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Publication Number: FHWA-RD-98-165
Date: July 1999
Guidebook on Methods to Estimate Non-Motorized Travel: Overview of Methods
1.1 Purpose of 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 attention 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. The guidebook is intended to provide a means of addressing the following related questions:
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" which 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 and/or to prioritize bicycle and pedestrian projects.
Figure 1.1: If We Build a New Bicycle or Pedestrian Facility, How Many People Will Use It?
While all of these methods focus on non-motorized travel, some important distinctions in scope can be identified. Some methods are directed specifically at either bicycle or pedestrian travel, while others are generally relevant to both. Some methods focus on demand for a specific facility, such as a bicycle lane or shared-use trail, while others focus on travel over an entire area, such as a city or census tract. Finally, the methods differ in the extent to which they consider trips made for recreational, as opposed to utilitarian, purposes(2).
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 and Europe, but examples are also included from Japan, Australia, and South America. While it is doubtless that some relevant sources and methodologies have been overlooked, the guidebook should serve as a reasonably complete review of methods currently available to the bicycle and pedestrian planner.
1.2 The Importance of Forecasting Demand
There are many compelling reasons both to apply existing methods of forecasting bicycle and pedestrian travel and to advance the state-of-the-practice in this area. If properly done, demand forecasting has a variety of uses including:
All of these reasons underscore the need to apply available demand forecasting methods and to continually advance these methods. Forecasts of demand provide a much needed complement to other considerations, such as improvements to safety and convenience for existing users, in planning bicycle and pedestrian facilities.
Nevertheless, many people in the bicycle and pedestrian planning and advocacy communities are skeptical of demand forecasting, and raise valid points about its limitations. Skeptics argue that the factors influencing non-motorized travel are largely attitudinal and cannot be easily described or quantified in models. They further believe that comprehensive efforts to improve facilities, policies, and social attitudes toward bicycling and walking are required, and that such measures would result in significant mode shifts that would not be predicted by existing models. Others take the philosophical viewpoint that conditions for bicyclists and pedestrians should be improved simply as a matter of fairness to existing users, regardless of whether new users would be attracted. Still others are concerned that a focus on predicting demand will divert much needed energy away from the actual implementation of bicycle and pedestrian improvements.
These arguments, although valid, should not detract from the usefulness of forecasting bicycle and pedestrian travel demand. A simple "if you build it, they will come" attitude is not sufficient given that resources for implementing projects are limited. Existing forecasting methods, even given their limitations, can help allocate resources toward the most beneficial projects and can help determine which improvements will attract the most new users. Furthermore, future developments have the potential to greatly increase the accuracy and usefulness of these methods. While qualitative assessment based on experience and judgment will continue to play a key role in identifying projects with the greatest benefits, quantitative methods can become increasingly useful in providing information for planning and decision making.
1.3 How to Use This Guidebook
This guidebook consists of two parts: Overview of Methods and Supporting Documentation. Overview of Methods provides a concise overview of the available methods and of general issues for consideration in forecasting demand for non-motorized travel. Supporting Documentation provides substantially more detail on the methods described in the guidebook and identifies sources and real-world applications for the methods.
The contents of Overview of Methods include:
Supporting Documentation includes:
1Bicycling and walking are the most common forms of non-motorized travel in most countries and the term "non-motorized" is used herein to refer collectively to bicycle and pedestrian travel. Nevertheless, the term "non-motorized" could also refer to many other forms of travel such as in-line skating, skateboarding, or horseback riding. The methods discussed in this document may be applicable to these other forms of non-motorized travel although specific applications have not been identified.
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Keywords: Bicycle, Pedestrian, Travel demand, Forecasting methods, Estimate.