Development of a practical on-line coordinated variable speed advisory system for work zones

An on-line coordinated methodology is presented to gradually reduce the speed level of the traffic flow approaching a downstream work zone bottleneck. The proposed approach uses a sequential, multi-stage speed reduction scheme with a set of the variable advisory speed signs whose values are determined in real time. The key parameters in the system, such as the driver compliance rates and the proportion of the speed reduction at each sign location, are also determined in real time. A simplified version with a two-stage reduction method was implemented at one of the I-494 work zones in the Twin Cites, Minnesota, for a three week period in 2006.