Pedestrian Accident

Time Distance Analysis

What opportunity did the driver and/or the pedestrian have to avoid the collision?

If either could go back in time and re-live the incident, what would they have done differently to avoid the actual outcome? Many times, it relates to visibility and time. However, it is almost always paramount to establish the speeds of both at the moment of impact. We can do that!

MDA experts use a combination of scene evidence and established physics procedures to pin down the impact speeds. Once that is done, we can immediately establish the positions of both at discreet time points prior to the impact. Some of those time points are critical to establishing the avoidance potential such as “ point of last opportunity “ and “ point of first perception “. We can establish these points precisely for you and illustrate them in 2D and 3D static drawings as well as in moving animations both in 2D and 3D which are very persuasive tools. Clarifying the pre-impact positions and timing is key to success.

Types of Pedestrian Collisions

The five different types of pedestrian collisions are:

Wrap Trajectory
The most common type of pedestrian collision, which usually involves a decelerating vehicle. In this type of collision, the pedestrian’s torso wraps up onto the vehicle’s hood.

Forward Projection
This is the most common type of pedestrian collision that occurs with children. This type of collision occurs when the pedestrian’s center of mass is lower than the leading edge of the vehicle.

Fender Vault
This type of collision involves both vehicles which are braking and non-braking. The pedestrian is contacted near an outboard edge: the torso is wrapped onto the hood of the vehicle, and the pedestrian exits off of the side of the vehicle.

Roof Vault
This type of pedestrian collision occurs when a pedestrian center of mass is higher than the leading edge of the vehicle. The pedestrian is lifted into the air because of the vehicle’s speed or a low roof line. Typically, these types of pedestrian collisions are caused by high impact speeds.

Somersault
This is the least common of pedestrian collisions and is due to high impact speeds. The pedestrian is flipped into the air (or is somersaulted) before striking the ground.

Determining what type of pedestrian collision requires an analysis of the collision scene, a vehicle examination and an examination of the pedestrian’s injuries. From the analysis of these examinations, a crash reconstructionist will be able to determine how a person was contacted by the vehicle, if the person went up onto the vehicle, how the person fell to the ground, and what occurred while the pedestrian was on the ground.

Pedestrian Accident Reconstruction

The movie shown here is an actual crash captured by a red light camera. Mike Kennedy, MDA senior re-constructionist, has recreated the accident making 3D animations from different points of view to illustrate the intricate details of a pedestrian collision.

Sample animations from red light camera reconstruction

Crashteams reconstruction experts provide detailed animation reports for every 3D animation to back up visually stunning animations with data.

Steps in Pedestrian Reconstruction

Almost all pedestrian cases are reconstructed with a view to determine the possibility of the incident being avoided, given the visibility opportunities, impact speed, pedestrian motion, and motor vehicle condition.

This means that the professional crash re-constructionist must complete the following tasks:

• Determine point of impact
• Determine visibility issues
• Generate accurate diagram (preferably in 3D)
• Calculate impact speed
• Calculate time vs position and velocity information

Once these tasks are complete, the reconstructionist can report on where the motor vehicle was located at various points in time, including where the motor vehicle was located when the first opportunity to recognize the pedestrian as a hazard occurred. From that position, the reconstructionist can predict the stopping distance based on the vehicle capability and standard perception response delay. Of course, the best way to demonstrate the results is in a 3D animation.

3D Scene Models

All MDA experts are highly skilled in generating a 3D environment which accurately replicates the actual scene of the incident. This model is based on the forensic mapping procedure which creates the overall geometry of the scene precisely, and the evidence of the incident, combined with locations that have been determined by the use of physics. The end result provides the readers/court with a complete understanding the event.