By Aubrey Samost
The logistics of
evacuating a major city are complex. The evacuation of New
Orleans during Katrina ran surprisingly smoothly, with very few traffic
accidents or fatalities, causing few resulting traffic backups.
evacuation plan enacted was the result of two less successful
hurricanes Georges and Floyd, both of which fortunately passed east of
the city. Committees of people went to work trying to improve the
evacuation plans to allow everyone to get out of the city in the
fastest and most efficient way possible. The result was the
creation of contraflow patterns for traffic in the city. There
were also some issues with getting everybody out of the city because a
lot of people did not own a car or were elderly and could not
evacuate. Another major issue was a failure of
communication. There was no way for officials to know which
routes out of the city were backed-up and which routes were flowing
freely (Wolshon, 2004).
There are many different
factors to take into account when trying to create an evacuation
plan. In New Orleans, the exit capacity is roughly 67% (American
Highway Users Alliance, 2006), which means that if all of the
evacuation goes smoothly, the roads outside of New Orleans will only be
able to evacuate two-thirds of the population in twelve-hours.
with the best exit capacity is Kansas City, with 98% (American Highway
Users Alliance, 2006) of the people able to leave the city in the peak
twelve hours. To improve New Orleans, there would have to be
wider roads with more entrance and exit points to prevent bottlenecking
on the major highways.
Another useful figure
that ties in with exit capacity is the internal traffic flow.
This is a measure of traffic within the city during an
evacuation. It is based on the average travel delay time during
an evacuation. New Orleans did fairly well in this category with
an average travel delay time of about 19%, corresponding to an internal
traffic flow rating of 81% (American Highway Users Alliance,
2006). This is measured with the Travel Time Index, which uses
the ratio of the commute in an evacuation to the time that it takes to
travel that distance on any normal day (Bureau of Business Research,
2006). In the case of New Orleans, it takes about 19% more time
to travel from one part of town to the other when there is an
evacuation going on then when there is no significant traffic.
The final major factor
in determining the overall evacuating capacity of a city is the
percentage of people who have access to a car. This does not mean
that they own a car. It only means that they can find a ride out
of the city, either with a neighbor, family member, or a friend.
In New Orleans, about 91% of the population has access to a car
(American Highway Users Alliance, 2006).
all of these factors are averaged together with different weights to
calculate the evacuation capacity of New Orleans. This figure is
used to rank New Orleans amongst other major towns. In a study of
thirty-seven major cities with a population of over one million people,
New Orleans ranked twelfth with an evacuation capacity of 67.3%
(American Highway Users Alliance, 2006). This number represents
the likely percentage of people who will be able to evacuate New
Orleans in the peak twelve hours of the evacuation process.
Another figure that can be calculated is the roadway capacity, or the
percentage of people who can theoretically evacuate the city if the
roads were the only limiting factor. This is found by averaging
the internal traffic flow and the exit capacity to get 74%, which is
higher than the evacuation capacity because the evacuation capacity
takes into account the people who do not have cars (American Highway
Users Alliance, 2006).
There are many ways to improve evcauation
rebuilding New Orleans. One option is to widen the highways from
six lanes. Evacuating the city is a difficult situation because
New Orleans is bounded on the north by the lake, which limits the
routes out. Consideration of public transportation as an
integral part of evacuating is another option. There are nine
percent of people
without cars who still need a way to evacuate, so it makes
sense to enlist the help of buses. Another possibility is to look
into creating safe shelters within the city limits. This gets rid
of the need to bus people long distances out of the city, which puts
less of a strain on the public transportation (American Highway Users
Alliance, 2006). There is all ready the Superdome, which could
easily be reinforced and more prepared to serve as an emergency
Overall, New Orleans already has
a functioning evacuation capacity, but it can be improvedt.
During Katrina, the
people who evacuated did so with very few problems. The major
issue right now is to understand why people could not or did not
evacuate the city. To keep New Orleans safe, it is necessary to
continue to improve the evacuation plan so that moves everyone to