Forensic Engineers and Consultants

Category Archive: Case Studies

Waterpark Woes

On July 12, 2024, a family entered the local water park to cool down. The family consisted of a mother and her two sons. While walking toward the wave pool area, the mother stepped off the wooden stairs and onto the surrounding concrete landing. As she did so, she slipped on a puddle of water that had accumulated on the surface. She fell backward, landing on her left side and striking her elbow and the back of her head against the stairs—effectively ending the family’s outing before it began.

Painted concrete is very slippery when wet due to the paint covering the asperities or “grip” on the walking surface. The less asperities present on the walkway surface, the more slippery the floor.

An investigation revealed that landing surface appeared to be a painted smooth concrete, which was visibly wet from foot traffic and nearby splashing of the wave pool. The concrete landing surface had been painted the week before the mother’s fall. The concrete walkway area did not contain any added asperities or “grit” to increase the surface traction in that area. The process of painting the concrete with paint covered any previous or inherent asperities or “grip” on the concrete walking surface, therefore decreasing the flooring’s slip resistance. When wet, the painted concrete had an even lower slip resistance than when dry. Given the location of the wave pool in proximity to the concrete, it was likely that the area would become wet and become a slip hazard. The mother likely slipped and fell on the wet concrete due to the lack of available traction for her to remain upright. She likely would not have fallen had the painted concrete had a higher slip resistance when wet through the application of added asperities or grit.

Anti-slip coatings can be applied to walkway surfaces to increase slip resistance. These coatings increase the available traction between the walking surface and the pedestrian’s foot.

Slip and falls occur when there is an unexpected loss of traction between a person’s foot and the walking surface. Here, the pedestrian loses balance and falls. The human gait cycle consists of four phases: the stance phase, the toe-off phase, the swing phase, and the heel-strike phase. Slip and falls are most likely to occur when there is an unexpected change in the slip resistance of the walking surface during the heel-strike phase of the gait cycle. The potential for a slip and fall event increases if there is an unexpected reduction in the walkway surface’s slip resistance and the available slip resistance is too low for the pedestrian to remain upright. Some factors that contribute to slips and falls include the type of flooring and the presence of moisture or contaminants on the floor.

There are effective measures to reduce the likelihood of a slip and fall event. The best way to control slip and fall hazards is to remove the hazard completely. If slip and falls are a concern, flooring with little slip resistance should be replaced with flooring material with higher slip resistance. If replacing the existing flooring material is not possible, then guarding against or separating pedestrians from inadvertent exposure to the slippery surface is an option. Adding a non-slip coating such as grit additive increases the slip resistance of the floor and separates the pedestrian from unintentionally encountering the hazard. Lastly, hazard warnings can be used in addition to either removing or guarding a hazard to prevent slip and fall events. Property owners and management should place conspicuous signs near the hazard to warn pedestrians of the potential slip hazard.

Ellen Szubski, Ph.D., CXLT, CPSI, AHFP, is a human factors consultant at The Warren Group. She earned a Doctorate of Philosophy in Human Factors Psychology and a Master of Science in Applied Psychology from Clemson University.  She did her dissertation on “The Influence of Pedestrian Biological Motion on Time-To-Collision Estimates at Night”.  She is also a Certified XL Tribometrist, Certified Playground Safety Inspector and a Certified Associate Human Factors Professional (AHFP). Prior to entering the forensic field, Ellen planned and conducted experiments for a major bicycle manufacturer. She also conducted laser strike perception studies for the Department of Defense.  Ellen applies her experience in Human Factors to the analysis of crash investigations and other personal injury matters. These matters often include collisions involving vulnerable road users and drivers, driver distraction, and slips, trips, and falls. She utilizes her knowledge of OSHA regulations, codes, and standards in her analysis of premises liability incidents and safety consulting.  Ellen is a current member of the Human Factors and Ergonomics Society (HFES) and it’s Forensic Professional Technical Group.

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Don’t Get Burned With Your Gas Grill!

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If there is one thing Americans can agree upon, it is the enjoyment that comes from an outdoor barbeque.  Whether a summertime cookout or a fall BBQ to watch a football game, we all love the fun and fellowship that comes from sharing a meal that was prepared outdoors on a grill or smoker.  In fact, 64% of Americans own a grill or smoker.  The great majority of these are LP fueled gas grills with comparatively few natural gas fired grills.  These products can be enjoyed safely when designed, installed, and used in a proper manner.  However, given the grill’s use of flammable fuel gas and high temperatures, the potential exists for things to go wrong and result in burn injuries or uncontained fires that spread to the surroundings. Read More

Civil Twilight Pedestrian Collision: A Case Study

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Susan, a 45-year-old runner, was jogging in the early morning approximately an hour before sunrise, also known as “civil twilight.” Civil twilight occurs both before sunrise and after sunset when the sun is below the horizon and the sky is partially illuminated. Susan was wearing dark athletic clothing and grey tennis shoes for her morning run. She was running on the sidewalk in a suburban area and began to cross the four-lane road at an unmarked crosswalk. Read More

Turkey Fryers- Product Design is Critical to Consumer Safety

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As the holiday season nears, thoughts turn to wonderful home-cooked meals with family.  Few things in life are more pleasurable than a traditional holiday turkey feast. Yet for an unfortunate few, holiday meal time can turn tragic if a turkey frying accident occurs.   While fried turkeys may be tasty, many fire safety experts feel that the reward is not worth the risk.  Read More

Rainy Day Troubles: A Slip and Fall Case Study

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An afternoon summer rain shower led to an elderly woman’s admittance to the hospital. Mrs. Jones, aged 68, entered a retail store to buy groceries for her visiting family. Mrs. Jones walked through the store’s vestibule toward the entrance where she slipped and fell, sustaining significant injuries. An investigation was conducted to determine the cause of the slip and fall incident.

The investigation revealed Read More

The Importance of Crane Wire Rope Lubrication

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Wire ropes are critical components of cranes and play a crucial role in ensuring the safety and efficiency of crane operations. To extend the life of these ropes and maintain their strength and performance, it is essential to regularly lubricate them. Read More

The Collision Reconstruction Matrix – The Human

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Murder, suicide, deceit, and intrigue… car crashes? You bet! In our next installment of the 9-Cell Collision Matrix let us dive a little deeper into the glue that binds all this together, the human element.

Photo by Mark Turner

Let’s begin with the most basic human element at the root cause of car wrecks, our old friend inattention. Inattention… a vast word that encompasses many lackadaisical conditions. The daydreaming 16-year-old in math class, the radio knob turner, the back seat talker, the quarter pounder with cheese eater, and perhaps the most offensive, the cell phone user. All very dangerous behind the wheel, and one very dangerous to your future… as it turns out, you will always need good math skills… ask me how I know? Driving is of course a divided attention endeavor, Read More

GREASE Is The Word…Ensuring Proper Functioning of Wet Chemical Fire Protection Systems in Commercial Cooking Operations

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Cooking equipment is the leading cause and is responsible for over half of fires in eating and drinking establishments (see Warren expert Chad Jones’ 2020 blog, Structure Fires in Eating and Drinking Establishments, for further reading on fire causes and NFPA 96 on duct inspection and cleaning). Fire extinguishing systems are also routinely provided over GREASE-producing cooking appliances. So why are some of these fires still so bad? GREASE is the word. Read More

The Vehicle (EDR)

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In a previous blog post, we began to delve a little deeper into the vehicle aspect of the 9-Cell Collision Matrix by taking a look at tires. Let’s now take a closer look at the very diverse and interesting topic of Event Data Recorder (EDR) data. Read More

Improperly Used Space Heaters Can Be Dangerous

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As the temperature outside slides from the cold to the “bitter” cold range on the thermometer, most people tend to turn the heat on inside their home. Some homes, however, do not have whole house heat or sufficient heating capacity and therefore the occupants  may rely on portable space heaters. Portable space heaters, used properly, can be a good choice to warm a small area of a home. Unfortunately, while they can warm your cold and tingling hands and feet, they can also warm nearby materials to the point of ignition. Read More

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