URBAN TRANSPORTATION STUDY PROCEDURES

Study Number 2-10-74-17, "Urban Transportation Study Procedures," was originally a three-year planning study. Condensed to a two-year study effort, the technical support and research effort will continue under an interagency agreement contract. Study 17 was directed toward providing continuing technical support for the Texas State Department of Highways and Public Transportation in the conduct of urban transportation studies throughout the State. Under this study, assistance was provided in the analysis and forecasting techniques relative to urban transportation studies. The maintenance and modification of computer programs previously developed was performed under this study. The determination of the feasibility and means of theoretically estimating the trip length frequency distirubtion for "synthetic" urban transportation studies was investigated. The development of a procedure by which the trip length frequency distribution is theoretically estimated resulted. The procedure was tested and compared with the observed trip length frequency distributions from 18 transportation studies conducted in Texas for home- based and nonwork trip purposes, nonhome based, and truck and taxi trip purposes; this procedure was found to yield acceptable results. The sensitivity of traffic assignment to input from the preceding modeling phases was evaluated. Different random trip matrices were assigned to a network and the resulting assignments were compared to the fully modeled assignment and ground counts. Based on the results of these analyses, a sketch planning approach is proposed which would be expected to produce assignment results of sufficient accuracy for preliminary system evaluation and comparison with other alternatives similarly modeled.