PITTSBURGH--According to the Centers for Disease Control and Prevention, workplace slips, trips and falls cost the U.S. economy $180 billion each year and represent the majority of nonfatal injury costs. While injury prevention strategies can save lives and reduce costs, one factor rarely taken into consideration is footwear. Researchers at the University of Pittsburgh's Swanson School of Engineering are exploring new techniques to better predict the wear rate of shoes in order to improve shoe design and replacement policies to reduce slip and fall accidents.
The proposal, "Impact of Worn Shoes on Slipping," was the recipient of a four-year, $1,519,208 R01 grant from the National Institute of Occupational Safety and Health. Principle investigator is Kurt E. Beschorner, Research Assistant Professor in the Swanson School's Department of Bioengineering. Co-Is are Joel M. Haight, Associate Professor of Industrial Engineering and Director of Pitt's Safety Engineering Program; and Mark S. Redfern, William Kepler Whiteford Professor of Bioengineering.
"Our primary mode of transportation is walking, and every time you move your feet you risk a slip or a trip that can lead to a fall," Dr. Beschorner said. "What we want to address is the preventative side to falling. We have preventative screenings for many health issues such as cancer. Yet relatively few studies have been done to reduce fall prevention by improving the slip resistance of shoes."
Dr. Beschorner compared the research to advances in tire technology and tread wear. Like the grip between a car's tires and the road, the friction between the sole of the shoe and a walking surface maintains a person's grip to the floor. Shoes that are heavily worn have a reduced coefficient of friction (COF) and are associated with increased risk of slipping. When worn, treads can no longer channel fluids from beneath the shoe. The fluid then becomes pressurized and the COF decreases, thereby increasing the chance of a fall.
The researchers note that knowledge gaps exist regarding the factors that contribute to shoe wear rate and the wear thresholds at which the COF begins to decrease. This gap inhibits design and selection of more effective wear-resistant shoes and preventative programs that replace shoes before they become too worn. To identify the underlying causes of shoe wear and the tread thresholds where shoes become unsafe, new technology developed by the research team will simulate wear using a robotic slip-tester and measure shoe tread hydroplaning using a fluid pressure measurement system. The research will also develop new computational models that can be used to predict shoe wear for new shoe sole designs.
"What makes this study unique is the systematic way in which shoe tread wear will be studied," Dr. Beschorner said. "We've developed novel technology to test shoe tread drainage to more precisely measure how shoe wear is impacting slipperiness. We will examine shoe wear and determine specific limits to wear, so that people know when to replace worn shoes. Then we will determine the critical factors that impact how quickly shoes wear, which can help manufacturers build a more durable shoe."