Speed limiters in cars

[LSWR Cavalier]

Two people killed in 'accidents' caused by going too slow. All the rest killed by excess speed.

 

[A0wen]

They used to hide behind a hedge on my drive home. It was entertaining to stay in low gear and gun the engine then grin at their disappointed faces as I trundled by at 30.

The people who participate in things like "Community Speed Watch" schemes are the ultimate 'shop thy neighbour' meddlers - the kind of people who write complaint letters to their MP and local papers in green ink.

 

[Bletchleyite]

The problem with speeding is it's easy to measure, automate and prosecute, especially cars (it's harder to trigger a camera specifically for a hgv so limits are set to the maximum (car/bike) limit, and nobody enforces vans doing 65mph on a dual carriageway, or lorries doing 50 up a single carriageway).

In England lorries are now able to do 50 on a single. The safety benefit of reduced overtaking was seen as better than the disbenefit from faster moving lorries.

For some reason Scotland didn't follow suit.

Motorways really are the safest roads.

Agreed.

 

[Meerkat]

Two people killed in 'accidents' caused by going too slow. All the rest killed by excess speed.

All the rest of what?

 

[Bletchleyite]

Two people killed in 'accidents' caused by going too slow. All the rest killed by excess speed.

It's fairly rare for excess speed to be the cause of an accident on a motorway. It is normally a factor that makes the outcome more severe.

 

[Domh245]

Two people killed in 'accidents' caused by going too slow. All the rest killed by excess speed.

Rather presumptuous...

There's a whole load of data around contributory factors, and the number of accidents (I couldn't find the data set that does individual K/SI by contributory factor - only numbers of incidents RAS50002) and "excess speed" was a contributory factor in 136 fatal incidents, whilst exceeding speed limit was factor in 203.

The largest contributory factor to fatal incidents in 2017 was "loss of control" at 395 incidents, and "driver/rider failed to look properly" at 386.

Nice try - but somebody has to programme a computer. So all you're doing is moving *which* human controls the vehicle and I'm not sure I'd trust the Musk-rat or the likes of Apple with that.

But once programmed, by multiple people (and ideally an industry standard 'box' that does it all) the chance of errors are much lower than thousands of individuals. It also makes it a damn sight more predictable which is probably one of the biggest issues of squishy drivers!

It's very unlikely to be Musk himself (I'd be frankly terrified if it was his own coding on live vehicles), and I'd also much rather have a "legacy" automotive industry group tackle it than a "big tech" firm.

 

[LSWR Cavalier]

The people who participate in things like "Community Speed Watch" schemes are the ultimate 'shop thy neighbour' meddlers - the kind of people who write complaint letters to their MP and local papers in green ink.

I do voluntary work too, in a quite different field. I should not like to do police work for them, without pay!

Where I live delivery vans are often parked with the engine running, one can imagine what might happen if a vehicle rolled away. Seems a very good case for vigilante cooperation: stop the engine, sieze the keys and wait for the cops to arrive to give the driver a good talking to!

 

[ABB125]

In England lorries are now able to do 50 on a single. The safety benefit of reduced overtaking was seen as better than the disbenefit from faster moving lorries.

For some reason Scotland didn't follow suit.

Possibly for the same reason that coronavirus rules are different in Scotland? Though they have sort of realised how foolish the decision not to increase the limit was, by allowing 50mph on the A9... (Yes I'm aware that on many Scottish roads, even 30mph in a lorry would be somewhat risky.)

The one thing that I don't understand is why vans still have a lower speed limit than cars. Modern vans are just as safe as cars, and just as capable of braking well. Why is it acceptable for a van to do 70mph on the M50 (with its narrow lanes in places), but only 60mph on the brand new A14 near Huntingdon (a road which is built to far higher standards)? Similarly with most high-quality non-motorway dual carriageways in this country (A34, A14, A42*, A50, A13, A2 etc, most of which would be motorways in any other country).

*This one is especially ridiculous: all that changes as you drive through the junction at Appleby Magna is the hard shoulder disappears.

 

[bramling]

It's fairly rare for excess speed to be the cause of an accident on a motorway. It is normally a factor that makes the outcome more severe.

This is exactly the problem. Like with Covid where things degenerated to an obsession with toilet rolls and masks, with roads the cause of all evils seems to be speed.

This completely ignores the fact that most accidents are caused by things like pulling out without looking, botched overtakes, misjudged lane changes, failure to anticipate a hazard, distraction, etc.

 

[LSWR Cavalier]

Depends what one means by speed.

I should include: following too close, driving while intoxicated, eating, drinking, telephoning, driving while tired (max speed zero). Failure to yield, many times there is a crash at 5 mph where the right speed would be zero.
Etc etc

 

[miami]

There's a whole load of data around contributory factors, and the number of accidents (I couldn't find the data set that does individual K/SI by contributory factor - only numbers of incidents RAS50002) and "excess speed" was a contributory factor in 136 fatal incidents, whilst exceeding speed limit was factor in 203.

I'd love some data on the number of people driving by the speed they drive at. I suspect that accidents with people driving significantly below the prevailing road speed (say the idiots doing 45 down the motorway) is a far higher proportion than those doing 70, or even 80. I.E. I strongly suspect the probability of accident given car driver driving too slowly on the motorway is higher than the probability of accident given car driver driving at the prevailing vehicle speed. Alas that's not data that's likely to be captured accurately enough.

But we do know that the vast majority of KSIs are not on the motorway, that motorway speeds are higher than non-motorway speeds, that the KSI/vehicle mile is lower on motorways than any other roads, that the majority of KSI accidents do not involve excess speed (of any type), and that in general it's not speed that kills, it's bad driving. But it's easier to measure speed, so bad drivers (say ones who have no idea what a traffic sign means) get to stay on the road.

 

[LSWR Cavalier]

I know that some people drive quite slowly on the motorway, I leave plenty of space so they do not 'surprise' me.

Some oversize transports go slowly, but smaller vehicles may be going slow, for whatever reason. It is my responsibility not to crash into them.

 

[Bletchleyite]

Depends what one means by speed.

I should include: following too close, driving while intoxicated, eating, drinking, telephoning, driving while tired (max speed zero). Failure to yield, many times there is a crash at 5 mph where the right speed would be zero.
Etc etc

OK, if you look at it that way I revise my statement thus:

It's fairly rare for exceeding the posted speed limit to be the cause of an accident on a motorway. It is normally a factor that makes the outcome more severe.

 

[A0wen]

I do voluntary work too, in a quite different field. I should not like to do police work for them, without pay!

Where I live delivery vans are often parked with the engine running, one can imagine what might happen if a vehicle rolled away. Seems a very good case for vigilante cooperation: stop the engine, sieze the keys and wait for the cops to arrive to give the driver a good talking to!

A vehicle would only roll away if left in neutral with no handbrake on - irrespective of whether it's engine is running, so that's a pretty daft comment.

And if you're doing regular drop deliveries you're in and out the van all the time, the regular start / stop of the engine can actually cause more problems than leaving it running.

 

[Bletchleyite]

The one thing that I don't understand is why vans still have a lower speed limit than cars. Modern vans are just as safe as cars, and just as capable of braking well. Why is it acceptable for a van to do 70mph on the M50 (with its narrow lanes in places), but only 60mph on the brand new A14 near Huntingdon (a road which is built to far higher standards)? Similarly with most high-quality non-motorway dual carriageways in this country (A34, A14, A42*, A50, A13, A2 etc, most of which would be motorways in any other country).

The dualled A5 after the end of the M54 is similar, and what is locally known as the A5D (diversionary) through MK is also a near-motorway-standard dual carriageway. Indeed other than that it's legal to cycle on it (though practically nobody ever does as it'd be grim and there are plenty of decent alternatives) it basically is a motorway now you consider that they don't require a hard shoulder any more. And then you've got the A55 up the North Wales Coast, part of which even has motorway restrictions (no cyclists etc) but isn't a motorway because they skimped a bit on some junctions and a hard shoulder.

I would agree that this differential is out of date and harks back to vans being far poorer to handle and with far poorer brakes than cars. That the exact same van with windows and seats in the back (I'm thinking Berlingos, Tourneo Connects etc) get the car limits just proves it's silly. They really should be brought into line.

I think what I'd do as part of such a thing is change the car and van national limits thus:
- Single carriageway 50mph (that would eliminate all overtaking except of very slow vehicles and so be a huge safety benefit, and many are now signed 50 anyway)
- Dual carriageway without a central reservation crash barrier (e.g. most of MK) 60mph
- Dual carriageway with a central reservation crash barrier as per motorway speeds

A vehicle would only roll away if left in neutral with no handbrake on - irrespective of whether it's engine is running, so that's a pretty daft comment.

There are a few reasons for not being supposed to leave engines running when away from the vehicle, but you're right, that isn't one of them. Theft is one (and accidents potentially caused by the thief), and another is the environmental issue of idling engines.

And if you're doing regular drop deliveries you're in and out the van all the time, the regular start / stop of the engine can actually cause more problems than leaving it running.

This is not true of modern vehicles. If it was, they wouldn't be provided with "start-stop" facilities for use in stop-start traffic and at traffic lights.

 

[A0wen]

This is not true of modern vehicles. If it was, they wouldn't be provided with "start-stop" facilities for use in stop-start traffic and at traffic lights.

The use profile of commercial vehicles is quite different to private cars - the regularity of stop / start would put much more strain on the engine and electrics in a commercial environment than for the usual use of a car by a private motorist. I have to say I *hated* the stop / start my last car had, infuriating. Ended up switching it off.

It's very unlikely to be Musk himself (I'd be frankly terrified if it was his own coding on live vehicles), and I'd also much rather have a "legacy" automotive industry group tackle it than a "big tech" firm.

Not sure I'd trust VW, BMW et al that much more. Emissions scandal anyone ?

 

[Bletchleyite]

The use profile of commercial vehicles is quite different to private cars - the regularity of stop / start would put much more strain on the engine and electrics in a commercial environment than for the usual use of a car by a private motorist.

No, it wouldn't. Modern engines are fine with it, the stop won't be for long enough to significantly affect the temperature of the engine, and vehicles so fitted are generally fitted with beefier starter motors and batteries to take account of the more frequent use.

I have to say I *hated* the stop / start my last car had, infuriating. Ended up switching it off.

No bias there at all then

I don't see what's not to like about it. It saves you fuel and saves pollution with no significant adverse consequence. And when you drop the clutch to engage a gear, it has restarted before you can even push the lever into gear.

 

[A0wen]

No, it wouldn't. Modern engines are fine with it, the stop won't be for long enough to significantly affect the temperature of the engine, and vehicles so fitted are generally fitted with beefier starter motors and batteries to take account of the more frequent use.



No bias there at all then

I don't see what's not to like about it. It saves you fuel and saves pollution with no significant adverse consequence. And when you drop the clutch to engage a gear, it has restarted before you can even push the lever into gear.

Except the very act of regular start and stop *does* wear engines and other components, you can "beef them up" all you like, but you're having to do that to offset some of that additional wear & tear.

And it's debateable whether or not it actually *saves* fuel - because again, more fuel is used starting the engine than if the engine had been left idling for a short time.

Not for the first time such benefits are more about "virtue signalling" than actual, tangible benefits. And often they are the exact opposite for the person who owns the product as they are paying more for an inferior product.

 

[Bletchleyite]

And it's debateable whether or not it actually *saves* fuel - because again, more fuel is used starting the engine than if the engine had been left idling for a short time.

No, it isn't. Are you thinking of fluorescent lighting?

 

[LSWR Cavalier]

A vehicle would only roll away if left in neutral with no handbrake on - irrespective of whether it's engine is running, so that's a pretty daft comment.

And if you're doing regular drop deliveries you're in and out the van all the time, the regular start / stop of the engine can actually cause more problems than leaving it running.

If the handbrake is used a lot the cable could break at any time, it might not even be pulled tight. Maybe one time in a thousand the van might roll away, with consequences suitable for a disaster movie.

Leaving a vehicle with the engine running could entice someone to steal the vehicle. Besides, it is illegal, or should be. Perhaps the drivers should get trolleys and walk more, instead of driving 20m between stops.

Imagine what could happen if a van rolled away on a steep Street in Bristol or Sheffield!

 

[Bletchleyite]

If the handbrake is used a lot the cable could break at any time, it might not even be pulled tight. Maybe one time in a thousand the van might roll away, with consequences suitable for a disaster movie.

What has that got to do with leaving the engine running? It's not normal practice to park in gear without the handbrake in 2021, that's old-fashioned practice from when handbrakes were not very good.

Leaving a vehicle with the engine running could entice someone to steal the vehicle. Besides, it is illegal, or should be.

Yes, that's one of the reasons you should not leave a vehicle unattended with the engine running. Furthermore if it's nicked your insurance will not cover you.

 

[AM9]

I would agree that this differential is out of date and harks back to vans being far poorer to handle and with far poorer brakes than cars. That the exact same van with windows and seats in the back (I'm thinking Berlingos, Tourneo Connects etc) get the car limits just proves it's silly. They really should be brought into line.

I would think that vans are often running around at their maximum loading weight (and sometimes in excess of that) so their suspension, tyres and brakes are much nearer to their limits than their car equivalents. There are also many vans with drum brakes where drums are pretty rare on passenger cars these days. Many smaller vans are effectively just cars with the rear seat removed and a reinforced load floor fitted. Take the Ford Fiesta van, a very popular vehicle which according to Ford's own publicity is as I said above, the three-door fiesta hatchback with the mods to make a loadspace. In it's spec. though it's payload, is much higher:

car kerb weight 1152Kg, gross weight (which includes driver, all passengers and any other luggage) 1516Kg​

van kerb weight 1105Kg, gross weight (which includes driver, all passengers and a maximum payload) 1635Kg​

i.e. the van has nearly 50% more payload than a car running on the suspension/brakes/tyres.
So the likelihood is of a van with its safety related components working much nearer their maximum designed level which ultimately affects the response to an emergency brake/steering action. Having a lower speed limit for vans is not an unreasonable restriction on safety grounds.

 

[LSWR Cavalier]

I broke two clutch cables on a French van, they are wire bowden cables. Do modern vehicles have such cables to hold the parking brake? Or is the system 'fail-safe'?

Just read about the cops stopping a vehicle rated 3500 kg, it seemed to be sitting low, weighed over 7000 kg loaded.

I guess modern engines wear and deteriorate too, eventually.

 

[ainsworth74]

Maybe one time in a thousand the van might roll away

I'm pretty confident that a failure rate of one a thousand on a handbrake, or at least a handbrake on a car built in perhaps the last thirty or forty years, would not pass muster from a quality control perspective and the automotive company selling such a vehicle would have been forced into recalling it. Dunno quite how often I put the handbrake on/off but I'd gamble my Fiesta over it's 81,000 miles of usage has seen the handbrake used several times more than a thousand times (possibly an order of magnitude greater) and so far I have yet to have it fail.

 

[Meerkat]

thus:
- Single carriageway 50mph (that would eliminate all overtaking except of very slow vehicles and so be a huge safety benefit, and many are now signed 50 anyway)
- Dual carriageway without a central reservation crash barrier (e.g. most of MK) 60mph

No no no no no! In modern cars that is far too slow.
It would be less painful (and less annoyingly wasteful) if they engineered down to the speed limit.
The M74 into Glasgow and Kingskerswell bypass are ridiculous - lavishly engineered roads with 50 limits. All that wasted land and money to make really annoyingly slow roads.

 

[miami]

That the exact same van with windows and seats in the back (I'm thinking Berlingos, Tourneo Connects etc) get the car limits just proves it's silly.

Haven't looked into it in depth as I don't drive one, but my understanding is car derived vans like that would have car limits. It's only things like transits which have van limits.

? It's not normal practice to park in gear without the handbrake in 2021

I get the feeling some drivers on the road still think double-de-clutching is still best practice.

I did have a terrible rental once with an electronic handbrake, and a Microsoft logo right next to it. Made double sure when I parked on a hill to point the wheels into the hedge and leave it in an appropiate gear

 

[Bletchleyite]

Haven't looked into it in depth as I don't drive one, but my understanding is car derived vans like that would have car limits. It's only things like transits which have van limits.

Berlingos, Tourneo Connects etc are van derived cars, not the other way round. The car gets the car limits but the van gets the van limit.

Yes, it's silly.

I get the feeling some drivers on the road still think double-de-clutching is still best practice.

I did have a terrible rental once with an electronic handbrake, and a Microsoft logo right next to it. Made double sure when I parked on a hill to point the wheels into the hedge and leave it in an appropiate gear

To be fair there are some modernish cars where parking in gear is sensible - for instance the Vauxhall Vectra-C handbrakes were awful and so when I had one I always parked in gear.

 

[LSWR Cavalier]

Anyone who has lived in a hilly place may have heard horror stories of vehicles running away. Best to park in gear, apply the handbrake, turn the wheels so that the kerb stops the vehicle if it tries to run away.

 

[Bletchleyite]

Anyone who has lived in a hilly place may have heard horror stories of vehicles running away. Best to park in gear, apply the handbrake, turn the wheels so that the kerb stops the vehicle if it tries to run away.

If parking on a hill these are good practice, yes. If parking on a pretty much level road, they are entirely unnecessary (though some still do it and it causes no harm most of the time).

I say "most of the time" because if someone shunts you and you've parked in gear it can cause gearbox damage as well as the obvious body damage.

 

[Factotum]

Do you actually mean under-reads, e.g. showing 40mph if doing 43? If so it is not roadworthy and so needs calibrating or replacing. (The chance of being caught is fairly low but I'm pretty sure it is a Construction and Use offence).

Over-reading, e.g. showing 43 if doing 40, is very common to avoid this.

No shows 40 when when doing 37. The actually speed is under the indicated speed.

This is exactly the problem. Like with Covid where things degenerated to an obsession with toilet rolls and masks, with roads the cause of all evils seems to be speed.

That is because speed is easy to measure