Improved Road Usage Through Congestion-Free Route Reservations

Road traffic congestion occurs as demand exceeds the capacity of particular road segments. The consequences (including traveling delay, fuel consumption, and emission of pollutants) have a major impact on cities, thus interest for new and innovative solutions to the problem remain high despite great efforts that have been made to alleviate the problem. The recent literature has shown that better management and control mechanisms could significantly curb the effects. One such mechanism, in which route reservations are made across congestion-free road segments, is elaborated in this work. The proposed route reservation scheme assumes that vehicles communicate their origin–destination pairs to a controller that identifies and reserves road segments to be traversed in the space and time dimension. The scheme is mathematically formulated, and two algorithms with complementary objective functions are discussed. In the first case, vehicles are routed through road segments that do not exceed their critical density while travel time is minimized. In the second case, road segments below critical density are used while reservations are made in such a way as to balance traffic across the available alternative routes. Analytical and simulation results demonstrate the considerable benefits that can be realized by applying the proposed solutions.