Capacity Analysis- Traffic analysis was conducted in accordance with the Transportation Research Boards' Highway Capacity Manual to document existing conditions. 56 intersections and 34 freeway segments along the Parkway East corridor were analyzed during the AM and PM peak periods based upon the traffic counts conducted earlier in the study. The results documented the existing levels of congestion on the Parkway and at key intersections, and will provide a baseline for the future year analysis and to assist in the calibration of the network model developed using Visum modeling software.
Network Model- The Visum network model projects the travel of vehicles throughout the network based upon land use patterns, origin-destination information, and the capacity and operation of the available roadway network. The model developed was based upon the regional model developed and maintained by the Southwestern Pennsylvania Commission, and was updated to incorporate the origin-destination information collected earlier in this study. Separate models were developed and calibrated for both the AM and PM peak periods, based on earlier traffic counts.
The model will allow the project team to evaluate the impact of potential roadway improvements on traffic patterns, based upon options such as reconfigured interchanges, new roadway connections, and increased capacity.
Simulation Model- A detailed model of the Parkway East Corridor was built using the Vissim microsimulation software. This model simulates the behavior and interaction of vehicles on the Parkway network, including queues at the Squirrel Hill tunnel, merging behavior at on-ramps, and the operation of traffic signals at intersecting roads. The model includes the entire length of the Parkway from the Fort Pitt Bridge ramps to the Turnpike interchange in Monroeville, and was calibrated to represent the existing conditions on the roadway using the aerial traffic counts and the travel patterns identified in the previous phases of this study. Separate models were built and calibrated to represent the AM and PM peak periods.
This model will be an important tool in evaluating the impact of possible improvements on the Parkway as the study moves forward. It will enable the project team to model and evaluate changes such as reconfigured ramps and interchanges, new lane configurations, and signal changes.