Traffic Engineering deals with the planning, design and implementation of traffic flow, and road infrastructure and facilities. This book provides in-depth information about road user characteristics and highway geometric design. It explains the collection and analysis of different types of traffic data, obtained as part of various studies. It also describes the design of different types of intersections and illustrates the use of road markings and lighting. Recent advances such as Intelligent Transportation System are also explored. This book will be useful to undergraduate and postgraduate students as well as to researchers and practicing engineers.
R Srinivasa Kumar is a faculty member of the Department of Civil Engineering, University College of Engineering, Osmania University, Hyderabad. He was awarded the Indian Roads Congress Commendation Certificate for the best research paper published in the IRC Journal (2001–02). He has also authored textbooks on highway engineering, pavement design and maintenance, and transportation engineering.
Preface Acknowledgements 1. Introduction to Road Traffic Engineering 1.0 Introduction 1.1 Traffic Problems 1.2 Reasons for Collecting Data 1.3 Types of Studies 1.3.1 Frequency of Traffic Data Collection Multiple Choice Questions Questions 2. Road User and Vehicle Characteristics 2.0 Introduction 2.1 Road User 2.1.1 Road User Characteristics 2.1.2 Reaction Process 2.1.3 Rate of Change of the Visual Angle 2.2 Vehicle 2.2.1 Vehicle Characteristics 2.3 Road Characteristics 2.3.1 Surface Characteristics 2.3.2 Lighting 2.4 Traffic Control Devices 2.5 The General Environment Multiple Choice Questions Questions 3. Highway Geometric Design 3.0 Introduction 3.1 Vehicle Dimensions 3.2 Terrain Classification 3.3 Design Speed 3.4 Cross-Sectional Elements 3.4.1 Boundary Lines 3.4.2 Right of Way or Road–Land Width 3.4.3 Carriageway Width and Road Width 3.4.4 Shoulder 3.4.5 Camber 3.5 Sight Distance 3.5.1 Safe Stopping Sight Distance (SSD) 3.5.2 Overtaking Sight Distance (OSD) or Passing Sight Distance (PSD) 3.5.3 Intermediate Sight Distance (ISD) 3.5.4 Intersection Sight Distance (ISSD) 3.5.5 Sight Distance at Medians 3.6 Superelevation 3.6.1 Design of Superelevation 3.6.2 Design Rate of Superelevation 3.6.3 Design Side Friction Factor 3.6.4 Analysis of Curve Radii 3.6.5 Attaining Superelevation 3.6.6 Rate of Change of Superelevation 3.7 Widening of Carriageway on Curves 3.8 Horizontal Curves 3.8.1 Sight Distance on Horizontal Curves 3.8.2 Transition Curve 3.8.3 Length of Transition Curve 3.8.4 Elements of the Transition Curve 3.9 Longitudinal Gradient 3.10 Compensation of Grade on Horizontal Curves 3.11 Vertical Curves 3.11.1 Types of Vertical Curves 3.11.2 Length of Vertical Curves 3.11.3 Sight Distance on Sag Curves Passing Under an Overhead Structure 3.12 Bus Bay 3.13 Road Humps and Bumps 3.14 Geometric Design of Bike Paths 3.15 Consistency in Highway Geometric Design Multiple Choice Questions Questions 4. Traffic Volume Studies 4.0 Introduction 4.1 Objectives of Traffic Volume Studies 4.2 Types of Traffic Counts 4.2.1 Vehicular Traffic Volume (or Flow) Survey 4.2.2 Pedestrian Traffic Volume Survey 4.3 Introduction to Pedestrian Volume Studies 4.4 Objectives of Pedestrian Volume Studies 4.5 Use Criteria for Pedestrian Volume Studies 4.6 Terminology 4.7 Types of Pedestrian Transport Networks 4.8 Factors Affecting Pedestrian Demand 4.9 Pedestrian Data Collection Methods 4.9.1 Manual Counting Techniques 4.9.2 Automatic Counting Techniques 4.10 Location of Counting Stations 4.11 Pedestrian Volume Characteristics 4.12 Design Volume 4.13 Presentation of Pedestrian Volume Data 4.14 Pedestrian Flow Characteristics 4.14.1 Pedestrian Walking Speed 4.14.2 Pedestrian Walking Space 4.14.3 Pedestrian Start-Up Time 4.14.4 Pedestrian Capacity 4.14.5 Pedestrian Speed–Density (V–K) Relationship 4.14.6 Pedestrian Flow–Density Relationship 4.14.7 Travel Time–Speed–Flow Rate Relationship 4.14.8 Pedestrian Speed–Flow Relationship 4.14.9 Pedestrian Speed–Space Relationship 4.14.10 Pedestrian Flow–Space Relationship 4.15 Level of Service (LOS) 4.15.1 LOS Criteria for Uninterrupted Flow Pedestrian Facility 4.15.2 LOS Criteria for Stairways and Queuing 4.15.3 LOS Criteria for Interrupted Flow Pedestrian Facility 4.16 Time–Space (TS) Analysis Method 4.17 Design Guidelines 4.18 Solved Problems Multiple Choice Questions Questions 5. Traffic Count Techniques and Analysis of Traffic Volume Data 5.0 Types of Traffic Counting Methods 5.1 Manual Traffic Count 5.2 Automatic Traffic Count (ATC) 5.2.1 Intrusive Sensors 5.2.2 Non-Intrusive Sensors 5.3 Factors Affecting the Selection of Technology 5.4 Duration of Traffic Count 5.5 Traffic Attributes 5.6 Presentation of Traffic Volume Data 5.6.1 Variations in Traffic Flow 5.6.2 Summary Tables 5.6.3 Graphic Summary of Flow at Intersections 5.7 Analysis of Traffic Volume Data – Basic Terminology 5.8 Traffic Volume Data Products 5.8.1 Monthly Average Days of the Week Traffic (MADWT) 5.8.2 Monthly Average Daily Traffic (MADT) 5.8.3 Monthly Average Weekday Daily Traffic (MAWDT) 5.8.4 Monthly Average Weekend Daily Traffic (MAWET) 5.8.5 Average Annual Weekday Traffic (AAWT) 5.8.6 Average Weekday Traffic (AWT) 5.8.7 Annual Average Daily Truck Traffic (AADTT) 5.8.8 Annual Average Weekday Traffic (AAWDT) 5.8.9 Annual Average Day of Week Traffic (AADWT) 5.8.10 Average Annual Daily Traffic (AADT) 5.8.11 Annual Average Weekend Traffic (AAWET) 5.8.12 Annual Vehicle Distance Travelled (AVDT) 5.8.13 Vehicle Miles Travelled (VMT) 5.8.14 Average Daily Traffic (ADT) 5.8.15 Axle Correction Factor (ACF) 5.8.16 Seasonal Correction Factor (SCF) or Seasonal Adjustment Factor (SAF) 5.8.17 Seasonal Average Daily Traffic (SADT) 5.8.18 Average Summer Daily Traffic (ASDT) 5.8.19 Seasonal Average Daily Traffic Adjustment Factors (SADTAF) 5.8.20 Peak Hour Factor (PFH) 5.8.21 Design Hour (DH) 5.8.22 Design Year (DV) 5.8.23 Design Hour Volume (DHV) 5.8.24 K-Factor or Design Hour Factor 5.8.25 Design Hour Truck (DHT) 5.8.26 Design Hour Factor 5.8.27 Directional Distribution (D) or Directional Split of Traffic 5.8.28 Directional Design Hour Volume (DDHV) 5.9 Solved Problems Multiple Choice Questions Questions 6. Spot Speed Studies and Characteristics 6.0 Introduction to Speed Studies 6.1 Spot Speed Study 6.1.1 Factors Affecting Spot Speed 6.1.2 Applications of Spot Speed Data 6.2 Other Definitions of Speed 6.2.1 Sample Size 6.3 Solved Problems Multiple Choice Questions Questions 7. Origin and Destination Studies 7.0 Introduction 7.1 OD Data 7.2 The OD Study Area 7.3 OD Data Collection Methods 7.3.1 Registration Questionnaire Survey 7.3.2 Mail-Back Questionnaire or Self-Completion Postcard Survey(or Roadside Handout Survey) 7.3.3 Roadside Interview Survey 7.3.4 Home Interview Survey 7.3.5 Tag-on-Car Survey 7.3.6 Carousel Method 7.3.7 Licence Plate Survey 7.3.8 Comments and Remarks 7.3.9 Other Methods Relating to ITS 7.4 Selecting a Method 7.5 Sample Size 7.6 Uses of OD Data 7.7 Presentation of OD Data 7.8 Solved Problem Multiple Choice Questions Questions 8. Travel Time and Delay Studies 8.0 Introduction 8.1 Factors Affecting Speed and Delay 8.2 Methods of Measurement of Travel Time and Delays on any Selected Length of a Route 8.2.1 Floating Car Method (Moving Observer Method) 8.2.2 Test Car Procedure 8.2.3 Licence Plate Matching Method 8.2.4 Fixed Time Interval Photographs 8.2.5 Elevated Observer Method 8.2.6 Field Interviews (Survey) 8.2.7 GIS and GPS Method 8.2.8 Bluetooth Technologies 8.3 Sample Size 8.4 Presentation of Travel Time and Delay Data 8.4.1 Tabular Form 8.4.2 Time Contour Map 8.4.3 Time Bar Chart 8.4.4 Speed Profiles 8.4.5 Frequency Distribution Curve 8.5 Solved Problems Multiple Choice Questions Questions 9. Intersection Delay Studies 9.0 Introduction 9.1 Types of Delays at Intersections 9.2 Methods of Measuring Delay Through Intersections 9.2.1 Stopped Vehicle Method 9.2.2 Elevated Observer Method 9.2.3 Sample Size 9.3 Speed and Delay Formulae 9.4 Solved Problems Multiple Choice Questions Questions 10. Traffic Flow Characteristics 10.0 Introduction 10.1 Traffic Stream Parameters 10.1.1 Space Headway and Time Headway 10.1.2 Lane Occupancy 10.1.3 Density 10.1.4 Lane Capacity 10.2 Fundamental Relationships Between Traffic Flow Parameters 10.2.1 Speed–Density (V–K) Relationship 10.2.2 Speed–Flow (V–Q) Relationship 10.2.3 Flow–Density (Q–K) Relationship 10.2.4 Density–Spacing (K–Ss) Relationship 10.3 Macroscopic Traffic Stream Models 10.3.1 Greenshield’s Linear Model 10.3.2 Greenberg’s Logarithmic Model 10.3.3 Underwood’s Exponential Model 10.3.4 Multi-Regime Models 10.4 Microscopic Traffic Stream Models 10.4.1 The Car-Following Theory 10.4.2 GM Model 10.5 Shock Waves in Traffic Streams 10.5.1 Shock Wave Speed 10.6 Level of Service 10.7 Equivalency Factors 10.7.1 Factors Affecting Equivalency Factors (PCU Values) 10.8 Design Service Volume 10.9 Solved Problems Multiple Choice Questions Questions 29411. Introduction to Intersections and Design Guidelines for At-Grade Intersections 11.0 Introduction 11.1 Access Management 11.2 Classification of Intersections 11.3 Classification of At-Grade Intersections 11.4 Low-Cost Traffic Management Techniques 11.5 Factors Considered in the Design of Intersections 11.6 Design Principles of At-Grade Intersections 11.6.1 Design Vehicle 11.6.2 Stopping Sight Distance 11.6.3 Sight Distance Triangles at an Intersection 11.6.4 Types of Sight Triangles at an Intersection 11.6.5 Sight Distance at Median 11.7 Principles of Channelisation 11.8 Elements of Channelisation 11.8.1 Alignment of Lanes 11.8.2 Islands 11.8.3 Kerbs 11.8.4 Directional Islands 11.8.5 Median Islands 11.8.6 Median End Treatment 11.8.7 Spacing of Median Opening or Median Break Spacing 11.8.8 Dividers 11.8.9 Splitter Islands 11.8.10 Tapers and Transitions 11.8.11 Auxiliary Lanes 11.9 Retrofit Actions 11.9.1 Retrofit Techniques 11.9.2 Specific Guidelines on Corrections to Skewed Intersections Multiple Choice Questions Questions 12. Design and Analysis of Rotary Intersections 12.0 The Concept of Traffic Rotary Operations 12.1 Advantages of Traffic Rotaries 12.2 Disadvantages of Traffic Rotaries 12.3 Suitability of Traffic Rotaries/Roundabouts 12.4 Design Criteria and Guidelines 12.4.1 Geometric Standards 12.4.2 Operating Standards 12.5 Data Collection and Analysis 12.5.1 Methods of Data Collection 12.5.2 Operational Performance Evaluation 12.5.3 Capacity Analysis 12.6 Solved Problems Multiple Choice Questions Questions 13. Design of Signalised Intersections 13.0 Introduction 13.1 Advantages of Signal Control 13.2 Disadvantages of Signal Control 13.3 Warrants for Traffic Signal Installation 13.4 Traffic Signal Design Elements 13.5 Data Collection 13.6 Traffic Control Signal Lights 13.7 Commonly Used Terminology 13.8 Types of Traffic Signal Controls 13.9 Concepts of Traffic Signal Time Design 13.9.1 Phasing 13.9.2 Saturation Flow Rate 13.9.3 Estimation of Saturation Flow 13.9.4 Lost Time 13.9.5 Cycle Time By Webster’s Method 13.9.6 Effective Green Time 13.9.7 Green Time 13.10 Signal Performance Measurement 13.10.1 Capacity of an Intersection 13.10.2 Degree of Saturation 13.10.3 Level of Service (LOS) 13.10.4 Other Parameters 13.11 Design of Isolated Fixed Time Signal 13.11.1 IRC: 93 Method 13.11.2 Guiding Standards 13.12 Introduction to Coordinated Signal Control Systems 13.12.1 Need for Coordinated Control 13.12.2 Basic Concepts of Signal Coordination 13.12.3 Factors Affecting Coordination 13.13 Types of Coordinated Traffic Signal Control Systems 13.13.1 Simultaneous Signal Control System 13.13.2 Alternate Signal Control System 13.13.3 Simple Progressive Signal Control System 13.13.4 Flexible Progressive Signal Control System 13.14 Review of Signal Timing 13.15 Solved Problems Multiple Choice Questions Questions 14. Basics of Queuing Theory and Delay Analysis 14.0 Introduction to Queuing Theory 14.1 Queuing System 14.1.1 Queuing System Classification 14.1.2 Little’s Theorem 14.1.3 Queuing Models 14.2 Analysis of Delay and Queuing at Signalised Intersections 14.2.1 Methods of Delay Analysis at Isolated Signalised Intersections Multiple Choice Questions Questions 15. Design Guidelines for Grade-Separated Intersections and Interchanges 15.0 Introduction 15.1 Grade-Separated Structures 15.2 Factors Affecting the Selection of an Interchange 15.3 Classification of Grade-Separated Structures 15.3.1 Overpass or Bridge 15.3.2 Underpass 15.4 Classification of Ramps 15.4.1 Classification of Ramps Based on Direction of Use 15.4.2 Classification of Ramps Based on Access Control 15.5 Interchange Design Principles 15.5.1 Cardinal Principles of Interchange Design 15.5.2 Secondary Principles of Interchange Design 15.6 Classification of Interchanges 15.6.1 Classification Based on the Number of Approach Legs 15.6.2 Classification Based on Directional Use 15.6.3 Classification Based on Access Control 15.7 Interchange Configurations 15.7.1 Three-Leg Interchanges 15.7.2 Diamond Interchanges 15.7.3 Single Point Urban Interchange (SPUI) 15.7.4 Diverging Diamond Interchange (DDI) 15.7.5 Double Crossover Merging Interchange (DCMI) 15.7.6 Three-Level Diamond Interchange 15.7.7 Variants of Diamond Interchanges 15.7.8 Multi-Level Stack Interchanges 15.7.9 Cloverleaf Interchanges 15.7.10 Parclo (Partial Cloverleaf Interchange) 15.7.11 Turbine Interchange 15.8 Guidelines for the Design of Interchange Components 15.8.1 Lane Balance 15.8.2 Weaving Section 15.8.3 Ramp Design 15.8.4 Ramp Spacing 15.8.5 Entrance Ramp Taper Design 15.8.6 Exit Ramp Taper Design 15.8.7 Gores 15.8.8 Sight Distance 15.8.9 Other Considerations 15.8.10 Access Control 15.8.11 Comparative and Evaluation Studies Multiple Choice Questions Questions 16. Parking Studies 16.0 Introduction 16.1 Basic Terminology 16.2 Classification of Parking Facilities 16.2.1 On-Street/ Kerb/Roadside Parking 16.2.2 Off-Street Parking 16.3 Steps in Parking Studies 16.4 Parking Surveys 16.4.1 In–Out Survey 16.4.2 Fixed Period Sampling 16.4.3 Licence Plate Method of Survey 16.5 Characteristics of Parking Facilities 16.6 Analysis of Parking Data 16.7 Parking Management Strategies Multiple Choice Questions Questions 17. Road Markings 17.0 Introduction 17.1 Classification of Road Markings 17.2 Line Markings 17.2.1 Centre Line 17.2.2 Transverse Markings 17.2.3 Hazard Markings 17.2.4 Block Markings 17.2.5 Arrow Markings 17.2.6 Directional Markings 17.2.7 Facility Markings 17.2.8 Object Markings 17.2.9 Colour Pavement Markings 17.3 Road Studs 17.4 Preview Distance Requirements 17.5 Phenomenon of Diffusion, Reflection, Refraction and Retroreflectivity 17.5.1 Measurement of Retroreflectivity 17.5.2 Instruments Used to Measure Retroreflectivity 17.6 Materials Used for Road Markings 17.7 Performance Assessment of Road Markings 17.8 Anti-Skid Tests on Road Markings Multiple Choice Questions Questions 18. Road Traffic Signs 18.0 Introduction 18.1 Classification of Signs 18.2 Basic Elements of Road Signs 18.2.1 Shape 18.2.2 Colour 18.2.3 Lettering 18.2.4 Symbols 18.3 Functional Aspects of Road Signs 18.3.1 Regulatory or Mandatory Signs 18.3.2 Warning, Cautionary or Precautionary Signs 18.3.3 Information/Guide Signs 18.3.4 Variable Message Signs 18.3.5 Object/Curve/Hazard Markers, Bollards and Junction Definition Posts 18.3.6 Miscellaneous Devices/Signs 18.4 Sign Legibility Distance 18.4.1 Australian Practice 18.4.2 Indian Practice 18.4.3 USSC Recommended Practice of Thumb Rule 18.5 Lateral Clearance and Location of Signs 18.5.1 Lateral Placement and Height 18.5.2 Longitudinal Placement 18.5.3 Sign Orientation 18.5.4 Sign Support Standards 18.5.5 Warrants 18.6 Illumination and Retroflection 18.7 Materials Used for Signs 18.8 The Cone of Retroreflection 18.9 Measurement of Retroreflectivity of Signs Multiple Choice Questions Questions 19. Roadway Lighting 19.0 Introduction 19.1 Factors Affecting Night-Time Visibility 19.2 Objectives of Roadway Lighting 19.3 Glossary of Terms 19.4 Lighting Laws 19.4.1 Inverse Square Law 19.4.2 Cosine Law 19.5 Types of Lamps 19.6 Lighting Requirements 19.7 Warrants for Lighting 19.8 Factors Affecting the Selection of Appropriate Lighting System 19.9 Lighting Correction Factors 19.10 Design Elements of Lighting System 19.10.1 Lateral Luminaire Light Distribution 19.10.2 Vertical Light Distribution 19.10.3 Luminaire Cut-Off Classification 19.10.4 Types of Poles 19.10.5 Pole Height 19.10.6 Pole Arms 19.10.7 Mounting Height and Type of Luminaire 19.10.8 Luminaire Arrangements 19.10.9 Lighting Level Requirements 19.10.10 Methods of Spacing of Lighting Units 19.10.11 Lateral Placement of Poles (Luminaire) 19.11 Design of Roadway/Street Lighting System 19.12 Methods of Pole Installation 19.13 Smart/Intelligent Street Lighting System 19.13.1 Components of ISL 19.14 Life Cycle Cost Evaluation Multiple Choice Questions Questions 20. Road Traffic Accident Studies and Reconstruction 20.0 Introduction 20.1 Objectives 20.2 Basic Report Information 20.2.1 Accident Location 20.3 Assessment of Accident Data 20.4 Collision Diagrams 20.5 Condition Diagrams 20.6 Measurement Systems 20.7 Fundamental Physics Formulae Used for Reconstruction of an Accident 20.8 Accident Reconstruction Formulae 20.8.1 Determination/Measurement of Drag Factor of a Road Surface 20.8.2 Determination of the Radius of a Simple Circular Road Curve 20.8.3 Determination of Critical Speed on Superelevated Road Curves 20.8.4 Determination of Minimum Speed of the Vehicle Before Sliding (From Straight Line Skid Marks) 20.8.5 Determination of Minimum Speed of Vehicle From Yaw Mark 20.8.6 Determination of Acceleration Factor of a Vehicle From Known Distance or Travel Time 20.8.7 Combined Speed of a Vehicle Skidding on Road Surface 20.8.8 Speed of a Vehicle Falling From a Downgrade/Upgrade 20.8.9 Determination of Velocities of Vehicles at Impact/Collision 20.8.10 Determination of Velocities of Vehicles Before Impact Using Vector Diagram Graphical Method Multiple Choice Questions Questions 21. Analysis of Accident Data and Road Safety 21.0 Analysis of Accident Data 21.1 Road Safety Vision 21.2 Road Safety Programmes 21.3 Road Safety Measures 21.4 Evaluation of Effectiveness of Road Safety Implementation 21.4.1 Chi-Square Test to Find Goodness of Fit 21.4.2 Chi-Square Test to Determine Association Between Two Variables 21.4.3 Chi-Square Test to Determine Effectiveness of Before and After Improvements From One Group of Data 21.4.4 Standard Normal Probability Method 21.4.5 Spearman Rank–Order Correlation Coefficient Multiple Choice Questions Questions 22. Intelligent Transportation System 22.0 Introduction 22.1 Historical Development of ITS 22.2 Objectives of ITS 22.3 Benefits of Intelligent Transportation System 22.4 ITS Design 22.5 Technologies Used in ITS 22.5.1 Geographic Positioning System 22.5.2 Communication Technologies 22.5.3 Geographical Information System (GIS) 22.5.4 Artificial Vision System 22.5.5 Digital Mapping 22.5.6 Data Acquisition and Exchange System 22.6 ITS Architecture 22.7 V-Development Model for ITS Projects 22.8 Subsystems of ITS 22.8.1 Vehicle Detection Station (VDS) 22.8.2 Variable Message Signs (VMSS) 22.8.3 Changeable Message Signs (CMS) Systems 22.8.4 Variable Speed Limit Sign (VSLS)/Lane Control Sign (LCS) 22.8.5 Speed Enforcement System or High-Speed Driving Deterrence System 22.8.6 Red Light Violation Detection System 22.8.7 Oncoming Traffic Indication/Warning System 22.8.8 Centre Line Shifting System 22.8.9 Vehicle Information and Communication (VIC) System 22.8.10 Automatic Incident Detection (AID) and Information Provision Systems 22.8.11 Road Weather Monitoring Systems 22.8.12 Over Height Vehicle Detection System 22.8.13 Automatic Number Plate Recognition (ANPR) System or Automatic Vehicle Licence Plate Recognition System 22.8.14 Electronic Toll Collection (ETC) System 22.8.15 Weigh-in-Motion (WIM) Systems 22.8.16 Traveller Information System (TIS)/Traveller Advisory Radio (TAR) 22.8.17 Parking Management and Guidance Systems 22.8.18 Tunnel Systems 22.8.19 Road Condition Information Signs (RCIS) Systems 22.8.20 Ramp Metering Systems (RMS) 22.8.21 Work Zone System 22.8.22 Other Systems Multiple Choice Questions Questions
References Appendix Index