You just got a letter that says the crash involved a "delta-v of 12 mph," and the insurer is using that number to question how badly anyone could have been hurt. Delta-v means the change in a vehicle's speed during a collision, measured from just before impact to just after impact. It is a crash-severity calculation used in accident reconstruction. A higher delta-v usually means greater force transfer, but it is not the same thing as the vehicle's travel speed, and it does not by itself prove how serious a person's injuries are.

In practice, engineers estimate delta-v from vehicle damage, crush measurements, event data recorder downloads, skid evidence, vehicle weights, and motion after impact. On Nebraska highways, that analysis can be complicated by crosswinds strong enough to push semis across I-80, so reconstruction may need to separate wind effects from collision forces. The Nebraska State Patrol may use these methods in major-crash investigations.

For an injury claim, delta-v often appears in disputes over causation and damages. Insurance companies may argue that a "low delta-v" crash could not have caused a neck, back, or brain injury. That argument is incomplete. Occupant position, seatback angle, head restraint setting, prior medical history, and multiple impacts all matter. Delta-v is one data point, not a legal rule, and it should be weighed alongside medical records, biomechanical evidence, and other proof of liability and injury.