Law Enforcement Vehicle Chase Quesiton

OP returning.

It appears, particularly from the initial responses, that many have misunderstood my question. I am not asking why police do not open up, guns blazing with all available firepower, any time the believe the possibility exists they might be able to hit the radiator of a fleeing vehicle. I had thought I was clear on that, but apparently not.

What I am asking is why they never employ a strategy of using a sharpshooter with an accurate, small caliber weapon to disable the cooling system of a fleeing vehicle. Do a google search on lengthy police chases where they chase the fleeing vehicle for dozens of miles, down limited access highways. The police often will close the entrance ramps in advance of the fleeing vehicle. I listed two such occurrences in my OP, there are many others.

The use of spike strips is fairly routine these days, and if they have the time to set up a spike strip deployment, they could probably get a sharpshooter in place. If done intelligently, the vehicle operator probably wouldn’t even know what was going on, at least until the “check engine light” came on, and even then, he’d probably just ignore it. Those in pursuit, however, would know immediately if the hit was successful as the smell of anti-freeze is quite distinct and unmistakable.

And, yes, it just is true that an ICE will be severely disabled in a matter of minutes if it looses coolant. A modern one would probably simply shut the engine off when the temperature got too high, while an older one would last until it blew a head gasket. When that happens, it might still run, but not in any big hurry and not for very much longer. Yes, the Navistar engines a while back were capable of running about 50 miles or so with no coolant, but they wouldn’t go much longer without shutting down, and during that time, they did not make much power.

What’s the annual cost of maintaining the satellite system and the laser equipment in all of the squad cars? pkbites speaks as though these are free.


Guns are dangerous, even in the hands of a sharpshooter. You’re asking for a shot to be made on a vehicle moving at high speed. The shot is going to be taken in the same general direction as the pursuing police cars, and potentially other cars as well. Once the car is in range, the shooter has at best a couple of seconds to take the shot, the range of which is going to change constantly until the car is past the shooter.

It’s a terrible, unsafe, unlikely shot given the circumstances it’s likely to occur in. The only benefit of which is to end a chase quickly. Chases tend to be dangerous only when they occur at high speed which makes your shot even less safe.

This guy estimates about 411,000 police vehicles in the US. Suppose the equipment costs $5K per car and lasts ten years, so $500 per car per year * 411K cars equals $205.5M per year (although somebody ought to check my math). Add that to my $680M figure from earlier, and we’re at $895.5M. Divide by 350 lives saved, and you get a per-life cost of $2.6M. So it’s still looking pretty good on a cost basis.

I’d still like to understand how the satellite and GPS are involved. ISTM that if the fleeing vehicle is OEM-configured to respond to a police-issued laser code, then there would be no need for anything else; it’d be like pointing your remote at the TV and pushing the “OFF” button.

As it happens, GPS tagging systems cost about $5K per police vehicle. This is a vehicle-mounted system that fires a GPS receiver; the projectile sticks to the fleeing vehicle and then broadcasts location/direction/speed so that pursuing officers can fall back and pursue them discreetly from a distance, which encourages the suspect to resume a sane driving speed. This system doesn’t rely on any OEM-installed equipment on the fleeing vehicle, so $205.5M would be the total nationwide cost for 100% implementation.

Asking a sniper to do that is like asking them to shoot a gun out of someone’s hand; It may sometimes happen but not with enough reliability to be a main option.

The best firing spot would be facing the target vehicle which would mean that pursuing police vehicles would be downrange of the target.

Y’all a bunch of pessimists. I’d be willing to bet a .50 cal could get a bullet through the radiator via the rear license plate. Might even give the driver a reason to reconsider his egress strategy.

Should work to disable; worst case, you could go to 20 mm, or just hit it with an EMP.

OK, as an engineer, I see all kinds of problems with this magical “shoot a laser to stop a car” sytem.

  1. Where is the sensor? Does the cop have to aim at a specific spot, or are there sensors all over the car to cover all possible angles?
  2. What’s to stop all the other cars that receive indirect or reflected signals from responding?
  3. (The big one). As soon as this is implemented, what’s to stop hackers (like, for instance, me) from reverse-engineering this, and harassing innocent drivers?
  4. If this system is widely implemented, dedicated car thieves will simply carry Cellular jammers.

Probably a better idea, and much easier to implement is keyless ignition with biometric ID.

To expand on this, assuming the sniper-officer is ahead of the chase & has his sniper rifle with him (& not stored in the SWAT truck), find a safe place to set up (the car is coming at you, you don’t want to be in the middle of the road, or even on the far side of your patrol car in case fleeing suspect hits your sniper’s vehicle & moves it into the sniper), gets the rifle out, calculate wind, distance, & elevation. You’d want the bullet & grill to meet at a set point (next to a sign, the end of a bridge, painted line in road, etc). Don’t forget for the bullet to get to the designated spot in the road you’d need to be able to calculate the speed of the car & hope he doesn’t speed up/slow down from the last report by a pursuing patrol car.

All of this is assuming that the suspect is probably on an interstate, without (m)any places to turn off; otherwise, the sniper is setup in the wrong place because the fleer turned. You also don’t want any civilian cars on the road (or any civilians downrange); it would be very bad PR to shoot an innocent civilian; have them lose control & wipe out, taking another car out at the same time, killing a couple of families.

Finally, remember snipers tend to be slow & methodical not rushing into their shot.
It would be far better to give PD helicopters offensive capabilities.

How will keyless ignition with biometric ID stop a fleeing vehicle?

As for your questions, here are some off-the-cuff answers about a hypothetical laser-based system for remotely disabling fleeing vehicles:

#1: Since the pursuing officer would be behind the fleeing vehicle, it would make sense for the receiver to be on the back of the fleeing vehicle.

#2: The transmitted signal could include information about compass heading, speed, or other details unique to the fleeing vehicle that would help ensure that only the fleeing vehicle gets disabled (e.g. “if you are receiving this signal AND you are on a compass heading of 185-195 AND you are moving at the same speed as this pursuing vehicle +/- 5 MPH, bring the engine to idle and apply moderate braking.”). Or an automatic license plate reader could read the plate, query the DMV for the VIN, and then transmit a laser signal that disables only the vehicle encoded with that VIN. A plate reader would not work well for cars with wrong/no plates, but I think such vehicles are not in the majority.

#3: Legal penalties would be one deterrent. A system that included a plate reader and DMV database access (the latter being forbidden to the general public) would also make it difficult for any hacker to succeed without engaging in cybercrime, which would be more risky than just blasting random cars with a disabling signal.

#4: a cellular jammer wouldn’t work against a laser-based device.

Your last point (and your comment about biometric ID) suggest an unwarranted focus on stolen vehicles. I don’t know the stats, but I’ll wager many (if not most) police vehicle pursuits don’t involve stolen vehicles, and those that do involve stolen vehicles aren’t typically driven by dedicated car thieves who think the whole thing through and take the time to defeat any remote-disable devices. Most pursuits just involve people with warrants, drugs, or bad attitudes driving an unstolen car. In general, it’s people who have a habit of not planning ahead very far in their daily life.

Wouldn’t the whole system be vulnerable to a piece of duct tape or coat of paint over the laser receiver? :confused:

See above re: people who have a habit of not planning very far ahead.

So, a system that will only work on the law-abiding and dumb criminals? :slight_smile:

Most of the people who run from police are dumb. Not an insult, just a fact. You can flatten their tires with spike strips so that they’re skittering around on rims at 5 MPH, and they still won’t give up, even when the impending outcome (arrest) is obvious. A system that relies on the stupidity of people who tend to flee from cops will probably be mostly successful.

To prevent tampering with the system by people with foresight and ill intent, it could be designed to do a self-diagnostic check at startup, and prevent the car from driving more than, say, 25 MPH until it gets fixed. There is precedent for this (i.e. automatically disabling a tampered vehicle) in diesel-powered vehicles that use SCR technology for emissions control. These vehicles consume diesel exhaust fluid from an on-board tank that the operator must periodically refill. If the tank gets empty (or the operator fills it with plain water), the system will put the engine in “limp home” mode (i.e. low power only) or disable it altogether in order to prevent the vehicle from operating in a non-emissions-compliant state.

You don’t think the auto industry ate the cost when airbags were mandated, do you?

The GPS system is already in service and is basically free.

That’s not the system I’m talking about. In fact, the info video I saw at the conference I attended made claim that their system was much better and cheaper than this and could even be installed into currently used laser speed guns for a few hundreds dollars.

Are GPS satellites capable of receiving and re-transmitting messages from the ground?

The more I think about it, the more the satellite sounds like some extraneous Rube Goldberg addition to the whole thing. Why wouldn’t the laser devices that are used to identify the cars (presumably by communicating with the other car’s device?) just send the stop signal directly?

Of course not. The bill always gets paid by the end customer. When the FAA mandates safety features/policies for commercial air travel, ticket prices rise. When the EPA mandates new emissions controls for cars, the prices of cars rise. If police intervention features are mandated for privately owned cars, the price paid by the buyers of those cars will again rise (and taxpayers will foot the bill for the extra equipment in police cruisers). This should not be surprising or controversial. We as a society pay more money for these things and we as a society reap the benefits of safer air travel, cleaner air, and fewer police pursuits with tragic outcomes.

Still not understanding how the system you were describing is supposed to work. How and to whom/what does the laser ID the car? How does GPS factor into this?

Yep, that much was clear since there’s no laser involved nor any disabling of the fleeing vehicle.

Are there any military-trained sharp-shooters or snipers aboard?

I’m going to admit very readily that, while I have range experience with pistols, rifles, and even a machine-gun, my knowledge of sniping comes only from First-Person Shooter video games. In those games, I’m not seeing a whole lot of motion; I’m sitting and waiting for a guard to come to the apex of his patrol rounds and putting a round through the base of his skull when he stops and pivots.

The OP’s ideal scenario would seem to be of a sniper sitting on a freeway overpass and shooting a speeding car that’s going to be heading underneath that overpass.

Assume a fleeing driver is moving at regular Los Angeles County empty freeway speed (i.e. 85 MPH to 90 MPH in a 65 MPH zone),
You want a sniper to hit a 2-foot high area with a projectile that’s between a quarter-inch and a half-inch. That projectile is moving – how fast? What speed toward the target-vehicle?

Can somebody figure out the geometry and math for me?



Assuming the super-sniper’s mental calculations are perfect, what’s the duration of the intersection of the blue back-slash and the red vertical pipe? In other words, how long is that radiator going to stay in that temporal shot-window? Hell, how long will the front of that car – call it roughly a five-foot height – be present above that green caret? How far ahead does our super-sniper have to aim? How much of a visual field does a good Leupold@ scope give the shooter – enough to see the car approaching AND the target-intersection at the same time?

If my super-sniper* shoots too early or calculates ahead of the approaching vehicle, he’ll be lucky if the bullet bounces off the pavement and ricochets up underneath the car where it will bounce around a bit, relatively harmlessly like a stone that fell off a construction truck. More likely, it’ll bounce off the pavement and become an airborne hazard for the driver and all the pursuing officers in their cars. If he shoots late and/or the approaching vehicle is moving faster than he expected, he’ll be lucky if the bullet goes through the target-vehicle’s front windshield% but, more likely, it will miss the target-vehicle and become an airborne hazard for the officers following in pursuit of our suspect.

You’re asking a HUMAN to do this?
Nah, don’t be nervous; there’s no pressure. It’s only the lives of your fellow officers (and the semi-related lives of their spouses and children) at stake here.
[My apologies for the crappy art – what’d’ya expect from ASCII characters?]
@ Well, that’s the one I used in Ghost Recon

  • We’re talking Martin Riggs, here, a guy who “did a guy in Laos, once, at 600 yards in high winds. There’s maybe ten guys in the world who could make that shot!”
    % and perhaps the driver and/or a passenger or two and maybe the rear windshield where it becomes an airborne hazard again.

I’m not aware of any part of the GPS system already in service that can shut down a vehicle’s engine, but maybe I’m not understanding how this system is supposed to work. Can you elucidate?