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EVALUATION ON THE PERFORMANCE OF SIGNALISED
ROUNDABOUT AT BULATAN SEKSYEN 15, BANDAR BARU
BANGI, SELANGOR
MUHAMMAD DANIAL BIN ROSLI
UNIVERSITI TEKNOLOGI MALAYSIA
NOTES : If the thesis is CONFIDENTIAL or RESTRICTED, please attach with the letter from
the organization with period and reasons for confidentiality or restriction
PSZ 19:16 (Pind. 1/13)
UNIVERSITI TEKNOLOGI MALAYSIA
DECLARATION OF THESIS / UNDERGRADUATE PROJECT REPORT AND
COPYRIGHT Author’s full name :
Date of Birth :
Title :
Academic Session :
I declare that this thesis is classified as:
CONFIDENTIAL (Contains confidential information under the
Official Secret Act 1972)*
RESTRICTED (Contains restricted information as specified by the
organization where research was done)*
✓ OPEN ACCESS I agree that my thesis to be published as online
open access (full text)
1. I acknowledged that Universiti Teknologi Malaysia reserves the right as
follows:
2. The thesis is the property of Universiti Teknologi Malaysia
3. The Library of Universiti Teknologi Malaysia has the right to make copies for
the purpose of research only.
4. The Library has the right to make copies of the thesis for academic
exchange.
Certified by:
SIGNATURE OF STUDENT SIGNATURE OF SUPERVISOR
970627-14-5295
IR. DR. SITTI ASMAH BINTI
HASSAN
MATRIX NUMBER NAME OF SUPERVISOR
Date: 30 MAY 2020 Date: 30 MAY 2020
“I hereby declare that we have read this thesis and in my
opinion this thesis is suffcient in term of scope and quality for the
award of the degree of Bachelor of Engineering (Civil)”
Signature : ________________________________
Name of Supervisor : IR. DR. SITTI ASMAH BINTI HASSAN
Date : 30 MAY 2020
EVALUATION ON THE PERFORMANCE OF SIGNALISED ROUNDABOUT
AT BULATAN SEKSYEN 15, BANDAR BARU BANGI, SELANGOR
MUHAMMAD DANIAL BIN ROSLI
A thesis submitted in fulfilment of the
requirements for the award of the degree of
Bachelor of Engineering (Civil)
School of Civil Engineering
Faculty of Engineering
Universiti Teknologi Malaysia
May 2020
ii
DECLARATION
I declare that this thesis entitled “Evaluation on The Performance of Signalised
Roundabout at Bulatan Seksyen 15, Bandar Baru Bangi, Selangor” is the result of
my own research except as cited in the references. The thesis has not been accepted
for any degree and is not concurrently submitted in candidature of any other degree.
Signature : ....................................................
Name : MUHAMMAD DANIAL BIN ROSLI
Date : 30 MAY 2020
iii
DEDICATION
To my parents.
Thank you for all the support and encouragement.
To my supervisor, Ir. Dr. Sitti Asmah binti Hassan.
Thank you for your guidance, advice, and support given in completing this
study.
To all my friends who assisted me in completing this study.
For all your assistance and support will always be remembered.
To all staff of Road Department at JKR Daerah Hulu Langat.
Thank you for the guidance and help given in completing this study.
iv
ACKNOWLEDGEMENT
First and foremost, all grateful and thanks to Allah S.W.T, the Lord of the
Universe, the most gracious and merciful on blessing.
I wish to express my sincere appreciation to my supervisor, Ir. Dr. Sitti
Asmah binti Hassan, for all the encouragement, guidance, and support. Without her
continued support, this thesis would not be the same as presented here.
My sincere appreciation also extends to all staff of Road Department and
Maintenance Department at JKR Daerah Hulu Langat, who have provided assistance
at various occasions. Their views and advices are useful in guiding me to finish this
thesis. Unfortunately, it is not possible to list all of them in this limited space.
And lastly, to my family members that always support me morally, I am
grateful to received such kind support from them.
v
ABSTRACT
Road network is really important in human daily life as they use it to access
from place to place. It is really important to make an assessment on road
performance to keep the traffic moving as smoothly as possible. In Bulatan Seksyen
15, Bandar Baru Bangi, drivers have to wait for a long time before they can enter the
roundabout due to traffic congestion. This study aims to evaluate junction
performance at signalised roundabout in Bulatan Seksyen 15, Bandar Baru Bangi.
Traffic volume and signal indication at the roundabout were obtained for two
weekdays for 14 hours from 6am to 8pm. The data was collected using manual
counting technique. Morning and evening peak volume were used in analysing the
level of service (LOS). The data was analysed to obtain control delay using
guidelines in Arahan Teknik Jalan 13/87. In this study, it was found that the traffic
approaches of the signalised roundabout experienced level of service in a range of D
and E which indicates unstable flow. It was suggested that the traffic signal system at
the roundabout to be changed to ramp metering or unsignalised system.
vi
ABSTRAK
Rangkaian jalan adalah sangat penting dalam penggunaan harian manusia
kerana penggunaannya untuk bergerak dari satu tempat ke tempat yang lain.
Penilaian ke atas prestasi jalan adalah sangat penting bagi memastikan trafik
bergerak selancar yang mungkin. Di Bulatan Seksyen 15, Bandar Baru Bangi,
pemandu perlu menunggu dengan lama sebelum mereka boleh memasuki bulatan
tersebut oleh kerana kesesakan yang berlaku. Kajian ini bertujuan untuk menilai
prestasi di bulatan berisyarat di Bulatan Seksyen 15, Bandar Baru Bangi. Jumlah
trafik dan petunjuk lampu isyarat di bulatan diperolehi untuk dua hari kerja selama
14 jam dari jam 6 pagi sehingga 8 malam. Pengumpulan data bagi kajian adalah
menggunakan pengiraan secara manual. Jumlah kenderaan pada waktu pagi dan
petang telah dipilih bagi menganalisa tahap perkhidmatan dalam rangkaian. Data
dianalisa untuk mendapatkan kelewatan kawalan menggunakan garis panduan yang
telah ditetapkan di dalam Arahan Teknik Jalan 13/87. Kajian ini telah mendapati
bahawa arah kemasukan trafik di bulatan berisyarat mengalami tahap perkhidmatan
di dalam skala D hingga E yang menunjukkan aliran tidak stabil. Adalah
dicadangkan supaya sistem isyarat trafik di bulatan ditukar kepada meter tanjakan
atau sistem tidak berisyarat.
vii
TABLE OF CONTENTS
TITLE PAGE
DECLARATION ii
DEDICATION iii
ACKNOWLEDGEMENT iv
ABSTRACT v
ABSTRAK vi
TABLE OF CONTENTS vii
LIST OF TABLES x
LIST OF FIGURES xi
LIST OF ABBREVIATIONS xii
LIST OF SYMBOLS xiii
LIST OF APPENDICES xiv
CHAPTER 1 INTRODUCTION 1
1.1 Background of Study 1
1.2 Problem Statement 2
1.3 Aim and Objectives of the Study 3
1.4 Scope of Study 3
CHAPTER 2 LITERATURE REVIEW 4
2.1 Introduction 4
2.2 Traffic Volume 4
2.2.1 Method to Determine Traffic Volume 5
2.2.1.1 Manual Counting 5
2.2.1.2 Automatic Count Devices 5
2.2.1.3 Video Recording 6
2.3 Type of Junction 7
2.3.1 Signalised Junction 8
2.3.2 Unsignalised Junction 8
viii
2.3.2.1 Two Way Stop Controlled (TWSC) 8
2.3.2.2 All Way Stop Controlled (AWSC) 10
2.3.2.3 Roundabout 11
2.4 Delay 12
2.5 Level of Service 13
2.5.1 American Approach 13
2.5.2 Australian Approach 13
2.5.3 Malaysian Approach 14
2.6 Ramp Metering 15
2.7 Analytical and Simulation Delay 18
2.7.1 Analytical Delay 18
2.7.2 Simulation Delay 20
2.7.2.1 SIDRA INTERSECTION 20
2.7.2.2 VISSIM 21
2.8 Summary 21
CHAPTER 3 RESEARCH METHODOLOGY 23
3.1 Introduction 23
3.2 General Framework 23
3.2.1 Site Selection 25
3.2.2 Identification of the Required Data 26
3.2.2.1 Field Geometry 26
3.2.2.2 Traffic Data 26
3.2.2.3 Traffic Signal Indication 26
3.2.3 Data Collection 27
3.2.4 Data Extraction 28
3.2.5 Data Analysis 29
3.2.6 Result and Discussion 30
CHAPTER 4 RESULT AND ANALYSIS 31
4.1 Introduction 31
4.2 Traffic Volume 31
4.3 Traffic Composition 41
ix
4.4 Delay and Level of Service 45
4.5 Chapter Summary 51
CHAPTER 5 CONCLUSION AND RECOMMENDATION 52
5.1 Introduction 52
5.2 Findings 52
5.2.1 Objective 1: To determine the traffic characteristic in
term of volume and composition 52
5.2.2 Objective 2: To determine the control delay at
signalised roundabout 53
5.2.3 Objective 3: To determine the level of service
(LOS) of each approaches 53
5.3 Recommendation for Future Works 53
REFERENCES 54
x
LIST OF TABLES
TABLE NO. TITLE PAGE
Table 2.1 LOS criteria for signalised junction 14
Table 2.2 LOS criteria for signalised roundabout 15
Table 2.3 LOS criteria for signalised junction 15
Table 2.4 Minimum requirement LOS for Malaysia Road 16
Table 3.1 Level of Service 29
Table 4.1 Vehicle volume per 1 hour interval from Persiaran Kemajuan to
Persiaran Pekeliling 33
Table 4.2 Vehicle volume per 1 hour interval from Persiaran Kemajuan to
Roundabout 34
Table 4.3 Vehicle volume per 1 hour interval from Persiaran Pekeliling to
Persiaran Wawasan 35
Table 4.4 Vehicle volume per 1 hour interval from Persiaran Pekeliling to
Roundabout 36
Table 4.5 Vehicle volume per 1 hour interval from Persiaran Wawasan to Tol
Bangi 37
Table 4.6 Vehicle volume per 1 hour interval from Persiaran Wawasan to
Roundabout 38
Table 4.7 Vehicle volume per 1 hour interval from Tol Bangi to Persiaran
Kemajuan 39
Table 4.8 Vehicle volume per 1 hour interval from Tol Bangi to Roundabout 40
Table 4.9 Summary of traffic composition 44
Table 4.10 Summary of current delay for AM peak hour 46
Table 4.11 Sumary of current delay for PM peak hour 46
Table 4.12 Actuated signal timing for Persiaran Pekeliling 46
Table 4.13 Actuated signal timing for Persiaran Wawasan 46
Table 4.14 Actuated signal timing for Tol Bangi 47
xi
LIST OF FIGURES
FIGURE NO. TITLE PAGE
Figure 2.1 Traffic stream at a four-leg TWSC junction 10
Figure 2.2 Traffic stream at a T-leg TWSC junctionError! Bookmark not defined.
Figure 2.3 Difference between freeway with ramp metering and
freeway without ramp metering 16
Figure 2.4 Ramp metering at roundabout 17
Figure 3.1 General Framework 24
Figure 3.2 Study Area 25
Figure 3.3 Manual traffic count at Bulatan Seksyen 15, Bandar Baru Bangi 27
Figure 3.4 Excel Form 28
Figure 4.1 Junction layout 32
Figure 4.2 Traffic composition at Bulatan Seksyen 15, Bandar Baru Bangi 41
Figure 4.3 Traffic composition from Persiaran Kemajuan to the roundabout 42
Figure 4.4 Traffic composition from Persiaran Pekeliling to the roundabout 42
Figure 4.5 Traffic composition from Persiaran Wawasan to the roundabout 43
Figure 4.6 Traffic composition from Persiaran Tol Bangi to the roundabout 43
Figure 4.7 Traffic volume at morning peak hour 44
Figure 4.8 Traffic volume at evening peak hour 45
Figure 4.9 Current level of service for signalised roundabout 47
Figure 4.10 LOS for unsignalised approaches for AM peak hour by using
SIDRA INTERSECTION 48
Figure 4.11 LOS for unsignalised approaches for PM peak hour by using
SIDRA INTERSECTION 49
Figure 4.12 LOS for ramp metering by using SIDRA INTERSECTION 49
xii
LIST OF ABBREVIATIONS
ATJ - Arahan Teknik Jalan
LOS - Level of Service
AWSC - All-Way-Stop-Controlled
TWSC - Two-Way-Stop-Controlled
HCM - Highway Capacity Manual
xiii
LIST OF SYMBOLS
d - Delay
S - Saturation flow
λ - Proportion of the cycle that is effectively green for the phase
x,X - Degree of saturation
C - Cycle length
g - Effective green
P - Proportion of vehicles arriving on green
𝑓PA
T
k
I
Q
c
𝑥0
sg
-
-
-
-
-
-
-
-
Supplement adjustment factor for platoon arriving during
green
Duration of analysis period
Incremental delay factor that is dependent on controller
settings
Upstream filtering/metering adjustment factor
Lane group capacity
Capacity
Degree of saturation below which the second term delay is
zero
Capacity per cycle
xiv
LIST OF APPENDICES
APPENDIX TITLE PAGE
Appendix A Data Collection Table 54
1
CHAPTER 1
INTRODUCTION
1.1 Background of Study
The analysis of transportation system is an important research as it concerns
the daily activities of millions of people moving within the city (Fancello, 2014). An
evaluation of transport network functionally has been widely studied. In general, the
studies quantify road network performance by means of key performance indicator
that represents the functionality of the network from a specific aspect. Some
investigation focuses on the quality of the traffic flow such as the ability to keep
traffic moving as smoothly as possible, using indicators that depend on the
geometrical characteristic: travel time, delay at junction and traffic flow (TRB,
2010).
Junction performance can be measured by determining the volume of
vehicles in certain period, identifying the level of service and the signal indication to
figure out the period of delay at road junction. In the transportation system, traffic
light is the vital component for the effectiveness of the traffic movement. The design
of the red, amber and green time must consider the volume, delay, accident
experience and geometrics. Increase of traffic intensity leads to situation when it
becomes impossible to provide a satisfactory level of traffic servicing with the help
of only traffic light signaling means. Congestion at a section of the road traffic
network with traffic signals is a situation when the average duration of the vehicle
delay exceeds the length of the traffic signaling cycle.
Signalised junction indicate to drivers when to enter the junction, thus
removing the problem for intuitive selection of safe gaps in the traffic flow. This in
turn minimizes the probability of crashes between the turning vehicles and oncoming
through traffic. Signalised junctions work on the premise that motorists at the stop
line are given right of way at the onset of effective green. However, when
approaching a signalised junction at high speeds and the light turns yellow it may be
difficult for the driver to discern whether they should run the yellow light or brake to
2
be safe. If the inter-green time is too short, only those vehicles that are close to the
junction will be able to continue through the junction safely. Signalised junction
should allow any vehicle, regardless of its location, to be able to safely stop or,
alternatively, safely proceed during the inter-green period.
This is done by making sure that any vehicle closer to the intersection than its
minimum braking distance can safely proceed through the junction without
accelerating or speeding. As an alternative, signalised roundabout can be installed.
However, roundabout is not the ultimate solution for road congestion. The quality of
service will started to decline as the traffic volume keep increasing by years until the
capacity of the roundabout cannot accommodate the traffic.
Highway Capacity Manual (HCM) developed by the transportation research
board of USA provides some procedure to determine level of service. The level of
service have been divided into six classes which is class A to class F. class A
represents the best performance of traffic where the traffic density will be low, with
no interruption flow speed control by driver desire, low volume, and the drivers
maintain their desire speed with little or no delay. Level F shows the worst quality of
traffic where the demand exceeded the capacity of the road.
1.2 Problem Statement
Due to the traffic growth, major problem which is traffic congestion started to
take place on several roads around Bandar Baru Bangi especially during peak hour
where people drive to work and back from work. One of the congested area is
Bulatan Seksyen 15 where it connects the main road from the residencies area and
Plaza Tol Bangi. Bulatan Seksyen 15 has shown a poor performance in term of
traffic movement where the traffic inside the roundabout moves very slowly thus
creating a long queue length from approaching lanes during peak hour. Even though
the roundabout has already been installed with traffic signal system which is semi-
actuated traffic lights at 3 approaches, it still cannot solve the congestion problem.
Thus, an assessment needs to be done on the roundabout in order to identify this
congestion problem.
3
1.3 Objectives
The aim of the research is to evaluate the signalised roundabout performance at
Bulatan Seksyen 15, Bandar Baru Bangi. To achieve the aim, this study is based on
the following objectives:
1. To determine the traffic characteristic in term of volume and composition.
2. To determine the control delay at signalised roundabout.
3. To determine the level of service (LOS) of each approaches.
1.4 Scope of Study
The scope of the study includes the process of determining the performance
at the signalised roundabout at Seksyen 15 Bandar Baru Bangi. The parameters that
were determined to assess the roundabout performance are traffic volume, signal
indication, and delay time. This study only takes into consideration of the signalised
approaches which is from Persiaran Kemajuan, Persiaran Pekeliling, and Tol Bangi
approaches of the Bulatan Seksyen 15.
4
CHAPTER 2
LITERATURE REVIEW
2.1 Introduction
In order to fulfill the objectives requirement, problem statement, and scope of
study, this chapter will describes several literature reviews. This literature review
will go through different methods to conduct data collection as well as all the
variables used in order to estimate the capacity and delay of the signalised
roundabout.
2.2 Traffic Volume
Traffic volume studies are conducted to determine the number, movements,
and classification of roadway vehicles at given location. These data will be used to
help determine the influence of large vehicles or pedestrian on vehicular traffic flow,
identify critical flow time period, or document traffic volume trends. The duration of
the sampling period depends on the type of count being taken and the intended use of
the data recorded. However, the count duration should avoid special event or
compromising weather condition (Sharma, 1994). Count duration typically are 15
minutes or 2 hours for peak periods, 4 hours for morning and afternoon peaks, 6
hours for morning, midday, and afternoon peaks, and 12 hours for daytime periods
(Robertson, 1994). These data can be used to determine the traffic composition, as
well as predicting the future traffic volume. This is essential for many applications,
including planning for maintenance and real-time traffic control improvements.
5
2.2.1 Method to Determine Traffic Volume
2.2.1.1 Manual Counting
Manual counting method is the most common method of collecting traffic
flow data which consist of assigning a group of people to record traffic as it passes.
Manual counts are typically used for duration of less than a day, and is not suitable if
it exceed a day. By using this method, it is possible to obtain data which cannot be
collected by mechanical counters, such as vehicles classification, turning
movements, and number of vehicles at intersections. However, field observations
require large group of people depending on the size of the study data needed. The
size of data collection team depends on the length of the counting period, the type of
count being performed, the number of lanes or crosswalk being observed, and the
volume level of traffic (Robertson, 1994). A manual count study includes three key
steps:
i. The aim of the manual count will be reviewed during the preparation.
This will help to determine the number of observers required, the field
procedure to follow, and the type of equipment need to be used.
ii. Observers must be positioned where they have a clear view of the traffic
but at the same time provide safety during the manual counting. The
observers may have the best point if they are positioned above the ground
level and clear of obstructions.
iii. Manual counts may produce a large number of data forms. If order to
keep the data forms organized, labelling must be done on all the data
forms. On each tally sheet, the observers should record the location, time
and date of the observation, and weather conditions.
2.2.1.2 Automatic Count Devices
Automatic count is deployed in cases where manual count method cannot be
implemented. In this method, vehicles are counted automatically without any human
involvement. Due to its function, this method can gather a large amount of data for a
6
longer period of time which may extend up to a week, month, or year (Chakravorty,
2015). Various instruments or equipment can be used for automatic count, which has
their own benefits and barriers. Some of the most widely used instruments are:
i. Pneumatic tubes
These are tubes that are mounted on top of road surface at location where
traffic counting is required. As vehicles pass over the tube, the resulting
compression sends a burst of air to an air switch, which will then be send
to a recorder that was installed by the road side.
ii. Inductive loops
Inductive loop detector consists of embedded turned wire. It includes an
oscillator, and a cable, which allows signals to pass from the loop to the
traffic counting device. Inductive loops are cheap, almost maintenance-
free and are currently the most widely used equipment for vehicle
counting and detection.
iii. Micro-millimeter Wave Radar detectors
Radar detectors actively emit radioactive signals at frequencies ranging
from the ultra-high frequencies (UHF) of 100MHz to 100GHz, and can
detect vehicular presence and speed. Thus, it can detect vehicular
volumes and classifications in both traffic directions.
iv. Piezo-electric cable
A sensing strip made from a metallic cable which responds to a vertical
loading from vehicle wheels passing over it by producing a corresponding
voltage. The cable is very good for speed measurement and axle-space
registration, and is relatively cheap in maintenance.
2.2.1.3 Video Recording
Video recording in traffic count refers to a method where a video recorder is
set up at the study area where the traffic is visible to the recorder. Video recording
has the perks to greatly simplify traffic data collection, saves time, reduce
requirement for field staff, and accurately record traffic without missing a movement
(Davies, 2011). Data collection methods using manual counting and automatic
counting devices are generally single-purposed, while video-based systems are much
7
more adaptable to different study types. Video-based systems are more efficient for
data collectors due to its versatility of data that can be extracted from the video.
Video recording method could produce a more accurate and detailed data
collection. This is because data collectors can count vehicles from pre-recorded
videos taken from traffic-monitoring cameras. Data collectors can pause, stop, and
replay the video at their convenience. This would reduce the probability of missing
data such as vehicles miscount which can happen when observing on the field due to
fatigue of the observers. This method also allows cross-checking where a different
data collector can review the video and correct any mistake made from the previous
users. This would reduce the error in the data counting that would have exist in
manual counting method where cross-checking could not be done unless two
counters were deployed at the observation point.
Despite the notable benefits of using video recording for traffic counting,
there have been some issues of using this method. One of the issues is the convenient
location to set up the video recorder. A consideration that should be taken during the
setup of the video recorder is not only focus on getting a good view but also security,
access, and in case of long survey, availability of power supply (Taylor et al., 2000).
2.3 Types of Junction
According to Arahan Teknik (Jalan) 11/87, junction is defined as area where
two or more roads cross or meet. Junctions are an important part of the road system
where their capacity controls the volume of traffic within the network system. When
more than one movement interacts, maneuver will occurs. Multiple maneuvers
should be avoided as they confuse drivers. Generally, there are two types of junction
which are used in design:
i. Signalised junction
ii. Unsignalised junction
8
2.3.1 Signalised Junction
At individual junction, a safe and efficient traffic flow must be provided by
allocating a traffic signal to ensure the traffic can run smoothly. On a network where
conflicts usually occur, a traffic signal is essential to eliminate the conflicting traffic
movements. Three signal indications are displayed (red, green and yellow). Red
indication means the road user should stop to give way to other approaches to pass
through the junction.
2.3.2 Unsignalised Junction
Unsignalised junction is the most common intersection type. Although their
capacities may be lower than other intersection types, it plays an important part in the
control of traffic in a network (Troutbeck, 1997). There are three types of
unsignalised junction which is two way stop controlled (TWSC), all way stop
controlled (AWSC), and roundabouts.
2.3.2.1 Two Way Stop Controlled (TWSC)
This junction is commonly used in the United States and abroad. To control
vehicles movement, stop signs were used at the junction. At TWSC junction, the stop
signs are located at the minor road approaches. If the junction is not controlled by a
stop sign, it is considered as major street approaches.
The priority of right-of-way given to each stream as stated by the Highway
Capacity Manual is used to mitigate conflicting traffic problems. Some streams have
absolute priority, whereas others have to give way or yield to higher-order streams.
Figure 2.1 and Figure 2.2 below show the relative priority of streams at both T-leg
and four-leg junctions. The figures illustrate traffic system of the United States of
America which is based on the left-hand drive. By convention, subscripts 1 to 6
define vehicle movements on the major street, and subscripts 7 to 12 define
movement on the minor street. Subscripts 13 to 16 define the pedestrian movements.
9
Figure 2.1 Traffic stream at a four-leg TWSC junction (HCM2000)
Figure 2.2 Traffic stream at a T-leg TWSC junction (HCM2000)
10
Movement of Rank 1 gives right-of-way to any through or right-turning
vehicle on the major street. Through and right-turning movements from the major
street have the highest priority at the TWSC junction. Movement of Rank 2 includes
vehicles turning left from the major street to the minor street and also right-turning
from the minor street to the major street. Movement of Rank 3 includes through
traffic from the minor street (in case of four-leg junction) and left-turning traffic
from the minor street (in case of T-leg junction). Lastly, movement of Rank 4
includes traffic turning left from the minor street.
2.3.2.2 All Way Stop Controlled (AWSC)
This junction, like TWSC junction, is widely used in the United States of
America and other countries in North America. All-ways stops function best when
the traffic volume at the intersection is high enough that vehicle conflicts are
common and when the traffic volume is evenly split between the intersecting streets
(Celniker, 1989). At this junction, the stop sign are located at all four approaches
which require all vehicles to stop.
While stopping at the stop line, drivers need to make judgement whether to
proceed into the junction according to the rules of AWSC junction. The rules of
AWSC junction are as follow:
1. The first vehicle to arrive at the junction receives the right-of-way. The
vehicles arriving after the first vehicle needs to wait for the first vehicle to
proceed.
2. When two vehicles arrive at the junction at the same time and are located
side-by-side, the vehicle on the right has the right of way.
3. When arriving at the junction head-to-head with another vehicle, the vehicle
going straight has the right of way than the vehicle turning left or right.
4. When two vehicles arrive head-to-head at the junction at the same time, and
both of the vehicles intend to turn to the same direction, the vehicle turning
right has the right of way.
According to FHWA, approximately 72 percent of fatal crashes occur at
unsignalised junction, and the most often factor of these crashes are due to drivers’
failure to yield the right of way.
11
2.3.2.3 Roundabout
At roundabout, traffic travels clockwise around a central raised island, and
entering traffic must yield to circulating traffic. According to ATJ 11/87, a
roundabout may be applicable as an option for intersection when the total traffic
volume from all directions is up to 6000 vehicles/hour. The size of roundabout varies
depending on the traffic demand at the intersection.
i. Mini – less than 20m in diameter of inscribed circle, less than 4m in
diameter of center circle
ii. Small – 20m to 50m in diameter of inscribed circle, 4m to 15m in
diameter of center circle
iii. Conventional – more than 50m in diameter of inscribed circle, more than
25m in diameter of center circle
However, roundabout design requires a larger land space in order to cater for
approaches of every intersection. But since the approaches are free flow
unsignalised, roundabout can have more than four legged intersection. The
roundabout can be signalised once it exceeds the capacity of 6000 vehicle/hour per
leg, if it is so required (ATJ 11/87 Amendment 2016). A roundabout design can also
accommodate for future expansion or upgrade if any of it approaches reach its
saturation capacity level, that is by converting the roundabout into an interchange
such as flyover or ramp to relief the traffic congestion for the particular approach
inside the roundabout.
12
2.4 Delay
Delay is one of the parameter to measure the operational quality or
effectiveness of signalised junctions. According to AASHTO, delay is defined as the
additional travel time experienced by a driver, passenger, or pedestrian due to
circumstances that impede the desirable movement of traffic. According to Mathew
T. V. in his journal Signalised Intersection Delay Model, the most frequently used
forms of delay is defined as follows:
• Stopped Time Delay
Stopped time delay is defined as the time a vehicle is stopped in queue while
waiting to pass through the intersection. It begins when the vehicle is fully
stopped an ends when the vehicle begins to accelerate. Average stopped time
delay is the average for all vehicles during a specified time period.
• Approach Delay
Approach delay includes stopped time delay but adds the time loss due to
deceleration from the approach speed to a stop and the time loss due to re-
acceleration back to the desired speed. Average approach delay is the average
for all vehicles during a specified time period.
• Travel Time Delay
It is the difference between the drivers’ expected travel time through the
intersection (or any roadway segment) and the actual time taken. To find the
desired travel time to traverse an intersection is very difficult. So this delay
concept is rarely used except in some planning studies.
• Time-in-queue Delay
Time-in-queue delay is the total time from a vehicle joining an intersection
queue to its discharge across the stop line on departure. Average time-in-
queue delay is the average for all vehicles during a specified time period.
Time-in-queue delay cannot be effectively shown using one vehicle, as it
involves joining and departing a queue of several vehicles.
• Control Delay
Control delay is the delay caused by a control device, either a traffic signal or
a stop-sign. It is approximately equal in time-in-queue delay plus the
acceleration-deceleration delay component.
13
2.5 Level of Service
Level of service (LOS) is a quality measure describing operational conditions
within a traffic stream, in terms of such service measures as speed and travel time,
freedom to maneuver, traffic interruptions, and comfort and convenience (TRB,
2000). There are six LOS defined for each type of facility that has analysis
procedures available. Letters designate each level. From A to F, with LOS A
representing the best operating condition and LOS F the worst. Each level of service
represents a range of operating condition and the driver’s perception on those
conditions.
2.5.1 American Approach
The average control delay per vehicle is estimated for each lane group and
aggregated for each approach and for the intersection as a whole. LOS is directly
related to the control delay value. According to HCM2000, Table 2.1 shows the
classification of level of service for signalised junction as follow:
Table 2.1 LOS criteria for signalised junction
LOS Control Delay per Vehicle (s/veh)
A ≤ 10
B > 10-20
C > 20-35
D > 35-55
E > 55-80
F > 80
2.5.2 Australian Approach
The classification of this approach is similar to American approach for
signalised intersection. However, SIDRA which is originated from Australia
highlighted the level of service classification for signalised roundabout (Akcelik,
2009). Table 2.2 shows the level of service classification for signalised roundabout
as follow:
14
Table 2.2 LOS criteria for signalised roundabout
LOS Control Delay per Vehicle (s/veh)
A ≤ 10
B > 10-20
C > 20-35
D > 35-50
E > 50-70
F > 70
2.5.2 Malaysian Approach
According to Arahan Teknik (Jalan) 11/87, the control delay per vehicle is
used as a measure of the level of service and this is a measure of driver discomfort,
frustration, fuel consumption, and lost travel time. The traffic forecast for any
junction design must fulfill the minimum requirement of level of service according to
the type of road and maintained throughout the forecasted year as mentioned in ATJ
11/87 in Table 2.4. Table 2.3 shows the level of service classification for signalised
junction as follow:
Table 2.3 LOS criteria for signalised junction
LOS Control Delay per Vehicle (s/veh)
A < 5
B 5.1 to 15.0
C 15.1 to 25.0
D 25.1 to 40.0
E 40.1 to 60.0
F > 60.0
15
Table 2.4 Minimum requirement LOS for Malaysian Road
Areas Category of Road Level of Service
Rural
Expressway
Highway
Primary
Secondary
Minor
C
C
D
D
E
Urban
Expressway
Arterial
Collector
Local Street
C
D
D
E
2.6 Ramp Metering
Ramp meters are traffic signals which can be found on freeway on-ramps to
regulate the rate or frequency of vehicles entering the freeway (Yang, 2019). Ramp
meter is a simple traffic signal where there is only two indication, red and green. At
metered ramps and under normal ramp metering control condition, the approaching
vehicles have to stop at the metering signal before the metering signals turns green.
The vehicles are then released individually into the mainline, often at a rate that is
dependent on the mainline traffic volume and speed at that time.
Ramp metering reduces overall freeway congestion by managing the amount
of traffic entering the freeway and by breaking up platoons that make it difficult to
merge onto the freeway (FHWA, 2017). In high traffic volume, ramp meters can
reduce stopped time delay even when considering time in queue on the ramp. By
allowing for smooth merging maneuvers, collision on the freeway can be avoided.
Without ramp meters in operation, multiple vehicles merge in tightly packed
platoons, causing drivers on the mainline to slow down or even stop in order to allow
vehicles to enter. This condition would lead to potential congestion and collision on
the mainline. Sensors are installed on both the freeway and the ramp to observe the
traffic stream condition and provide information to the metering system.
16
Sensors on the freeway consist of detector loop which will detect the gap
between vehicles and provide a green light indication on the ramp meter controller to
allow a vehicle to pass through and merge smoothly into the mainline. There are two
types of sensors that are installed on the ramp which is the demand sensor and end of
queue sensor. Demand sensor feed information to the ramp meter controller on
vehicle presence on the ramp while the end of queue sensor is placed at the entrance
of the ramp to prevent backups onto local streets by releasing the queue when the
ramp reaches maximum capacity. Figure 2.3 shows the difference on freeway when
ramp metering is placed.
Figure 2.3 Difference between freeway with ramp metering and freeway without
ramp metering
Other than freeway, ramp metering can also be installed at roundabout that is
having traffic congestion. A metering signal is a traffic light, used in high volume
areas, which regulates the number of vehicles passing a certain point (Mosslemi,
2008). In the case of roundabouts, the metering signal is the signal that is being
17
controlled to create gaps in flowing traffic. The traffic output can be greatly
improved by operating metering signals at roundabouts which have uninterrupted
entry flows from some approaches.
The problem of unbalanced traffic flows can be resolved by a metering signal
installed on a high-volume roundabout approach by momentarily detaining drivers at
the entrance. It offers motorists the opportunity to enter the flowing highway at the
other approaches. Roundabout metering signals are often built on a part-time basis on
selected approaches, because they are only needed during heavy demand situations
during peak hour (Akçelik, 2006). It is important to consider the selection of the
metered approach and controlling approach correctly.
Metered approach is the entry at which red signals stop the traffic. This is the
approach that creates problems because of an uninterrupted traffic flow for its
preceding entrance. The preceding approach is commonly called the controlling
approach. Detectors are typically mounted in the controlled approach and are
attached to the metering signal for real-time monitoring. Figure 2.4 shows the typical
ramp meter installation at a roundabout.
Figure 2.4 Ramp metering at roundabout
18
2.7 Analytical Delay and Simulation Delay
Delay is the most important measure of effectiveness at a signalised junction
because it relates to the amount of lost travel time, fuel consumption, and the
frustration and discomfort of drivers (Akgungor & Bullen, 2014). Delay also can
compare the performances of an intersection under different control, demand and
operating conditions. The accurate prediction of delay is, therefore, very important,
but its accurate estimation is difficult due to random traffic flows and other
uncontrollable factors. Delay can be estimated by measurement in the field,
simulation, and analytical models. Of these methods, analytical estimation is the
most practical and convenient.
2.7.1 Analytical Delay
Many stochastic steady-state delay models use the assumptions that arrivals
are random and departure headways are uniform but these assumptions are
impractical in general (Akgungor & Bullen, 2014). Stochastic steady-state delay
models are only valid for under-saturated conditions and predict infinite delay when
the power exceeds the arrival flows. The deterministic models for this are more
practical for predicting delay for over-saturated conditions, but these models ignore
the effect of randomness in traffic flow.
Time-dependent delay models were developed to overcome the shortcomings
in both stochastic steady state and deterministic delay models. Using the coordinate
transformation method, these models combine stochastic steady state and
deterministic models. They have models of delay which are more practical.
There are three different time dependent delay models (Australian, Canadian
and the Highway Capacity Manual (H.C.M.)) commonly used to estimate delay at
signalised junctions. There is a delay parameter k in all of these models that is fixed
but this k parameter and does not account for the effects of variable traffic demands
and variable time periods of analysis.
The H.C.M. delay model provides reasonable results for under-saturated
conditions but predicts higher delays for over-saturated conditions compared with
19
other delay models. With increasing degree of saturation the difference between the
H.C.M. delay model and other delay models increases. Hence it is not advised to
delay calculations for higher values. The H.C.M. delay model has been derived for a
time period of 15 minutes and hence, the estimation of delay using this model is
limited to time periods of 15 minutes duration.
The level of delay at a signalized intersection is a function of many
parameters including the capacity, the traffic volume, the amount of green time
available, the degree of saturation, the analysis time period, and the arrival patterns
of vehicles. H.C.M. prescribes delay per vehicles (s/veh) as;
……Equation 1
Akcelik has derived the Australian delay model which is an approximation to
Miller’s delay model. The Australian delay model predicts zero overflow delay
before the overflow delay term is applied for low degrees of saturation. The
minimum degree of saturation value depends on capacity per cycle, and a symbol 𝑥𝑜
is given. The Australian model for delay is expressed as follows:
𝑑 = C(1−λ)2
2(1−λ𝑥)+ 900𝑇[ (x-1)+√(𝑥 − 1)2 + 12(
𝑥−𝑥0
𝑐𝑇) ] …………………… Equation 2
and
𝑥𝑜 = 0.67 + 𝑠𝑔
600 ………………………………………………………….. Equation 3
The Canadian delay model which was derived by Whiting is commonly
applied to predict delay at signalised junction. Like other time-dependent delay
models, the model consists of two terms that have uniform and overflow delay
terms.. The Australian and Canadian delay models have a similar structure, but
different coefficients in the overflow delay term. After some revision, the Canadian
delay model is expressed as follows:
20
𝑑 =C(1−λ)2
2(1−λ𝑥)+ 900𝑇[ (x-1)+√(𝑥 − 1)2 + (
4𝑥
𝑐𝑇) ] ………………….……. Equation 4
2.7.2 Simulation Delay
Road traffic congestion comprises of several complex procedures and
incorporates numerous components cooperating simultaneously. Improving traffic
signal timing and coordination is one of the most widely used method to relieve
congestion and enhance mobility of traffic. In such problem condition, a simulation
model can be a very effective tool as it provides evaluations for various traffic
condition (Ismael et al., 2018).
Simulation models are useful tools that enable the traffic engineer to model
real-life traffic conditions without disrupting everyday operations. Simulation
models are also a low cost alternative to actual field implementation of traffic
improvement measures. Theoretical improvements can be modeled before they are
introduced in highway applications to obtain the best course of action in a given
scenario. In a sense, they enable the traffic engineer to improve driving conditions
by a trial and error method that will reduce delay to a minimum.
One of the issues that can arise from using traffic modeling packages is how
well does the package model a given traffic condition (Benekohal et al., 2001).
Some users may prefer a specific modeling program in all cases, others may use a
different program because it has a user-friendly interface. In either case, the results
obtained from the simulation may not be what actually occurs in the field. It may be
true that software previously accepted as able to provide accurate modeling may in
truth not be applicable to a particular traffic situation. There are several software for
traffic performance analysis such as Highway Capacity Software, Synchro,
SimTraffic, VISSIM, and SIDRA.
2.7.2.1 SIDRA INTERSECTION
SIDRA INTERSECTION is a software used as an aid for design and
evaluation of individual intersections and networks of intersections. It can be used to
21
analyse signalised intersections (fixed-time / pretimed and actuated), signalised and
unsignalised pedestrian crossings, roundabouts (unsignalised), roundabouts with
metering signals, fully-signalised roundabouts, two-way stop sign and give-way /
yield sign control, all-way stop sign control, single point interchanges (signalised),
freeway diamond interchanges (signalised, roundabout, sign control), diverging
diamond interchanges. It can also be used for uninterrupted traffic flow conditions
and merge analysis.
SIDRA INTERSECTION was first released in 1984 and has been under
continuous development in response to user feedback. In February 2017, the latest
versions of the software were in use by about 1930 organizations with about 8200
licenses in 84 countries. The countries where SIDRA INTERSECTION was used
most extensively were USA, Australia, Europe, New Zealand, South Africa, Canada,
Malaysia and Singapore.
2.7.2.2 VISSIM
VISSIM is a microscopic, behavior-based multi-purpose traffic simulation to
analyze and optimize traffic flows (Barcelo, 2010). It offers a wide variety of urban
and highway applications, integrating public and private transportation. VISSIM was
developed by PTV Planung Transport Verkehr AG in Karlsruhe, Germany in 1992. It
can be used for the analysis and evaluation of road traffic.
At present, in the fields of the urban roads, highways, and integrated transport
system, VISSIM is one of the most common software (Zhou et al., 2014). VISSIM
simulation software includes individual vehicles, and has a detailed definition of the
vehicle travel behavior, tracking and record. Therefore, it can more accurately
calculate the vehicle delay.
2.8 Summary
Junction performance is an important measure as it is part of traffic system
components. In this study, the signalised roundabout will be evaluated in order to
ensure whether it serve a good performance or otherwise. The parameter that is
22
needed to measure the performance of the signalised roundabout is traffic volume,
signal indication, and delay. Manual counting was chosen as the method to carry out
traffic count. Level of service based on Arahan Teknik Jalan 11/87 was used to
estimate delay at the roundabout based on the parameters stated.
23
CHAPTER 3
RESEARCH METHODOLOGY
3.1 Introduction
This chapter describes the method to carry out the study. The main objective
of the study is to evaluate the performance of signalised roundabout by determining
the level of service of the road. The study was started with identifying the problem,
which is expressed as problem statement. The second step was setting the objectives
of the study. Then, based on the targeted objectives, literature review of the study
was extracted from different resources and reviewed. In this chapter, the rest of the
steps required for conducting this study are going to be explained.
3.2 General Framework
The general framework shown in Figure 3.1 illustrates the main steps
required to be followed for carrying out the study. After the problem was stated and
the objectives were set at the beginning of the study, the rest of the steps that is
needed to be followed in order to acquire the results and findings were established
and organized in the form of flowchart. Components of the general framework are
described in the following section of this chapter.
24
Figure 3.1 General Framework
Problem Statement
Site Reconnaissance & Pilot
Study
Field Data Collection
Data Extraction
Data Analysis
Result and Discussion
Conclusion
Aim and Objective
Literature Review
Study Method Formulation
Defining Required Data
25
3.2.1 Site Selection
Bulatan Seksyen 15, Bandar Baru Bangi was selected as the location for the
case study after observation and discussion with the local authority which is Jabatan
Kerja Raya Daerah Hulu Langat, Selangor. Bulatan Seksyen 15 is a roundabout
connecting Tol Bangi, Persiaran Wawasan, Persiaran Pekeliling, and Persiaran
Kemajuan. Bandar Baru Bangi is a township situated in Hulu Langat region, in
southeastern Selangor. It is named after the small town of Bangi situated further
south. Figure 3.2 shows the roundabout for the study area, where three approaches of
the roundabout are signalised with semi-actuated traffic signal system which is from
Persiaran Wawasan, Persiaran Pekeliling, and Tol Bangi while approach from
Persiaran Kemajuan is unsignalised. Each approaches of the roundabout composed of
three lanes both ways with one lane situated for left turning. Each signal timing is
independent with each other, which means they are not synchronize. The area is
commercial and residential.
Figure 3.2 Study Area
26
3.2.2 Identification of the Required Data
Before starting any study, a set of parameters and required data should be
identified in order to carry out the analysis systematically without any missing
variables and re-doing the data collection. To avoid interruption in the analysis stage,
the following sets of parameters were defined.
3.2.2.1 Field Geometry
This includes all the existing and required on information about the layout of
the junction such as junction of approaches, number of lanes, lane widths, and
roundabout size. These data were collected by measurement achieved in field.
3.2.2.2 Traffic Data
The traffic data includes all the necessary information about the
characteristics of the traffic stream. They were classified into:
• Traffic volume: Number of vehicles crossing the stop line of each approach
in unit of time
• Type of vehicles: Traffic stream are not composed of identical vehicles, and
each type of vehicle has a different impact on the traffic characteristics.
Therefore, traffic volume was classified into different vehicle groups.
3.2.2.3 Traffic Signal Indication
This includes all the information about the traffic signal provided at the
junction such as cycle time, green time, extended green time, and clearance interval
for each phases.
27
3.2.3 Data Collection
In order to do an evaluation of the performance at the junction, traffic volume
and signal indication at the roundabout were obtained. The data was obtained with
the help from JKR Hulu Langat staff using manual counting technique. Two
observers were positioned at each approach where one observer counted the vehicles
going into the roundabout while the other observer counted the vehicles left turning
to next junction. The data was collected for two days which is on Tuesday and
Wednesday, from 6am until 8pm. Based on the collection of the two days data, only
the highest traffic flow was used to evaluate the current signalised roundabout
performance.
Figure 3.3 Manual traffic count at Bulatan Seksyen 15, Bandar Baru Bangi
28
3.2.4 Data Extraction
The recorded data was then extracted and summarized into the required
forms. Traffic data volume was converted into pcu/hour to obtain the total traffic
composition for each approach as the data was used as an input in calculation of
control delay.
Figure 3.4 Excel form
29
3.2.5 Data Analysis
The data was then analysed by using guideline in Arahan Teknik (Jalan)
13/87 based on the input data determined in the data collection. Input data is from
traffic volume that have been converted into pcu/hour for each approach based on the
highest peak time and signal indication during data collection. The equation of
control delay is written as below:
d =9
10[
𝑐(1−𝜆)2
2(1−𝜆x)+
𝑥2
2(𝑞
3600)(1−𝑥)
] sec…………………………………… Equation 5
Where
q = traffic volume, pcu/sec
S = saturation flow, pcu/sec
λ = effective green, g/c
c = cycle time
x = degree of saturation, q/λs
From the control delay obtained from the Equation 5, the level of service
from each approach was determined by referring to Table 3.1 which has been
discussed in Chapter 2.
Table 3.1 Level of Service
LOS Control Delay per Vehicle (s/veh)
A < 5
B 5.1 to 15.0
C 15.1 to 25.0
D 25.1 to 40.0
E 40.1 to 60.0
F > 60.0
30
3.2.6 Result and Discussion
The final step of the operation analysis process was interpreting the results. If
the result does not meet the requirement according to ATJ 11/87 which stated the
minimum allowable level of service, the roundabout needs to be upgraded. SIDRA
INTERSECTION software was used to model the new traffic signal control for the
roundabout.
31
CHAPTER 4
RESULT AND ANALYSIS
4.1 Introduction
The aim of this study is to evaluate the road performance of a signalised
roundabout. In this chapter, detailed analysis of the evaluation process is presented.
The analysis process starts from traffic volume studies, signal indication, control
delay measurement, and level of service.
4.2 Traffic Volume
The site is a signalised roundabout which consists of four approaches namely
Persiaran Kemajuan, Persiaran Pekeliling, Persiaran Wawasan, and Tol Bangi. Each
approaches are composed by three lanes each direction with one lane situated for left
turning, with each lane is 3.5m wide. Persiaran Kemajuan, Persiaran Pekeliling, and
Tol Bangi approaches have a 2.5m wide built out median while Persiaran Wawasan
has a 4m wide built out median. Figure 4.1 shows the layout of the junction.
32
Figure 4.1 Junction layout
Manual counting technique was used for traffic volume studies of Bulatan
Seksyen 15, Bandar Baru Bangi. Table 4.1 to Table 4.8 shows the summary of traffic
volume for all eight directions of the junction respectively. The traffic volume count
was conducted for 14 hours which is from 6am until 8pm. Based on the data
collected, it was found that the traffic data collected on Wednesday has the highest
traffic flow compared to the traffic data collected on Tuesday. The total number of
observed vehicles on Wednesday was 61,690 vehicles. From the previous Chapter 3
in data collection, it was highlighted that the highest peak time volume between
morning peak and evening peak will be chosen to determine the current performance
of the signalised roundabout. Based on data extraction, it is found that the peak hour
in the morning is from 7am until 8am while the peak hour in the evening is from 5pm
until 6pm.
33
Table 4.1 Vehicle volume per 1 hour interval from Persiaran Kemajuan to Persiaran
Pekeliling
Time Motocar and Taxi
Small van and utility
(Light - 2 axle)
Lorry and Big
Van (Heavy - 2 axle)
Lorry with 3 axle or Trailer (Heavy
and exceed 2
axle)
Bus Motorcycle Total
0600-0700 72 14 7 4 17 73 187
0700-0800 335 66 3 3 4 139 550
0800-0900 49 29 10 1 4 63 156
0900-1000 143 73 22 17 14 102 371
1000-1100 126 58 8 4 2 43 241
1100-1200 177 36 16 1 3 51 284
1200-1300 207 68 19 4 4 76 378
1300-1400 202 32 15 2 3 57 311
1400-1500 213 40 12 1 3 60 329
1500-1600 193 97 22 7 4 83 406
1600-1700 304 137 15 2 3 153 614
1700-1800 418 160 20 3 3 227 831
1800-1900 323 59 15 1 31 289 718
1900-2000 317 142 37 19 12 254 781
Total 3079 1011 221 69 107 1670 6157
34
Table 4.2 Vehicle volume per 1 hour interval from Persiaran Kemajuan to
Roundabout
Time Motocar and Taxi
Small van and utility
(Light - 2 axle)
Lorry and Big
Van (Heavy - 2 axle)
Lorry with 3 axle or Trailer (Heavy
and exceed 2
axle)
Bus Motorcycle Total
0600-0700 80 19 5 3 15 83 205
0700-0800 524 153 8 6 1 92 784
0800-0900 233 76 27 17 3 75 431
0900-1000 305 64 49 39 0 71 528
1000-1100 236 75 61 42 0 83 497
1100-1200 282 55 49 17 0 62 465
1200-1300 272 62 31 20 0 71 456
1300-1400 312 124 65 29 3 75 608
1400-1500 341 172 42 40 0 58 653
1500-1600 276 113 39 34 1 61 524
1600-1700 307 109 71 66 0 79 632
1700-1800 224 72 27 20 4 120 467
1800-1900 210 56 17 12 0 87 382
1900-2000 190 41 10 7 0 77 325
Total 3792 1191 501 352 27 1094 6957
35
Table 4.3 Vehicle volume per 1 hour interval from Persiaran Pekeliling to Persiaran
Wawasan
Time Motocar and Taxi
Small van and utility
(Light - 2 axle)
Lorry and Big
Van (Heavy - 2 axle)
Lorry with 3 axle or Trailer (Heavy
and exceed 2
axle)
Bus Motorcycle Total
0600-0700 110 10 4 1 4 54 183
0700-0800 128 8 3 0 6 112 257
0800-0900 270 6 3 3 2 132 416
0900-1000 137 8 14 2 2 86 249
1000-1100 154 20 12 0 1 169 356
1100-1200 116 11 7 0 1 29 164
1200-1300 217 20 9 2 3 53 304
1300-1400 198 15 7 0 6 67 293
1400-1500 163 18 4 0 2 69 256
1500-1600 137 15 7 2 5 53 219
1600-1700 193 4 9 2 5 107 320
1700-1800 70 3 2 0 1 49 125
1800-1900 157 7 3 0 2 121 290
1900-2000 142 15 9 0 5 93 264
Total 2192 160 93 12 45 1194 3696
36
Table 4.4 Vehicle volume per 1 hour interval from Persiaran Pekeliling to
Roundabout
Time Motocar and Taxi
Small van and utility
(Light - 2 axle)
Lorry and Big
Van (Heavy - 2 axle)
Lorry with 3 axle or Trailer (Heavy
and exceed 2
axle)
Bus Motorcycle Total
0600-0700 1121 37 8 2 24 178 1370
0700-0800 1515 77 11 1 6 685 2295
0800-0900 1272 73 17 8 17 475 1862
0900-1000 911 80 39 7 4 214 1255
1000-1100 731 96 40 9 2 176 1054
1100-1200 900 30 36 6 6 127 1105
1200-1300 1168 77 48 6 9 220 1528
1300-1400 1087 64 46 8 4 167 1376
1400-1500 978 57 23 5 17 152 1232
1500-1600 764 71 37 4 1 149 1026
1600-1700 970 94 34 2 3 164 1267
1700-1800 1250 13 19 6 34 237 1559
1800-1900 872 39 13 1 8 204 1137
1900-2000 884 61 6 3 5 194 1153
Total 14423 869 377 68 140 3342 19219
37
Table 4.5 Vehicle volume per 1 hour interval from Persiaran Wawasan to Tol Bangi
Time Motocar and Taxi
Small van and utility
(Light - 2 axle)
Lorry and Big
Van (Heavy - 2 axle)
Lorry with 3 axle or Trailer (Heavy
and exceed 2
axle)
Bus Motorcycle Total
0600-0700 102 10 3 0 0 11 126
0700-0800 187 16 0 1 0 72 276
0800-0900 126 16 1 3 0 61 207
0900-1000 69 17 4 1 0 23 114
1000-1100 79 12 5 9 0 15 120
1100-1200 88 27 6 14 0 21 156
1200-1300 89 17 9 3 0 20 138
1300-1400 84 20 3 5 0 19 131
1400-1500 98 17 5 2 0 14 136
1500-1600 87 12 10 6 0 11 126
1600-1700 193 17 3 4 0 31 248
1700-1800 442 90 6 2 1 57 598
1800-1900 499 75 5 1 0 40 620
1900-2000 170 12 2 2 0 22 208
Total 2313 358 62 53 1 417 3204
38
Table 4.6 Vehicle volume per 1 hour interval from Persiaran Wawasan to
Roundabout
Time Motocar and Taxi
Small van and utility
(Light - 2 axle)
Lorry and Big
Van (Heavy - 2 axle)
Lorry with 3 axle or Trailer (Heavy
and exceed 2
axle)
Bus Motorcycle Total
0600-0700 167 20 5 0 6 43 241
0700-0800 573 33 0 0 5 93 704
0800-0900 305 19 10 1 2 44 381
0900-1000 196 13 9 3 3 35 259
1000-1100 198 21 19 1 3 52 294
1100-1200 256 27 15 0 1 59 358
1200-1300 360 30 16 0 6 71 483
1300-1400 329 23 15 1 3 68 439
1400-1500 282 51 10 1 3 60 407
1500-1600 298 29 8 1 2 91 429
1600-1700 347 38 6 0 3 107 501
1700-1800 610 25 13 1 6 103 758
1800-1900 378 14 6 1 6 136 541
1900-2000 197 13 3 0 4 48 265
Total 4496 356 135 10 53 1010 6060
39
Table 4.7 Vehicle volume per 1 hour interval from Tol Bangi to Persiaran Kemajuan
Time Motocar and Taxi
Small van and utility
(Light - 2 axle)
Lorry and Big
Van (Heavy - 2 axle)
Lorry with 3 axle or Trailer (Heavy
and exceed 2
axle)
Bus Motorcycle Total
0600-0700 235 18 24 5 0 142 424
0700-0800 673 101 6 4 1 186 971
0800-0900 846 40 14 10 3 304 1217
0900-1000 431 48 13 6 1 116 615
1000-1100 172 9 22 19 1 29 252
1100-1200 146 21 10 5 0 35 217
1200-1300 179 56 35 18 0 34 322
1300-1400 193 74 25 19 0 8 319
1400-1500 185 55 14 8 1 27 290
1500-1600 161 40 9 9 2 16 237
1600-1700 191 30 23 25 1 26 296
1700-1800 180 55 26 13 0 47 321
1800-1900 202 5 9 10 0 120 346
1900-2000 85 26 4 3 0 31 149
Total 3879 578 234 154 10 1121 5976
40
Table 4.8 Vehicle volume per 1 hour interval from Tol Bangi to Roundabout
Time Motocar and Taxi
Small van and utility
(Light - 2 axle)
Lorry and Big
Van (Heavy - 2 axle)
Lorry with 3 axle or Trailer (Heavy
and exceed 2
axle)
Bus Motorcycle Total
0600-0700 205 48 11 2 4 27 297
0700-0800 795 194 7 13 4 173 1186
0800-0900 771 186 22 12 2 275 1268
0900-1000 482 120 28 11 2 92 735
1000-1100 296 6 22 10 3 85 422
1100-1200 571 41 49 14 4 62 741
1200-1300 430 78 19 14 3 67 611
1300-1400 425 54 27 9 2 54 571
1400-1500 641 47 18 2 0 123 831
1500-1600 618 97 24 17 0 66 822
1600-1700 565 121 22 14 4 70 796
1700-1800 563 79 18 7 1 133 801
1800-1900 465 51 6 2 2 175 701
1900-2000 370 120 15 2 2 130 639
Total 7197 1242 288 129 33 1532 10421
41
4.3 Traffic Composition
Each type of vehicle has a different impact on traffic characteristic of a traffic
stream. Therefore, traffic volume observed during the study time was classified into
six main categories of vehicles. Figure 4.2 illustrate the distribution of the traffic
volume based on the vehicle types at Bulatan Seksyen 15, Bandar Baru Bangi. Figure
4.3 to Figure 4.6 illustrate the traffic composition at Bulatan Seksyen 15 according to
each approaches into the roundabout. From the traffic composition pie chart, it can
be concluded that the majority of the traffic volume is composed of passenger cars
with 67% (41,371 vehicles), and the second highest is motorcycles with 19% (11,380
vehicles).
Figure 4.2 Traffic composition at Bulatan Seksyen 15, Bandar Baru Bangi
67%9%
3%
1%
1%19%
TRAFFIC COMPOSITION AT BULATAN SEKSYEN 15, BANDAR BARU BANGI
Motocar and Taxi
Small van and utility (Light - 2axle)
Lorry and Big Van (Heavy - 2axle)
Lorry with 3 axle or Trailer(Heavy and exceed 2 axle)
Bus
Motorcycle
42
Figure 4.3 Traffic composition from Persiaran Kemajuan to the roundabout
Figure 4.4 Traffic composition from Persiaran Pekeliling to the roundabout
55%
17%
7%
5%
0%
16%
TRAFFIC COMPOSITION FROM PERSIARAN KEMAJUAN
Motocar and Taxi
Small van and utility (Light - 2axle)
Lorry and Big Van (Heavy - 2axle)
Lorry with 3 axle or Trailer(Heavy and exceed 2 axle)
Bus
Motorcycle
75%
5%2%
0%1%
17%
TRAFFIC COMPOSITION FROM PERSIARAN PEKELILING
Motocar and Taxi
Small van and utility (Light - 2axle)
Lorry and Big Van (Heavy - 2axle)
Lorry with 3 axle or Trailer(Heavy and exceed 2 axle)
Bus
Motorcycle
43
Figure 4.5 Traffic composition from Persiaran Wawasan to the roundabout
Figure 4.6 Traffic composition from Tol Bangi to the roundabout
74%
6%2%
0%
1%
17%
TRAFFIC COMPOSITION FROM PERSIARAN WAWASAN
Motocar and Taxi
Small van and utility (Light - 2axle)
Lorry and Big Van (Heavy - 2axle)
Lorry with 3 axle or Trailer(Heavy and exceed 2 axle)
Bus
Motorcycle
69%
12%
3%
1%
0%
15%
TRAFFIC COMPOSITION FROM TOL BANGI
Motocar and Taxi
Small van and utility (Light - 2axle)
Lorry and Big Van (Heavy - 2axle)
Lorry with 3 axle or Trailer(Heavy and exceed 2 axle)
Bus
Motorcycle
44
After the data was extracted according to each approaches, it was converted
into pcu/hour to obtain total vehicle for that approach. Table 4.9 shows the summary
of the traffic composition according to peak time. From Table 4.9, it is found that the
morning peak time has the highest volume compared to evening peak time. Based on
Figure 4.7 and 4.8, Persiaran Pekeliling was recorded with the highest number of
vehicles during both morning and evening peak hour, followed by Tol Bangi.
Table 4.9 Summary of traffic composition
Direction Veh/hour pcu/hour
AM PM AM PM
Persiaran Kemajuan
784 467 852 491
Persiaran Pekeliling
2295 1559 1911 1474
Persiaran Wawasan
704 758 673 726
Tol Bangi 1186 801 1242 795
Figure 4.7 Traffic volume at morning peak hour
0
500
1000
1500
2000
2500
PersiaranKemajuan
Persiaran Pekeliling Persiaran Wawasan Tol Bangi
Traffic Volume at AM peak hour
45
Figure 4.8 Traffic volume at evening peak hour
4.4 Delay and Level of Service
Control delay was calculated based on the formula mentioned in Equation 5
in Chapter 3. Table 4.10 and Table 4.11 summarise the calculation for control delay
for the signalised approaches which is from Persiaran Pekeliling, Persiaran
Wawasan, and Tol Bangi. Table 4.12 to Table 4.14 shows the actuated signal system
timing for current signal indication where F1 indicates the phase for approaching
lane entering the roundabout and F2 indicates the phase of the circulating traffic
inside the roundabout. The results from the calculation of the level of service has
shown that the LOS for the traffic stream is in category E and D (Figure 4.9). This
level of service can be categorised as unstable flow where the waiting time exceeds
the cycle time before proceeding the stop line.
0
200
400
600
800
1000
1200
1400
1600
1800
PersiaranKemajuan
Persiaran Pekeliling Persiaran Wawasan Tol Bangi
Traffic Volume at PM peak hour
46
Table 4.10 Summary of current delay for AM peak hour
Approach Persiaran Pekeliling
Persiaran Wawasan
Tol Bangi
Traffic Volume (veh/h)
2295 704 1186
Traffic Flow, q (pcu/h)
1910.8 672.69 1242.09
Cycle time, c 150 123 125
Green time, g 60 70 65
Effective green, ge 40 46.667 43.333
λ 0.267 0.379 0.347
s 3675 3675 3675
x 1.950 0.482 0.975
delay, d 76 26 36
LOS E D D
Table 4.11 Summary of current delay for PM peak hour
Approach Persiaran Pekeliling
Persiaran Wawasan
Tol Bangi
Traffic Volume (veh/h)
1559 758 801
Traffic Flow, q (pcu/h)
1474.21 726.24 794.64
Cycle time, c 150 123 125
Green time, g 60 70 65
Effective green, ge 40.000 46.667 43.333
λ 0.267 0.379 0.347
s 3675 3675 3675
x 1.504 0.521 0.624
delay, d 61 27 31
LOS E D D
Table 4.12 Actuated signal timing for Persiaran Pekeliling
GAP MIN MAX FLASH AMBER RED
F1 3.5 10 60 5 3 2
F2 5 10 70 5 3 2
Table 4.13 Actuated signal timing for Persiaran Wawasan
GAP MIN MAX FLASH AMBER RED
F1 5 10 70 4 2 3
F2 3.5 10 35 4 2 3
47
Table 4.14 Actuated signal timing for Tol Bangi
GAP MIN MAX FLASH AMBER RED
F1 5 10 65 5 3 2
F2 4 10 40 5 3 2
Figure 4.9 Current level of service for signalised approaches
In the previous Chapter 2, the minimum required level of service for the
signalised junction according to ATJ 11/87 is category D. If such level of service
cannot be sustained throughout the design life of the projected forecast the designer
has to propose a mitigation measure. Current level of service in the study area does
not fulfill the minimum requirement since the level of service at Persiaran Pekeliling
approach has a LOS of E. Therefore, we need to propose a mitigation measure for the
signalised roundabout.
According to Jabatan Kerja Raya Hulu Langat, the local authority in charge
for the road in the study area, several changes have been made on the traffic signal
D (D)
D (D)
E (E)
AM (PM)
48
timing in order to gain a smooth traffic stream for the approaching lanes. However,
they could not find a traffic signal timing that could maintain the smooth traffic
stream for a long period of time because congestion keep happening after several
months the changes is made. Thus, a different method need to be propose other than
redesigning the signal indication for the roundabout.
By using SIDRA INTERSECTION software, two methods has been proposed
which are installing ramp metering and changing the signalised approaches to
unsignalised approaches. Based on the proposed method, the level of service for
some approaches are slightly improved after implying the changes. Figure 4.10 and
Figure 4.11 shows the level of service for the roundabout if the signal control system
is removed, while Figure 4.12 shows the level of service for the roundabout if ramp
meter replaced the existing vehicle actuated signal system.
Figure 4.10 LOS for unsignalised approaches for AM peak hour by using
SIDRA INTERSECTION
49
Figure 4.11 LOS for unsignalised approaches for PM peak hour by using
SIDRA INTERSECTION
Based on Figure 4.10, Persiaran Pekeliling and Tol Bangi has shown a good
performance with LOS A while Persiaran Wawasan has shown a poor performance
with LOS F. In Figure 4.11, all approaches has shown a good performance with LOS
A. This result indicates that turning the signalised roundabout into unsignalised
roundabout could improve the level of service for the roundabout. However, the level
of service for Persiaran Wawasan approach for evening peak hour has poor
performance with LOS F. Thus, an improvement need to be done in order to improve
the level of service for the respective approach.
50
Figure 4.12 LOS for ramp metering by using SIDRA INTERSECTION
Based on Figure 4.12, Persiaran Pekeliling is the metered approach while
Persiaran Wawasan is the controlling approach. At controlling approach, detector
loops were installed to detect incoming vehicles while at the metered approach, a
traffic signal is installed to provide signal indication. The sensor at the controlling
approach will have a setback distance from the stop line which will detect the
presence of vehicles after several vehicles have started to queue at the approach.
When the sensor is triggered, it will send information to the traffic signal at the
metered approach to indicate a red light. This will allow the vehicles at the
controlling approach to enter the roundabout with less interruption from the metered
approach.
After a minimum or maximum red time is reached, the traffic signal will turn
green again. In a situation where the queue at the controlling approach is short and
51
does not trigger the sensor, the traffic signal at the metered approach will always be
green. However, another detector loops will be installed at the metered approach
with certain setback distance. After this sensor is triggered, the traffic signal will turn
green while neglecting the queue at the controlling approach. This is to avoid a very
long queue at the metered approach which may cause a serious traffic congestion.
Several other options have been tested and this arrangement provides the best
level of service among others options. Persiaran Kemajuan and Tol Bangi
approaches have shown a good performance with LOS A, Persiaran Wawasan
approach shows a LOS C and Persiaran Pekeliling approach shows a poor
performance with LOS F. Tol Bangi and Persiaran Wawasan has shown an improved
LOS from the signalised signal system from LOS D to LOS A and C. However,
Persiaran Pekeliling has dropped in performance from LOS E to LOS F.
4.5 Summary
Based on the results presented in this chapter, the following conclusion can
be made:
i. Traffic volume at the junction for 14 hours observation was 61,690
vehicles. It was found that the highest traffic composition is passenger car
and the second highest is motorcycle. Based on all four approaches,
Persiaran Pekeliling has the highest volume of vehicles with 22,915
vehicles along the period of data collection.
ii. From the data collection, control delay was determined by using
guidelines in ATJ 11/87. Current level of service for the junction are LOS
D and LOS E which does not comply with the minimum requirement for
the junction performance which is LOS D. Therefore, converting the
signalised approaches into unsignalised approaches or ramp metering
have been proposed as the mitigation measures.
52
CHAPTER 5
CONCLUSION AND RECOMMENDATIONS
5.1 Introduction
This research presents the evaluation of road performance at signalised
roundabout in Bulatan Seksyen 15, Bandar Baru Bangi. From the study, it was found
that the level of service for the traffic stream is on category D and E. The problem
can be seen in the Persiaran Pekeliling approach where it indicates LOS E. This is
due to high traffic volume but having a short green period. Therefore, in can be
concluded that the approaches experience unstable flow. A mitigation measure need
to be done to solve the congestion problem. Thus, converting the signalised
approaches to unsignalised approaches or ramp metering were suggested as the
method to mitigate the problem.
5.2 Findings
5.2.1 Objective 1: To determine the traffic characteristic in term of volume
and composition
The volume of vehicles at signalised roundabout was determined for two
weekdays from 6am to 10pm and the highest volume between the days was used for
data analysis. Manual counting technique was used to obtain the traffic volume. It
was found that the highest traffic composition is passenger car, followed by
motorcycle. Based on the four approaches at the roundabout, Persiaran Pekeliling
approach shows the highest number of vehicles with 22,915 vehicles. The total
number of vehicles at the roundabout is 61,690 vehicles for 14 hours duration.
53
5.2.2 Objective 2: To determine the control delay at signalised roundabout
Control delay was determined in order to identify the performance of the
signalised roundabout. Control delay was determined by using Equation 1 as
mentioned in Chapter 3. It was found that the average delay time for the roundabout
is between 20 and 80 seconds (76 sec, 26 sec, 36 sec, 61 sec, 27 sec, and 31 sec).
5.2.3 Objective 3: To determine the level of service (LOS) of each approaches
Level of service was obtained by calculating the control delay by using
guidelines in Arahan Teknik Jalan 11/87. By referring the table for level of service in
the guideline, it was found that the level of service for the traffic stream is between
category D and E. The problem can be seen in Persiaran Pekeliling approach where it
recorded LOS E.
5.3 Recommendation for Future Works
The mitigation measures of this study was modeled by using SIDRA
INTERSECTION and was only used to determine the level of service of the
signalised roundabout if it is converted into unsignalised system. Therefore, to obtain
other alternative method to mitigate the congestion problem, it is recommended that:
1) Collect the traffic volume of vehicles entering each approaches to
determine the vehicles journey and proportion of vehicles entering each
approaches. This data can be used to model the roundabout using VISSIM
software to get a detailed level of service considering the trip journey of
each vehicles on the roundabout.
2) Redesign the traffic signal timing to obtain a satisfactory control delay of
each signalised approaches by using available guidelines.
54
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Appendix A Data Collection Table
Negeri : Seksyen :
Daerah : Jalan :
Tarikh : No. Laluan :
Hari : KM :
0600-0700
0700-0800
0800-0900
0900-1000
1000-1100
1100-1200
1200-1300
1300-1400
1400-1500
1500-1600
1600-1700
1700-1800
1800-1900
1900-2000
2000-2100
2100-2200
Jumlah
JumlahMasaMotokar
dan Teksi
Van kecil &
Utiliti
(Ringan - 2
gandar)
Lori & Van
Besar
(Berat - 2
gandar)
Lori
dengan 3
gandar
atau Treler
(Berat -
Bas Motosikal