Dynamic Speed Control to Improve Freeway Safety in Bad Weathers

Sight distance decreases in bad weather and stopping distance increases. Collisions may occur if vehicles on freeways encounter sudden deceleration under bad weather conditions. This study developed a dynamic speed control to reduce collision risks on freeways given various bad weather conditions. A car-following model was used to simulate the traffic operation in bad weather. The time-to-collision was used to evaluate the collision risks. Five typical bad weather conditions were tested. Results showed that the dynamic speed control algorithm effectively reduced collision risks in various types of bad weather conditions. The strategy outperformed the previous one in reducing collision potential.