Current accident statistics evaluate that multi-collision crash events represent 25~30% of all crashes. A post- crash feature introduced a few years ago attempts to mitigate the impact severity and quantity of these secondary impacts.

The feature has several names:​ Post-crash braking (PCB), Multi-collision Braking (MCB) or Secondary Collision Mitigation Braking (SCM or SCMB).

SCMB uses the crash sensing systems and the brake systems. After a significant crash event , the vehicle will attempt braking in order to reduce the residual velocity with the goal to reduce, even possibly avoid, subsequent collisions.

The first objective is to confirm the safety field problem of multi-collision events and further evaluate their devastating effects in terms of fatalities and injuries.

The second objective is to evaluate the increase in fatality and injury risks from single to multiple collision events. A theoretical potential safety benefit is evaluated, considering an SCMB feature with the capability to avoid all secondary collisions in multi-collision events.

Finally, in the third and deepest analysis, 3 realistic levels of braking decelerations are considered for SCMB. The risks levels for other major post-collision risks were quantified. The potential safety benefits of SCMB with the braking decelerations are evaluated for the avoidance of these 3 post-collision risks:​ subsequent collisions, VRU impacts, and rollovers.

Disambiguation:​ in this paper, “secondary collision” does not mean another accident which occurs as a result of congestion caused by a primary accident. “Secondary collisions” are defined as the subsequent collisions (impacts), after the first impact of a vehicle involved in an accidental event containing a chain of impacts.