May 26, 2010

Article: Exemplars and Urban Legends 
Article: Investigating Low-Speed Rear-End
Meet the Expert:  Tony Bocchichio, B.S.M.E 

Exemplars and Urban Legends

You are at the gas station, standing next to your car, filling up your tank, when your cell phone rings. Should you answer it? Because you have heard that a cell phone can create a large enough spark which could ignite gas fumes and cause a huge explosion. But wait…is that true or just an urban legend?

Solving puzzles like this one is often similar to what forensic engineers do; with one major exception. While a television show like “Mythbusters” gets to solve these problems on the front end (for fun or before anything bad happens), forensic engineers usually get called in on the back end (after something bad has happened).  This calls for a different approach as often the original situation the incident occurred in has been altered in some way by the incident itself.

For example, there has been an explosion at a gas pump and a cell phone manufacturer finds itself in litigation.  The plaintiff’s attorney alleges that the cell phone was dangerous and defective in that when their client answered a call, a spark was created by the phone which ignited the gas fumes near the pump.  The forensic engineers involved scurry off to prove this can or cannot happen.  Since this specific situation cannot be recreated very well using a burnt car and melted cell phone, any test would need to be conducted with a similar vehicle and cell phone. These substitutes worthy of imitating the original pieces of equipment are called exemplars.

There are many advantages to using exemplars.

· No spoliation of evidence.  Even if the original equipment may be available for testing, often times testing will result in the alteration or destruction of the original equipment, which can be an undesirable affect on evidence that needs to be preserved.

· Theory versus Scientific Fact.  The more science an expert can put behind his or her opinion, the stronger that opinion is.  Drawing conclusions from calculations made from measurements and descriptions can be valid, however seeing results in a practically applied situation that back up what those calculations indicate certainly adds strength to any conclusion.

· Demonstrative Evidence.  A three dimensional, physical, real time, credible demonstration creates a much more powerful impression than a two dimensional paper report.  A jury can instantly visually grasp points made with exemplars, the result of which often aligns their perception with the expert’s opinion.  If a picture is worth a thousand words, an exemplar is certainly worth more.

So, cell phone at the pump…urban legend?  Yes!  According to the show Mythbusters, “A properly-working cell phone poses almost no danger of igniting gasoline, even when surrounded by gasoline vapor with the optimum fuel-air mix for ignition. The actual risk comes from an electrostatic discharge between a charged driver and the car, often a result of continually getting into and out of the vehicle.”

Investigating Low- Speed Rear-End Collisions

No damage - - no injury.  This is a common misconception.  Lack of damage to the car's exterior does not mean there is no damage.  One must look carefully at the bumper isolation systems or bumper supports and the frame of the vehicle.  The bumper isolation system is nominally designed to protect the vehicles safety systems, such as the front and rear lights. The isolation system is not designed to prevent cosmetic vehicle damage. Today's passenger cars are required to have bumper isolation systems, but trucks and SUV’s are not.  Whether there is external damage or not, when two vehicles collide there is always energy transfer from one vehicle to the other.  This energy transfer will result in movement of the occupants, and movement that is violent enough will cause injuries.

In an ideal scenario, all of the vehicles are available for inspection immediately after the crash, and prior to repair.  When this happens, the damage to the vehicles is easily inspected, measured, and analyzed.  Typically however, many months or years have passed before an accident reconstruction is undertaken.  The history of the vehicles between the time of the crash and the time of the inspection may be unknown.  Many questions arise as a result of inspection delays.  Do we have access to the car or has it been sold or even destroyed?  If we have access, does the car we are looking at accurately portray the vehicle condition and damage at the time of the accident?  Has the vehicle been repaired?  Were the brush guard and three-point harness installed on this SUV at the time of the crash?  If we know the bumper was replaced but the trunk lid and taillights were undamaged, what conservative assumptions can we make?  What if the subject vehicle is no longer available?  Can we measure an exemplar vehicle and analyze the crash based on a fully crushed bumper?  What can we learn from pictures of the damage?  At this point, known facts have to be pulled together with conservative assumptions in order to make an accurate reconstruction.

Based on the damage to the vehicle, and/or other factors known about the collision, the reconstructionist analyzes the impact energy and determines the change in the velocity of the struck vehicle. This information is then passed on to a biomechanical engineer. The biomechanical engineer creates a computer model of the vehicle and occupants and analyzes the crash dynamics to determine the forces and torques applied to anatomical segments of the models.  The resulting forces and torques are then compared to the forces and torques required to produce reported injuries.  An opinion can ultimately be offered whether the reported injuries are consistent with the reconstructed crash.

Meet the Expert:  Tony Bocchichio, B.S.M.E

Mr. Bocchichio is one of CED’s mechanical experts with experience in automotive and heavy vehicle accident reconstruction, product liability and analysis of mechanical systems. Mr. Bocchichio holds a Bachelor of Science degree in Mechanical Engineering Technology from Wentworth Institute of Technology. In addition, he is a member of the American Society of Mechanical Engineers (ASME), Society of Automotive Engineers (SAE) and National Association of Professional Accident Reconstruction Specialists, Inc. (NAPARS). He is certified as a traffic accident reconstructionist by ACTAR and fire and explosion investigator.

Mr. Bocchichio joined CED in 2001. He specializes in accident analysis with experience in vehicle and marine accident reconstruction, including: analysis of causation, vehicle dynamics, impact points, speed determination, time-distance analysis, visibility analysis and testing, video recreation, light bulb filament analysis, occupant kinematics, photogrammetry, skid and acceleration testing, low-speed impact analysis and human factors. Mr. Bocchichio is a key member of the company’s Vehicle Crash Group (VCG) and has provided expert testimony in a court of law.

Academic Background:

• B.S., Mechanical Engineering - Wentworth Institute of Technology, Boston, MA.
• Certified Mold Inspector - Certified Mold Inspectors & Contractors Institute, Hurricane, UT.
• Accredited Traffic Accident Reconstructionist, ACTAR 2061
• Certified Fire & Explosion Investigator / Certified Vehicle Fire Investigator

Areas of Expertise:

• Dynamic Analysis
• Mechanical Engineering
• Accident Reconstruction
• Heavy Vehicle Analysis
• Mechanical Systems
• Human Factors
• Testing & Analysis
• Mold Origin & Cause
• Water Intrusion