Traffic: IPTM's Special Problems

Article excerpt

Accident Reconstruction

Since its inception more than two decades ago, Institute of Police Technology and Management (IPTM) has been training law enforcement personnel in myriad subjects, from Crime Scene Processing to Street Gang Identification to Homicide Investigation. They provide advanced training in Narcotic Investigation, Motorcycle Officer Skills, Latent Print Development and Traffic Crash Investigation. One of the favorite IPTM programs is the annual Special Problems in Accident Reconstruction.

Over 200 accident reconstructionists from all across the United States attended this year's conference. Many reconstruction organizations stage motorcycle crashes as a part of their members' ongoing training. The trick, however, is to find a safe and suitable way to deliver a moving, rider-less motorcycle into a fixed barrier or another vehicle. During an Illinois Association of Technical Accident Investigators (IATAI) motorcycle crash test some years ago, all kinds of problems beset those in charge of figuring a way to keep the bikes upright throughout the launch phase. IPTM found probably the most ideal way.

A retired military bomb rack was affixed to the front of a 1999 Chevrolet 2500 pickup truck. The pickup got up to speed and then braked hard an instant before crashing into the target, but the motorcycle kept going. In order to keep each bike upright, two bars held the front wheel in place. When the pickup truck braked just short of the target, a six-pound test line attached to a lever-activated valve on a compressed-air tank triggered the valve that instantly released the two bars holding the front wheel. The motorcycle's inertia moved the lever forward and the line snapped as the valve opened, allowing the front tire guides to retract and the motorcycle to be upright and at full speed as it headed for the target.

Dennis Toaspern of Binghamton, NY, designed and built the bomb rack from scratch specifically for such motorcycle crash tests. A former motorcycle dealer, Dennis is a consultant to attorneys in motorcycle accident cases.

Although the tests were supposed to be motorcycle-into-car, it didn't always happen that way. Motorcycles with manikin riders occasionally go awry, completely miss the target or flop over before getting there. But for motorcycles sliding on the side, values of 0.3-0.55 are still valid. For readers familiar with the Severy crash tests, his fork-deformation speed estimate is clearly not applicable for bikes with USD forks.

Speaking of speed estimates, conservation of linear momentum (COLM) has long been the workhorse of accident reconstruction. It has also long been said that such methodology should not be used in collisions involving vehicles of disparate weights, such as a motorcycle and a car. Well, not necessarily. Bruce McNally, who was with the Millinocket, ME, Police Department for about six years before going to work for Northeast Collision Analysis, demonstrated during his breakout session how in some cases COLM works.

Besides material on motorcycle accidents, Richard Gill, PhD, of Applied Cognitive Sciences, treated the attendees to a Human Factors presentation. Gill has worked in mechanical engineering and experimental psychology but specializes in human factors. He said that the perception-reaction time (PRT) that crash investigators have used for years should be changed to PCRT, with the C standing for cognition. And he said that the typical one and a half seconds isn't really accurate depending on the situation and the number of bits of information a motorist may have to process.

Gill reminded us that the two and a half seconds used by AASHTO was for sign placement and, due to the aging population, 3. …