SCSC2003 Abstract S1272

SHAKER: a Maximum Throughput Model for Toll Collection Facilities

SHAKER: a Maximum Throughput Model for Toll Collection Facilities

Submitting Author: Dr. Marguerite Zarrillo

Abstract:
SHAKER is a queuing model for vehicles utilizing toll collection facilities. Currently, SHAKER determines a plaza’s maximum throughput using one of three types of driver-decision designs. First, SHAKER can determine a plaza’s throughput by basing a driver’s lane choice on the number of vehicles in the queue, in other words, the model assumes drivers choose the lane that provides their required service but also has the smallest number of vehicles in the queue. Second, SHAKER can also determine a plaza’s throughput by assuming drivers choose the lane that has the shortest queue length. And third, SHAKER can determine a plaza’s throughput by assuming drivers are quite skilled and choose a lane that provides their required service but minimizes their time-in-the-queue.
Throughput was determined from plaza characteristics such as lane number, lane type and processing rates. The results of the calculations met constraints set by the characteristics of the arriving traffic. For instance, variables such as the percentage of arrivals that were patrons utilizing the electronic toll collection, ETC, service and the percentage of arrivals that were semi-trucks requiring non-ETC services influenced the plazas' throughput outcome. Functions describing the processing rates for ETC vehicles in the mixed lanes were also developed; mixed lanes provide service to more than one type of traffic category type. The functions were based on variables such as vehicle-lengths, distance between queued vehicles, vehicle acceleration and deceleration rates, stopping times at the tollbooths and driver reaction times. Videotapes and transaction data at a toll plaza in Orange County, Florida, provided necessary input to calibrate SHAKER.



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