Entrance ramp control for travel-rate maximization in expressways☆

The steady state optimization of expressway system operations when peak demands exceed capacities is investigated. An alternative approach of using travel-rate or average traffic flow of the whole expressway system instead of input rate as the criterion of optimization is adopted. This leads to a linear programming problem. Residual effects of peak-period traffic are taken into consideration in computing total time to return to normal traffic pattern. For the example considered, this total clearing time for a control scheme using travel-rate maximization is slightly less than that for one using input rate maximization. In addition, travel-rate maximization control has a tendency to discourage vehicles making short trips to use the freeway system during the peak period.