Departure Time Choice Model in the Presence of Time-of-Day Toll Pricing

Express Toll Lanes (ETL) initiative is Maryland's statewide initiative aimed to provide cost-effective way for congestion management including toll pricing and managed lanes. As a consequence, this initiative is expected to implement toll pricing on major Maryland's corridor including the Intercounty Connector (ICC), the capital beltway (I-495), and the I-95. One of the pricing schemes considered by the initiative is the time-of-day toll pricing scheme where toll price is adjusted in correspondence to the time of day or on the basis of the traffic conditions. This pricing scheme is gaining attention as a travel demand management strategy by providing incentive to travelers with more flexible departure time to travel during off peak period, thereby shifting peak travel demand. Meanwhile, travel demand model that forecasts the time when trips are taken need to be developed. Modeling departure time is essential for policy makers evaluating travel demand management alternatives, such as time-of-day toll pricing. Different toll prices by time of day induce traveler to perceive departure time choice similar to the mode choice selection. This modeling framework is challenging for analysts. First, the choice of departure time has to be identified or approximated either by simulation or by means of stated preference survey. Next, the interdependency of departure time choice and mode choice has to be carefully examined. The traditional approaches dealing with time of day estimate time of day factors (TODF) from observed data and assume that the same behavior will pertain in the future; this technique is used to estimate traffic volume by time period using the TODF. The newer methodologies such as "Peak Spreading" improve the limitation of TODF approach by accounting for the excess demand in certain corridors during the peak period and allow for more realistic assessment of travel condition in the future. However, peak spreading approach has relatively weak behavioral foundation and cannot fully address travel response to system changes; for instance, it cannot be used to fully analyze policy changes or the effects of travel demand management actions. The departure time choice, on the other hand enable analyst to assess the extent to which travelers respond to congestion at disaggregate level. Despite the widespread interest in the concept of departure time choice, there is very little empirical study on the impact of departure time choice in the presence of time-of-day toll pricing (especially in Maryland). This project proposes an empirical study that integrates the joint effects of departure time and mode choice. We will consider variables affecting departure time such as travel time, travel cost, travel time reliability and activity duration. The presence of time-of-day toll pricing will be taken into account in the model estimation process to develop a model that represents behavioral responses to pricing. Possible response of traveler to pricing in term of mode shift and departure time shift will be carefully examined. The extent to which the model could aid local agencies to achieve several objectives including toll revenue, system performance, and environmental impact will be examined.