European research has shown that pole mounted variable speed limit (VSL) signs and gantry mounted VSL combined with lane control signs (LCS) are successful traffic engineering applications used to manage traffic conditions during congestion, incidents, crashes and inclement weather. Based on this, the number of pole mounted VSL applications will expand and VSL/LCS will be applied for the first time on Queensland motorways. These systems will allow for a reduction in the posted speed limit at times when road safety and performance are compromised but a permanent reduction in speed is inappropriate. This paper reports on an extensive data analysis of existing Brisbane metropolitan motorways based on average annual daily traffic (AADT), peak period speed differentials, hours of flow breakdown, crashes during the peak traffic period and crashes occurring as a result of inclement weather. These categories have been used to propose site selection criteria for the placement of VSL and VSL/LCS. Optimum placement will ensure enhanced motorist safety and motorway efficiency as well as economic and environmental benefits. (a) For the covering entry of this conference, please see IRRD Abstract no. E216410.
Samenvatting