Feasibility of Validating the Shirley Highway HOV Lane Demand Model in Texas (1103-1)

This research report presents an assessment of the feasibility of validating the Shirley Highway (I-395) High-Occupancy Vehicle (HOV) Lane Demand Model in Texas. The results of the study suggest that the Shirley Model has not been sufficiently developed at this time to warrant additional testing outside the Shirley corridor. In fact, additional testing within the Shirley corridor will be needed to determine whether the preliminary model represents the "best" model that could be estimated from the dataset, and whether the model can accurately replicate travel choice decisions observed in the Shirley corridor. A review of currently available alternatives to the Shirley Model is also presented. While these procedures could be used to develop a range of demand estimates that appear reasonable for many sketch planning applications, they are still fairly crude and more refined estimation procedures are clearly needed. It is recommended that any additional efforts to validate the Shirley Model in Texas be undertaken through a separate research project and that local efforts focus on the development of HOV lane demand estimation procedures based on experiences gained in operating HOV facilities in Texas. These two independent, though clearly complementary, efforts should be closely coordinated to facilitate a possible merging of efforts at some time in the future.