USE OF DISAGGREGATE TRAVEL DEMAND MODELS TO ANALYZE CAR POOLING POLICY INCENTIVES

Increased emphasis is being placed on short-range transportation options as a means of reducing energy consumption, air pollution, and traffic congestion. The research presented evaluates potential car pooling incentives and analyzes the direct and indirect effects of such policies. The travel analysis is based on three disaggregate travel demand models that predict mode choice for the work trip (including drive alone, transit, and the car pool alternative); frequency, destination, and mode choice for the nonwork trip; and household automobile ownership level. The analysis is conducted ina case study framework by using data from Washington, D.C. For each of many randomly selected households, the travel response to a candidate policy is simulated probabilistically by sequentially proceeding through the three models. By predicting the results at the level of each individual household, the models can stratify areawide travel impacts by any socioeconomic or geographic characteristic, e.g., income groupings. Results indicate that most policies result in modest reductions in travel for the work trip but that this may be partially offset by increased nonwork trip making induced by the increased number of automobiles left at home. When a policy influences both work and nonwork trips (gasoline price increases for example) nonwork travel decreases significantly more than work trip travel, which confirms the more discretionary nature of nonwork travel.