. of

deaths

Estimated mid- year

population (in

lakhs)

Rate of accidental deaths

(col.3/col.4)

(1) (2) (3) (4) (5)

1. 2004 277263 10856 25.5

2. 2005 294175 11028 26.7

3. 2006 314704 11197.75 28.1

4. 2007 340794 11365.53 30.0

5. 2008 342309 11531.3 29.7

(Source: National Crime Records Bureau, 2008)

8

In the Bhopal city, the traffic scenario can be observed from the table provided by the

Regional Transport Office (RTO), Bhopal. The table presents the motor vehicle population

from the year 1999 to 2009.

Table 1.2 Motor vehicle population in Bhopal

Year 1999 2003 2006 2009

Truck 3489 4241 4889 5435

Other goods

vehicle

1967 4109 6147 8170

Bus 2325 2637 2939 3233

Taxi 3206 6107 8998 11,918

Auto-rickshaw 8582 9566 10,954 12,451

Two-wheeler 2,10,218 2,92,522 3,87,308 4,50,291

Car 15,945 24,916 37,015 45,370

Jeep 2621 3044 3417 3949

Tractor 8993 9512 10,132 10,765

Trailer 2829 3548 4110 4720

Others 710 651 396 415

Total 2,60,885 3,60,853 4,76,305 5,56,717

(Source: Regional Transport Office, Bhopal, 2009)

From the above table, it can be seen that the overall motor vehicle population is increased by

more than 2 times in this decade. Hence by considering the future perspective too, it becomes

very important to design the roads and intersections in according to the future needs.

It is observed that well over half of the fatal and serious road accidents occur at intersection.

The intersections in these roads are the bottleneck for them because the efficiency safety,

speed, cost of operation and capacity of the facility depends on the intersection design to a

great extent. Each intersection involves through or cross traffic movement on one or more of

the highways and may involve turning movements between these highways. Such movements

can be facilitates by various geometric design and traffic controls, depending on the type of

intersection. Hence there is an urgent need for the proper designing of the various important

intersections on the basis of current real time information as well as future predictions and

also satisfying various codal provisions setup by IRC.

9

1.4. Scope of the Study

The Scope of this study is limited to re-appropriation of five intersections of the Bhopal city

which are chosen according to variance in their traffic and their situation in the Bhopal area,

viz Mangalwara Junction is located in old Bhopal city, where there are large number of

pedestrians as well as 2-wheelers, and also heavy commercial vehicles due to transport

business near, while on the other hand Jyoti Talkies Intersection is situated in New Bhopal

city in commercial area of M P Nagar which has a huge number of 2-wheelers as well cars

and small buses of city transport. The Piplani Junction and J.K, Road Junction are having

large numbers of heavy commercial vehicles like trucks and dumpers flowing through them,

MANIT Intersection has large number of 2-wheelers due to its connection with MANIT

college, and also it has huge traffic flowing from the kolar road to new market and Nehru

nagar and vice-versa.

1.5. Thesis Organisation

This thesis is divided in to 6 different chapters. Chapter 1 provides the general introduction of

intersections, objective of this thesis, its need as well as scope of work done in this thesis. In

chapter 2, literature review of various research papers has been done, as well as the analysis

of the codal provisions in this regard has been exercised. Chapter 3 gives the brief idea of the

methodology followed for designing the intersections in Bhopal city. In chapter 4 the

improved design of the junctions under consideration is rendered and at last in chapter 5 the

conclusion of the whole operation is given and future recommendation are furnished for the

intersection design.

10

CHAPTER 2: LITERATURE REVIEW

2.1. Review of Research Papers

Study of the various research papers in this arena is done and some of important findings are

summarised below:

NCHRP Report 650 (2010), describes common safety issues at median intersections on rural

divided highways and presents innovative geometric and operational treatments for

addressing those issues. It includes recommendations for modifications to the AASHTO A

Policy on Geometric Design of Highways and Streets (Green Book) and the Manual on

Uniform Traffic Control Devices (MUTCD). According to this report, Median-separated

highways provide distinct benefits over undivided roadways (two-lane or multilane roads

without medians). Medians separate opposing traffic, provide a recovery area for out-of-

control vehicles, provide a stopping area in case of emergencies, allow space for speed

changes and storage of left-turning and U-turning vehicles, minimize headlight glare, and

provide width for future lanes.

Research has shown that the percentage of total expressway crashes which occur at two-way

stop-controlled (TWSC) intersections increases as the mainline traffic volumes increase and

that all intersection crashes increase and become more severe as minor roadway volumes

increase. The majority of crashes at TWSC expressway intersections tend to be right-angle

crashes. The most problematic of these (with respect to severity) tend to be those occurring in

the far-side intersection (i.e., after the minor road driver has travelled through the median).

After addressing potential design issues such as insufficient sight distance, the traditional

approach to addressing safety problems at expressway intersections is to improve the traffic-

control devices, implement traffic signal control, and eventually construct an overpass or

interchange. However, traffic signals do not always improve safety: they may only change

the crash type distribution. In general, traffic signals in rural areas are discouraged for several

reasons including violation of driver expectations and difficulty in servicing and maintaining

signals in remote locations. The final alternative is to build an interchange at the intersection.

The construction of an reduces the cost advantage of building an expressway as compared

with building a freeway, and the mix of at-grade intersections and interchanges tends to

violate driver expectations.

11

Although this report identifies many issues, most must be solved by others in the future. For

example, although thorough reviews of the Green Book and the MUTCD were conducted

with many resulting recommendations, these are meant for the consideration for groups

themselves, and it is ultimately their responsibility to actually modify the contents of those

manuals. Furthermore, the safety effectiveness of the rural expressway intersection treatments

examined in the case studies can only be determined if state transporting agencies (STAs) are

willing to deploy and to evaluate them rigorously. While the recommendations that follow are

specific, others must implement them to positively impact rural expressway inter-section

design and safety.

Kent J. Fugal et al (2008), emphasis on the Design for Single-Lane to Dual-Lane

Roundabout Expandability. Roundabout planners and designers are often faced with

situations where a multi-lane roundabout will be required to handle the design-year traffic

volumes, but where a single-lane roundabout would be sufficient for a number of years. Due

to issues of safety, complexity, driver familiarity, and sometimes cost, it may be desirable to

construct a single-lane roundabout that can be expanded in the future. Two alternatives for

the initial single-lane layout are presented, including advantages and disadvantages of each.

One alternative involves building the full outside footprint and widening inward, while the

other involves building the central island and splitter islands in the ultimate configuration and

widening outward. The paper also includes a case study of the Amity Avenue/Happy Valley

Road Roundabout in Nampa, Idaho.

According to author, an expandable design should always begin with a good dual-lane layout.

Dual-lane operation and design are much more complex than single-lane. While single-lane

roundabout operations can be forgiving, to an extent, of shortfalls in the design, the safety

and efficiency of dual-lane roundabouts generally suffer significantly from even “small”

design problems. Expanding a “good” single-lane design does not necessarily result in a

“good” dual-lane design. However, a good single-lane, initial-build layout can often be

readily developed as a first phase of the development of a dual-lane roundabout. The designer

must fully check the dual-lane layout to ensure that it will function with the intended safety

and efficiency as he or she would do if a dual-lane roundabout were being constructed right

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

circulating speed control (fastest path analysis). It should also be checked for potential

entering and exiting lane path overlap issues and proper handling of pedestrians and bicycles.

12

This paper explores the characteristics of a good expandable roundabout design, including

basic procedures that should be followed. However, it does not discuss roundabout design in

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

expandable roundabout. Those steps include:

1. Development of the proposed dual-lane roundabout geometry,

2. Development of an initial-build, single-lane layout consistent with the proposed dual-

lane geometry, and

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

The author accentuated the fact that it would be undesirable to construct a dual-lane

roundabout initially when a single-lane roundabout would adequately handle the traffic for

many years. Roundabouts should not be overbuilt for a number of reasons. These include

concerns with operational simplicity, safety, and cost.

Ragnhild Davidse (2007) is concerned with the possibilities offered by road design and

driver assistance systems to improve older adults’ safe and independent mobility by

compensating for their age-related functional limitations. The author’s aim is to identify those

characteristics of intersections that may contribute to the over-representation of crashes that

older drivers are considered legally responsible for. These characteristics were traced by

looking at the functional limitations of older people and the demands they make on

intersection design. It was assumed that if the design elements of an intersection allow for the

functional limitations of older people, the crash involvement of older drivers will be low and

vice-versa. The validity of these assumptions was tested by the inspections of the

intersections that have different shares of crashes involving older drivers.

The intersection inspections indicated that priority regulation is a predator of the crash

involvement of older drivers. Crashes involving older drivers occur more often at yielding-

controlled intersections than at the intersections with traffic lights. It reveals that the

following intersection design elements appear to allow for the older drivers functional

limitations: a positive offset of opposite left-turn lanes, roundabouts, and a high in service

contrast level for road markings, background plates for traffic lights, long sight distances,

advance warning signs, and protected-only operations of traffic lights. However, the actual

effect that they have on the safety of older drivers has hardly been tested yet.

In this research paper, two strategies were followed to look for intersection design elements

that play a role in the difficulties that older drivers encounter in traffic: 1) inspections of

13

intersections that have different shares of crashes involving older drivers, and 2) a review of

the literature on intersection design elements that appear to take the functional limitations of

older drivers into account.

The intersection inspections were guided by the concept of task difficulty. It was expected

that the crash risk of older drivers would increase with the complexity of the traffic situation,

provided that drivers have to make decisions with regard to road users that are about to cross

their path, and provided that drivers cannot use their experience to make these decisions.

These expectations were only confirmed for one of the intersection characteristics that were

expected to determine the need for decision making with regard to other road users:

implementation of right of way. It turned out that at intersections at which no crashes

occurred in which older drivers were involved, traffic was more often regulated by means of

traffic lights than it was at intersections at which relatively many crashes occurred in which

older drivers were involved. At the latter intersections, traffic was more often regulated by

means of yield signs.

The intersection inspections that were carried out within the scope of this thesis had a rather

exploratory character and the number of intersections that were inspected was relatively

small. However, the concept of task difficulty and its application to the difficulty of passing

intersections deserve it to be studied in a more systematic way. They evaluated the effects of

a positive offset of opposite left-turn lanes and protected only operations of lights on driving

behaviour in a driving simulator and instrumented car respectively. Neither of the

adjustments had a significant effect on driving behaviour.

Kay Fitzpatrick et al (2002) emphasizes on the issues to be considered in developing an

Intersection design guide. He throws light on the fact that safe and efficient operation of an

intersection is directly related to its design, and decisions made during the design of an

intersection occur after examining a series of tradeoffs. The resources available to designers

can limit effective intersection design. The wealth of information published in the past years

demonstrates that there are several new ideas on how to better design intersections.

Unfortunately, if these ideas are not readily available or included in the reference materials

used by designers, they will not become generally accepted or used. So he accentuated on the

importance of the use of past data for the design purpose. The prime objective of author is to

produce a reference document for the Texas Department of Transportation (TxDOT), that

14

provides information on each of the design elements associated with an intersection and

discusses related geometric and operational issues involved in urban intersection design.

The project is a three-year effort and is structured into two phases. The first phase (Phase I)

took place during the initial 12 months of the project, and this report summarizes the first-

year activities. A wide variety of issues were raised in the discussions. Issues that received

repeated interest among the engineers and designers interviewed included:

o Pedestrian issues: curb cuts, crosswalks, and protrusions.

o Drainage: ponding and flow across the intersection.

o ROW: conflicting or unknown locations for utilities, utility access, utilities clearance,

obtaining ROW, establishing requirements, and customary practice.

o Traffic control device issues: wide medians, islands and pedestrians, mast arm length,

number of signal heads, internally illuminated street signs, protected/permissive

operations, marked crosswalks, illumination, and use of span wire.

o Intersection layout: dual lefts, turn bays, turn priorities, bicycles, sight distance, skew

angle, traffic counts, cost estimates, driveways, pavement design, and acceleration lanes.

This research is designed to provide TxDOT and other interested parties with useful and

practical information on operations and design for intersections. This includes chapters on

Intersection Function, Design Control and Criteria, Design Elements, Cross Section,

Roadside, Drainage, Street Crossing, Signals, Marking, Signs, Influences from Other

Intersections.

Synthesis of Highway Practice 264 (1998), provides information on current practices with

respect to the planning, design, and operation of modern roundabouts in the United States.

Administrators, engineers, and researchers are continually faced with highway problems on

which much information exists, either in the form of reports or in terms of undocumented

experience and practice. In an effort to correct this situation, a continuing NCHRP project,

carried out by the Transportation Research Board as the research agency, has the objective of

reporting on common highway problems and synthesizing available information. The

synthesis reports from this endeavour constitute an NCHRP publication series in which

various forms of relevant information are assembled into single, concise documents

pertaining to specific highway problems or sets of closely related problems.

15

The concept of the modern roundabout to move traffic more efficiently through un-signalized

intersections has evolved from conventional traffic circles. This report of the Transportation

Research Board presents a discussion of modern roundabout applications in the United

States, based on a survey of state and local transportation agencies, which provided

information on 38 individual roundabouts. The synthesis demos information on the design

guidelines used in the United States as well as those of other countries. Other major areas of

interest with regard to roundabouts include safety issues; traffic capacities and delays; issues

related to pedestrians, bicyclists, and the visually impaired; costs; and location criteria to be

considered for roundabouts.

Modern roundabouts have become a subject of great interest and attention over the last few

years in the United States. This interest is partially based on the great success of roundabouts

in Europe and Australia, where intersection design practice has changed substantially as the

result of the good performance of roundabouts and their acceptance by the public. The public

reaction to roundabouts has been positive in general. This is substantiated by the survey

respondents, by opinion surveys, and by reporting in the press.

Some concerns were raised regarding pedestrians at roundabouts, especially with regard to

the absence of clear right-of-way control. This perceived problem is related to some degree to

the belief by the general public that signalized intersections bring the greatest safety to

pedestrians. These concerns tend to disappear after the pedestrians have an opportunity to use

the roundabout.

For bicyclists, the preferred arrangement in the case of single-lane and low-speed

roundabouts is to stop bicycle lanes before they reach the roundabout and to let bicycles

circulate in mixed traffic through the circle. For larger, multi-lane roundabouts, it appears

preferable to provide separate bike paths, or to provide for mixed bicycle/pedestrian paths, or

reroute bicyclists.

To conclude, roundabouts can have significant benefits in terms of safety, delays, and

capacity. Another major new benefit is related to the aesthetic and urban design

improvements resulting from the landscaping and sculptural elements in the central island.

This synthesis has portrayed the roundabouts starting from its history and evolution to the

modern use in United States. It has summarized the design guidelines that are being used in

16

the United States and in other countries. It also throws light on the safety of roundabouts. It

also talks about the issues related to pedestrians, bicyclist, and the visually impaired.

Bruce Hellinga et al had given Signalized Intersection Analysis and Design and its

implications of day-to-day variability in Peak. This paper presents findings of a study that

quantifies the impact of day-to-day variability of intersection peak hour approach volumes on

intersection delay and demonstrates that this impact is not insignificant and therefore should

not be ignored. Finally, the study explores the number of days for which intersection

approach volumes should be counted in order to establish intersection delay within a desired

level of confidence.

Intersection performance as measured by delay is a function of many factors including, signal

timing plan, turning movement traffic demands, traffic stream composition, pedestrian

volumes, intersection geometry, temporal variation in traffic demands, the headway

distribution of each traffic stream, driver characteristics, weather and road surface conditions

and visibility. Some of these factors are invariant for a given intersection operating under a

defined signal control strategy (e.g. geometry and signal timing plan) while others vary (e.g.

weather, traffic demands, etc.). This paper seeks to address the following specific questions:

1. What degree of day to day variability exists in the peak hour traffic volume and to what

extent are traffic volumes on different intersection approaches statistically correlated?

2. What impact does the day to day variation in the peak hour volume have on intersection

performance as measured by delay?

3. For how many days are turning movement counts required in order to estimate the

intersection performance with a given level of confidence?

In this paper the answers of these questions were given using empirical data to quantify the

distribution of day-to-day peak hour traffic volumes and the degree of statistical correlation

between approach volumes. On the basis of these observations and conclusions, the following

recommendations are made:

1. Additional field data should be obtained from another region to confirm the findings of

this study.

2. The impact on intersection performance of day-to-day variability of other factors such as

the PHF and turning movement proportions should be examined.

17

3. The presence of significant auto-correlation in the intersection peak hour traffic volumes

could impact the number of observations required to estimate intersection performance

within a specified tolerance. Consequently, an analysis should be conducted to quantify

the extent of auto-correlation and the impact that this has.

4. Criteria should be established to incorporate the day-to-day variability of volume within

existing signalized intersection evaluation and analysis methodologies.

2.2. Review of IRC Codal Provisions

IRC-SP-41, ‘Guidelines for the Design of At-grade Intersection in Rural and Urban Areas’

and IRC-SP-65, ‘Recommended Practice for Traffic Rotaries’ has been reviewed in this

regard and some main codal provisions are depicted below:

2.2.1. Factors covering design

Road intersections are critical element of a road section. They are normally a major

bottleneck to smooth flow of traffic and a major accident spot. The general principles off

design in both rural and urban areas are the same. The basic difference lies in the design

speeds, restriction on available land, sight distance available and the presence of larger

volume of pedestrians and cyclists in urban areas. Design of a safe intersection depends on

many factors. The major factors can be classified as under.

A. Human Factors.

a) Driving habits,

b) Ability to make decisions,

c) Driver expectancy,

d) Decision and reaction time,

e) Conformance to natural paths of movement,

f) Pedestrian use and habits.

B. Traffic considerations

a) Design and actual capacities,

b) Design hour turning movements,

c) Size and operating characteristics of vehicle,

d) Type of movement (diverging, merging weaving, and crossing),

e) Vehicle speeds,

18

f) Transit involvement,

g) Accident experience,

h) Traffic Mix i.e., proportion of heavy and light vehicles, slow moving vehicles,

cyclists etc.

C. Road and Environmental considerations

a) Character and use of abutting property,

b) Vertical and horizontal alignment at the intersection,

c) Sight distance,

d) Angle of the intersection

e) Conflict area,

f) Speed-change lanes,

g) Geometric features,

h) Traffic control devices,

i) Lighting equipment,

j) Safety features,

k) Environmental features,

l) Need for future upgrading of the at-grade intersection to a grade separated

intersection.

D. Economic factors

a) Cost of Improvements,

b) An effect of controlling of limiting right-of-way on abutting residential or

commercial properties where channelization restricts of prohibits vehicular

movements.

2.2.2. Basic Design Principles

In the design of an intersection the primary considerations are safety, smooth and efficient

flow of traffic. To achieve this, the following basic principles must be followed.

2.2.3. Uniformity and Simplicity

Intersections must be designed and operated for simplicity and uniformity. The design must

keep the capabilities and limitation of drivers, pedestrians and vehicles using intersection. It

should be based on the knowledge of what a driver will do rather than what he should do.

19

Further all the traffic information on road signs and markings should be considered in the

design stage, prior to taking up construction work. All the intersection movements should be

obvious to the drivers, even if he is a unfamiliar to the area. Complex design which required

complicated decision-making by drivers should be avoided. There should be no confusion

and the path to be taken by the drivers should be obvious. Undesirable short cuts should be

blocked. Further, on an average trip route, all the intersections should have uniform design

standards so that even a newcomer to the area anticipates what to expect at an intersection.

Some of the major design elements in which uniformity is required are design speed,

intersection curves, vehicle turning paths, super-elevations, level shoulder width, speed

change lane lengths, channelization, types of curves and type of signs and markings.

Fig 2.1: general types of At-grade Intersections

20

2.2.4. Minimise Conflict Points

Any location having merging, diverging or crossing manoeuvres of two vehicles is a potential

conflict point. Fig. 2.2 shows the potential conflict points for different types of intersections.

The main objective of the intersection design is to minimise the number and severity of

potential conflicts between cars, buses, trucks, bicycles and pedestrians and whenever

possible, these should be separated. This can be done by:

i. Space separation : by access control islands through channelising

ii. Time separation : by traffic signals on waiting lanes.

Some of the common methods used to reduce conflict points are:

a) Convert a 4-armed intersection having 32 conflict points to a roundabout having only

12 conflict points. Round-about treatment may not, however, be warranted at most of

rural locations except those close to the urban areas.

b) Signalise intersection. As Fig. 2.2 shows introduction of a two-phase signal reduces

the conflict points at 4 armed intersections from 32 to 16. If more phases are

introduced and separate lanes provided for turning traffic, conflict points can be

virtually eliminated. (Provisions of signals may however, be justified only at a few

rural locations carrying heavy traffic). Research abroad has shown that signals

increase accidents at simple intersections with low volumes but reduce them at

complex and/or high volume intersections.

c) Channelising the directional traffic by selective use of channelising islands and

medians. Some of these techniques are shown in Fig. 2.3 shows how the conflict

points can be reduced on a 3-armed intersection by introducing combinations of

channelising islands.

d) Changing priority of crossing by introducing the GIVE WAY or STOP signs for

traffic entering the junctions from minor road, By this, traffic causing the conflict is

restrained.

e) Staggering a 4-armed junction by flexing the two opposing arms of the side road to

create two T-junctions. When staggering is employed, it should be ensured that

minimum distance between two junctions is 45 m and desirably right-left staggers are

created. (Fig. 2.4).

21

Fig 2.2: Potential Conflict Points at Different Types of Intersection

22

Fig 2.3: Channelisation Technique Illustrating Basic Intersection Design Principles

23

Fig 2.4: Staggering of the Intersections

A study of conflict points and accidents records by classifying accidents according to the

types of conflicts would greatly help in adopting appropriate engineering measures for

intersection design. For illustration, an example of a 3-armed intersection as shown in Fig.

2.5 may be considered. The Figures (a) to (i) show the various left turning & right turning

movements, and the percentage of accidents classified according to types of collision.

Following measures can be considered for improving safety:

24

i. The accident situations in Figs. 2.5 (c), (d) and (h) involving right turning vehicles in high

percentage of accidents can be prevented by controlling traffic movement either manually

or by traffic signals.

ii. Provisions of acceleration lane on the major road for the left turning traffic flow from the

minor road could prevent traffic situation, Fig. 2.5 (f).

iii. A separate right turning lane on the major road could minimise or prevent rear and

collision at Fig. 2.5 (g).

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

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

v. Deceleration lanes for left turning traffic from major road would also ensure better safety

for situations at Fig. 2.5 (e).

25

Table 2.1 Intersection Design Data

Intersection Design Data Peak Hour _____________ Hrs. To ____________ Hrs.

Peak Hour Design Traffic

Name & Location of Intersection __________________________________________

From Leg A*

Entering Leg B* Leg C* Leg D* Remarks

Type Nos PCU

Equi-

valency

PCU Nos PCU

Equi

valency

Nos PCU

Equi

valency

1 2 3=1x2 1 2 1 2

Fast Vehicles

1. Passenger cars,

tempos, auto

rickshaw,

tractors, pickup

vans

1.00

2. Motor cycle.

scooters

0.50

3. Agricultural

tractor Light

Commercial

Vehicles

1.50

4. Trucks, Buses 3.00

5. Tractor-Trailer,

Truck Trailer

Units

4.50

TOTAL FAST

Slow Vehicles

6. Cycles 0.50

7. Cycle

Rickshaws

1.50

8. Hand Cart 3.00

9. Horse Drawn 4.00

10. Bullock-Carts 8.00

TOTAL SLOW

PEDESTIAN NOS.

* Specify the name of an important place or land on this leg such as Market leg, Temple leg,

etc.

26

Separate report sheets will be needed for the other legs of the intersection. The volume of the

above traffic in terms of number of vehicles and in PCU should then be reflected in the

diagrams. If the numbers of legs in the intersection are 3 or more than 4, these figures should

be suitably modified.

vi. In the urban/sub-urban areas and intersection near villages with substantial pedestrian

movements, the peak hour data on persons crossing the intersecting road arms should

be collected for the design of a well planned pedestrian crossing facility at the

intersection.

2.2.5. Parameters of Intersection Design

2.2.5.1. General

Intersections are designed having regarded to flow speed, composition, distribution and

future growth of traffic. Design has to be specified for each site with due regard to physical

conditions of the site, the amount and cost of land, cost of construction and the effect of

proposal on the neighbourhood. Allowances have to be made for space needed for traffic

signs, lighting columns, drainage, public utilities etc. The preparations of alternative designs

and comparison of their cost and benefits is desirable for all major intersections.

2.2.5.2. Design Speed

Three types of design speeds are relevant for intersection element design:

i. Open highway or "approach" speeds.

ii. Design speed for various intersection elements. This is generally 40 percent of

approach speed in built up areas and 60 percent in open areas.

iii. Transition speeds for design of speed change elements i.e. changing from entry/exit

speed at the intersection to merging/diverging speed.

In rural areas ruling design speed should be used, but minimum can be adopted in sections

where site conditions and costs dictate lower speeds. In urban areas a lower or higher value of

design speed can be adopted depending on the pressure of physical controls, road side

developments and other related factors. A lower value is appropriate for central business

areas and higher in sub-urban areas.

27

2.2.5.3. Design Traffic Volumes

Intersections are normally designed for peak hour flows. Estimation of future traffic and its

distribution at peak hours is done on the basis of past trends and by accounting for factors

like new development of land, socio-economic changes etc. Where it is not possible to predict

traffic for longer period, intersection should be designed for stage development for design

period in steps of 10 years. Where peak hour flows are not available they may be assumed to

be 8 to 10 percent of the daily flow allocated in the ratio of 60:40 directionally.

2.2.5.4. Radius of Curves of Intersection

The radii of intersections curves depend on the turning characteristics of design vehicles their

numbers and the speed at which vehicles enter to exit the intersection area. The design curve

is developed by plotting the path of the design vehicles on the sharpest turn and fitting curves

or combination of curves to the path of inner rear wheels. Generally four types of curves are

possible to fit in with the wheel paths of a turning vehicle.

Table 2.2 Design Speeds in Urban Areas

S.No. Road Classifications Design Speed

(Km/h)

1. Arterial 80

2. Sub-arterial 60

3. Collection street 50

4. Local street 30

2.2.5.5. Design Vehicle

IRC: 3 – 1983 recognises three types of roads design vehicles namely single unit truck, semi

trailer and truck trailer combination. Passenger cars are not considered as design vehicles in

rural areas as savings in construction using this vehicle cannot be justified on economic basis.

As such nearly all intersection curves in rural areas should be designed for either single unit

trucks/buses of 11/12 m length, or semi-trailer combination of 16 m length or truck trailer

combination of 18m length. On most rural highways semi trailer combination would be used

for design, whereas in non arterial urban areas a single unit truck or bus can form the basis

for design. In purely residential areas, alone a car forms the basis of design.

28

There are five common situations in design of intersections and each one has to be generally

designed for following conditions:

Table 2.3 Conditions for Design of Intersection according to their Situation

S.No. Location of

Intersection

Curve Design

1. Rural Section Design for single unit truck is preferred for intersection

with local minor roads. Semi-trailer design is preferred

for major road intersection where large paved areas

result, channelization also becomes essential.

2. Suburban Arterial

Section

Designed for semi-trailer with speed change lanes and

channelisation. Three-centred compound curves are

preferred.

3. Urban Arterial &

sub Arterials

Designed for single unit truck.

4. Urban Central

Business District

Designed for single unit trucks for minimum curve radii

with allowance for turning vehicles encroaching on

other lances.

5. Residential area Designed for cars only with encroachment of tracks

into other lanes.

Table 2.4 Dimensions and Turning Radii of Some of the Typical Indian Vehicles

S.No. Make of Vehicle Length

(m)

Width

(m)

Turning

Radius (m)

1. Ambassador 4.343 1.651 -

2. Maruti Car 3.300 1.405 4.400

3. TATA (LPT 2416)

3-axled truck

9.010 2.440 -

4. TATA (LPO 1210)

Full forward control Bus Chassis

9.885 2.434 10.030

5. TATA (LPO 1616)

Bus Chassis

11.170 2.450 -

6. Leyland Hippo Haulage 9.128 2.434 10.925

7. Leyland (18746)

Taurus

8.614 2.394 11.202

29

8. Leyland

Beaver Multi Drive

12.000 2.500 -

9. Mahindra Nissan

Allwyn Cabstar

5.895 1.870 6.608

10. Swaraj Mazda Truck (WT 49) 5.974 2.170 6.400

11. DCM Toyota (Bus) 6.440 1.995 6.900

Table 2.5 Dimensions & Turning Radii of Design Vehicles

S.No. Vehicle Type Overall

Width

(m)

Overall

Length

(m)

Overhang

Front (m)

Minimum Turning

Rear (m) Radius (m)

1. Passenger Car (P) 1.4 – 2.1 3 –

5.74

0.9 1.5 7.3

2. Single Unit Truck

(S.U.)

2.58 9 1.2 1.8 12.8

3. Semi Trailer and

Single unit Bus

(WB-12m)

2.58 15.0 1.2 1.8 12.2

4. Large Semi-Trailer

(WB 15m)

2.58 16.7 0.9 0.6 13.71

5. Large Semi-Truck

Trailer (WB-18m)

2.58 19.7 0.6 0.9 18.2

30

2.2.5.6. Auxiliary Lanes

Three types of auxiliary lanes are provided at intersections. These are storage lanes, right

turning lanes, acceleration lanes and deceleration lanes. The last two together are also called

speed change lanes. Provision of these increases the capacity of intersection and improves

safety. The length of these lanes depends on the volume of traffic entering or leaving the side

road. The shape of these can be either parallel lane with sharp taper or a direct taper or with a

transition curve. Fig. 2.6 shows the method of introducing addition lane using transition

curves.

2.2.5.6.1. Storage lanes/right turning lanes

Storage lines are generally more important in urban areas where volume of right turning

traffic is high and if not catered for, blocks the through traffic. Normal design procedure

provides for storage length based on 1.5 times the average number of vehicles (by vehicle

type) that would store in turning lane at peak hour. At the same time the concurrent through

lane storage must also be kept in view, as it may occur that the entry to turning lane may

become inaccessible due to queued vehicles in through lane. Fig. 2.7 shows several methods

of introducing turning lane at intersections. Figs. 2.8 and 2.9 show satisfactory method of

widening at intersections and widening for turning lanes at intersections.

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

31

Fig 2.7: Provisions of Turning Lanes at Intersections

32

Fig 2.8: Method of Widening of Intersections

33

Fig 2.9: Method of Widening for Turning Lanes at Intersections

34

In places where not more than one or two vehicles are expected to wait for right turn, such as

in rural areas, the storage lane may be provided as per Table 2.7.

Table 2.6 Length of Right Turning Lane

Design Speed (km/h) Length of storage lane including 30 – 45

m taper

120 200

100 160

80 130

60 110

50 90

2.2.5.6.2. Speed Change Lanes

Speed change lanes are more important in rural areas. In urban areas such lanes are rarely

required but provision of short lanes to assist merging and diverging manoeuvres are

provided in conjunction with channelising islands. Speed change lanes should are uniformly

tapered and have a setback of 5.4m at the tangent point of curve leading into or out of minor

road. The turning lane should be reduced in width to 4.25m by carriageway marking etc. as

shown in Fig. 2.10.

Fig 2.10: Typical Dimension of Road Intersections

35

2.2.5.7. Channelising Island

The objectives of providing channelising island are to

i. Control speed and path of vehicles at the intersection;

ii. Control angle of conflict;

iii. Separate conflicting traffic streams;

iv. Provide shelter to vehicles waiting to carry out certain manoeuvres;

v. Assist pedestrians to cross;

vi. reduce excessive carriageway areas and thus limit vehicle paths; and

vii. Locate traffic control devices.

The general types of island and their shapes are shown in Fig. 2.10. To ensure proper

functioning of each type of islands, principles given below for each should be adhered to.

2.2.5.7.2. Corner or directed islands

Figures 2.12 illustrate the design features of corner islands and the considerations which

govern their sizes and shapes. Corner or Directional Islands (normally triangular) should

meet the following requirements:

a) Is should be of sufficient size to be readily identified and visible. For an island to be

clearly seen it must have an area of at least 4.5m2 in urban areas and 7m

2 in rural

areas and should usually be bordered with painted raised kerbs. Smaller areas may be

defined by pavement marking Accordingly triangular islands should not be less than

3.5m and preferably 4.5m on a side after rounding of curves.

b) It should be offset from normal vehicle path by 0.3m to 0.6m. The layout should be

tested using the track diagram for all turning movements.

c) Is should be provided with illuminated sign or a bollard at suitable places e.g. apexes

of islands. It should be of sufficient size to enable placement of such traffic control

devices.

d) It should be accompanied by suitable carriageway marking to show actual vehicle

paths. Marking should be made conspicuous by use of refectories materials.

e) Is should be properly marked for night visibility.

36

2.5.7.3. Centre or divisional islands

Centre islands require careful location and designing. They require careful alignment and are

invariably accompanied by widening of right-of-way. Centre or divisional islands should

meet the following requirements.

a) It should be preceded by a clearly marked or constructed natural area of not less than

1.5 sec. travel time at approach speed.

Fig 2.11: General Types and Shapes of Islands

37

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

38

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

39

2.2.6. Definitions

(1) At grade intersection An intersection where all roadways join or cross at the

same level.

(2) Diverging The dividing of single stream traffic into separate

streams.

(3) Intersection angles The angle between two intersection legs.

(4) Merging The converging of separate streams of traffic into a

single stream.

Fig 2.14: Rotary Elements

(5) Rotary Intersection A road junction laid out for movement of traffic in

one direction round a central island.

(6) Rotary Island A traffic island located in the centre of an intersection to

compel movement in a clock-wise direction and thus

substitute weaving of traffic around the island instead of

direct crossing of vehicle pathways.

40

(7) Weaving The combined movement of merging and diverging

of traffic streams moving in the same general

direction.

(8) Weaving length The length of a section of a rotary in which weaving

occurs.

2.2.7. Shape of Rotary Island

The shape of the rotary island depends upon various factors such as the number and

disposition of the intersecting roads and the traffic flow pattern. While finalising the shape of

the rotary island, traffic streams within the rotary should be given dominance over the

streams of traffic entering from different roads. Asymmetric shapes either wholly curved or

with a combination of straight and curves may often provide the only satisfactory solution.

Some of the more common shapes and disposition of the rotary islands are discussed below

2.2.7.1. Circular

A circular shape is suited where roads of equal importance intersect at nearly equal angles

and carry nearly equal volume of traffic, Fig.2.15, under these conditions, with a circular

shape, a constant and regular flow is achieved.

Fig 2.15: Circular Shaped Rotary

41

2.2.7.2. Squarish with rounded edges

This is a modification of the circular shape and is composed of four straights or four large

radii curves roughly forming four sides of a square, Fig 2.16 and four small radii curves at the

corners. The advantage of this layout is that it is suitable for predominantly straight ahead

flows.

Fig 2.16: Squarish rotary with rounded edge

2.2.7.3. Elliptical, elongated, oval or rectangular shapes

The above shapes are provided to favour through traffic, to suit the geometry of the

intersecting legs, or to provide a longer weaving length. Fig 2.17 and 2.18 are illustrative.

42

Fig 2.17: Elliptical Rotary

Fig 2.18: Rectangular shape

43

2.2.7.4. Complex intersection with many approaches

Fig 2.19 gives a layout of a complex intersection whose shape is dictated by the existence of

a large number of approaches.

Fig 2.19: Layout of complex Rotary Intersection

44

CHAPTER 3: METHODOLOGY

Major steps of the proposed methodology are as follows:

3.1 Review of relevant literature

The research paper given by various researchers in this arena are reviewed and the

relevant codal provisions in the IRC are being analyzed and their brief summary is being

described in this thesis.

3.2 Selection of study area

a) The study area includes old and new Bhopal, for satisfying heterogeneity of the

problem as different conditions prevails in different junction areas.

b) Following are the junctions that are taken under the scope of this study:

i. J.K. road Intersection

ii. Piplani Intersection

iii. Jyoti Talkies Intersection

iv. MANIT Intersection

v. Mangalwara Intersection

3.3 Conducting Surveys

For the understanding of the existing situations at the site and for getting the required true

data, following surveys are being done:

a) Total Station survey of the Intersections, to find out the existing or available cross

section of all legs of Intersection, existing surroundings structures at that Intersection,

space available and possibilities for modification and construction of all members of

Intersection for future expansion.

b) Traffic volume survey at all legs of Intersection.

3.4 Analysis of the surveyed data and design of intersections

Then the analysis of the surveyed data is done in order to design the junction on the basis

of the real time data and in accordance with the relevant IRC codal provisions.

45

CHAPTER 4: DEVELOPMENT OF MODIFIED INTERSECTIONS

4.1 Design of J.K. Road Intersection

The intersection under consideration is a three legged intersection. The two legs are of Raisen

road which is National Highway. This through route carries high intensity of traffic including

heavy commercial vehicles. The third leg leads to JK Road which passes through many

residential and commercial establishments and joins the Ayodhya By-Pass. At present the

intersection is uncontrolled intersection as there are no pavement markings, physical dividers

like median on through route, channelizing islands, traffic signals and no pedestrian crossing

facilities. The situation is worsened by the encroachments on all three legs of the intersection.

Visibility at night is very poor leading to possibility of conflicts. Therefore to design the

Intersection for the safe and efficient functioning, peak hour traffic volume surveys at the

intersection are carried out. The observations and recommendations for the intersection are as

follows:-

1. The peak hour traffic volume of the three legged Intersection is found out as 6800

PCU per hour. This traffic intensity at the intersection is very high for the safe

operation of traffic at the intersection in its present situation.

2. The intersection in its present situation is unable to handle the high volume of

crossing and turning traffic especially during peak hours. The junction has become

completely incapacitated and present traffic management measures are inadequate to

deal with such a high intensity traffic volume.

3. At present there is no traffic signal at the intersection. It is suggested to provide traffic

signals. This signalization should also have pedestrian timings. (IRC:93-1985).

Traffic signal at the intersection needs to be designed based on real time data.

4. The junction should be signalized with necessary widening on all the legs of the

intersection as shown in the drawing sheet.

5. Encroachment on all the three legs should be removed to enhance the capacity of the

junction.

6. To streamline the vehicular traffic and to provide refuge to the pedestrians crossing

the road channelizing islands are proposed as shown in the drawing sheet.

7. Necessary traffic signs and pavement markings need to be provided at the

intersection. (IRC: 35-1997 and IRC: 67-2001).

46

8. No bus stops should be located within the 75 meter length from the junction.

Therefore all the existing bus stops at the junction which lie within the 75 meter

should be removed. Also the location of the bus stops should be at the farther side of

the junction.

9. To enhance the visibility of the junction at night, it is recommended to provide High

Mast light to lighten the junction area.

47

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

48

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

49

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

50

4.2 Design of Piplani Intersection

The peak hour traffic volume survey at the Piplani Petrol Pump intersection was carried out.

The observations and recommendations for the intersection are as follows:-

1. The peak hour traffic volume at the first three legged Intersection Sonagiri side i.e.

considering the three legs is found out as 6000 PCU per hour. The peak hour traffic

volume at the BHEL side i.e. considering the three legs is found out as 6500 PCU per

hour. This traffic intensity at the intersection is very high for the safe operation of

traffic at the intersection.

2. An at grade intersection having traffic volume in excess of 10000 PCU per hour,

warrants for a grade separated intersection (IRC: 92-1985). In this case the total traffic

volume at the staggered junction is 12500 PCU per hour which is very high and it

warrants for a grade separated intersection.

3. The maximum volume that a traffic rotary can handle efficiently is about 3000

vehicles per hour entering from all intersection legs and rotaries are most adaptable

where the volumes entering the different intersection legs are approximately equal.

(IRC: 65-1976, Recommended Practice for Traffic Rotaries)

4. At present intersection gets locked frequently because of high volume of crossing and

turning traffic especially during peak hours. The staggered junction has become

completely incapacitated and present traffic management measures are inadequate to

deal with such a high intensity traffic volume.

5. At present there is no traffic signal at both the intersections. It is suggested to provide

traffic signals.

6. The junction should be signalized with necessary widening on all the legs of the

intersection as shown in the drawing sheet.

7. Encroachment on all the four legs should be removed to enhance the capacity of the

junction.

8. As traffic volume is very high, the available width of carriageway is insufficient to

accommodate the vehicles.

9. To streamline the vehicular traffic and to provide refuge to the pedestrians

channelizing islands are proposed as shown in the drawing sheet.

10. Necessary traffic signs and pavement markings need to be provided at the

intersection.

11. Traffic signal at the intersection needs to be designed based on real time data.

51

Fig 4.4: Details of Existing Piplani Intersection

52

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

53

Fig 4.6: Details of Proposed Piplani Intersection

54

4.3 Design of Jyoti Talkies Intersection

The Jyoti Talkies intersection is a four legged intersection. The Board office leg & leg

towards Chetak Bridge are the part of major road; this through route carries very high

intensity of traffic. The third leg goes toward M.P. Nagar Zone-I and fourth leg towards M.P.

Nagar Zone-II which are highly dense commercial areas, so both of these two legs also

having high volume of Domestic Vehicles.

At present the intersection is a Rotary intersection and is not having pavement marking,

channelizing islands, traffic signals, medians for through route and no pedestrian crossing

facilities. Therefore to design to intersection peak hour traffic volume surveys at the

intersection has been carried out. The observations and recommendations are as follows:

1. The peak hour traffic volume of the four legged Intersection is found out as 5500

PCU/hour. The present situation is not fulfilling the safe and efficient operation of

traffic due to high intensity of traffic volume.

2. An at grade Intersection having traffic volume in excess of 10000 PCU per hour,

warrants for a grade separated Intersection (IRC: 92-1985). In this case the total

traffic volume at the rotary Intersection is 5500 PCU per hour which is very high and

it warrants for a grade separated Intersection.

3. The maximum volume that a traffic rotary can handle efficiently is about 3000

vehicles per hour entering from all Intersection legs (IRC: 65-1976).

4. The present Intersection gets locked frequently because of high volume of crossing

and turning traffic especially during peak hours. The rotary junction has become

completely incapacitated and present traffic management measures are inadequate to

deal with such a high intensity traffic volume.

5. The junction should be signalized with necessary widening on all the legs of the

Intersection as shown in the drawing sheet.

6. The channelizing islands should be provided to streamline the vehicular traffic and

refuge for pedestrians crossing the road according to drawings.

7. The pavement marking & traffic signs should be provided at the intersection. (IRC:

35-1997 & IRC: 67-2001)

55

Fig 4.7: Details of Existing Jyoti Talkies Intersection

56

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

57

Fig 4.9: Details of Proposed Jyoti Talkies Intersection

58

4.4 Design of MANIT Intersection

The intersection which is under consideration is a four legged intersection; one is towards

Bittan Market, second is towards New Market, third is towards Nehru Nagar and fourth is

towards MANIT. In this intersection three legs are having (Except MANIT Leg) high volume

of traffic, all these three legs having residential and commercial establishments nearby. The

Nehru Nagar leg is connected to Bhadbhada Road, which is have number of quarries, the

Nehru Nagar leg and Bittan Market leg have traffic including heavy vehicles like trucks and

dumpers. The Intersection is presently uncontrolled Intersection not having channelizing

islands, traffic signals, pedestrian crossing facilities, pavement marking, visibility at night etc.

The observations and recommendations for safe and efficient functioning of that intersection

are as follows:

1. The peak hour traffic volume of the four legged Intersection is found out as 4800

PCU/Hr. The present situation is not fulfilling the safe operation of traffic.

2. Presently the Intersection is unable to handle the crossing and turning traffic at high

volume during peak hours.

3. The capacity of Intersection is inefficient and traffic management measures are

inadequate to deal with such high traffic volume intensity.

4. The existing Rotary diameter is inadequate so minimize the Rotary diameter

according to given drawing, therefore heavy volume of traffic can be accommodate at

the intersection.

5. All the legs should widened according to given drawings with providing channelizing

islands at three major roads to streamline the traffic and provide refuge for pedestrians

crossing the road.

6. The pavement marking & traffic signs should be provided at the intersection. (IRC

835-1997 & IRC: 67-2001)

7. The high mask light should be provided at junction area for better visibility at night.

8. Existing bus stops should be removed and locate it 75 meter away from intersection

that too on the further side of the Intersection.

59

Fig 4.10: Existing Details of Manit Intersection

60

Fig 4.11: Proposed details of Manit Intersection

61

4.5 Design of Mangalwara Intersection

Mangalwara junction is a five legged intersection and all the legs having high volume of

traffic intensity. The intersection is surrounded by dense commercial as well as residential

establishments. One of the leg which is Itwara road carries high intensity of traffic including

heavy commercial vehicles due to transport business nearby, so that lot of commercial

vehicles stand here and there for loading and unloading work, and create congestion of traffic

every time.

Presently the intersection is uncontrolled intersection and not having channelizing islands,

traffic signals, pedestrian crossing facilities, pavement markings and high mask lights for

proper night vision.

Therefore to design the intersection for the safe and efficient functioning, three days peak

hour traffic volume survey at the intersection was conducted. The observations &

recommendation for the intersection are as follows:

1. The peak hour traffic volume of the five legged intersection is found out as 5200

PCU/hour. This traffic intensity is very high for the safe and efficient operation of

traffic at the intersection in its present situation.

2. The cross section of intersection legs is unable to handle the high volume of crossing

and turning traffic during peak hours. The junction become completely in capacitated

such a high volume of traffic intensity.

3. Signals should be provided at the intersection. This signalization should also have

pedestrian timings (IRC: 93-1985). The traffic signals should be designed based on

real time data at that intersection.

4. All the five legs should be widened according to given drawings with providing

channelizing islands to streamline the traffic and provide refuge for pedestrians

crossing the road.

5. The pavement marking & traffic signs should be provided at the intersection (IRC:

35-1997 & IRC: 67-2001).

6. High mask light should be provided at junction area for better visibility at night.

62

Fig 4.12: Existing Details of Mangalwara Intersection

63

Fig 4.13: Overlap of Existing and Proposed Mangalwara Intersection

64

Fig 4.14: Details of Proposed Mangalwara Intersection

65

CHAPTER 5: CONCLUSIONS AND RECOMMENDATIONS

5.1 Conclusions and Recommendations

1. The increase in road accidents at intersections is one of the burning issues in the

present situation as rapid growth of population coupled with increasing economical

activities, particularly in the urban area play an important role for the tremendous

growth in motor vehicle.

2. The number of fatalities and injuries as a result of accidents at intersection in Bhopal

is serious enough to demand attention of responsible administrative authority. The

total number of fatal accidents as well as related fatality at intersections in the city is

increasing over the year. Persons killed per 100 accidents as high as 33 during the

year 2009.

3. The buses are the most risky, as far as vehicle-wise accidents are concerned. Truck

and three wheelers are the second and third most risky vehicles, respectively.

4. The intersections are redesigned according to IRC recommendations.

5. The intersection is the most important part of the roads and highways to give prime

attention for their proper planning and designing.

6. If the traffic volume will exceeds the 10000 PCU per hour at an at-grade intersection,

a separate grade intersection is suggested.

7. The junction should be free from encroachment on all the legs to enhance the capacity

and proper visibility.

8. To streamline the vehicular traffic and to provide refuge to the pedestrians,

channelising islands should be provided.

9. The necessary traffic signs and pavement markings need to be provided at the

intersections

10. Traffic signals should be provided whenever required and their design should be

based on real time data.

11. A road safety audit at intersections must be carried out by road professionals to

compare existing characteristics of the intersections, that may be related to congestion

66

and accidents (width of carriageway, obstacles at the intersection, signalized or not,

design of signal, visibility, channelising islands, quality of surfacing, traffic sign and

marking etc) to standard characteristics meeting safety requirements.

12. On heavily trafficked intersections, more account should be taken of the needs of the

pedestrians and cyclists.

67

REFERENCES

1) Indian Roads Congress, Guidelines for the Design of At-Grade Intersections in Rural

and Urban Areas, IRC : SP-41-1994.

2) Indian Roads Congress, Recommended Practice for the Traffic Rotaries, IRC : 65-

1976.

3) Indian Roads Congress, Geometric Design Standards for Urban Roads in Plains, IRC

: 86-1983.

4) Indian Roads Congress, Space Standards for Roads in Urban Areas, IRC : 69-1977.

5) Indian Roads Congress, Guidelines for Pedestrian Facilities, IRC : 103-1988.

6) Indian Roads Congress, Dimensions and Weights of Road Design Vehicles, IRC : 3-

1983.

7) National Crime Records Bureau, Accidental Deaths and Suicides in India, Ministry of

Home Affairs, Government of India, New Delhi, 2008.

8) Vehicular Population Data, Regional Transport Office, Bhopal, 2009.

9) Kent J. Fugal, Mayor Tom Dale and Stephen J. Lewis, “Design for Single-Lane to

Dual-Lane Roundabout Expandability”, May 2008, National Roundabout Conference

2008, Kansas City, Missouri.

10) Kay Fitzpatrick, Angelia H. Parham, and Mark D. Wooldridge, “Issues to consider in

developing an Intersection Design Guide”, September 2002, Texas Transportation

Institute.

11) Report on “Median Intersection Design for Rural High-Speed Divided Highways”,

National Cooperative Highway Research Program report 650, 2010.

12) A synthesis of Highway Practice, “Modern Roundabouts Practice in the United

States”, National Cooperative Highway Research Program Synthesis 264, 1998.

13) Bruce Hellinga “Signalized Intersection Analysis and Design – Implications of Day-

to-Day Variability in Peak”.

14) Ragnhild Davidse, “Assisting the Older Driver”, 2007.

15) Kadiyali L.R., “Traffic Engineering and Transport Planning”, Khanna Publications,

New Delhi 2008.

16) Khanna S.K. and Justo C.E.G., “Highway Engineering”, Nemchand Brothers,

Roorkee, 2005.