| Evacuation Route Planning: Novel Spatio-temporal Network Models and Algorithms |

| Shashi Shekhar : Biography , Homepage |

| Computer Science Department, University of Minnesota. |

| http://www.cs.umn.edu/~shekhar |

DETAILS: TAG models node/edge attributes as functions of time rather than fixed numbers. Thus node/edge capacities, node occupancies, etc. are modeled as time-series. Second, it iteratively considers all pairs of sources and destinations. In each iteration, it schedules evacuation of a group of evacuees across the closest source-destination pair. Special graphs construction is used eliminate redundant computation in this step. Non-stationary ranking of alternative routes during a evacuation is addressed by a linear-cost earliest-arrival-index on input TAG with travel-time-series. Experiments with real and synthetic transportation networks show that the proposed approach scales up to much larger networks, where software based on linear programming method crashes. In addition, linear programming approach needs an estimate of upper bound on total evacuation time to construct TEG represntation by replicating transportation network for every time-instant during evacuation. Incorrect estimate of upper bound on total evacuation time may lead to either a failure to produce any solution or excessive computational costs. For smaller networks, where software based on linear programming can be used, CCRP produces high quality solutions with evacuation times comparable to those achieved by linear programming methods.

Evaluation of our methods for evacuation planning for a disaster at
the Monticello nuclear power plant near Minneapolis/St. Paul Twin Cities
metropolitan area shows that the new methods lowered evacuation time relative
to existing plans by identifying and removing bottlenecks,
by providing higher capacities near the destination and by choosing shorter routes.
In 2005, CCRP was used for evacuation planning (transportation component) for
the Minneapolis-St. Paul twin-cities metropolitan area. It facilitated
explorations of scenarios (e.g. alternative locations and times) as well
as options (e.g. alternative transportation modes of pedestrian and vehicle).
It also led to an interesting discovery that * walking able-bodied evacuees
(instead of letting them drive) reduces evacuation time significantly for
small area (e.g. 1-mile radius) evacuations. *

In future work, we plan to formally characterize the quality of solutions identified by the CCRP approach. We will explore new ideas, e.g. phased evacuations and contra-flow, to further reduce evacuation times. In addition, we would like to improve modeling of other transportation modes such as public transportation.