Methodology SHAKER and the Capacity Analysis of Five Toll Plazas

Abstract

Modeling traffic at toll collection facilities can assist in computing plaza capacity and performance. It may help planners and operators decide on which lane configurations are appropriate for specific hourly approach volumes and vehicle types. On a network of toll roadways, it can be used to identify bottleneck locations. This is accomplished by comparing a plaza’s capacity to the capacity of a highway segment’s just downstream. Both the characteristics of the approaching traffic as well as the roadway conditions before and at the plaza come into play. Choosing a lane configuration with an adequate number of dedicated electronic toll collection lanes that match the approaching traffic demand is one key to maximizing the toll plaza throughput. The capacity of a toll lane is simply the lane’s average hourly processing rate under queuing conditions as measured in the field. Measurements must take place when there is uniformity in the type of toll collected in the lane as well as uniformity in the type of vehicle being processed. The average hourly processing rates for several categories of traffic and tolling type have been measured in the field and have been collected for this study. Complexity is added to the model when configuring a mixed lane that either provides several methods of toll collection, or provides the same toll collection type to several different categories of customers, or provides toll collection in a manner that is a mixture of these two. SHAKER was developed to address these issues and compute capacities of toll plazas that consist of mixed lanes as well as dedicated lanes. This study also applied the SHAKER methodology to 5 real toll facilities plazas on the Florida Turnpike. The model was both calibrated and validated using these data.