• Covers traffic flow relationships and traffic impact analysis, collision analysis, road safety audits, advisory speeds
• Applications for horizontal and vertical alignment, highway geometric design, traffic operations, traffic safety, civil engineering topics
• Engineering considerations for highway planning design and construction are included, such as hydraulics, geotechnical engineering, and structural engineering

Dr. Daniel Findley, P.E. is a Senior Research Associate with the Institute for Transportation Research and Education in Raleigh, NC. He specializes in asset management and inventory, horizontal curve safety, economic impact analysis, multi-modal transportation, unique transportation engineering studies, and logistics. He holds a Ph.D. in Civil Engineering from North Carolina State University and is a licensed Professional Engineer (PE) in North Carolina.

Bastian J. Schroeder, PhD, PE, Director of Highway Systems, Institute for Transportation Research and Education (ITRE)

This part describes the basic process of planning and forecasting traffic demands and future conditions of the transportation system. Many planning applications are closely tied to new developments on a local or regional scale that are expected to impact traffic patterns. Transportation professionals use these planning methods to forecast how much traffic is expected in future-year analyses, where that traffic is expected to go, what routes that traffic is expected to take, and what modes of transportation travelers are most likely to choose. These methods aim to predict and estimate how drivers, the human element in any transportation problem, are likely to behave and act based on prior observations and historic trends. The text presents critical planning concepts and terms, and then introduces the reader to the four-step forecasting process used in transportation planning. The discussion includes data needs and sources for planning analyses, as well as mathematical models used to complete various steps in the forecasting process. The part concludes with a discussion of planning applications and software use, as well as practice problems to further explore and apply the concepts presented in the text.

Transportation planning; Four-step process; Traffic impact analysis; Trip generation; Trip distribution; Mode choice; Traffic assignment; Travel demand modeling

Contents

2.1 Introduction 19

2.1.1 Purpose of Transportation Planning 19

Metropolitan Planning Organization 21

State Department of Transportation Planning Organization 23

Regional Transportation Planning Organization 23

Prioritizing Transportation Investments 24

Emphasizing Agency Coordination 25

Planning Applications and Topics 26

2.1.2 Accuracy and Error in Forecasting 27

2.2 Planning Concepts and Four-Step Process Overview 27

2.2.1 Regional and Statewide Planning Process 27

2.2.2 Traffic Impact Analyses 30

Scope 31

Process 32

Typical Mitigation Strategies 33

2.2.3 Highway Functional Classification System 34

2.2.4 Planning Data and Data Sources 37

Traffic Counts 38

Average Daily Traffic 39

Design Hourly Volume and Directional Design Hourly Volume 40

Peak Hour Volume 43

2.3.1 Planning Definitions and Terms 45

2.3 Trip Generation 49

2.3.1 Land Use Types 50

2.3.2 Estimating Generated Trips 51

2.4.1 Sample Network Application of Trip Generation 54

2.4 Trip Distribution 54

2.4.1 Gravity Model 56

2.4.2 Use of Data and Calibration 58

2.4.3 Sample Network Application of Trip Distribution 60

2.5 Mode Choice 64

2.5.1 Trip End Models 64

2.5.2 Trip Interchange Models 65

Variables Impacting Mode Choice 66

Utility Models 67

Types of Logit Models 69

2.6 Traffic Assignment 70

2.6.1 Network, Paths, and Skimming 70

2.6.2 Shortest Path Assignment 73

2.7.1 Capacity-Constrained Assignment 77

2.7.2 Dynamic Traffic Assignment and Other Advanced Algori

Part One: Introduction to Highway Engineering Concepts
Part Two: Transportation Planning
Part Three: Horizontal and Vertical Alignment
Part Four: Highway Geometric Design
Part Five: Traffic Operations
Part Six: Traffic Safety
Part Seven: Other Considerations for Highway Engineering