Interrelations of Reaction Time, Driver Sensitivity, and Time Headway in Congested Traffic

Reaction time, driver sensitivity, and time headway are traffic parameters that are critical for understanding and modeling traffic stability and wave propagation. Both theoretical and empirical relationships between these three parameters are examined with vehicle trajectory data. A few clear and distinct relationships are identified, and driver reaction time is found to be closely related to time headway, especially in the deceleration phase. Time headway can be accurately predicted when reaction time and the initial time headway are known. In a traffic simulation, a range of values also exists for the product of driver sensitivity and reaction time to avoid unrealistic speed fluctuations and collisions.