About 15 years ago, Europe suffered several catastrophic highway tunnel disasters that resulted in the loss of lives. When examining the aftermath, investigators found that many people had stayed in their vehicles instead of exiting and seeking emergency exits. European researchers then began to reexamine engineering in tunnels and ways to move people to an emergency exit if they cannot move their cars. One of the many recommendations resulting from that effort was the adoption of the green emergency sign that has become an international symbol for emergency exit, but is not widespread in the United States.
The Texas A&M Transportation Institute (TTI) is conducting a project, sponsored by the National Cooperative Research Program, that tests the effectiveness of the sign in the event of a tunnel disaster.
“This study was requested by AASHTO through NCHRP because there is currently no uniform system or strategy in U.S. tunnels to guide drivers when an emergency happens,” said TTI Associate Research Scientist and project supervisor Laura Higgins. “So the issues Europe has been dealing with are ones the United States may encounter in the future.”
One of those issues is that in the event of a disaster that traps vehicles in a highway tunnel, how do you get people out of there safely and efficiently? According to Higgins, the answer is very often that they have to get themselves out of there because they may be blocked by other vehicles and emergency vehicles may be unable to get to them.
“In the event self-evacuation is needed, how do you make that happen?” said Higgins. “There were two main questions we wanted to address: how do you let people know if they are stopped in traffic that they need to leave their car to evacuate and how do you direct people to the emergency exits in an environment where there may be smoke and reduced visibility?”
To conduct the research, the team constructed a 60-foot tunnel inside TTI’s Environmental and Emissions Research Facility, located at Texas A&M University’s Research Campus.
The 63 research participants were presented with different emergency response scenarios to gauge their reactions. Researchers used different types of lighting for the signs throughout the project, from having the signs glow with LEDs to glow-in-the-dark signs. The tunnel also had lit pathways, which could be alternated between a solid line, flashing, or blinking in the direction of the exit. Artificial smoke was added to the tunnel so that the signs and lighted pathways could be tested for best visibility by participants.
“We are now looking at a couple of different things—we have the data now we are working on the analysis,” noted Higgins. “Maybe the most interesting part of the testing was to see if people in the United States would understand the green running man symbol, which is the international symbol for exit. The encouraging thing was the majority of the participants understood the general idea of what the sign meant.”
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