Experimental analysis of reaction time to brake

Road safety is affected by human factors. This should suggest to engineers that driver’s behaviour has to be considered more in depth. Driver’s reaction time deeply impacts on the safety of driver’s manoeuvres. Psychological sciences approach is not properly consistent to objectives of road engineering. Therefore the results can not be extended immediately to road engineering. Technical regulations of different countries often disagree. This paper presents an experimental investigation performed using a driving simulator whose main objective is to analyse the variability of driver’s reaction time for different traffic flows. Twenty young adults participated in the study driving five times the same scenario, increasing every time the traffic flow. All the risky drivers behaviours (defined as a sudden braking of the driver to avoid an imminent collision) occurred during the simulations were recorded and post processed. The authors refer to effective brake reaction time defined as the interval between the instant of perception and the instant that the driver reaches the action’s aim (instant of maximum deceleration in the braking phase). The study analyses the variability of brake reaction time with traffic flow and driver’s speed at the time of risk perception. The outcomes have important influences on road design and traffic management in terms of safety with great impact to those design standards that depend on reaction time.