A head-on collision occurs when the front of one vehicle collides with the front of another. These types of accidents are extremely dangerous because of the cumulative speed of the vehicles colliding in opposite directions. Crash analysis experts often refer to the combined difference in crash speed or terminal speed. For example, if two vehicles collide head-on while traveling at 30 klm/h the collision speed between the two vehicles will be equal to 60 klm/h. If the same two cars collided and one of them was stopped, then the speed of the other would be 60 klm/h.
Another reason why head-on collisions are so dangerous is because they often cause large and sudden changes in speed. Accident analysis experts refer to the change in speed as Delta-V change in speed. The sudden and significant change in speed is directly related to causing damage. The number one reason for a head-on collision is improper lane usage by one of the drivers. In other words, when a driver enters oncoming traffic. Inappropriate lane usage is often the product of inattention to distracted driving. Our expert analysts can often work out the effects involved in a collision through various equations based on conservation of momentum and release of energy.
Additionally, by quantifying the change in Delta-V speed of one vehicle, our expert analysts can resolve with the change in Delta-V speed of the second vehicle participating in the accident.
The total Delta-V velocity change of a vehicle, or the change in velocity due to the collision, is an essential resource for dedicated accident analysts. Many vehicles have the ability to record the longitudinal change in Delta-V speed if the vehicle is involved in a severe collision. The recording is stored in a component of the vehicle’s airbag electronic module called the Event Data Recorder or EDR. When the principal direction of the force acting on a vehicle and the longitudinal change in Delta-V velocity during a crash are known, then the total change in Delta-V velocity experienced during a crash can be derived. When vehicles are moving head-on the vehicle movements are dictated by momentum. Momentum is a vector quantity that has both magnitude and direction.
A traffic accident analyst can quantify momentum by multiplying the weight of the vehicles by their speed. In the image above, if we assume that both vehicles weigh roughly the same, then we know that the blue car was moving much faster at the time of the collision due to the frontal trajectories of the vehicles.
