Red, Yellow or Green!

On the Scene E-Newsletter, Edition 131, January 26, 2011

Ideally, there would be a traffic video camera at every intersection to resolve all such conflicts.  And although such cameras are being used more widely, the vast majority of intersections are not monitored.  Even when they are monitored, the data is typically only stored for 20-30 days.  This is one reason it is vital to contact CED as soon as an accident is reported.  Our engineers can frequently respond within hours to secure any time-sensitive evidence.  In this particular case, there was no video camera.

Without video evidence and with conflicting witness testimony, the engineer had to carefully examine other evidence to determine the fault for this collision.  The subject intersection in this matter was controlled by vehicle sensors in the roadway.  The sequencing of the lights was controlled by a programmable controller.  For this intersection, the only record of the programming was a diagram on the original installation drawings of the traffic signals.  The CED engineer used the Traffic Signal Timing Manual published by the Federal Highway Administration (FHWA) to interpret the diagram.  Then the engineer conducted a site survey to verify that the programming was consistent with the installation drawings.  Other factors considered were vehicle speed and stopping distances, traffic volume, roadway alignment, sight distances, weather and visibility,  Even without video evidence, but based on the details of the witness testimony and physical evidence the CED engineer was able to conclude which vehicle had the right of way.

By systematically examining the entire accident, CED engineers can usually make conclusions regarding who is at fault in a collision. CED has a dedicated Vehicle Crash Group (VCG) to investigate and opine on almost every type of vehicle accident. Our engineers are not only experts in auto collisions but also investigate tractor trailer, boat, recreational vehicle, train and plane accidents.