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Guidebook on Methods to Estimate Non-Motorized Travel: Supporting Documentation

1.0 Introduction

1.1 Overview

This document is the second volume of the two-volume Guidebook on Methods to Estimate Non-Motorized Travel where the first volume, Overview of Methods, provides a concise overview of available methods for predicting future levels of bicycle and pedestrian travel or "travel demand." The Overview of Methods also discusses general issues for consideration in forecasting demand for non-motorized travel. This volume, the Supporting Documentation, provides substantially more detail on the methods described in the guidebook and identifies sources and real-world applications of the methods.

This volume is organized as follows:

Section 2.0 (Documentation of Methods) -- An in-depth, structured description and evaluation of each method, including multiple variations on some methods as well as real-world applications.

Section 3.0 (Bibliography) -- An annotated bibliography of references on demand forecasting methods, supporting tools and techniques, and factors influencing the choice to walk or bicycle.

Section 4.0 (Contacts) -- A list of individuals and organizations contacted in developing this guidebook.

The contents of the Overview of Methods include:

Section 1.0 -- A discussion of the purpose of the guidebook and the importance and uses of forecasting bicycle and pedestrian travel demand.

Section 2.0 -- An introduction to non-motorized travel demand forecasting, including ways in which travel behavior can change, general approaches to travel demand forecasting, factors specifically influencing bicycle and pedestrian travel, and differences in forecasting bicycle vs. pedestrian travel.

Section 3.0 -- An introduction to 11 classes of methods and a one-page overview of each which includes a description, typical applications, advantages, and disadvantages. Section 3.0 also contains a summary of key characteristics and uses of each method as well as a guide to choosing an appropriate method for a specific purpose.

Section 4.0 -- A summary of the guidebook and a discussion of the limitations of existing forecasting methods and future research needs for improving non-motorized demand forecasting.

1.2 Purpose of the Guidebook

The need for improved conditions for bicyclists and pedestrians has received increasing attention in recent years in transportation planning circles. Planners are recognizing a growing popular interest in bicycling and walking for health and recreation, the desire to promote alternatives to automobile travel for environmental reasons, and the need to provide safe and convenient travel options for the entire population. At the same time, the question of how many people will actually use new or improved bicycle and pedestrian facilities is gaining interest and importance. Planners and policy makers need to be convinced that the benefits of improvements are worth the costs. Furthermore, they want to know where to spend limited resources to get the most "bang for the buck" as measured by benefits to users.

This guidebook was developed in response to the need to predict bicycle and pedestrian or "non-motorized" travel.⁽¹⁾ The guidebook is intended to provide a means of addressing the following related questions:

• If we build a new bicycle or pedestrian facility, how many people will use it?

• If we improve an existing facility or network, how many additional people will choose to walk or bicycle?

• What types and combinations of improvements will have the greatest impact on increasing non-motorized travel?

• How will improvements to non-motorized travel conditions affect motor vehicle use?

The guidebook describes and compares the various methods that have been developed to predict future levels of bicycle and pedestrian travel, i.e., travel demand. The guidebook also discusses other quantitative methods that support demand forecasting but do not actually predict future demand. These include (1) analyses of the potential market for bicycling and walking; (2) "level of service" measures and "environment factors" that describe the quality of the supply of bicycle and pedestrian facilities; and (3) supporting tools and techniques such as Geographic Information Systems (GIS) and preference surveys. The guidebook is intended to be used by bicycle and pedestrian planners, technical staff, researchers, advocates, and others who may wish to apply these methods to estimate bicycle and pedestrian travel demand or to prioritize bicycle and pedestrian projects.

1.3 Research Methodology

The guidebook is based on an extensive international review of both published and unpublished sources. Most of the methods were developed in the United States, Canada, and Europe, but examples are also included from Japan, Australia, and South America.

Members of the research team conducted an extensive outreach effort to identify research activities (both past and present), methods, and ideas for the project. This consisted of a networking effort that began with people who are well known in the field of bicycle and pedestrian planning and other individuals who are known to the research team. Simultaneous to the direct networking, the Internet was used as a means of outreach through a variety of discussion lists. All told, more than 65 contacts were made. These included other consulting firms, research and/or cycling organizations in foreign countries, practitioners, and individuals. The complete list of contacts made or targets of outreach is presented in Section 4.0.

In addition to the networking effort, a literature review was conducted to identify relevant published sources. It should be noted that not all of the methods discovered in this literature review are of recent vintage. The rise of the energy crisis and the environmental movement in the 1970s led to considerable interest and research into bicycle and pedestrian planning issues during this period. As an example, in 1978 the Federal Highway Administration published a three-volume Pedestrian Planning Procedures Manual (Kagan, Scott, and Avin, 1978). The manual outlined a 27-step process for forecasting pedestrian travel demand and prioritizing pedestrian projects in central business districts and other large activity centers. At the same time, discrete choice modeling techniques were pioneered and developed for the purposes of forecasting travel. These techniques were applied specifically to forecasting bicycle travel in a number of studies conducted in the late 1970s and early 1980s.

As relevant methods were identified from the networking and literature review efforts, they were documented in a database. The final version of this data base is presented here as Section 2.0, "Documentation of Methods." This data base served as a structure for an organized discussion and evaluation of each method, and also served as the basis for categorizing and describing the methods as presented in the guidebook.

1.4 Overview of Methods

Nineteen method entries were completed in the data base. For purposes of the discussion in the guidebook, the entries were grouped into 11 classes of methods having similar characteristics. These were further grouped according to the four major purposes of the methods: demand estimation, relative demand potential, supply quality analysis, and supporting tools and techniques. Table 1.1 describes the four major purposes and 11 classes of methods. Table 1.2 shows how the 11 classes of methods correspond to the 19 method entries contained in Section 2.0.

Some of the entries in section 2.0 describe one specific method, as developed by a particular practitioner, while others contain descriptions of two to four similar methods. Decisions as to whether to group methods of the same type in one entry or to treat them in separate entries were primarily based on the similarity of the methods and on the length of the discussion for each. Treatment of some methods in separate entries is not meant to imply that a greater importance is attached to that specific method, and is not meant to endorse the use of those methods over others.

Table 1.1 Categorization of Available Methods.

Table 3.1 Categorization of Available Methods (continued)

Table 1.2 Organization of Methods in Supporting Documentation.

FHWA-RD-98-166