Speed limiters in cars

philthetube

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Incidents like this make me wonder if speed restrictors in cars, h=to hold cars to sp0eed limits should be introduced.


This would greatly reduce car crime and save lives on British roads.

My instincts are against this but the more stup0id things I read about drivers doing, the more I wonder.
 
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Tazi Hupefi

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I've often wondered why cars aren't limited to 80 mph, (given enforcement of a 70 road doesn't start until 79mph).

Only reason I can think is that a relatively small number leave the UK and drive in countries where the speed limit is higher, or use their car on private land / race tracks, although you would think that an authorised garage would be able to disable/enable it for such circumstances, with appropriate auditing and enforcement.

I'm not sure it would actually reduce crime significantly, as cars are not generally being stolen for joy riding anymore, they are usually driven sensibly and quietly away to be cut up. High speed police persuits are relatively rare to start with.

I do think it would improve safety though, and possibly better environmentally.
 

87 027

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Some (most)? modern cars enable the driver to set a speed limiter to avoid accidentally going over the limit but of course this is under the driver's control. An absolute upper limit might be feasible but wouldn't solve the problem of excess speed on roads below the national speed limit. I don't believe technology to enforce lower speed limits and override the driver is yet reliable enough. We discussed this recently - posts 185 and above in the thread below. Post 195 gives the example where a car misread a 50mph sign for 5mph

 

philthetube

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I am not talking about a voluntary system but one where the car enforces speed limits, there should be no need for cars to read signs as GPS technology could deal with this.

Google maps manage to tell me what the speed limit is in any area, occasionally wrong but only because not updated, so it should be possible.
 

Tazi Hupefi

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I am not talking about a voluntary system but one where the car enforces speed limits, there should be no need for cars to read signs as GPS technology could deal with this.

Google maps manage to tell me what the speed limit is in any area, occasionally wrong but only because not updated, so it should be possible.
If you are relying on Google Maps to tell you the correct speed limit, you'll find yourself with penalty points eventually! One of the biggest "defences" raised to speeding is that they were simply doing what the sat nav told them. Speed limits change frequently, and variable speed limits are becoming common. GPS technology isn't the problem, it's ensuring the speed limits themselves are correct, and would need to be in real-time.

You'd probably also not be totally surprised to hear that local authorities are generally so poorly funded these days, or under staffed, or staffed with less experienced recruits that determining what the speed limit actually is, and not just what the sign says, is somewhat more complicated than it seems. From defective Orders to contractors installing signs a couple of metres away from where the speed limit actually starts etc.
 

87 027

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The GPS position needs to be ultra-accurate and there are examples in the other thread of this not being so at the current time. Specifically a newspaper reporting the example of a car on a motorway slamming on the brakes where a road with a lower speed limit crossed over the motorway
 

Bletchleyite

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I quite like having a manual limiter, it stops you going over by accident. Very useful.

I'm not sure what the relevance of speed is to some muppet driving onto a crossing, though?
 

SargeNpton

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I am not talking about a voluntary system but one where the car enforces speed limits, there should be no need for cars to read signs as GPS technology could deal with this.

Google maps manage to tell me what the speed limit is in any area, occasionally wrong but only because not updated, so it should be possible.
Is GPS good enough to differentiate between the 70mph motorway that you are driving on and the 30mph road that it is crossing? Both will have the same GPS coordinates.
 

Bletchleyite

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Is GPS good enough to differentiate between the 70mph motorway that you are driving on and the 30mph road that it is crossing? Both will have the same GPS coordinates.

In my experience definitely not. Some sort of balise system would be needed to make this work reliably and not result in the brakes coming on dangerously on a fast road.
 

philthetube

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If the Muppet was speeding then that would not have been happening, if the car was stolen then far less cars would be stolen, and mort thieves caught then the ability to only proceed at 30mph would make a huge difference to offending rates, massively reducing road deaths and incidents like this on the railway.
 

Bletchleyite

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If the Muppet was speeding then that would not have been happening, if the car was stolen then far less cars would be stolen, and mort thieves caught then the ability to only proceed at 30mph would make a huge difference to offending rates, massively reducing road deaths and incidents like this on the railway.

The best way of dealing with issues deriving from car theft is to stop people nicking cars. Immobilisers make a difference, but maybe there is a need for a further step of some kind.
 

philthetube

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There would be no need to have brakes applying harshly in the event of a perceived overspeed, just preventing acceleration would do the job.

When using Google maps to navigate the only inaccuracies I have seen have been due to input faults, and this should be avoidable in the case of a national system. I have never seen my phone suddenly flash to 30 mph when driving down the Motorway, though I do admit that it picks up speed cameras off other roads.
 

skyhigh

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You'd need a system that could:
Be able to be retrofitted to existing cars
Would need to be tamper proof
Would be able to deal with variable speed limits
Would always be up to date and have correct data
Would be able to tell with complete accuracy what road you're on (particularly where a motorway is parallel to another road, sometimes when it's pretty much only a fence separating them - and I can think of examples like this).

A system like this would be incredibly expensive to implement, in my opinion. Ultimately I think the people who are likely to have high-speed car chases are the people who are most likely to disable the system.

It's also worth noting that in the level crossing incident, even if the car was only doing 30mph into the side of the train it still would have caused pretty major damage.
 

LSWR Cavalier

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The problems seem insurmountable.

Now the cops have free capacity after covid, (did I read about planned recruitment of more officers too?) they should be concentrating on enforcement of maximum speed limits. Need cost nothing, might even make a small profit!
 
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Ediswan

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Is GPS good enough to differentiate between the 70mph motorway that you are driving on and the 30mph road that it is crossing? Both will have the same GPS coordinates.
Some are. They work out which road you are on and do not get confused by such crossings (where there is no junction).
 

87 027

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Out of interest the risk of severe space weather disrupting GPS satellites and/or signal reaching the ground and affecting communications and navigation systems is included in the 2020 UK National Risk Register. Not a problem for sat-nav but of more concern in situations which might be regarded as safety critical
 

Bletchleyite

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Some are. They work out which road you are on and do not get confused by such crossings (where there is no junction).

None of them are quite good enough to be used with automatic vehicle control systems, because the system jamming the brakes on or even a loss of power could be massively dangerous.
 

apk55

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Many insurance companies are now requiring cars to be fitted with an electronic GPS tachograph. So there will be increasingly more requirements for cars to avoid exceeding speed limits and getting warning letters from insurance companies. I personally would like a manual limiter so to help keep to speed limits even though I am very good at keeping to speed limits ( Only one ticket (speed awareness course) in over 40 years of motoring)
 

Bletchleyite

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Many insurance companies are now requiring cars to be fitted with an electronic GPS tachograph.

I've not come across one that has that as an absolute requirement, though some certainly offer discounts for it (which can be substantial if young or inexperienced).

Manual limiters are very common now, certainly pretty much every modern car with cruise control will have it as it's just software on top of the same hardware. I particularly like them for motorway roadworks where it's easy to drift over but it's usually too busy to use non-adaptive cruise control.
 

Ianno87

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If you are relying on Google Maps to tell you the correct speed limit, you'll find yourself with penalty points eventually! One of the biggest "defences" raised to speeding is that they were simply doing what the sat nav told them. Speed limits change frequently, and variable speed limits are becoming common. GPS technology isn't the problem, it's ensuring the speed limits themselves are correct, and would need to be in real-time.

Is GPS good enough to differentiate between the 70mph motorway that you are driving on and the 30mph road that it is crossing? Both will have the same GPS coordinates.

For the race track example, GPS should be good enough to say "I see you're at Brands Hatch, off you go then!" No different to how e-Scooters self-limit their speed in certain areas today.

GPS should not however replace following individual 30/40/50/60/70mph road signage on normal roads; although perhaps could be a blanket 40mph limit in town areas for example (where there are no higher speed roads).
 

Ediswan

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None of them are quite good enough to be used with automatic vehicle control systems, because the system jamming the brakes on or even a loss of power could be massively dangerous.
I would agree with that. Mine shows what it believes the speed limit to be, but has no connection to the cruise control.

There is also the wrinkle that some sections of dual carriageway have different speed limits in different directions.
 

alxndr

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I don't think we're in a position to have anything that limits control of a car based on what the car thinks the speed limit is, using any system that's currently in place. I don't see any reason not to restrict the maximum speed of the vehicle to 70 mph though, as long as there's a way to disable it for using on private roads/racetracks to maintain people's rights to drive faster away from the public (and hefty fines if found disabled on a public road). I frequently drive company vehicles limited to 70 mph, and to be honest, its a less stressful experience knowing that all you can do is get there when you get there.
I don't believe technology to enforce lower speed limits and override the driver is yet reliable enough. We discussed this recently - posts 185 and above in the thread below. Post 195 gives the example where a car misread a 50mph sign for 5mph

I've also seen an example where someone was driving down an access track along the railway and the car set the limiter to 110 mph as it picked up the railway speedboard.

There would be no need to have brakes applying harshly in the event of a perceived overspeed, just preventing acceleration would do the job.

When using Google maps to navigate the only inaccuracies I have seen have been due to input faults, and this should be avoidable in the case of a national system. I have never seen my phone suddenly flash to 30 mph when driving down the Motorway, though I do admit that it picks up speed cameras off other roads.
I've seen plenty of issues, and worse on other sat nav systems. Even other systems of the same model and same age have had different quirks, with the worst being the speed dropping to 50 mph and then 30 mph on the motorway. Slip road speeds are particularly random in my experience, and I wouldn't fancy joining a motorway stuck at 30 mph.
It's also worth noting that in the level crossing incident, even if the car was only doing 30mph into the side of the train it still would have caused pretty major damage.
It might not have made it through the fence though...
 

apk55

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Speed limits do not mean that it is safe to drive at that speed. For example I know of roads with a 50 limit where there are bends that can not be taken at speeds over 30MPH. And situations can develop on a road where it becomes unsafe to go at the road speed. No doubt some idiots will drive on the limiter and crash as a result.
 

CarltonA

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My car has an economy alarm which sounds like a drumroll when exceeding a certain RPM in different gears. The top gear (6th) is set to sound at 66mph. It is fairly annoying so I generally drive below that on the motorway. That to me is far better than setting the speed limiter as it allows flexibility to overtake etc. I get over 60mpg usually which is great for a stingy person.
 

philthetube

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To repeat one point I made earlier, which seems to have been missed by a couple of posters, there is no need to build a harsh brake application into the system, just stopping the ability to accelerate would be enough.
 

mmh

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To repeat one point I made earlier, which seems to have been missed by a couple of posters, there is no need to build a harsh brake application into the system, just stopping the ability to accelerate would be enough.

I have to wonder then what the actual point of such a system would be. In my local area the road which must have the highest amount of speeding is a few miles of 50mph dual carriageway, sandwiched by 30 miles plus of a continuous 70mph limit. (The road itself doesn't change in quality, but has a lower speed limit as that section is through a town and has substandard short sliproads) On this road invariably the left lane is doing exactly 50mph, the right lane for those ignoring the limit and doing 60 plus. Your system would prevent few from speeding there, but would make it considerably more dangerous.
 

Nippy

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My car has an economy alarm which sounds like a drumroll when exceeding a certain RPM in different gears. The top gear (6th) is set to sound at 66mph. It is fairly annoying so I generally drive below that on the motorway. That to me is far better than setting the speed limiter as it allows flexibility to overtake etc. I get over 60mpg usually which is great for a stingy person.
What car is that? So I can avoid it whilst looking for my new one......
 
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Bald Rick

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My car has an economy alarm which sounds like a drumroll when exceeding a certain RPM in different gears. The top gear (6th) is set to sound at 66mph. It is fairly annoying so I generally drive below that on the motorway. That to me is far better than setting the speed limiter as it allows flexibility to overtake etc. I get over 60mpg usually which is great for a stingy person.

That sounds awful, in every sense.

What car is that? So I can avoid it whilst looking for my new on

Agreed!
 

87 027

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To repeat one point I made earlier, which seems to have been missed by a couple of posters, there is no need to build a harsh brake application into the system, just stopping the ability to accelerate would be enough.
The original question though was about holding cars to speed limits…


I have to wonder then what the actual point of such a system would be. In my local area the road which must have the highest amount of speeding is a few miles of 50mph dual carriageway, sandwiched by 30 miles plus of a continuous 70mph limit. (The road itself doesn't change in quality, but has a lower speed limit as that section is through a town and has substandard short sliproads) On this road invariably the left lane is doing exactly 50mph, the right lane for those ignoring the limit and doing 60 plus. Your system would prevent few from speeding there, but would make it considerably more dangerous.
Quite
 

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