Here's a scenario that happens all the time: the police have engaged a criminal in a high speed car chase. Or imagine this scenario: a possible terrorist is driving a truck toward a sensitive building. How can police stop these vehicles?
The spike strip is the most common technology in use today. It is a very simple device - a strip covered in hollow spikes. Once a car runs over a spike strip, all four tires go flat. You can see a spike strip in action at the beginning of this video:
As the video points out, however, spike strips do not disable a vehicle. Even with flattened tires, the vehicle can still move. And many cars now have run-flat tires
The video then demonstrates the next generation in spikes - the X-Net. The idea here is entanglement. A full-size net wraps itself around both front tires and locks them up. The car (or truck) skids to a stop and can't move any further.
For even more advanced entanglement, there's the SQUID (Safe Quick Undercarriage Immobilization Device), which you can see stopping a truck here:
The SQUID is a lot more complicated than the X-Net. The advantage of that complexity is that the SQUID can sit harmlessly on a road until it is triggered by a radio signal. Here's what happens once triggered:
1) Six long barbed strips shoot out of the SQUID base horizontally. The strips are made of strapping that gets entangled in the axles like the X-Net.
2) Then a second set of lines, triggered by an infrared sensor looking for the heat signature of the engine, explode vertically out of the base and into the undercarriage.
What the SQUID hopes to avoid is this kind of situation where the spike strip disables a police car.
The next level of deterrent uses electromagnetic pulses to blow out a car's computer system and kill the engine. This video shows the effect of EMP on a car:
These articles describe a pulse beam that can stop a car 50 meters away using the same kind of pulse:
The ultimate approach would be to build cars so that police can stop them on command. For example, OnStar is experimenting with the ability to stop cars that have been reported stolen:
Police would like to extend this ability to any car:
According to the article:
This tracking system uses satellite navigation to locate a car, whose position is shown on a website. The car is also fitted with a receiver which can receive text messages.
Should the car be stolen the owner – or a company acting on his or her behalf – can use a text message to send instructions to the car's on-board computer.
It can switch on the headlights, sound the horn, slow the car down or – if it is stopped – immobilise it completely.
According to Police Review, officers would welcome access to the technology as an alternative to devices such as "stingers", which they currently use.