In 1997 ramp metering was installed on the M8 motorway in Glasgow - 10 years after the pioneering implementations on the M6 in the West Midlands. (Ramp metering is the control of traffic as it enters the motorway to improve traffic flow.) During that time policy objectives have changed and the technology available to effect control has developed substantially. The paper presents the Glasgow scheme in some detail and compares the M8 and M6 implementations in terms of control strategies, infrastructure, and effectiveness. Particular features of the recent Glasgow implementation are: (1) The combined use of ramp metering, VMS to influence route choice and dynamic UTC control; (2) The use of rapid traffic signal cycling to generate small platoons; and (3) The desire to manage traffic in the motorway corridor as a whole (including parallel routes) and not just on the motorway itself. Both the M8 and M6 implementations have been the subject of detailed before/after monitoring and both delivered significant benefits in terms of their respective objectives. These assessments are brought together in a comparative summary.
Abstract