Speed likely contributed to a loss-of-control of the Audi but it was the “Can-Opener” separation of its structure that was likely a major factor in the deaths of three of its occupants in a July 3, 2020 Edmonton Alberta crash.
The results of vast numbers of controlled crashes performed by various government agencies and research institutions shows that a vehicle travelling at 50 km/h will sustain about 40 centimetres of crush on its front end when it strikes an immovable barrier. This is a classic demonstration of the kinetic energy that exists while a vehicle is in motion and how that energy must be dissipated (“gotten rid of”) in order to come to rest.
In a vast number of real-life, single vehicle collisions, a vehicle is usually travelling too fast as it rounds a curve and the driver begins to take braking and steering actions when the vehicle begins to go out of control. During this long time and distance speed (and kinetic energy) is lost as the vehicle yaws (fish-tails or drifts) about its vertical axis. Next an impact occurs and more speed (and more kinetic energy) is lost. Finally the vehicle is redirected by the impact and slides or tumbles for an additional time and distance to its final rest position as all of its speed (and all of its kinetic energy) is lost at final rest.
In modern times investigators can simply download event data from an event data recorder (EDR or “black box”) in order to find out precise information about what happened during a crash. But that information is never made available to news agencies and the public. Instead what the public is told is that speed, alcohol or driver distraction were likely factors in the crash long before any objective data is analysed from the EDR . If other factors were involved the public will never know about them.
In the above photo we can estimate what speed might have been involved independent of any data from the EDR. The traditional method is to work backwards from the final rest position of the vehicle and consider how much kinetic energy could have been dissipated along each step of the vehicle’s motion leading back to where the incident began. The primary issue of interest in the present scenario is the conclusion that the vehicle’s speed caused the deaths of three of the vehicle’s four occupants (the driver apparently survived). Let us say that someone believed the vehicle was travelling at the excessive speed of 80 km/h when it struck the Starbucks building.
Working backwards from the vehicle’s final rest position we might estimate that the vehicle travelled about a car length from its point of impact with the Starbucks building to its final rest position. Even if all 4 wheels were locked during this motion of about 5 metres a speed only about 30 km/h would be lost. If all of the vehicle’s four wheels were not locked (more likely scenario) and a deceleration equal to only 2 wheels being locked is applied, the speed loss becomes only about 25 km/h. So where does the remaining (80-30) speed loss come from? It must come from the evidence of damage to the car and destruction of the building. That becomes more complicated because we do not know the characteristics of the buildings structure. But given that Sir Issac Newton has told us that forces in an impact must be equal and opposite, we can judge that the severity of the damage on the car must provide some clue as to the severity of the impact and the speed lost.
One clue is to review the numerous results of other impacts where a vehicle has crashed into a modern, retail or residential building. This is common in parking lots or city streets when a driver mistakes the accelerator pedal for the brake. We see numerous photos of such instances where there appears to be considerable breakage of glass and bricks but the car remains relatively “uncrushed” and the driver is only shook up.
These numerous instances tell of the nature of the structure of these buildings and the fact that they are brittle and fall apart at relatively low forces. It is known that vehicles have weak spots that when struck can cause the structure to rupture/separate. This is rarely discussed as many persons who are responsible for driver safety would have much explaining to do.
The characteristics of the damage to the Audi in the Edmonton crash have not been discussed but are not consistent with a high speed at the time of contact with the building. Such a high speed impact should have demonstrated itself in more damage to the building.
While it may be true that the Audi was speeding at the time that its driver lost control in the curve, much of its speed could have been lost on approach to the impact with the Starbucks building. Other critical facts such as the use of seat-belts would also need to be known to understand why the three occupants of this vehicle sustained their fatal injuries.
In an assessment of what matters, it is important to recognize the difference between what caused a collision and what caused the injuries to the occupants inside the striking vehicle. The causes are rarely the same. In any impact there are at least two impacts. The first is between the vehicle and its environment (another vehicle, a tree, a building etc.). The second impact is between the occupant and the vehicle interior (unless there is a complete, undisturbed ejection). One might also continue to note that a third impact might be between the body and individual organs ( such as an aorta tear during high deceleration). Approaches such as these can help investigators in recognizing what factors need to be considered in any collision reconstruction.