The effects of currently imposed truck restrictions on transportation demand estimates, the mix of trucks in congested traffic, and truck travel times and trip length are examined. During the past 3 years, the Chicago Area Transportation Study (CATS) has been developing the Transportation System Development Plan for 2010. The travel demand process incorporates the results of a 1986 commercial vehicle survey, 1980 and 2010 socioeconomic variables, and network characteristics in the traditional four-step demand modeling process. The CATS practice of combining truck trips with automobile trips in the form of automobile vehicle equivalences before path assignment does not accurately reflect demand on a number of major Chicago area roadways where truck restrictions exist. The assignment procedure has been adjusted to prevent trucks from being loaded to resticted roadways. The resulting traffic assignment shows the significant effects of the restrictions on the vehicle mix of congested roads. A comparison of restricted versus unrestricted demand estimates shows that truck restrictions affect truck travel times and trip lengths. It was determined that these restrictions significantly affect the transportation industry and do not appear to be effective in reducing overall congestion in selected locations.
Abstract