PSZ 19:16 (Pind. 1/07)

UNIVERSITI TEKNOLOGI MALAYSIA

DECLARATION OF THESIS / POSTGRADUATE PROJECT PAPER AND COPYRIGHT

Author’s full name : USMAN TASIU ABDURRAHMAN

Date of birth : 6TH MARCH 1986

Title : APPLICATION OF DIRECT AND INDIRECT METHODS FOR

MEASURING FREE-FLOW SPEED ON ROADWAYS

Academic Session : 2013/2014

I declare that this thesis is classified as:

I acknowledged that Universiti Teknologi Malaysia reserves the right as follows:

1. The thesis is the property of Universiti Teknologi Malaysia.

2. The Library of Universiti Teknologi Malaysia has the right to make copies for the purpose

of research only.

3. The Library has the right to make copies of the thesis for academic exchange.

Certified by:

SIGNATURE SIGNATURE OF SUPERVISOR

A03842721 ASSOC. PROF. DR. OTHMAN CHE PUAN

(NEW IC NO./PASSPORT NO.) NAME OF SUPERVISOR

Date: 28TH MAY 2014 Date: 28TH MAY 2014

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)

NOTES: * If the thesis is CONFIDENTAL or RESTRICTED, please attach with the letter from

the organization with period and reasons for confidentiality or restriction.

“I hereby declare that I have read this project report and in my opinion

this project report is sufficient in terms of scope and quality for the award of

degree of Master of Engineering (Civil – Transportation and Highway)”

Signature : ………………………………………

Name : ASSOC. PROF. DR. OTHMAN CHE PUAN

Date : 28th

May 2014

APPLICATION OF DIRECT AND INDIRECT METHODS FOR

MEASURING FREE-FLOW SPEED ON ROADWAYS

USMAN TASIU ABDURRAHMAN

A project report submitted in partial fulfillment of the

requirements for the award of degree of

Master of Engineering (Civil – Transportation and Highway)

Faculty of Civil Engineering

Universiti Teknologi Malaysia

MAY 2014

ii

DECLARATION

I declare that this project reportentitled “Application of direct and indirect

methods for measuring free flow speed on roadways” is the result of my own

research except as cited in the references. Thisreporthas not been accepted for any

degree and is not concurrently submitted in candidature of any other degree.

Signature : ………………………………….

Name : USMAN TASIU ABDURRAHMAN

Date : 28th

May 2014

iii

I dearly dedicate this piece to my beloved Mum,

Hajia Ummulkhair Bint Sheikh Tijjani Usman;

and Dad, Alhaji Tasiu Abdurrahman.

iv

ACKNOWLEDGEMENT

All praises are due to Allah. Peace and blessings upon His messenger, the

best Human ever, Prophet Muhammad Sallallahu alaihi wasallam.

I wholeheartedly acknowledge an immense guide from my supervisor:

Assoc. Prof. Dr. Othman Che Puan, who spared time, energy and resources for the

realization this research.

Kudos to my family, lecturers, friends and colleagues, for the day-to-day

support, that actively contributed to my success. A colossal appreciation goes to

Engr. Mahadi Lawan Yakubu and Engr. Muttaka Na’iya Ibrahim for the enormous

effort towards the successful completion of this work.

Vote of thanks to the Kano state Government – Nigeria, under the leadership

of Engr. (Dr.) Rabiu Musa Kwankwaso for the financial platform provided for this

program.

v

ABSTRACT

Free flow speed (FFS) is the drivers’ desired speed on roadways at low

traffic volume and with the absence of traffic control devices. The determination of

FFS is a fundamental step in the analysis of two-lane highways. FFS can either be

determined using field measurements or estimated using existing empirical models.

Malaysian Highway Capacity Manual (MHCM) provides a model for estimating

FFS based on base-free-flow-speed (BFFS), roadway’s geometric features and

proportion of motorcycles in the traffic stream. This model was compared against

observed FFS obtained using Moving Car Observer (MCO) method which was in

accordance with the suggested two-way flow rate below 200 veh/h, by the Highway

Capacity Manual (HCM). Mean speeds were observed at higher flow rates and

adjusted accordingly using a model provided by the HCM. Moving car observer

method was used for collecting the relevant data related to travel time, speed, flow

rate and traffic composition, by using a video recording instrumented test vehicle.

The roadway geometric features were measured manually. Field measurements

were carried out on ten directional segments of rural two-lane highways in Johor,

Malaysia. Field data obtained were analyzed to estimate FFS on each segment.

Statistical analyses indicate that there is a statistically significant difference between

the FFS observed using MCO method and the estimated FFS using MHCM method.

Such a finding suggests that there is a need to review the validity of the model

provided in the MHCM for accuracy of the analyses.

vi

ABSTRAK

Laju aliran bebas (FFS) adalah kelajuan yang diingini oleh pemandu ketika

memandu dalam keadaan aliran lalu lintas rendah dan jalan raya tanpa peranti

kawalan lalu lintas. Penentuan FFS adalah langkah asas dalam analisis jalan raya

dua lorong. FFS boleh ditentukan menggunakan ukuran di lapangan atau model

empirical sediada. Manual Kapasiti Lebuhraya Malaysia (MHCM) menyediakan

model empirical untuk menghitung FFS berdasarkan laju aliran bebas asas (BFFS),

ciri-ciri geometri jalan dan jumlah motorsikal dalam aliran lalu lintas. Model ini

dibandingkan dengan data FFS yang dicerap menggunakan Kaedah Pemerhati

Bergerak (MCO) yang disukat ketika aliran rendah, iaita kurang dari 200 kend/jam.

Purata laju ketika aliran tinggi juga dicerap dan diselaraskan mengikut model HCM.

Kaedah pemerhati bergerak digunakan untuk mencerap data yang relevan dengan

masa perjalanan, laju, kadar alir dan komposisi lalu lintas menggunakan kenderaan

yang dilengkapi dengan kamera video rakaman. Geometri jalan disukat secara

manual. Cerapan data lapangan dilakukan bagi sepuluh segmen jalan mengikut arah

lalu lintas bagi jalan rural dua lorong di Johor, Malaysia. Data lapangan yang

diperolehi dianalisis untuk menganggarkan FFS pada setiap segmen. Analisis

statistik menunjukkan bahawa terdapat perbezaan statistik yang signifikan antara

FFS cerapan dengan menggunakan kaedah MCO dan FFS yang dianggarkan

menggunakan kaedah MHCM.

vii

TABLE OF CONTENTS

CHAPTER TITLE PAGE

DECLARATION ii

DEDICATION iii

ACKNOWLEDGEMENT iv

ABSTRACT v

ABSTRAK vi

TABLE OF CONTENTS vii

LIST OF TABLES xi

LIST OF FIGURES xiii

LIST OF ABBREVIATIONS/SYMBOLS

xiv

LIST OF APPENDICES xvi

1 INTRODUCTION 1

1.1 Overview 1

1.2 Background 2

1.3 Statement of the problem 4

1.4 Aim and Objectives 4

1.5 Scope and Limitation 5

1.6 Significance of the Study 5

2 LITERATURE REVIEW 7

2.1 Overview 7

2.2 Speed 8

2.2.1 Time mean speed 8

viii

2.2.2 Space mean speed 9

2.3 Road Segments 9

2.4 Two-Lane highways 10

2.4.1 Classification of Two-Lane Highways 11

2.5 Level of Service 12

2.5.1 LOS for Two-Lane Highways 13

2.5.2 LOS for Multilane Highways 14

2.6 Speed and travel time Studies 15

2.6.1 License plate method 16

2.6.2 Test vehicle method 17

2.6.2.1 Driving techniques 17

2.6.2.2 Manual Data Collection 19

2.6.2.3 Automatic Data Collection 19

2.6.3 Vehicle Signature Matching Method 20

2.6.4 Transit Speed and Delay Study 21

2.6.5 Platoon Matching Method 21

2.6.5.1 Direct Observation Method 22

2.6.5.2 Aerial Surveys 22

2.6.6 Box-Cox Method 22

2.6.7 Other Speed and Travel Time Study

Methods 23

2.7 Malaysian Highway Capacity Manual 23

2.7.1 Free-Flow Speed Determination Using

MHCM 25

2.8 Factors affecting free-flow speed 28

2.8.1 Lane width 28

2.8.2 Shoulder width 28

2.8.3 Access points 29

2.8.4 No-Passing Zones 29

2.9 Moving Car Observer Method 30

2.1 Conclusion 34

ix

3 METHODOLOGY 35

3.1 Overview 35

3.2 General Framework of the Methodology 36

3.3 Site Selection 37

3.3.1 Study Site Locations 37

3.4 Data Requirements 40

3.4.1 Geometric Features 41

3.4.2 Traffic Data 41

3.4.3 Instrumentation 42

3.5 Site Data Collection 42

3.5.1 Field Measurements 43

3.5.2 Field Observations 43

3.5.3 Traffic Data Collection 44

3.5.3.1 Video VBox Setting 46

3.5.3.2 Test Runs 45

3.6 Data Extraction 46

3.7 Data Analysis 47

3.7.1 Phase 1 – Data Analysis 48

3.7.1.1 Malaysian Highway Capacity

Manual Method 48

3.7.1.2 Moving Car Observer Method 49

3.7.2 Phase 2 – Data Analysis 50

3.7.2.1 Malaysian Highway Capacity

Manual Model 50

3.7.2.2 Highway Capacity Manual

Adjustment Model 51

3.8 Conclusion 52

4 RESULTS AND DISCUSSIONS 53

4.1 Overview 53

4.2 Phase 1: MCO Application 53

4.2.1 Geometry of the Segments 54

4.2.2 Moving Car Observer Method 55

x

4.2.3 Malaysian Highway Capacity Manual

Method 56

4.2.4 Comparison of FFS estimates from

MCO and MHCM Approaches 57

4.2.4.1 Regression Analysis 59

4.2.4.2 Statistical T-Test 61

4.3 Phase 2: Models Comparison 61

4.3.1 Geometry of the Segments 62

4.3.2 HCM Adjustment Model 62

4.3.3 MHCM Estimation Model 64

4.3.4 Comparison of the HCM and MHCM

Estimation Models 65

4.4 Conclusion 68

5 CONCLUSION 69

5.1 Overview 69

5.2 Research Findings 70

5.3 Recommendations for Future Research 71

5.4 Concluding Remarks 72

REFERENCES 73

BIBLIOGRAPHY 75

APPENDICES 77

xi

LIST OF TABLES

TABLE NO TITLE PAGE

2.1 LOS Criteria for Class I two-lane highways (TRB, 2000) 14

2.2 LOS Criteria for Class II two-lane highways (TRB, 2000) 14

2.3 Level of Service Criteria for Multilane Highways (TRB,

2000) 15

2.4 Free-flow speed reduction for lane width and paved

shoulder width (HPU, 2011) 26

2.5 Free-flow speed reduction for access points density (HPU,

2011) 27

2.6 Free-flow speed reduction based on proportion of

motocycles (HPU, 2011) 27

4.1 Roadways Geometry 54

4.2 Free Flow Speed Using Moving Car Observer Method 55

4.3 Free Flow Speed Using MHCM Method 57

4.4 Comparison of Estimated FFSs 58

4.5 Geometry of the Roadways 62

4.6 FFS Using HCM Adjustment Model 63

xii

4.7 FFS Using MHCM Estimation Model 64

4.8 Comparison of FFS Estimation Models 65

xiii

LIST OF FIGURES

FIGURE NO. TITLE PAGE

2.1 Speed Classes 8

2.2 Moving-Observer Method 31

3.1 Methodology Flowchart 36

3.2 Video VBox Components 44

4.1 Comparison between FFSMCO and FFSMHCM 59

4.2 Relationship between FFSMCO and FFSMHCM 60

4.3 Comparison between FFSHCM and FFSMHCM 67

xiv

LIST OF ABBREVIATIONS/SYMBOLS

ANOVA - Analysis of Variance

APD - Access Points Density

ATS - Average Travel Speed

BFFS - Base Free Flow Speed

CAM - Camera

DMI - Distance Measuring Instrument

ER - Passenger-car equivalent for RVs

ET - Passenger-car equivalent for trucks

fAPD - Adjustment for access points density

fLS - Adjustment for lane width and shoulder width

fm - Adjustment for motorcycles

FDOT - Florida Department of Transportation

FFS - Free Flow Speed

FFSm - Mean Free Flow Speed

fHV - Heavy-vehicle adjustment factor

GPS - Global Positioning System

HCM - Highway Capacity Manual

HPU - Highway Planning Unit

ITE - Institute of Transportation Engineers

Km/h - Kilometre per Hour

KST-UTR - Kampung Sungai Tiram-to-Ulu Tiram

KUL-KTG - Kulai-to-Kota Tinggi

LOS - Level of Service

Lw - Lane Width

MCO - Moving Car Observer

xv

MHCM - Malaysian Highway Capacity Manual

MRS-END - Mersing-to-Endau

NB - Northbound

PCE - Passenger Car Equivalent

PMc - Proportion of Motorcycles

PNT-KKP - Pontian-to-Kukup

PR - Proportion of recreational vehicles

Pt - Proportion of Trucks

PTSF - Percent Time Spent Following

q - Average Directional Flow Rate

REN – KUL - Renggam-to-Kulai

RV - Recreational Vehicle

SB - Southbound

SFM - Mean traffic speed

SHw - Shoulder Width

SPSS - Statistical Product and Service Solutions

T - Mean travel time

TRB - Transportation Research Board

UAV - Unmanned Aerial Vehicle

VBox - Video Box

Vf - Observed Flow rate

WIM - Weight in Motion

xvi

LIST OF APPENDICES

APPENDIX TITLE PAGE

A Traffic Volume Extraction Form 78

B Raw Data for Six Directional Segments 80

C Regression Analyses Output 84

D Paired Sample T-Test Output 89

E Raw Data for Four Directional Segments 92

F Passenger Car Equivalents (PCE) 95

G Speed Reduction Tables (HPU, 2011) 97

H Statistical T-Test Output 99

I Google Images of the Study Routes 102

CHAPTER 1

INTRODUCTION

1.1 Overview

Speed refers to a measure of the rate of motion. It is a distance travelled per

unit time spent travelling. Speed is a fundamental measure of traffic performance of

road segments. Vehicles on road travels at absolutely different speeds, no single

speed can be assigned to the whole vehicles on traffic stream. Speed can be

presented in a number of ways such as in the form of spot speed, travel speed,

running speed and free-flow speed.

Free-flow speed (FFS) refers to an average speed of vehicles on road

segments not close to an intersection under conditions of low vehicular density

(Roess et al. 2004). It is a significant variable used in estimating the expected

operating conditions of highways, and it is only possible when the traffic volume on

the road segment is below capacity. A key step in analyzing capacity and level of

service for uninterrupted flow condition is the determination of free-flow speed.

FFS together with demand flow rates are used in determining average travel speed

of roadway facility. FFS is also used to determine urban street class, to estimate

running time for roadway segments, and to analyze capacity and level of service

2

for uninterrupted flow conditions (HPU, 2011). In addition, FFS is an important

factor used to analyze the performance of highways.

Free-flow speed being the desired speed of drivers, at low volume situation

and with absence of traffic control devices, is affected by a number of factors, such

as number of lanes, lane widths, lateral clearance, access point density, geometric

design and visibility. Other factors with little influence include speed limit, level of

enforcement, horizontal and vertical alignment, weather and lighting conditions

(TRB, 2000).

1.2 Background

For two-lane highways, free-flow speed is measured or determined at two-

way flow of 200veh/h or less. In cases where the two-way flow is above 200veh/h,

volume adjustment has to be made to the FFS. However, the magnitude of free-flow

speed depends on the physical characteristics of the highway. According to the

American highway capacity manual (HCM) (TRB, 2000), FFS will be lower on

sections of highway with restricted horizontal and/or vertical alignment and it tends

to be lower when posted speed limits are lower.

FFS is also considered as the theoretical flow of vehicle on road segment

when density on the road is zero. That is when there are no vehicles present on the

road. This speed can generally be determined in two methods, i.e. field

measurement and estimation. There are a number of ways for determining the FFS

using field measurement procedure, among which is the Malaysian highway

capacity manual (MHCM) method. Under this study, Moving Car Observer (MCO)

Method was checked for its applicability on Free-flow speed measurements.

3

Moving car observer method was originally proposed by Wardrop and

Charlesworth (1954) as a way of estimating journey time and average flow of traffic

travelling in either direction on road segment. The method is based on the

measurements made by the moving observer (in a vehicle) through the traffic. The

observer is expected to travel in a test car in the direction of the stream considered

(with flow) and be recording the number of vehicles overtaken and the number of

vehicles passed. A run is also made against the flow (from the other direction),

counting the number of opposing vehicles met during the run. In both runs, the

journey time of the test car is recorded (Wright, 1973). These measurements are

then used in computing speed-flow relationships for the road segment. Multiple

runs are always encouraged for accuracy.

Malaysian Highway Capacity Manual (MHCM) (2011 version) being a

product of the Highway Planning Unit (HPU) of the ministry of works, Malaysia, is

the second version of the Malaysian highway capacity manual, i.e. after the 2006

version. The manual was organized as a result of laborious empirical studies carried

out to establish related capacity values and relationships best representing the

highway situations in Malaysia. The manual provide a model for the determination

of free-flow speed on two-lane highways based on the base free-flow speed and

some adjustments with regard to the traffic and roadway conditions. The adjustment

factors considered in the manual are the lane width and shoulder width, access point

density and the proportion on motorcycles in the traffic.

The base free flow speed is a speed that reflects the alignment of the facility

and the character of the traffic. It is determined based on speed data, design speed

of the facility, posted speed limits and local knowledge of operating condition on

similar facilities to the roadway under consideration.

4

1.3 Statement of the problem

It is not uncommon to find out two or more different approaches to same

entity yielding entirely or relatively different results or outcomes, even when

measured on the same facility and during the same period. In which case, a study

will then be needed to find out how are those approaches related to one another, and

how reliable are their outcomes in relation to one another. This is because; different

approaches for computing same entity sometimes fail to comply with one another.

Considering the importance of free-flow speed in traffic engineering, it is

therefore necessary to determine the free flow speed on roads as accurate as

possible. This study therefore focused on the determination of free flow speed using

two approaches, i.e. the Malaysian highway capacity manual method and the

moving car observer method. Each of the two methods has a different approach and

procedure for the determination of the free flow speed, using different factors. The

study compared results obtained from the two approaches, figure out the

applicability of the moving car observer method used, in relation to the Malaysian

highway capacity manual method, and then a conclusion was drawn in form of

relationship between the two approaches. Free flow speed estimation models (with

varying inputs) were also compared.

1.4 Aim and Objectives

This study is aimed at determining free-flow speed on two-lane highways

using Malaysian highway capacity manual method making base with observed free-

flow speed using moving car observer method.

5

The study is based on the following objectives

i. To estimate and compare free flow speeds on selected two-lane highways

using the Malaysian highway capacity manual method and the moving car

observer method.

ii. To estimate and compare free flow speeds using HCM adjustment model

and MHCM estimation model.

1.5 Scope and Limitation

This study focused on free flow speed determination along six selected

directional segments on two-lane highways in Johor Bahru, Malaysia - using the

Malaysian highway capacity manual method and the moving car observer method.

Four more directional segments (on two-lane highways as well) were considered for

free flow speed estimation using HCM adjustment model and MHCM estimation

model. Roads with different traffic conditions were considered.

1.6 Significance of the Study

The Malaysian highway capacity manual method of computing free flow

speed is quite different from the moving car observer method. The MHCM

approach focuses mainly on the geometric features of the road in addition to base

free flow speed (BFFS).

6

Moving car observer method is a method depending on data taken while in

motion on that very road. The speed computed by this method is as a result of

multiple runs performed, taking along the statistics of the vehicles in motion on that

road segment with regard to the direction of movement and relative to the

movement of the test vehicle.

The different directions taken by these two approaches in finding out

roadway conditions, might yield different results or otherwise when conducted on

the same facility (road segment). To know whether these two approaches can prove

the reliability of one another or not, a comparison study needs to be conducted

using the two approaches on the same facility. This study highlighted how the two

approaches relate to one another in terms of free flow speed on two-lane highways.

For a similar reason, FFS estimation models need such comparative task; as

such MHCM FFS estimation model was compared against HCM FFS adjustment

model, at the end of this study.