Lesson

Consult with traffic engineers early in the process of no-notice evacuations to secure the use of traffic management resources and to identify routes for evacuation and re-entry.

Experience from an emergency incident in which 3,000 residents were evacuated under no-notice conditions due to a toxic chemical spill.

February 2006
Utah,United States

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Lesson Learned

In March 2005, railroad workers in a rail yard in South Salt Lake City, Utah discovered a tanker car from which a large quantity of toxic chemicals had spilled onto the ground. The risk that a hazardous chemical fire might erupt and that toxic fumes would spread led the city to evacuate approximately 3,000 residents from the nearby neighborhood. The residents used their personal vehicles to evacuate. Incident command notified residents of the evacuation by using a reverse 911 system and by dispatching police officers door-to-door on every street.

During the evacuation, the police department, Department of Public Safety and the Highway Patrol closed sections of the roads near the toxic spill and barricaded local streets with road blocks to prevent re-entry. After residents had successfully evacuated, incident command revised their estimate of the duration of the evacuation as taking much longer, and utilized an authorized traffic management contractor to support transportation management. The contractor closed the interstate using barriers, deployed electronic signs, managed traffic flow and developed a plan for the rush hour commute for the following day. Key lessons learned are:
  • Involve traffic engineers earlier in the incident. Initial estimates by incident command were that the evacuation would be in place for several hours, and that the roads would be re-opened before the next day’s rush hour. However, when it became apparent that the local roads and sections of the interstate would be closed longer than anticipated, and possibly lasting until the next day’s morning commute, incident command called upon traffic engineers to develop a plan to control traffic flow for the morning rush hour and manage the road closures. In a review of the incident, the Utah Department of Transportation recommended that incident command involve traffic engineers as early as possible in the evacuation process to aid in traffic management including road closures, the control of traffic flow, the selection of interstate ramps for closure and the development of a plan to divert traffic from closures and hazardous areas to safe zones.
  • Increase the use of portable message signs. The use of portable message signs enables incident command and traffic managers to provide accurate and timely information to the public about roadway conditions and road closures, and directions to safe zones and shelters. Portable message signs enable traffic managers to direct traffic by using a “soft closure” of a roadway as opposed to erecting physical barriers. Large-scale evacuations may require that state and local DOTs can access a large number of portable message signs than may not be on hand; local and state DOTs that have contracts in place which allow them to acquire additional signs in emergencies.
  • Do not overlook the importance of using variable message signs on surface streets. Deploying variable message signs on surface streets has proven highly useful in no-notice evacuations. The signs direct local residents who are fleeing the evacuation zone and guide travelers who were diverted to local surface streets from the closed sections of the interstate. Further, variable message signs were useful outside of the incident zone because they guided the drivers who were traveling through the area. For example, by activating message signs approximately 50 miles to the north and 120 miles to the southeast of South Salt Lake City, traffic managers notified drivers who were approaching the area to bypass the evacuation zone.
  • Use traffic engineers for the re-entry plan. Traffic management is a critical part of a successful re-entry plan. It includes tasks such as evaluating whether closed roadways are safe and ready to be re-opened, educating the public about the re-opening of roads, determining when traffic can be restored, providing traffic control for the return of residents and directing traffic flow upon re-entry. Re-entry plans should also address the procedures required for the re-opening of critical infrastructure facilities such as sewer, water, gasoline stations, grocery stores, and hospitals or urgent care facilities, which should be done before residents are allowed to return.
This case study of a successful no-notice evacuation demonstrates the importance of involving professional transportation management as early as possible in the emergency. Because the nature of an emergency renders it difficult to predict the how long it may last or its size, it is important to enlist the aid of transportation experts (as well as other emergency personnel) early in the incident. Utilizing experienced transportation planners can improve the safety and efficiency of the evacuation and its impacts by improving the selection of appropriate places for road closures and ramp blockades, the re-direction of traffic (particularly in rush hour conditions) and the placement of portable message signs.

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Source

Technical Memorandum For Federal Highway Administration on Case Studies: Assessment of the State of the Practice and State of the Art in Evacuation Transportation Management - Task 3

Author: Stephanie Wilson-Goure, Nancy Houston, Andrea Vann Easton

Published By: Federal Highway Administration

Source Date: February 2006

Other Reference Number: FHWA-HOP-08-014

URL: http://www.ops.fhwa.dot.gov/publications/fhwahop08014/index.htm

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Notes

Lesson of the Month for November, 2008 !


Lesson ID: 2008-00450