"Tesla Model 3 owner died in a tragic accident with a semi truck. The Model 3 went under the truck’s trailer resulting “in the roof being sheared off as it passed underneath,” which is known as a “side underride” accident." Is it possible to stop the car?

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    $\begingroup$ Sure. You enforce trucks to be designed safely with side rails for crash protection, like they already are in Europe. See gov.uk/government/publications/… $\endgroup$
    – alephzero
    Jul 19, 2019 at 14:05
  • $\begingroup$ Where in the world is 262km/h a legal speed on a road that will be shared by trucks? You don't design cars to survive crashes caused by the driver being an idiot. $\endgroup$
    – alephzero
    Jul 19, 2019 at 14:12
  • $\begingroup$ It's a top speed of the car. And second I want to know the answer -- is it possible or not to make this car more safe in theory? Thanks for answers! And I do not want precise calculations, just an estimate. $\endgroup$
    – John Smith
    Jul 19, 2019 at 14:15
  • $\begingroup$ Are you adding the cost to your question? If so, you should ask only a specific question, see engineering.stackexchange.com/help/on-topic $\endgroup$
    – Solar Mike
    Jul 19, 2019 at 14:18
  • $\begingroup$ Ok. no cost then. $\endgroup$
    – John Smith
    Jul 19, 2019 at 14:19

2 Answers 2


In high speed collisions essentially the human body fails under high g negative acceleration even if the structure of the car or cabin or test vehicle is strong enough to survive the collision.

strange things can happen that may not immediately be visible such as brain injury due to boiling of Cerebrospinal fluid because of the vacuum created by rapid deceleration of the skull during the crash when the race car helmet contacts the dashboard, (contracoup brain injury). This boiling will create craters in the brain. That is why there is helmet restraints to the back and sides of the seat.

In design of structure of the cars for crash survivability the general strategy is to protect the occupants by placing sacrifice high energy absorbing structure around the cabin. these sacrifice collapsible structures are commonly the wheel and suspension structure, ribbed and perforated framing bars and studs, engine and other substantial components. they will bend and deform while absorbing the crash energy and providing precious time (in milliseconds) and room for the occupants to break the impact.

Good restraints and padded potential contact surfaces, relocating objects which could be dangerous in a crash from the cabin, are other parts of the strategy.

An absolutely rigid structure is not part of the optimal strategy.

Here is some tables on human crash tolerance.

Human G acceleration tolerance

Eiband chart of crash survivability

  • $\begingroup$ Is it possible to make something like folding back seats which will remove head of the driver/passangers from that zone? Will it be still too abruptly and fast for a person to survive? $\endgroup$
    – John Smith
    Jul 20, 2019 at 5:49

At 262 km/h (163 mph) there are many other aspects to that particular crash type than just front pillars. Even with pillars designed to stop the car many other factors could kill the driver. Maybe look at NASCAR stock cars for a better idea of high speed safety. Roll cages, Lexan instead of glass, helmets, seats/harness that severely restrict movement, etc. They are designed from the ground up for high speed impact.

  • $\begingroup$ What about using better materials without changing design of the car too much? $\endgroup$
    – John Smith
    Jul 19, 2019 at 16:42
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    $\begingroup$ It's not the quality of materials that matter as much as the momentum of the drivers body. Stopping the body from that speed instantaneously is going to cause injury. Even if the drivers body is well secured the internal organs are not. $\endgroup$ Jul 19, 2019 at 16:52
  • $\begingroup$ @UseitorLoseit while you might be able to design seat and straps to keep the organs in place, how will you keep the driver’s head on their shoulders? Which is a big issue... $\endgroup$
    – Solar Mike
    Jul 19, 2019 at 17:03
  • $\begingroup$ Absolutely. Doesn't a NASCAR stock car seat have a strap that attaches to the helmet to prevent the head loss scenario? $\endgroup$ Jul 19, 2019 at 19:27
  • $\begingroup$ @UseitorLoseit that's to help reduce the g-force loading in turns I think... $\endgroup$
    – Solar Mike
    Jul 19, 2019 at 20:01

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