Linking Ramp Metering and Variable Highway Speed Limits

Pilot schemes for variable speed limits and ramp metering respectively have been implemented on the UK highway network since the mid 1990's. The outcomes of the pilot studies show that these traffic management techniques can assist in the reduction of accidents, traffic congestion and emissions. The performance of these individual control measures may be improved by linking the control of ramp metering and variable speed limits. This paper suggests a new approach using the mainline speed as a control variable and investigates possible benefits and the feasibility of such a system.