We've just seen another attack where a vehicle was used as a weapon. My thoughts are with all those affected by the tragedy.

Many people are wondering how such attacks can be stopped. It's hard for intelligence to detect: a lone terrorist, no communications, no need to acquire weapons or suspicious chemicals. Sensitive facilities, such as airports and transport hubs already have bollards to prevent such attacks. But this doesn't help when ad-hoc crowds form, such as Bastille Day.

Could technical controls in vehicles prevent such attacks? A vaguely similar approach is used in high-quality colour printers to stop counterfeiting. Indeed, many cars have a number of sensors that can detect collisions, and some already take automatic action to avoid collisions.

It's not clear if these would stop a terrorist: perhaps they would stop a drunk driver mowing down a crowd, but a terrorist will try to disable the safety feature. And there are new safety risks if we prevent drivers overriding such systems: they may prevent a driver taking desperate action to avoid a tragedy.

To keep this question in line with Stack Exchange rules: answers must be evidence based, and focus on the question: Can technical controls prevent vehicle ramming attacks? This is not the place for open-ended discussion of vehicle safety or terrorism.

  • I don't see it mentioned elsewhere, but collision avoidance is already present in many new vehicles. Easy to get hold of a vehicle without it, and probably easy to disable though. This doesn't need to be specifically targeted at terrorism. Jul 16, 2016 at 7:55
  • Call me a cynic, but I don't think targeted attacks can be stopped by tech. If you don't take away the source of their motivation, people will always find a way to harm others if they really want to.
    – Jacco
    Jul 17, 2016 at 12:49

4 Answers 4


Bollards are the traditional approach. Normally to prevent vehicles from attacking high-value targets such as banks, embassies, etc.


In this shot in Istanbul, they protect sidewalks.


They can be disguised as flower boxes, benches, street lights, garbage bins, etc, etc. The important part is to make sure there are no gaps... and that they're not run-of-the-mill street furniture, but genuinely tough enough to stop a truck.

For the situation in France, it might have given people who ran off the street some immediate protection, and may have stopped the truck before it could do much more harm.

It might not be high tech, but low tech is a kind of tech.

Looking at Google streetview, the location had no protections at all: https://goo.gl/maps/KjuXwxHHnM62

  • 1
    Sensitive facilities, such as airports and transport hubs already have bollards to prevent such attacks. But this doesn't help when ad-hoc crowds form, such as Bastille Day.
    – paj28
    Jul 16, 2016 at 6:25
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    See the photo of the Istanbul street, and also notice they use them on parts of the Promenade: goo.gl/maps/GYgnhMAft3F2
    – mgjk
    Jul 16, 2016 at 12:08
  • Ok, thanks. I had originally written off bollards because you can't have them everywhere. But hey, every defence has its flaws. Bollards hit the sweet spot of fairly decent protection without excessive interference.
    – paj28
    Jul 18, 2016 at 10:32
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    Concrete Jersey barriers are mobile and can be as effective as bollards. I don't have technical details, so I'm not going to post this as an answer.
    – A. Darwin
    Jul 24, 2016 at 8:35

In-vehicle controls are probably a nonstarter because they are too prone to disabling and there are way too many cars on the road already without it in any given country (see also: the problem with Gun control). The weak points to a vehicle attack are: 1) it is so large you cant possibly conceal it prior to the attack and 2) the vehicle itself (typically) relies on a number of electrical systems to keep going. There actually is a technology already developed to take advantage of this: directed EMP devices. If vehicle based attacks continue, I would expect police to start deploying these as a countermeasure.

  • 3
    Can't conceal it? Which one is the terrorist? The directed EMP device is interesting though.
    – paj28
    Jul 15, 2016 at 19:58
  • 2
    Oh, that would be even crazier than the UK trying to ban crypto
    – Rory Alsop
    Jul 16, 2016 at 7:06
  • @paj28 if someone stuck in a traffic jam acting erratic and hostile qualifies as a terrorist, we would fill 10 gitmo's a week... j/k but the point is that you can always see a vehicle coming, you dont need a body scanner or metal detector or sniffing dog (to compare to the other typical terrorism methods)
    – Jeff Meden
    Jul 17, 2016 at 17:21

I do not think an in-vehicle solution would work. What prevents terrorists from building their own vehicle that does not include such solutions? Given that they already produce bombs, they could definitely produce a deadly vehicle out of an old tractor and some steel. This has already been done and the result wasn't pretty - thankfully he was aiming for mass property destruction rather than killings.

The best technical solution would simply be hard to pass barriers that let light vehicles pass while being very hard to cross for heavy vehicles, even via brute force. At the very least, this would prevent terrorists from bringing heavy vehicles, even though a light vehicle could still do damage.

In the end, terrorism is a human problem, not a technical one and no technical solutions will completely solve it. We can make it harder of course, but there will always be incidents until the source of the evil is destroyed or at the very least prevented from enrolling new members (by poisoning their communication channels like social networks with policemen posing as wanna-be terrorists).


There is a system already in use by the military to help prevent sudden jams in flight controls in helicopters from damaging the control system as a whole. Shear Pin Actuated Decoupler(SPAD) pins break free when this occurs and causes the helicopter to have to change to a different method in order to continue control of the aircraft.

I believe a system like this could be implemented in vehicles. Something along the lines of SPAD's being implemented to break free and cause the vehicle gas pedal to no longer function when to much force is applied. ie. smashing the gas pedal would cause the SPAD to shear and render the pedal dis-functional. Emergency vehicles could easily be left out of this system implementation.

Obviously there are ways around this so the SPAD system would need to be applied in an area of the acceleration assembly where it would be the most difficult to tamper with.

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    You don't need to smash the gas pedal to kill people, even a gentle acceleration is enough on a big vehicle like a truck. On the other hand, there are some situations where you need to smash the gas pedal to not get killed. Jul 15, 2016 at 20:54

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