An analysis on transit pick-up points for vulnerable people during hurricane evacuation: A case study of New Orleans

Abstract

In emergency evacuation there is always a need for transit for those who do not have access to private transportation or cannot walk to safety. Particularly affected among this section of society are the poor, the disabled, and the elderly. Several cities have established prepositioned pick-up points to serve this section of the population but the number and location of the pick-up points have usually been decided using professional judgment or based on experience from past storms. As the vulnerable section of the population typically have low mobility, getting transit pick-up points close to areas of greatest need is important in order to provide better service, improve the efficiency of evacuation, and even decrease the loss of life. In this study, the spatial distribution of the population is estimated using a modified dasymetric mapping method, which estimates population distribution in terms of 30m × 30m land parcels. In each parcel, the vulnerable population is estimated from the proportion of disabled, aged, and zero car-owning persons in the area as determined from census data. Using Orleans parish in New Orleans as a case study and assuming a catchment area of ½ mile around each of the 17 existing pick-up points, the number of vulnerable persons served by the existing system was estimated. To determine whether the 17 pick-up points could be better located to serve the vulnerable optimally, the set of all eligible pick-up sites were first identified and then the pick-up points serving the greatest need were identified using integer linear programming. The results show that the 17 optimally located pick-up points triple the vulnerable population that could be served. On the question of whether 17 is the right number of pick-up points to employ, analysis shows there is a steadily decreasing average value served per pick-up point as the number of pick-up point increases. At some stage it would probably no longer be efficient to create additional pick-up points but provide a feeder service from small demand to larger demand pick-up points or link smaller demand pick-up points on a route to serve several pick-up points with a single service.