Expertly Speaking

Breaking Technology

Automatic Emergency Braking Doesn’t Always Prevent Pedestrian Collisions

Robert T. Lynch, PE, Principal Collision Reconstruction Engineer

Automatic Emergency Braking (AEB) is generally designed to automatically apply the brakes when a rear-end vehicle collision is imminent. This technology has been shown to mitigate rear-end impacts; however, this technology is not always capable of detecting pedestrians crossing in front of a vehicle.

AAA has conducted testing of vehicles equipped with AEB and found that in 60% of the tests, the vehicle failed to stop, from an initial speed of 20 miles per hour, before striking the pedestrian dummy. The testing was performed during daylight hours with adult pedestrian dummies. The tested vehicle performed worse at higher speeds, under dark conditions, and with child dummies.

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Parked, but Watching

Laurence R. Penn, Forensic Animation/Video Specialist

A recently released video shows a car attempting to parallel park on a city street when suddenly the car speeds up in reverse, drives over a designated bike lane, and with the help of a ramped barrier, flips upside down, very narrowly avoiding a number of pedestrians as they flee the chaos. This is exactly the kind of thing that triggers my paranoia of eating at the outdoor seating of an unbarricaded restaurant sidewalk or pulling into the bollard-less parking spaces directly in front of my children’s daycare. Luckily no one was seriously injured.

What’s interesting in this case is the fact that this video was recorded on two cameras, located on the rear and side of a witness vehicle that was parked in front of the open spot. When you are walking down the city street, you pay no attention to the parked vehicles. Yet, they may be paying close attention to you. Even though this witness vehicle was parked and unattended, it was silently recording its surroundings, likely in many more directions than the video shows. The owner of the vehicle was then able to access the video at the time of the incident to provide it to authorities. Though it is not evidently clear why the driver gunned it in reverse, the dynamics of the incident are obvious in this case. We analyze video from many cases involving mass transportation vehicles such as busses and trucks which already have systems to record from cameras installed in multiple locations. While passenger vehicle manufacturers currently do not install multiple recordable cameras, that is undoubtedly soon to change and many of our cases will include analysis of this type of captured video in the future.

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Coffee Brewer

Coffee Brewer Water Supply Line Failure

John R. Yannaccone, PE, Senior Mechanical Engineer

Case Synopsis: Upon opening for business following a long holiday weekend, a building maintenance person discovered water leaking into the lobby of the building. The source of the water was found to be leaking from a plastic water line that supplied water to a coffee brewer. The water supply was turned off and it was discovered that the water line had developed a hole near the coffee brewer.

Expert Analysis: Photographs of the area of water supply tubing showed the tubing had bulged outward and then burst. There was no evidence that the tubing had been bent or abraded, leading to its failure. The area of bulging was indicative of the tubing being exposed to either high pressures or high temperatures. The plastic material the tubing was made from was suitable for a cold-water supply line and was rated above the expected temperature and pressure for the water supply. A review of the coffee brewer’s installation manual indicated they recommended the brewer be installed with copper tubing.

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Event Data Recorder

Event Data Recording Developments in Recreation Vehicles

R. Scott King, BSME, Principal Automotive/Mechanical Engineer

Event data recorders (EDRs) in passenger vehicles and commercial trucks have been in use for nearly 20 years. During that time, they have helped answer many questions regarding how those vehicles have been operated, and performed, in the moments preceding crashes and other recordable events. Indeed, passenger vehicle EDRs have become so prevalent they have even become subject to federal regulations. And now, implantation of that technology has begun to spread to the recreational vehicle segment.

A recent investigation involving a popular inverted, three-wheeled motorcycle revealed it was equipped with a data recorder capable of recording parameters such as speed, brake, and accelerator control for approximately 60 seconds preceding engine shutdown. In that case, the engine stopped running as a result of the crash, thus relevant data was recorded. The data was retrieved using the manufacturer’s proprietary software and the analysis thereof provided important information regarding the circumstances of the incident. Using what was learned in that investigation, researchers looked beyond the subject vehicle to determine whether its manufacturer had deployed this or similar technology in other vehicles. The findings were surprising.

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Cervical Injuries Causally Related to Defective Amusement Ride

Robert J. Nobilini, Ph.D., Biomechanical Engineer

Case Synopsis: The plaintiff was riding a rollercoaster style ride at an amusement park when she incurred significant cervical injuries. Plaintiff described being thrown sideways to her right, feeling pain in her neck, and immediately experiencing neurological symptoms from the neck down. When the car returned to the station, the plaintiff could not feel or control her extremities.

Expert Analysis: An examination of plaintiff’s medical records revealed that she had incurred a herniated nucleus pulposus at the C5-6 level of her cervical spine with spinal cord impingement. During her deposition, plaintiff described that the car went into a sharp left turn, throwing her to the right, causing her right shoulder to strike the padded metal restraint rail that was mounted to the car. An examination of the subject ride revealed that the right siderail on the incident car was bent outward. Maintenance records for the ride revealed that the park was having issues with the speed of the ride increasing over the months leading up to the incident. It was determined that the increased speed of the ride, particularly as the cars moved through the sharp turns, created higher than expected lateral loads on patrons. The outward bending of the right siderails on the incident car was evidence that patrons were being thrown laterally into the rail with great force. During the incident, the plaintiff was thrown laterally towards the rail. Because the rail was displaced outward, the plaintiff was able to accelerate over a greater distance before striking the rail. As a result, she struck the rail at a greater than expected velocity, exposing her to a higher rate of deceleration. As plaintiff’s right shoulder struck the rail, her head continued to move laterally, forcing her cervical spine into extreme side bending, which resulted in her injuries.

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Playground Fall

James Weagley, MS, ATC, Recreation Expert

Case Description/Summary: The plaintiff, a young boy participating in a summer camp program, fell from a playground structure when he was startled by a counselor yelling for him to get down. He sustained injuries, which required surgery and left him with residual pain and loss of motion. The plaintiff claimed that the playground was unsupervised during the time of the incident.

Analysis: According to the plaintiff’s attorney, the boy had been hanging on the outside of the playground structure and was startled when a playground supervisor yelled at him, causing his fall. Per the training manual, staff members were encouraged not to yell when they observe a child not complying with playground rules, as it might frighten them and cause an accident. The playground supervisor’s deposition indicated there were 30-50 children at the camp. The staff consisted of 10 counselors/counselors in training, a supervisor and assistant supervisor. Each staff member received a manual and training prior to the start of camp. The manual section entitled “Playground Safety” specifically required staff to be proactive by insuring proper use of all equipment. Staff members were required to demonstrate the correct method of use before the children were able to go on the playground. The plaintiff received instruction from the summer camp staff about proper use of the playground equipment and his mother reported providing instruction to him as well.

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