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Where the Lamp-Post Falls


Laurence R. Penn, Senior Forensic Animation/Video Specialist ::::

 

An old residential lamp post, weakened by a recent storm, fell unexpectedly and damaged two vehicles parked below. The owner of one of the vehicles claimed to have sustained injuries from the falling lamp post while entering her vehicle. The actual lamp-head was the part identified as the culprit for the injury.

However, the vehicles’ orientation and proximity to the post made the story difficult to comprehend. Three scene photos were camera-matched using photogrammetry, and as part of the process, the approximate position of the fallen post and lamp-head were calculated. The results were imported into 3D software and the arc of the falling lamp post was established.

When viewed from multiple angles, the reconstructed scene showed that the plaintiff was likely not in a position to be injured by the lamp-head, as described in the testimony.

Laurence R. Penn, Senior Forensic Animation/Video Specialist at DJS Associates, can be reached via email at experts@forensicDJS.com or via phone at 215-659-2010.

Tractor-Trailer Sustains Severe Fire Damage


Tractor Trailer Fire Damage

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

A commercial tractor-trailer sustained severe fire damage during an overnight stay in a parking area of a heavily traveled interstate. No one was in the truck at the time of the fire; however, security surveillance cameras recorded the event and the video became an important element of the ensuing investigation.

A preliminary engineering review included a study of the truck’s recent maintenance and repair records, as well as an interview with the truck owner. This identified two areas on the truck that warranted a detailed visual examination. It also identified potentially relevant parties for the subsequent, joint-expert examination. Specifically, the truck owner produced service records reflecting battery and starter repairs performed one month before the loss. He also reported that after those repairs, he had trouble starting the truck, along with other electrical problems. He returned to the shop that performed the repairs; however, those complaints went unremedied.

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Don’t always blame the Tread and Riser for the Fall


Flight of Stairs Engineer

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

Case Synopsis: Plaintiff testified that she was in the process of descending a flight of stairs, one step at a time. She had stepped down onto the first tread with both feet and was stepping down onto the second tread with her right foot when her foot went out in front of her. The heel of her foot barely contacted the front edge of the second tread, and she fell backwards down the rest of the stairs.

Expert Analysis: Plaintiff’s expert opined that the stair treads were shorter than what was required by present code and that there were inconsistencies in the tread and riser dimensions. He concluded that the plaintiff’s fall was due to these issues.

Plaintiff’s medical records revealed that 16 years prior to her fall she was diagnosed with avascular necrosis of the left hip due to osteoporosis and underwent a hip replacement. Since her hip replacement, she descended stairs one step at a time. Four months prior to her fall, she underwent a revision of her left hip.

Biomechanical research has shown that descending stairs too slowly lengthens the time a person has to support their weight on one leg and increases the risk of a fall. Plaintiff’s testimony that her right leg went out in front of her and that she barely contacted the front edge of the second tread was consistent with the plaintiff’s left leg giving way due to her prior left hip issues. As a result, her center of mass began falling backwards causing her right foot to move forward of the second tread.

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Sprinkler Piping Installation – Code NFPA 16D Violation


sprinkler-piping

James J. Shields, P.E., Mechanical Engineer ::::

Case Synopsis – A housing development company began a large multi-dwelling housing construction project at a site in Southeastern Pennsylvania. The development company hired a General Contractor to design and construct the site along with the erection of hundreds of homes. The project was planned by the development company to require several years for completion. As a first step in the process, the General Contractor obtained a building permit and produced a set of overall design drawings for the entire site, along with a set of design details for home construction. As is commonly the case, the General Contractor was responsible for the hiring of all sub-contractors. In addition, before commencing the work, all sub-contractors were required to sign a construction agreement with the General Contractor.

Approximately one year after the housing project had begun and certain housing sections had been completed, the housing developer and a prospective homeowner entered into an Agreement of Sale. The homeowner moved into the home about six months after signing the Agreement and lived in the home uneventfully for close to nine years. However, at that time, a severe water leak emerged from behind the drywall in the second-floor master bedroom. The water deluge from the leak was so great that it flowed through the wall, flooding the second story floor and pouring down two floors to the basement before the source of the water leak could be located and isolated. A vertical section of drywall was removed to expose the source of the water, which appeared to be originating from the sprinkler piping, although the exact location of the leak was still unknown. When the sprinkler system valves were shuttered the leak stopped, although, by then the volume of water released had created significant damage. The water was being supplied from the Township Water System, and the shutoff valves were able to isolate the home sprinkler system from the water supply.

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The Importance of Event Data in Low Speed Collisions


Event Data Recorder

Robert T. Lynch, PE, Principal Collision Reconstruction Engineer ::::

All model year 2013 and newer vehicles equipped with an event data recorder (EDR) that are sold in the United States need to adhere to the requirements set forth in 49 CFR Part 563 of the federal standards.

Part 563 establishes minimum requirements for an EDR. In particular, an EDR must record an event if the vehicle experiences a Delta-V (change in velocity) above 5 mph from any direction: front, rear or side. When a vehicle sees a Delta-V greater than 5 mph, the EDR will record 5 seconds of pre-crash speed, braking, and acceleration data, as well as severity data for the impact itself.

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Speed from Video – Captain Video’s Specialty


James R. Schmidt, Jr., BSME, Sr. Collision Reconstruction Engineer ::::

I’m a collision reconstruction engineer with over 23 years of experience in the field. I’m affectionately known in the office as Captain Video, given my love for the evaluation of vehicle speed and crash-related parameters from surveillance videos.

Basic evaluation from stationary camera:

A 2019 Toyota Sienna minivan passes in front of a stopped dash cam. Speed from video is evaluated therefrom. Speed is distance over time. The easiest way to perform the evaluation is to look at the timeframe required to travel the vehicle’s wheelbase (i.e. the distance from the front wheel or axle to the rear wheel or axle). So, in this example, the minivan travels its 119 inch wheelbase in 7 frames of a 30 frame-per-second video. Distance is 119 inches, or 9.92 feet. Time is 7 frames divided by 30 frames per second, or 0.233 seconds. Calculating speed … 9.92 feet divided by 0.233 seconds is 42.5 feet per second, or ~29 mph. FYI, this was a 35mph speed limit roadway.

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