A fatality should not be expected in this type of head-on impact.

The OPP uploaded several photos of two vehicles involved in a fatal collision on Hwy 48 north-east of Toronto over the weekend. The photo above shows the two involved vehicles. A 25-year-old female occupant of one of the vehicles reportedly sustained fatal injuries. While the reasons why occupants do not survive such impacts may be complicated by unreported facts, the public should become critical observers of incidents like these that do not provide an obvious reason for the fatal consequence.

The safety of modern, light-duty vehicles has improved greatly over the decades such that the collisions that were deemed not survivable only 40 years ago are certainly survivable today.  This is particularly true of frontal impacts of two vehicles approaching from opposite directions such as the one shown in the photo above. A distance approaching 1.5 metres from the front end of such a typical vehicle to the location of an occupied front seat is the key factor enabling the controlled ride-down of the occupants. A wide variety of safety systems can be deployed in the 1/10th of a second of such a crash that were not present 40 years ago.

In those earlier years most persons did not wear seatbelts and even if these restraints were worn they were of poor design. Similarly the frontal structures of those older vehicles did not crush in a controlled manner such that in many instances the structure of the crushed vehicle would penetrate into the occupant’s space. Air bags were also not available but even the early air bag systems were too aggressive and caused their own safety problems. Although some challenges remain, for the most part air bag systems have improved while being incorporated into the full system of other safety devices.

While it is not apparent to the general public, a key ingredient in the improved safety of head-on crashes was the implementation of “pre-tensioners” in restraint systems. In earlier days seat belt loading marks were measured by investigators to determine how they were being used at the time of an impact. That data showed that the loading did not occur until the occupant was in a “full-forward” position, similar to the position if the occupant had placed their seat in a full forward position on the seat’s adjustment track. Clearly this was not a recipe for improving the safety of occupants because the restraining was occurring too late in the crash. There are many reasons why this is not a good idea but this will not be discussed here. The point is that pre-tensioners are fired in the same manner as an air bag causing about 4 inches (10 centimetres) of webbing to be pulled toward the occupant’s body. This is a tremendous improvement in the commencement of ride down at an early stage resulting in tremendous improvement in occupant safety.

In summary the photo above shows a classic case where the frontal structures of both vehicles appear to have performed well. Although there is a lot of crush this is a good result. Crush is needed to dissipate the kinetic energy possessed by both vehicles prior to impact. The full frontal engagement of both vehicles is somewhat uncommon but it suggests that most of the kinetic energy would have been dissipated by the vehicles and that the impact force was relatively close to the centre-of-gravity of each vehicle. While this is not ideal it also allows the full frontal mass of the vehicles to be involved in the dissipation. Most head-on collisions involve in the range of a 50 percent overlap and therefore half a vehicle’s frontal structure is not helping in the controlled ride-down. So there are trade-offs.

A good crush is demonstrated by the lack of rearward displacement of the A-pillars of each vehicle. The A-pillars are those that are located on each side of the windshield. Where there is rearward displacement of such pillars there is often a compromising of the near-occupant’s seating space and this is a bad result. So seeing the lack of any A-pillar displacement is a good sign.

Proper engagement, with manageable crush on both vehicles suggests that this head-on collision should have been survivable.

Also, while there appears to be substantial crush it is not overwhelming. Examining the position of the front wheels In the wheel-wells is also a general indicator of the extent of maximum crush as well as the degree of crush of the front edges of the hood of each vehicle. All these facts point to a collision severity that was manageable.

So these facts lead to the expectation that the occupants of each vehicle should have survived the crash. So why did a 25-year-old female sustain fatal injuries in this crash? This question should not be left unanswered. While there may be reasons that have not been explained or revealed, the public should be prepared to recognize when something is not quite right in the reporting of such tragedies.