Calibration of Highway/Transit Speed Relationships for Improved Transit Network Modeling in FSUTMS
In FSUTMS, transit networks are built based on highway networks. For transit vehicles operating on exclusive right-of-way (Mode 8 in the standard FSUTMS transit network), their speeds are independent of the highway speeds. However, the majority of transit vehicles in Florida share right-of-ways with automobiles and their speeds are affected by the highway speeds, and vice versa. The current practice considers this interaction by assuming that transit speeds are a linear function of highway speeds, and a total of fifteen such highway/transit speed functions are defined for use in all urban areas of Florida. Users may specify a number of functions to use for different combinations of modes, area types, and facility types. Additionally, they may change any of the functions to reflect their own transit system performance. The accumulated travel times, calculated by dividing the link lengths with the transit speeds obtained from the speed functions, then become the main disutility for the associated transit modes in the modal split process.
The methodology used to develop the speed conversion curves is developed when only one-digit area and facility types were used for highway links. This research is thus aimed at calibrating new highway/transit speed relationships by two-digit area and facility types for transit modes 4 (local bus) and 5 (express bus) defined in the standard FSUTMS transit network. The specific objectives of this research are:
- Development of peak and off-peak transit/highway speed update functions using speed data obtained from representative urban areas in the state; and
- Evaluation of the performance of the resulting speed functions