Incorporating Toll-Lane and High-Occupancy Toll-Lane Effects into the Dallas System Planning Methodology

Abstract

The Dallas System Planning Methodology (SPM) was developed jointly by the Texas Department of Transportation, the North Central Texas Council of Governments, Dallas Area Rapid Transit, and the Texas Transportation Institute as a transportation-corridor and system-analysis tool to bridge the gap between regional planning and detailed corridor design. SPM allows for the examination of peak-hour person movement for different types of facilities within a corridor and estimates the associated public costs (e.g., right-of-way, construction, operation, congestion, and environmental costs). The objective of SPM is to find the alternative with the lowest total public cost. It was decided to enhance SPM by adding toll lanes and high-occupancy toll (HOT) lanes as alternatives for evaluation against other combinations of general-purpose lanes, high-occupancy vehicle (HOV) lanes, and express lanes. The results of this project confirmed previous findings that low- and moderate-demand facilities are best served by improving general-purpose lanes in the corridor and, in some cases, by adding express lanes. Using the criteria of lowest total public cost, the evaluation of toll lanes in the test corridors showed that congested corridors with all toll lanes or with combinations of general-purpose and toll lanes did not perform as well as the alternatives, which included a combination of general-purpose and HOV lanes. However, the alternatives that combined general-purpose lanes with HOT lanes tended to perform as well as—and in some cases, slightly better than—HOV lanes.