Assessment of Yield Treatments at Frontage Road-Exit Ramp and Frontage Road-U-Turn Merge Areas

摘要

The goal of this research project was to assess the effectiveness of the wide variety of frontage roadexit ramp and frontage roadU-turn yield treatments that exist in Texas. In meeting this goal, researchers collected field data at a number of sites around the state of Texas that represent the array of current yield treatments in practice. In order to assess the plethora of prevailing operating characteristics (i.e., variances in speeds, volumes, driveway densities, etc.), the research team utilized simulation modeling procedures to compensate for the impracticability of the data collection effort that would be required for every possible combination thereof. Several key operational and geometric features of each case study site were carefully collected and analyzed to produce a calibrated model for each case study condition. Two levels of simulation analysis were used in this project. First, the research team developed a Level 1 procedure that involved selection of real-world sites for data collection, analysis, and simulation model calibration. After calibration of the model for each site, different yielding treatments were applied to each calibrated site. Comparisons were then made to determine if any one treatment performed better than the others. This procedure enabled researchers to look at some problematic sites that currently exist in the field and incorporate signal timing, current weaving patterns, speed and volume into the analysis. Since Level 1 analysis was limited to the geometric and traffic conditions at the selected sites, a Level 2 analysis was performed to consider the performance of various yield treatments on a wide variety of feasible scenarios/combinations of geometric and operating conditions.