Backups originating from destinations have been observed during evacuation. These backups usually occur due to congestion at the destination network, which result in spillbacks onto the evacuation routes. These spillbacksresult in queuing and delays that hamper evacuation operations. This paper presents theoretical proofs for the fundamental flow/speed/concentrationrelationship and the speed-accumulation relationship (Greenshield's, Greenberg's and Bell-shaped model) at a network level. These relationships and, the relationships between inflow-accumulation and outflow-accumulation at a network level are studied using microscopic simulation. A strategy is developed (called the Network Breathing Strategy) to improve dissipation of vehicles into the destination network using these relationships between network level variables. A comparison of the network breathing strategy toa do-nothing strategy in a simulation network showed a statistically significant increase in the number of vehicles dissipated into the network. This indicates that the application of such strategies on the destination networks would help improve evacuation operations by clearing evacuation routes and reducing queuing.
Abstract