Abstract
The ramp metering system is deployed at over 80 sites throughout the Highways Agency's network. The operational sites have been assessed and it hasbeen shown that ramp metering reduces journey times through congested junctions by an average of 13% across all sites evaluated. Experience gained during the installation, calibration and operation of the first thirty sites highlighted the potential for greater benefits to be realized through further algorithm development to: (1) reduce calibration effort; (2) improve system performance; and (3) allow ramp metering techniques to be used onmotorway to motorway junctions.