How the use of average speed control could influence driver behaviour when implementing 80mph speed limits

The DfT are currently considering the use of an 80mph speed limit, which could be used on parts of the motorway network, either as a blanket approach for all National Speed Limit (NSL) sections, or on selected routes. The implications of this change could be significant, in terms of journey reliability, road user safety and environmental considerations. One risk mitigation tool that has been widely discussed is the use of average speed enforcement to ensure that any such change would not be significantly detrimental to safety and flow. This paper explores the likely impact of such an approach.