Tag Archives: Mechanical Engineer

Staging Collisions: Can Physical Evidence Determine Intent of Parties Involved?

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

A good friend of my consistently preached at educational seminars across the country that “Collision reconstruction is application of the laws of physics to physical evidence left as a result of a collision.” He also encouraged his listeners to trifurcate their traffic collision cases into their basic components: The vehicle, roadway, and driver. Indeed, these mantras formed the framework within which virtually all his collision reconstruction analyses were performed. However, it has always been understood that physical evidence (including vehicle event data) often do not enable a reliable understanding of the intent of the parties involved in a collision.

Recently, five people from the New Orleans area were indicted on federal fraud charges for alleged staged collisions with commercial motor vehicles. The accused actors in these alleged schemes not only planned and executed the collisions but utilized at least one attorney to bring the knowingly fraudulent claims and a small network of medical professionals to create false and inflated medical records. In each case, reconstructing the collisions in the typical, conventional manner allowed reconstruction engineers to establish the pre-crash vehicle speeds, the collision dynamics, and the forces involved. Bio-medical engineers could also evaluate the claimed injuries in terms of those collision forces. All this engineering led to whatever conclusions the physical evidence and science permitted; however, it was only through a variety of “red-flags” that insurance investigators uncovered a pattern.

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Seatback Strength

John R. Yannaccone, P.E., Sr. Mechanical Engineer

In 1966, the National Traffic and Motor Vehicle Safety Act established a set of safety standards for motor vehicles and established the National Highway Safety Bureau, now known as the National Highway Traffic Safety Administration (NHTSA). The Federal Motor Vehicle Safety Standard (FMVSS) 207, which focuses on the strength of vehicle seats, was among the standards established. FMVSS 207 includes a requirement for the strength of the seatback, which is tested by applying a rearward force near the top of the seatback and limits the post-test deformation after the seat is subjected to a specified moment or torque (a force applied at a distance). For decades, engineers have argued the FMVSS 207 requirements are inadequate for the safety of occupants in rear impacts.

When a vehicle is struck from behind, the seatback provides the primary means of restraint to the occupant. When the seatback deforms rearward, it can result in several issues. Once the seat reaches around 45° recline angle, it starts to lose the ability to retain the occupant and they begin to slide up the seatback. This can result in the occupant impacting the rear seat with their head or being ejected from under the seatbelt, exposing the occupant to a wide range of injuries. In addition to affecting the front seat occupants of the vehicle, this deformation of a seatback can expose backseat occupants to potential injuries.

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Pedestrian Injuries in “Backover Events”


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

The automotive and vehicle safety industries call them “Backover Events”: the accidental, unintended reverse (or backing) maneuver, often resulting in injuries to pedestrians and by-standers. In a recent report to Congress, the National Highway Traffic Safety Administration (NHTSA) estimates nearly 200 deaths and 8,000 injuries occur each year from these events, despite long-standing vehicle design standards targeting their reduction. To be sure, those design standards and requirements, as well as voluntary efforts by the manufacturing communities, have had a positive effect, for without them the statistics would likely be far worse. Recently, however, the automotive industry took an additional major step to reduce the risk and occurrence of such events. Specifically, beginning with the 2018 production year, all passenger vehicles are required to have backup cameras. Typically utilizing in-dash screens, these devices provide a rearward-looking view typically not provided by the vehicle’s mirrors. A driving force behind this requirement was reducing backover events involving small children that are typically small enough to fit within a vehicle’s so-called “blind spot”. Now into its second year of production, regulators are awaiting data to evaluate the efficacy of these new systems.

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Trailer Separation Mayhem

lowboy trailer gooseneck

John R. Yannaccone, P.E., Sr. Mechanical Engineer

Case Synopsis: A heavy duty equipment hauler was delivering a large piece of equipment to an industrial plant. After the equipment was off-loaded, the driver wanted to reconfigure the low-boy gooseneck trailer by removing a section of the trailer so it was shorter for the trip back to his employer. The middle section of the trailer needed to be unbolted and removed to allow the front and rear section of the trailer to be re-connected for the return trip. The driver asked if the industrial plant had anyone to assist him in shortening the trailer, to which they offered one of the plant’s truck mechanics to assist him.

The trailer manufacturer had specific instructions regarding the sequence of steps to safely separate the mid section of the trailer, using cribbing and the hydraulics of the gooseneck to manipulate the trailer. The truck driver was directing the plant mechanic as they worked together to remove the bolts holding the center section of the trailer. During the process, the driver instructed the mechanic to tap/drive out a shim between two sections of the trailer. When the shim came free, a portion of the trailer dropped down and landed on the foot of the mechanic, trapping it under the trailer. Other workers at the plant used a forklift to lift the trailer section off the mechanic’s foot. He suffered severe crush injuries to his foot, which resulted in permanent disability.

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Coffee Brewer Water Supply Line Failure

Coffee Brewer

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 Recording Developments in Recreation Vehicles

Event Data Recorder

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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