Demand Diversion Model Calibration for HOV Lanes based on Travelers’ Characteristics

High occupancy vehicle (HOV) lanes increase the capacity of freeways by providing the incentive of a shorter travel time to those using buses, vanpools and carpools. These lanes are designed to move more passengers per vehicle-trip and to save travel time. HOV lanes may increase the efficiency of a road through a reduction in the number of single occupant vehicles. Considering the high expenses of constructing these lanes, it is necessary to justify their efficiency through research. In this paper, demand diversion models are proposed and calibrated based on the data gathered through a field survey designed exclusively for this purpose. The questionnaire included 13 questions regarding travelers’ characteristics and their stated preferences towards carpooling based on different time-saving scenarios. The field interview survey administered in 2012 on seven days at four gas stations with rather long queues resulted in the collection of 489 filled questionnaires. Based on the final 419 questionnaires validated, logit models were estimated using travel time reduction for educational and work trip purposes.
Results show that time reduction is not the only effective factor in carpooling selection, but other factors like cost reduction and convenience can also be effective. Three scenarios providing a range of potential impacts of HOV lanes on diversion of single occupant vehicle trips is considered. In the specific hypothetical scenario considered in this paper, the range of diversion to HOVs was found to lie between14 and 44 percent, which may show a significant impact on the performance of the urban transportation systems through system management strategies.