Four automatic speed warning signs were installed in Hampshire as a joint experiment by TRRL and the county council. The signs were located at the villages of west Meon and Droxford in the Meon valley (A32), just within 30 mile/h speed limit zones, and near middle wallop army base (A343), where only the 60 mile/h national speed limit for single-carriageway roads applied. Vehicles exceeding a pre-set trigger speed activated the signs which then displayed 'slow down please'. Later the message was amended to 'slow down 30' ('45' at middle wallop). speed measurements, supported by control data, were made at regular time intervals before and after installation, at the signs and in the villages. Speed reductions in the centre of the villages at West Meon and Droxford were very small, but some drivers appeared to be reacting to the presence of the signs by slowing down before reaching them. The data indicate an overall reduction in injury accidents of 52 per cent, although this result is not statistically significant. It may be that the signs alert drivers to be more attentive to the road ahead, even if they do not slow down. At middle wallop, the sign did not have an effect on speeds and there was no change in injury accidents. (Author/publisher)
Abstract