Friday, October 20, 2006

Evacuation Report Card for U.S. Cities

The American Highway Users Alliance just published an interesting study of the evacuation capacity of highway systems in 37 major U.S. urban areas - those with populations of 1 million or more.

The cities' highway systems were graded in three dimensions:

  • Exit Capacity: Capacity of major roadways leading out of an urban area.
  • Internal Traffic Flow: Traffic flow within the urban area, allowing access to exit roadways.
  • Automobile Access: The percentage of city residents with access to an automobile
Highlights of the study included:
  • Half of the 37 cities received an "F." (New Orleans got a "D.")
  • Only one city, Kansas City, received an "A."
  • Landlocked cities scored the best, because evacuation is possible in any direction. Every city that scored "C" or above is landlocked.
  • The three largest cities in the U.S. had the lowest scores: New York, Chicago, and Los Angeles.
Specific problem areas are:
  • The majority of cities lack sufficient exit capacity, with New York and Chicago having the most severe problems.
  • Los Angeles and Chicago have especially bad internal traffic flow.
  • New York scores lowest by far on automobile access, because many city residents rely on public transit.
It seems to me that disaster planners in smaller cities could do this kind of analysis, too. While it does not take into account any obstacles that are caused by the disaster itself (e.g., bridges washed out in a hurricane or destroyed in an earthquake), it provides a good baseline snapshot of a city's ability to clear itself out.


Anonymous said...

The 34 page report never mentioned the role of pedestrians in emergency evacuations. However, walking was the primary means of evacuating Manhattan on 9-11. For perspectives on walking on 9-11 and during the 2003 blackout, see Episode 114 of "Perils For Pedestrians" on Google Video at

Kansas City hardly deserves an A. Pedestrians trying to leave downtown Kansas City during an emergency would have a real challenge because of the poor pedestrian access on the bridges over the Missouri River.

John Bowen said...

I agree completely.

In addition to those who regularly walk, a lot of people can get stranded when public transportation systems shut down. They have no choice but to go on foot.

I had this experience in July, when I happened to be in St. Louis on the night that this storm rolled through the city.

I'd taken the MetroLink train to the city, and when the storm knocked out the trains' power, I was stuck. Fortunately I was able to call a family member who drove across the river from Illinois and picked me up.

But if it had been an earthquake rather than a storm, and the bridges had been damaged, the problems would have been greatly compounded for public transit riders like myself.

A lot of inland river cities would have to deal with this problem.