Paratransit buses, more commonly known as minibuses, are a fairly common sight on the roads of many American communities. Public transit and social service agencies, among others, often use the 16- to 20-seat vehicles in order to provide access to public transportation to people with disabilities, as required by the Americans with Disabilities Act of 1990.
It may come as something of a surprise, then, that paratransit buses sold in the United States are exempt from Federal Motor Vehicle Safety Standards, the rules developed to ensure occupants’ safety during vehicular accidents and to minimize the severity of their injuries. Fortunately, in Florida, one researcher is leading a team that works to ensure the safety of those who depend on paratransit buses for transportation.
Jerry Wekezer is a Distinguished University Professor specializing in civil engineering at the Florida A&M University-Florida State University College of Engineering. Since 1999, he has worked with the Florida Department of Transportation to test various types of paratransit buses for crashworthiness—their ability to survive a side impact and rollover accidents with minimal harm to occupants.
“Every year, the Florida Department of Transportation buys over 300 paratransit buses, which then are distributed to local agencies throughout the state,” Wekezer said. “Because there are no federal safety standards for these vehicles, the state seeks to do everything it can to make sure they’re safe before putting them on the road.”
At the college, Wekezer has established a Crashworthiness and Impact Analysis Laboratory that performs finite element studies and laboratory tests on individual vehicle components to determine how well they stand up to various types of dynamic impact. Members of Wekezer’s seven-person team, ranging from undergraduates to postdoctoral research associates, also develop complex computer models to determine how well specific types of paratransit buses will perform in collisions.
“It would be very expensive to obtain actual paratransit buses for crashworthiness and rollover testing—a single bus can cost more than $60,000,” Wekezer said. “So what we have done with this lab is develop methods for testing specific components, such as side panels and connections, to determine how they respond to loads that simulate a side-impact collision. The data collected from these tests then are applied to validate finite element models used for a comprehensive crashworthiness and safety assessment of these buses.”
Finite element modeling is a computational process in which a three-dimensional object is developed in order to make very specific predictions as to how the vehicle will be affected by a variety of impact conditions. In the case of paratransit buses, the model can be divided into more than a half-million individual pieces, or elements.
“Finite element analysis is a sophisticated tool that enables us to predict how a vehicle will perform under adverse conditions,” Wekezer said. “It also allows us to share our findings with the manufacturers so that they can take steps to remediate any problems that we find. For example, a common problem that we see is weak connections between the side panel and the roof or floor. Sometimes a simple fix, such as placing additional bolts at key connection points, is all that is needed to make a vehicle sufficiently crashworthy. The manufacturer would much rather make an inexpensive fix like this than have to do an in-depth analysis into the design of its buses.”
Although federal safety standards for paratransit buses do not yet exist in this country, Wekezer has been instrumental in their development and implementation in Florida and in Europe. He is leading a group under the auspices of the United Nations Economic Commission for Europe, which is charged with developing a revised European standard for crash and safety assessment of small buses. These bus safety rules now apply to all 27 member states of the European Union as well as 44 members of the U.N. (excluding the United States). The Florida Department of Transportation also has adapted a portion of the European standards as they relate to rollover test procedures.
Read more about the FAMU-FSU College of Engineering’s Crashworthiness and Impact Analysis Laboratory at www.eng.fsu.edu/~wekezer.