In 1978, the Transportation Research Board published NCHRP Report 187, "Quick-Response Urban Travel Estimation Techniques and Transferable Parameters." That report described transferable parameters, factors, and manual techniques for a simple planning analysis. This report and its default data have been used widely, in one form or another, in many transportation studies. The report has been an invaluable travel-data source. However, the manual techniques have been largely supplanted by microcomputer planning models, and the parameters and factors are based on data from the 1960s and early 1970s. Under NCHRP Project 8-29, Barton-Aschman Associates, Inc., updated the travel demand estimation techniques and parameters presented in NCHRP Report 187 using more current travel survey procedures and data. To provide the most reliable information to practitioners, the Federal Highway Administration provided funds for a follow on effort, NCHRP Project 8-29(2). In this project, Barton-Aschman Associates, Inc., collected additional data to validate the trip-generation rates and trip-distribution friction factors developed in the initial project. In addition to a thorough review of the four-step travel demand process with common extensions, the report provides transferable parameters for use when area-specific data are not available or need to be checked for reasonableness. The material focuses primarily on the needs of smaller urban areas, but some material will be useful to other areas. In general, more complex procedures will be needed for large urban areas, growing medium-sized urban areas, and severe air quality nonattainment areas. Area-specific parameters will almost always be preferable to transferred parameters, though it may not be cost-effective to develop them for smaller urban areas. The techniques and parameters are organized to be easy to use in many of the widely available travel demand forecasting programs. A case study illustrates how the techniques and parameters can be applied in a typical study. Those interested in looking more deeply into transferable parameters should visit the 1995 Nationwide Personal Transportation Survey World Wide Website at http://www-cta.ornl.gov/npts. This website allows anyone to develop parameters like those in this report based on the 1995 NPTS data. (A)
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