Analysis of Managed Lanes on Freeway Facilities

Abstract

This report documents and presents the results of a study for evaluating the performance of Managed Lane (ML) facilities on freeways. A methodological framework is for analyzing freeway facilities with ML and General Purpose (GP) lanes operated in parallel. The framework acknowledges that the composition and behavior characteristics of the ML traffic stream are expected to be quite different from those for the GP lanes in terms of traffic volume, free-flow speed, capacity, vehicle type, etc. It further considers that there may still be certain levels of interactions between these two lane groups, especially for those facilities that do not have physical (barrier) separations, either en route or at access points, between them. Within that framework, different modules were developed based on sensor-measured or simulation-generated data, including the characterization of ML speed-flow relationship, the frictional effect of adjacent lane traffic speed, the adjustment for cross-weave effects, and the development of side-by-side facility-wide ML and GP performance measures. Thus, the proposed methodology is sensitive to different GP and ML segment types (basic, weaving, etc.) and separation styles (none, buffer, barrier), and is capable of analyzing extended facilities across multiple time periods.