HPT

 

10.0 Safety of Life:

10.4Differential Speed:

Differential speed is the principal value in predicting automobile and human carnage during traffic accidents. It is the velocity difference between two moving objects or one fixed and one moving object. On a typical roadway, two cars traveling in opposite directions at 55 mph would have a differential speed of one-hundred and ten (110) mph. A car traveling at fifty-five (55) mph which runs into a bridge abutment or tree collides with a differential speed of fifty-five (55) mph. Accident damage, and to some extent, death and injury, can be reasonably predicted based on the mass of the objects closing at various differential speeds and the amount of energy absorbing structure incorporated within a vehicle. Many high speed racing tracks have flexible safety walls (known as Safer Barriers) or a series of tires tied together that absorb the impact of an errant car. On roadways, guard rails absorb some differential speed during impact, however, are placed primarily to guide vehicles back into the flow of traffic and avoid contact with off-road objects.