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UWM Civil Engineer Shares Insights In Evacuation Planning

Carolyn Bucior
UW-Milwaukee civil engineer Troy Liu

Hundreds of thousands of people will descend on Washington, D.C., starting tomorrow for events related to President-elect Donald Trump’s inauguration - and protests against it.  But what if an emergency requires an evacuation of large parts of the city? Thanks in part to the efforts of a Milwaukee researcher, plans for such an evacuation exist. 

Troy Liu, an associate professor of civil engineering at UW-Milwaukee, has been working on evacuation plans for many different cities, states and coastal regions for over ten years. According to Liu, the two major events that initiated mass evacuation planning are hurricanes and sporting events.

However, after September 11, 2001, terrorist attacks became another major concern and cause for evacuation planning, especially for Washington D.C. In 2009, Liu designed evacuation plans for Barack Obama’s first inauguration.

Evacuation planning is a complicated task - the 2009 inauguration had more than 500 possible scenarios to plan for, according to Liu. These scenarios can range from locations, accidental causes, chemical threats, landmarks, human error, etc., and the teams planning for the worst never stop preparing.

"It's kind of like multi-layer, multi-task, and multi-scenario coordination," Liu explains. Through studying previous plans, an evacuation task force builds upon them with modern programming.

"We actually study their plans, but we just computerize those plans," he says. "We give the local authorities an option to try and use the plan for multiple scenarios and simulate how the plan will do well or badly in hundreds of scenarios."

Credit Troy Liu / UW-Milwaukee
Potential highway routes for an evacuation during the 2009 presidential inauguration.

It is the hundreds of hypothetical simulations and patterns created that allow local authorities the time and preparation needed to set aside resources to aid in evacuations or rescuing, if necessary. Liu also notes that each scenario is dealt with as a "local event" to avoid panic through an entire region.

However, one major weakness of evacuation plans is the limited capacity of roads that create major bottlenecks, according to Liu.  "We have a certain demand, but have a very limited capacity in the transportation network and people try to increase the capacity of the network," he explains. Steps such as lane reversals actually cause greater problems and inconsistent capacity between sections, essentially creating the same problem drivers experience when there is construction on the highway - merging and a lot of congestion. Liu adds that this technique uses a lot of resources, is dangerous and increases the risk for accidents, especially when the unknown factor of human behavior is added. 

Instead, Liu recommends future plans "try to keep consistent capacity for evacuation and only invest resources on the critical bottleneck locations."

Audrey is a WUWM host and producer for Lake Effect.