Estimating Drivers’ Misperception of Vertical Alignment on Horizontal Curves

The effect of combining horizontal and vertical curves on operational conditions has been the subject of research over the last 20 years. Many reports demonstrated that the combinations of horizontal curves with crest and sag vertical curves would influence the curvature appearance. Thus, drivers may misperceive the curvature and take the wrong action when driving on the horizontal curves combined with vertical curves. This could cause safety problems to the drivers. This paper focused on proposing a new indicator (wheel path) to evaluate the driver’s misperception of the curvature in the section where horizontal curves was combined with vertical curves.