Review technologies and state-of-the-practice algorithms for ramp metering

Both recurring and non-recurring congestion on the nation's urban freeways have became a major problem threatening the economic growth of many urban centers. One of the potential solutions to this continuously worsening traffic congestion problem is the control of the influx of traffic to the freeway through the use of ramp metering strategies. The concept of ramp metering implies that the amount of traffic entering a freeway from on-ramps will be regulated in such a way that the traffic on the freeway will not exceed freeway capacity.