COMPARISON OF TRAFFIC ASSIGNMENTS IN EVACUATION MODELING

The Nuclear Regulatory Commission (NRC) requires that all electric uti lities develop and update evacuation plans for the areas surrounding t heir nuclear power plants, The evacuation of people around these plant s has certain peculiar transportation-related characteristics, such as the location of the incident is fixed, the evacuation area is predete rmined by NRC, and all the inhabitants must he evacuated from the affe cted area, These characteristics pose a challenge to evacuation planne rs and modelers, The developed evacuation models should incorporate th ese characteristics and address the peculiarities of the evacuation pr ocess. Hobeika et al, leave developed a mass evacuation computer progr am (MASSVAC 3.0) that models the evacuation process; and utilizes the traffic assignment of all-or-nothing and Dial's algorithm to simulate the traffic movements during evacuation, The objective of this paper i s to describe the upgrade of MASSVAC 3.0 to MASSVAC 4.0, which incorpo rates merr modeling features such as the user equilibrium (UE) assignm ent algorithm, which was not available in MASSVAC 3.0. The focus of th is paper, however, is on comparing the assignment results of Dial's al gorithm with the UE algorithm using performance measures such as the e vacuation time, the number of congested links, and the computer execut ion time. The results show that the evacuation performance measures ar e largely dependent on the highway network structure and the number of vehicles produced in an emergency planning zone. Generally, it was fo und that the UE algorithm was more efficient than the Dial's algorithm in the three performance measures mentioned above. In addition, the U E algorithm showed better results when traffic management strategies w ere adopted to improve the vehicular capacity of the highway network.