Tag Archives: car accident expert

Car accident expert Dr. John Lloyd has served attorneys nationwide for 25+ years in biomechanics, human factors, helmet testing and motorcycle accident expert

Accident Reconstruction

In the United States there are 11 million motor vehicle accidents each year, more than 400,000 of which result in death. The most common injuries resulting from automobile accidents are to the head, brain, neck, and low back. The evaluation of such cases often involves a team of experts, including accident reconstruction, biomechanics and human factors experts.

As an expert witness in biomechanics and human factors as well as a certified accident reconstructionist for motorcycle crashes, automobile accident, and truck collisions, r. John Lloyd is a highly qualified testifying expert witness.

accident reconstruction expert Dr. John Lloyd

Accident Reconstruction

First the accident reconstructionist evaluates the physical evidence from a crash scene, including skid marks, gouges and other roadway markings, along with crush information from the vehicles along with their final rest positions. This evidence is used to calculate the change in velocity of the subject vehicles. 

Biomechanical Analysis

lloyd accident reconstruction biomechanica modelingThe complete anatomy of the crash (pre and post impact vehicle speeds, whether or not seat belts were worn, faulty airbags, etc.) is conveyed to the biomechanics expert.

Biomechanists use this information to determine occupant kinematics (motion of the vehicle occupants in response to the impact), kinetics (forces acting on various body parts as a result of the collision) and injury mechanisms. This can include the impact to the head and forces transmitted to the brain, blunt trauma to the low back, and shear forces to the cervical vertebrae. Findings are used to determine whether impact locations and forces provide a causal explanation for claimed injuries. Hence the biomechanist can provide rationale as to whom was at fault for the sustained injuries.

As an expert witness in biomechanics and human factors as well as a certified accident reconstructionist for motorcycle crashes, automobile accidents, truck collisions, in addition to bicycle and pedestrian accidents, Dr. John Lloyd is highly valued expert for the evaluation of motor vehicle crashes.

Call Dr. Lloyd at 813-624-8986 or email DrJohnLloyd@Tampabay.RR.com to discuss how he can be of help to you with your case.

Crash Data (EDR) Retrieval

Crash data retrieval (EDR) is a tool used by accident reconstructionists to download pre and post collision information from vehicles to determine driver behavior, impact severity and the cause of the crash.

Much like an airplane, almost all vehicles in the United States are equipped with a ‘black box’. In the event of an impact critical information about the crash as well as pre-crash information is recorded and stored in this black box, also known as an event data recorder (EDR). The process of obtaining this data is known as crash data retrieval.

It is a common misunderstanding that EDR data is only temporarily saved in the vehicle’s ‘black box’ and is erased after a short period of time. In the event of an airbag deployment, EDR data is almost always recorded and permanently stored. This data is never erased. Whereas, in a non-deployment event (i.e. airbags did not go off), if the event meets the manufacturer’s propriety algorithms to trigger recording, that data is saved, but can be overwritten if the vehicle is involved in subsequent collisions.

Motor vehicle crash data retrieval

crash data download from vehicle event data recorder

This information of vital importance when investigating a crash includes:

  • Speed
  • Change in Velocity (Delta-v)
  • Acceleration / Deceleration 
  • Braking 
  • Pre-crash Steering Inputs/ Angle
  • Seatbelt Usage and airbag deployment

crash data retrieval toolSpecialized equipment is required to access the EDR.

Unfortunately, law enforcement investigating a crash typically only retrieve the information from the Crash Data Recorder in the event of a traffic homicide. Hence, it is up to the accident reconstruction experts to download this information from the vehicles.

EDR data can help an accident reconstructionist to determine:

  1. pre-crash driver behavior
  2. crash severity
  3. who was at fault

Combined with his biomechanical expertise, Dr. Lloyd can use the information from the EDR to determine:

  1. occupant kinematics (motion in response to crash)
  2. whether injuries are consistent with crash severity