Speed / Time / Distance in Pull-From-A-Stop Accidents

Todd O. Hutchison, ACTAR.

 

"I was going down the road, minding my own business and all of a sudden this car came out of nowhere in front of me."

When interviewed, the other driver said “I came up to the stop sign and stopped and looked and nothing was coming, so I pulled out. The next thing I know your insured plowed right into me.” When there are no witnesses how do you handle this claim? How do you determine who’s at fault in causing this wreck?

This scenario is all too common for most claims adjusters. The answers to the following four key questions are important in determining the solution to the problem.

  • First, decide who had the right of way.
  • Second, determine how fast the vehicles were traveling at the point of impact.
  • Then decide how long it would take for the vehicle pulling from the stop sign to reach the point of impact.
  • Finally it’s necessary to know how far back the other vehicle was when the stop sign vehicle began to accelerate.

An accident reconstruction can assist in answering these questions and in turn help assess liability.

The Scene Investigation

A timely scene investigation by an experienced Accident Reconstructionist will reveal impact gouge marks and/or offset scuff marks to show where the point of impact occurred. If there are pre-impact skid marks from one or both of the vehicles the location and direction of skidding will help to determine the angle of impact and the type of actions each party took just before impact. Measurements will be made of the roadway, impact and departure path markings, and the vehicles’ final rest locations all of which will be positioned on a scale diagram for analysis.

Vehicle Inspection

The involved vehicles will be inspected, measured and photographed to determine the vehicle crush profiles and to determine the extent of damage. The crush profiles will assist the investigator in determining the speeds of the vehicles and the angle that the vehicles impacted into one another. The vehicle inspection will gather other pertinent information that may include whether or not the turn signals, brakes, or headlights were in use at the time of the collision or if there were any pre-existing vehicle defects. Most modern day vehicles are equipped with Crash Data Recorder (CDR) information that will not only show the vehicle speeds at discrete time intervals as the vehicle approached the impact but also other data which will assist in determining what occurred in the crash. The CDR will show whether the vehicle was accelerating or braking leading up to the collision and whether the driver or front seat occupant had on their seatbelts. Many of the CDRs can show data such as brake fluid pressure, steering angle and even tire pressure. The information can be used along with other calculations to plot the vehicles approach path.

"Once a thorough investigation of the crash location and the vehicles is completed this data is then utilized to determine the speed / time / distance relationship between the vehicles as they approached the area where the collision occurred."

The first step is to determine the impact speeds of the vehicles. This can be done by obtaining the speeds though the Crash Data Recorder or by calculating the vehicle speeds by software that uses conservation of energy or linear momentum equations. In order to utilize these methods a detailed inspection of the scene and vehicle is needed. Once the impact speed of the vehicles is determined the next step is to determine the vehicle's angle of approach. After establishing the angle of impact the vehicles can then be place backwards in time along their angle of approach. By placing the vehicles along their approach paths, it can help to determine if the drivers were attentive or not. If the vehicle could be seen for more than a few seconds and no evasive action was taken to avoid the collision it’s clear that inattention or some other health related factor may have been involved.

If you need help with a similar analysis or other accident reconstruction assessment contact us to talk with an investigator.

 


 

 

 
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