Modeling Driver Behavior by Using the Speed Environment for Two-Lane Rural Roads

Roadway safety involves the three components of the roadway system: the people, the vehicle, and the roadway. When the design corresponds to what the driver hopes to find, the road is consistent; the most widely used methods to evaluate design consistency are based on analysis of the operating speed profile. When the roadway alignment does not violate driver expectations, the possibility of drivers making errors is reduced. The aim of this experimental study is to obtain widely valid formulas during the design phase to predict the speeds that will actually be found on rural roads. Studies have shown that the dominant influences on curve speed are local curvature and the speed environment pertaining to the road section. The environment speed is a driver’s preferred speed of travel within a road section with relatively homogeneous alignment. For the purposes of this study, this speed was taken as the 85th percentile speed measured on a tangent or on the curve with the highest radius in a homogeneous road section.