In 1994, the final report for NCHRP Project 8-29, "Travel Estimation Techniques for Urban Planning," was completed. This report contains default travel demand parameters that can be used by urban areas that do not have locally derived travel demand data or models. This report also was designed to replace the earlier report, NCHRP Report 187, "Quick Response Urban Travel Estimation Techniques and Transferable Parameters." NCHRP Report 187 was developed in the late 1970s and the updating of the report in NCHRP Project 8-29 was based on the assumption that there had been considerable progress in travel demand model development since the 1970s, particularly for small- and medium-sized urban areas. Unfortunately, not very many survey data were available during the life of the 8-29 contract. The primary source of data for the NCHRP Project 8-29 report was the NPTS data and a small collection of travel surveys and resulting model calibrations.

NCHRP Report 187 contains a wide range of trip generation rates, from about 14 person trips/household for small urban areas to approximately 7 person trips/household for large urban areas. NCHRP Project 8-29 found no justification for this wide differential and, in fact, could only identify a small variation in trip rates by urban area size. Consequently, the rates presented in the NCHRP Project 8-29 report vary only by a small amount from an average trip rate of 9 person trips/household. Recent model development efforts for small- to medium- sized urban areas allow the opportunity to verify these rates. Other improvements to the NCHRP Project 8-29 report have also been identified.

The objective of this project was to review the NCHRP Project 8-29 report and revise the report as appropriate.

The project included the following tasks: (1) Using the recently available travel demand data, review and update the trip generation rates contained in Chapter 3 of the NCHRP Project 8-29 report. (2) Using recently available travel demand data, review and update the trip distribution friction factors contained in Chapter 3 of the NCHRP Project 8-29 report and expand them to include different urban area size factors, if appropriate. (3) Incorporate the Case Study, Chapter 12, into each of the report chapters.

Report Availability: NCHRP Report 365,"Travel Estimation Techniques for Urban Planning," has been published. NCHRP Report 716, Travel Demand Forecasting: Parameters and Techniques, is an update to NCHRP Report 365.