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TRUE STORY: High Definition Scan Solves Overpass Dispute

The story you are about to read is true. Only the names have been removed to protect the innocent.

Background: A tow truck boom struck a highway overpass, allegedly causing more than $100,000 in damage to the bridge.

Suspects:
The tow truck boom.
Prior vehicle impact.

Assignment: Determine what damage, if any, was caused by the tow truck impact and, if damaged, the necessary repairs.

Just the Facts: The driver of the tow truck stated that he struck the bridge in the left hand lane of a six-lane interstate highway. The only damage to his truck from this impact was scratched paint. The state department of transportation’s assessment of the bridge noted damage to several beams on this bridge and determined repairs required in excess of $100,000. 

After an initial on-site inspection and discussions with the tow truck driver and representatives from the state department of transportation we determined that this particular bridge had been struck by another truck within the prior two years and subsequent repairs had not been performed.  The dilemma we now faced was which damage occurred when. After conversations with the responding Department of Transportation engineer we realized that he was unaware of the prior vehicle impact and based the damage report on all of the damages observed without any conversations with eyewitnesses as to where the tow truck actually struck the bridge. We then performed a high definition scan of this bridge and the tow truck to see if we could identify matching witness marks (fingerprints of the tow truck if you will). This scan allowed us to obtain accurate and detailed measurements of the bridge, without stopping traffic.

Information from this scan showed that the damage and deformation to one of the beams was not representative of the tow truck in question. We also noted that the severity of the deformation to this beam did not correspond to the cosmetic damage suffered by the tow truck. Further evaluation also showed that the maximum speed of the tow truck driver at the time of impact was lower than that required to cause the damaged observed. 

Findings: Our conclusion was that the tow truck was responsible for cosmetic scrapes only and not the deformed structure. The structural deformation was caused by a prior impact with the bridge by another vehicle.