Methodology to Calculate Sight Distance Available to Drivers at Skewed Intersections

A methodology was developed to calculate sight distance available to drivers at skewed intersections of minor roads that are controlled by stop signs. The methodology considers the fact that the sight distance may vary depending on the position of the driver and the different lines of sight given to the driver by different types of vehicles. Through field observations, factors are found that affect the sight distance available to drivers. The factors include intersection geometry, the vehicle’s dimension, and the driver’s field of view. With the sight triangle properly drawn, equations were developed for calculating the available sight distance considering these factors. Values of sight distance were compared with stopping-sight distance of vehicles on the crossroads by varying design speeds and intersection angles. Nomographs were developed that can be used by road designers or operators to check if a skewed intersection satisfies the sight-distance requirement.