Signs of change in wet weather conditions

For many years throughout the world, a number of systems have been introduced which provide dynamic advice to motorists on the real time status of the road network. The most common of this real-time information has been congestion related, allowing motorists to take alternate routes to reduce travel time.

However in the RTA?s Southern Region, a number of systems have been developed to provide real-time information which can improve road safety by allowing drivers to in some way modify their speed behaviour based on advice on approaching changed road conditions. Such systems combine hazard detection, which continually monitor road conditions and obtain information to display on changing message signs. Changeable message signs have also been provided at several locations, which are connected to presence detectors to advise drivers when queues build up at sites with restricted sight distances. These displays revert to a different message when queues are not present.

In August 2001 in association with a suite of road improvements for wet weather conditions, a changeable sign was installed at a sub-standard curve location where wet weather conditions significantly increases the hazard to motorists. In wet weather and when the pavement is wet, the advisory warning provided to motorists changes to reflect the increased risk at the site.

This paper examines how the available technology has been adapted to the wet weather problem. It examines the effect the sign has had on changing driving speeds based on the changed advice for different conditions as motorists travel through the curve and the associated before and after accident pattern at the site. The total effect of the wet weather treatments is also examined.