The effect of the close-following warning sign, originally tested at ascot, is reported at a further four trial sites. The sign was illuminated whenever the gap between two vehicles was less than 1.6 seconds. Two different messages were compared in the trial. Measurements of inter-vehicle gaps were made at a number of monitoring sites 'downstream' from the signs and at independant control sites. Additionally, individual vehicle-pairs were observed and measured at two signs and subsequent monitors before and after the signs were in use. The improvement in drivers' behaviour was similar to that at the original site at ascot. There was a reduction of approximately on third in the number of drivers following at less than 1.0 second. Both messages were effective in producing a decrease in close-following, with no appreciable different between the two. Accident data were collected and analysed, but an overall statistically significant change was not discernable in the data available. (Author/publisher)
Abstract