This website contains a mass evacuation transportation planning model. "This model estimates the time required to evacuate patients in healthcare facilities and transport them to receiving facilities. To begin, click the 'New Scenario' button. Then fill out the data elements on the Scenario Input Page, including the characteristics of the vehicles used, characteristics of the evacuating and receiving hospitals, and other factors that affect travel time."
Agency for Healthcare Research and Quality: http://www.ahrq.gov/prep/massevac/