Developing Microscopic Toll Plaza Model Using Paramics (2006)

Simulation modeling is the most cost-effective way of studying real life transportation problems, either existing or anticipated, without disturbing the balance of the transportation system. There is a vast suite of simulation models available in market, ready to choose from macroscopic, mesoscopic, or microscopic in nature, to study different transportation system elements like freeways, highways, signalized and un-signalized intersections. However, most of these network simulation models, like PARAMICS, VISSIM, CORSIM etc, do not come readily available with built in toll plaza models. On the other hand, many researchers have independently developed toll plaza models, which can only model an isolated toll plaza without the road network. These toll plaza models, which are based on queuing theory (and some are macroscopic in nature), do not take into account headway, gap acceptance, or inter-vehicle interaction to follow a lead car or to perform lane changing maneuvers. Vehicles just upstream of the toll plaza are assigned to one of the toll lanes, solely based on the payment method (manual, automatic coin machine, or electronic toll collection) and queue lengths at the toll lanes. For instance, if a vehicle is traveling in the leftmost lane and the rightmost toll lane has the shortest queue length, then the queuing model will assign this vehicle to the rightmost lane, and the vehicle will do unrealistic maneuvering to reach to the assigned toll lane instantly. Microscopic network simulation models simulate the vehicular movements based on lane-changing and car-following rules. If such a model could be customized to serve the purpose of the toll plaza simulation, it will simulate the vehicular movements just upstream and downstream of the toll plaza more realistically. Being a network simulation model, it can also model the road network integrated with the plaza, which can be used to study the entire toll road corridor, unlike the isolated toll plaza models. In addition to being a microscopic network simulation model, PARAMICS has many simulation tools, which can be customized to develop a network model with enhanced toll plaza simulation capabilities. PARAMICS also provides the flexibility of using an aerial picture of the toll plaza and upstream/downstream sections of the road as overlay, to ensure that the toll plaza model operates under similar geometric conditions as the real plaza. Using an overlay, exact details of the transition area can be fed into the model. In real life, there is a smooth transition (in terms of the number of lanes and the width of the roadway) from the uniform free-flowing section of the roadway to the toll plaza. Detailed representation of the transition area, in terms of geometry and curb of the roadway along with the number of lanes, is essential for a realistic toll plaza simulation. This kind of detail is not available in a queuing model. As the roadway approaches the toll plaza, it contains more lanes compared to its upstream segments. However, in a simulation model vehicles have a tendency to maintain the same old lanes, and the newly added lanes remain unoccupied by the vehicles. Next-lane Allocation feature in PARAMICS can be used to map upstream lanes onto downstream lanes, preventing this unrealistic behavior from occurring in the simulation model. It tells the vehicles in a particular upstream lane to choose from one or more of the downstream lanes as per the settings. Next-lane allocation can be used in such a manner that all the downstream lanes are utilized. PARAMICS has several other tools such as Restrictions Manager, Vehicle Type Manager, Lane-choices Rules, HOV Lanes, and Vehicle Actuated (VA) Signals which can be used in combination to build a toll plaza model. A microscopic 'Holland East Plaza - SR408' network model has been developed using PARAMICS V5.1. This model contains the plaza and the downstream section of SR 408 Westbound till I-4 interchange in downtown Orlando. This model has been successfully calibrated and validated for the mainline toll plaza and ramp volumes for year 2004. Several hypothetical incident scenarios were simulated to study an entire corridor from the toll plaza to Interstate 4. It was found that the volumes on I-4 off-ramp and SR 408 mainline were affected the most under incident conditions. Volumes for other ramps were not affected in the same proportions. An incident on mainline toll road affected the throughput of the plaza significantly, but the same is not true for an incident on an off-ramp. Travel times to I-4 off-ramps and SR 408 thru lanes were the most sensitive in each of the incident scenarios. In case of the elimination of tolls during the hurricane evacuation, the throughput of the plaza increased significantly. Travel times for the vehicles coming through the plaza and going to different destinations decreased significantly, while it increased for vehicles using on-ramps, because of their inability to merge in the mainline traffic due to the increased toll road volume. The developed model in this thesis has the potential of transportation network wide applications with multiple toll plazas.