Effects of distance and speed on driver stop-versus-cross decision at traffic signals

Driver response to termination of the green signal is examined in an observational study of on-road driver behaviour, and by using the stopping probability as the performance index. The computation and modelling of the stopping probability and its application are presented and discussed. Data were collected for a total sample of 1192 first-stopping and last-crossing vehicles at four junction approaches by using digital video photography. Logistic regression was used to model the reduced data. It was found that the stopping probability was higher for greater distance from the stop line and for slower speed, with attenuation by distance × speed interaction. Significantly, distance and approach speed exerted influential, but non-uniform, effects upon the driver's decision to stop or to cross. Essentially, the net effect was found to be distance dominance when near the stop line, time dominance in the intermediary, and speed dominance when further away. Human factor considerations in terms of risk-taking and perceptual and judgment errors were conjectured to explain the non-uniform behavioural response as manifested in the different dominance modes.