Effect of On-Ramp Geometric and Operational Factors on Vehicle Activity

Abstract

The microscopic vehicle activity levels for a random sample of 7,288 vehicles were measured and analyzed for cars and trucks on 26 entrance ramps in Louisville, Ky. Approximately 12.3 million distance measurements were recorded and used to calculate vehicle speeds, accelerations, and power requirements. This study was performed to examine the effects of geometrical and operational characteristics on changes in vehicle activity levels on entrance ramps. Linear regression and hierarchical-based regression tree methods were used to determine the impacts of the ramp characteristics. The regression analyses revealed that grade had the greatest impact on vehicle acceleration and power requirements in the Louisville area while ramp curvature, length of curvature, and mainline traffic flow rates had impacts under specific conditions. The results of the multivariable regression produced models that could explain up to 70% of the power demand based on ramp geometric and operational characteristics.