Reference:
A. Hegyi,
B. De Schutter, and
J. Hellendoorn,
"Optimal coordination of variable speed limits to suppress shock
waves," IEEE Transactions on Intelligent Transportation
Systems, vol. 6, no. 1, pp. 102-112, Mar. 2005.
Abstract:
When freeway traffic is dense, shock waves may appear. These shock
waves result in longer travel times and in sudden, large variations in
the speeds of the vehicles, which could lead to unsafe situations.
Dynamic speed limits can be used to eliminate or at least to reduce
the effects of shock waves. However, coordination of the variable
speed limits is necessary in order to prevent the occurrence of new
shock waves and/or a negative impact on the traffic flows in other
locations. In this paper we present a model predictive control (MPC)
approach to optimally coordinate variable speed limits for freeway
traffic with the aim of suppressing shock waves. First, we optimize
continuous valued speed limits, such that the total travel time is
minimal. Next, we include a safety constraint that prevents drivers
from encountering speed limit drops larger than, e.g., 10 km/h.
Furthermore, to get a better correspondence between the computed and
the applied control signals, we now consider discrete speed limits. We
illustrate our approach with a benchmark problem.