MINIMUM PASSING SIGHT DISTANCE FOR COMPLETING OR ABORTING THE PASSING MANEUVER

A kinematic model is presented which incorporates both acceleration and deceleration during the passing maneuver on 2-lane, 2-way roads. It is shown that during the passing maneuver there exists a dilemma zone where it is not safe to complete or to abort the maneuver. The recommended passing sight distance values are tabulated. Their derivation is based on making the dilemma zone zero, thus always providing at least one safe option. The results are discussed of an investigation of the sensitivity of passing sight distances with respect to acceleration, deceleration, relative velocity, and passing speed. Based on the study results, it is recommended that MUTCD (Manual on Uniform Traffic Control Devices) minimum passing sight distance should be reviewed. The report recommends passing sight distances using AASHTO's values of acceleration rates and deceleration distances to obtain decereration rates.