Reducing the default urban road speed limit to 20 mph

[roversfan2001]

I've generally found that in most cars I've had it's easiest to drive in a given limit if you select the gear that is the first number of the limit. That is, 2nd for 20, 3rd for 30, 4th for 40, 5th for 50 and 6th (if you have one) for 60+. The exception is my present Kuga which has hellish turbo lag problems* if you use 6th for anything less than about 65 and gives you a very jerky ride on an undulating road, though it's fine if the road is totally flat. It'd be less noticeable on a traditional large-engined diesel, it's noticeable on this because it's a small engine (1.5) that couldn't pull the skin off a rice pudding until the turbo has spun up.

This is totally counter to what most instructors teach, and to what the flashing warning on the dash says.

In my 1.2 petrol I'm in 4th gear as soon as I go above 30 and 5th gear from about 45. I've still not cracked what gear to be in for 20mph, neither 2nd or 3rd give very smooth rides.

 

[thejuggler]

Non turbo, Auto petrol with adaptive cruise control, no issue maintaining any speed from 20mph.

 

[AM9]

I hae a 1.2L non-turbo petrol engined car. It will happily do any speed from 20-30 in third and 25-40 in fourth. On medium hills in 30 zones I sometimes stay in third either to keep aat/below 30 downhill or to maintain effertless climbing of hills. Crawling at 5-10 in traffic can be a bit tiresome but I put that down to my choice of choosing driving on busy roads.
Of course, there may be some dragging of heels implementing any changes to 20 limits, but soon, the proponderance of EVs will mean that the reasons for complaint will fade away. Those resisting change to EVs might find that clinging onto their pet type of car becomes even more difficult with speed limits that their cars perform badly at.

 

[ABB125]

Blanket low speed limits are, in general, not a good idea. From an urban perspective, 20 is fine on residential roads (though a lot of people ignore the limit), but the "main road" should be 30 (or more where appropriate). In rural areas, it can be a bit more difficult. And as always, local circumstances should always be taken into account (which is why I'm not a fan of blanket restrictions in general (not just speed limits)). My preference is for it to be uncomfortable to exceed the limit, because then hardly anyone will.

The A38 through Birmingham is an interesting case study. From M5 junction 4 to Rubery, it's national speed limit, but few people seem to go more than 50. It's certainly "exciting" in my car at GPS 70 (great fun on the few occasions I use that bit), though because it's quite steep uphill from the M5, I usually don't bother wasting fuel accelerating to 70 up the hill.
There's a very short section of 40, then it's 30 all the way until the A38(M). However, the majority of people want to do 40 along here. I believe that, until a couple of years ago, the limit on much of this bit was 40, but the "something must be done" brigade got it reduced to 30 (and would probably love it to be 20, despite that being totally ridiculous). 40 is, in my opinion, an appropriate limit for this section, with a few exceptions, such as the S4* section south of the A4540. The bit through the city centre I wouldn't want to be more than 30 though, as it's exciting enough as it is! The forward visibility if you're in the right hand land of the Queensway tunnel heading north is basically nil... Plenty of people try to do 40 (or more) along here though.
North of the M6, the limit is 40 (at least as far as the A452, I've not been beyond there but I assume it stays the same until Minworth, whereupon it becomes NSL). People generally stick to this (though obviously you get the occasional **** who ignores all speed limits everywhere). If 40 is fine north of the city centre, why not south thereof?

Another thing to bear in mind is that there will always be a minority of people who totally ignore the limit (eg: 70 in a 30 area). Any calls for speed limits to be reduced following (for example) an accident caused by one of these drivers should be refused completely: had the limit been less, the driver would still be ignoring it, and thus there would be no difference in the outcome of whatever accident might have occurred. Case point being a drunk driver doing approaching 100 crashing into a house next to the road near where I live (not in Birmingham), which is in a 50 limit. Plenty of locals were demanding the limit to be reduced, which would have no effect on that particular crash (and would also cause other issues on that stretch of road, but I won't go into that as it's off topic).

 

[Bletchleyite]

Blanket low speed limits are, in general, not a good idea. From an urban perspective, 20 is fine on residential roads (though a lot of people ignore the limit), but the "main road" should be 30 (or more where appropriate). In rural areas, it can be a bit more difficult. And as always, local circumstances should always be taken into account (which is why I'm not a fan of blanket restrictions in general (not just speed limits)). My preference is for it to be uncomfortable to exceed the limit, because then hardly anyone will.

My personal view would be as defaults, for all vehicles unless a legally mandated limiter is lower:

Residential non-thoroughfare street: 20mph or even in some cases "play street" with absolute pedestrian priority
Urban thoroughfare, single carriageway or dual with homes directly onto it: 30mph
Urban thoroughfare segregated from but close to homes/business premises: 40mph (I'm thinking of the likes of the A59 through Maghull* or parts of the East Lancs Road - typically the houses aren't on the main road but have a small "slip road" in front of them)
Rural single carriageway with no centreline markings: 40mph (I could be swayed to 30)
Other single carriageway: 50mph
Other dual carriageway: 60mph
Motorway: 70mph

I would also extend the limits (only 20 is really relevant) to include bicycles. Most cyclists don't exceed 20 so it'd not be relevant to them, but there are some in London who do ride excessively aggressively above that speed in 20 limits e.g. central London and it could do with being stopped. They probably would come under "wanton and furious cycling" but it's hard to prosecute that.

* https://www.google.com/maps/@53.51767,-2.9398059,3a,75y,191.57h,77.19t/data=!3m7!1e1!3m5!1sJhRRdmfI2XpxVqG0G7xVdQ!2e0!6shttps://streetviewpixels-pa.googleapis.com/v1/thumbnail?panoid=JhRRdmfI2XpxVqG0G7xVdQ&cb_client=maps_sv.tactile.gps&w=203&h=100&yaw=95.870285&pitch=0&thumbfov=100!7i16384!8i8192

 

[jfollows]

My personal view would be as defaults, for all vehicles unless a legally mandated limiter is lower:

Residential non-thoroughfare street: 20mph or even in some cases "play street" with absolute pedestrian priority
Urban thoroughfare, single carriageway or dual with homes directly onto it: 30mph
Urban thoroughfare segregated from but close to homes/business premises: 40mph (I'm thinking of the likes of the A59 through Maghull* or parts of the East Lancs Road - typically the houses aren't on the main road but have a small "slip road" in front of them)
Rural single carriageway with no centreline markings: 40mph (I could be swayed to 30)
Other single carriageway: 50mph
Other dual carriageway: 60mph
Motorway: 70mph

Although there's nothing objectionable to me in your proposal, and I'm aware that we're getting off the specific topic of this thread, this will all get undone by the "something must be done about this" brigade. For example, the A5103/Princess Road/Princess Parkway is now 30mph from before Barlow Moor Road into Manchester (with a brief 40mph in the last truly segregated part in Hulme) whereas it used to be 40mph with a couple of 30mph stretches which made sense, and which accord with your 40mph definition above. So there were wails from people who don't look properly along the lines of "I thought it was 40" when they were penalised for speeding. Yes, it's a busy road and, yes, people were killed by collisions from cars along it, but I'm not convinced that the reduced speed limit has made any difference other than to the consciences of the politicians responsible for its reduction - they can no longer be blamed for "doing nothing".

 

[JamesT]

Are human reaction times any different?

Are stopping distances any different in other countries?

Looking at this Dutch theory test tutorial:

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At 50 km/h

reaction distance 15 m
braking distance 12.5 m
stopping distance 27.5 m

The UK highway code has a stopping distance of 23 m at 30 mph.

In terms of the reaction time component, there may an argument for increasing it - https://chalkdustmagazine.com/blog/stopping-distances-highway-code-wrong/
However, for the actual braking the distances are based around the performance of the average car of the 1940s. I imagine most other countries introduced their stopping distance guide in a similar way. (If they didn't just licence/steal the UK TRL testing data). The blanket 2x for wet and 10x for ice seem suspiciously round, was there actually empirical data behind it?
But cars have moved on significantly in that time. The average car now has wider tyres, probably ABS, so in general will likely stop in a much shorter distance when the brakes are actually applied.

 

[AM9]

In terms of the reaction time component, there may an argument for increasing it - https://chalkdustmagazine.com/blog/stopping-distances-highway-code-wrong/
However, for the actual braking the distances are based around the performance of the average car of the 1940s. I imagine most other countries introduced their stopping distance guide in a similar way. (If they didn't just licence/steal the UK TRL testing data). The blanket 2x for wet and 10x for ice seem suspiciously round, was there actually empirical data behind it?
But cars have moved on significantly in that time. The average car now has wider tyres, probably ABS, so in general will likely stop in a much shorter distance when the brakes are actually applied.

And how should these minimam stopping distances be applied to HGVs or even heavily loaded pick-ups with or without trailers?

 

[ABB125]

And how should these minimam stopping distances be applied to HGVs or even heavily loaded pick-ups with or without trailers?

Presumably in the same way that they are now?

 

[Bletchleyite]

Although there's nothing objectionable to me in your proposal, and I'm aware that we're getting off the specific topic of this thread, this will all get undone by the "something must be done about this" brigade. For example, the A5103/Princess Road/Princess Parkway is now 30mph from before Barlow Moor Road into Manchester (with a brief 40mph in the last truly segregated part in Hulme) whereas it used to be 40mph with a couple of 30mph stretches which made sense, and which accord with your 40mph definition above. So there were wails from people who don't look properly along the lines of "I thought it was 40" when they were penalised for speeding. Yes, it's a busy road and, yes, people were killed by collisions from cars along it, but I'm not convinced that the reduced speed limit has made any difference other than to the consciences of the politicians responsible for its reduction - they can no longer be blamed for "doing nothing".

Yes, I think there are too many semi-segregated urban dual carriageways at 30, when most should be 40.

A fully segregated urban road not intended to be used by pedestrians in any form (e.g. those in Milton Keynes) should generally be NSL unless there's another important reason to slow it e.g. queues being common (as is probably the case on the road through Hulme you mention), but with the proviso that I would reduce single/dual NSL for cars by 10mph to bring into line with van NSL, which would reduce overtaking, the largest risk on single carriageways because it results in very high closing speeds, and would also knock a bit off closing speeds on duals without a central Armco barrier.

 

[jfollows]

I honestly think that "minimum stopping distances" are a nonsense invented for the purpose of the driving test, and they are meaningless - I have no clue what they are or what they mean to me, I'm not stupid and I was able to parrot them to my examiner for my test in 1978, but my mind doesn't work in a way that makes knowing that it's 51 yards from 30mph (or whatever) useful.
EDIT And the thing about the number of double-decker buses (is that still used?) was bonkers squared!

 

[johncrossley]

Lower speeds reduce traffic noise, which is a consideration rarely discussed.

 

[Bletchleyite]

Lower speeds reduce traffic noise, which is a consideration rarely discussed.

Notably that's why that Maghull example is good - it uses trees as a noise barrier.

 

[AM9]

Presumably in the same way that they are now?

I'm not sure what you are saying. Now, there is a common set of stopping distances for all vehicles, but there's been a suggestion here that those figures were derived from what cars in the 1940s could achieve. Although heave goods vehicles have much improved braking systems and tyres to match, their weights have also increased fourfold, and they are capable of reaching the road speed limit a lot quicker than the immmediate post war trucks did. Thus they are more likely to be travelling at similar speeds as cars in urban areas.

 

[Bletchleyite]

I'm not sure what you are saying. Now, there is a common set of stopping distances for all vehicles, but there's been a suggestion here that those figures were derived from what cars in the 1940s could achieve. Although heave goods vehicles have much improved braking systems and tyres to match, their weights have also increased fourfold, and they are capable of reaching the road speed limit a lot quicker than the immmediate post war trucks did. Thus they are more likely to be travelling at similar speeds as cars in urban areas.

The suggestion is that if you're driving something that isn't a family car then you need to adapt your spacing from other road users accordingly.

 

[AM9]

I honestly think that "minimum stopping distances" are a nonsense invented for the purpose of the driving test, and they are meaningless - I have no clue what they are or what they mean to me, I'm not stupid and I was able to parrot them to my examiner for my test in 1978, but my mind doesn't work in a way that makes knowing that it's 51 yards from 30mph (or whatever) useful.
EDIT And the thing about the number of double-decker buses (is that still used?) was bonkers squared!

But road design, traffic signals timings and most importantly road users are used to the figures that they learn (despite the fact that many serious collisions are directly as a result of drivers thinking they know better.)

 

[jfollows]

But most importantly road users are used to the figures that they learn

That's my point, I only said "it's 51 yards from 30mph (or whatever)" because I had to look it up, I've not learned any figures, I don't have the least clue what they are or what they mean in practice to me and my driving.
I totally agree that road planners should take them into account, of course.

But, of course, I could be the bad exception amongst drivers here! My driving's definitely not perfect, although I'm pleased to say the last penalty points on my license were dated 5/5/05 so I've probably got better over time ...... or just been lucky.

 

[johncrossley]

Is there a correlation between desire for higher limits and penalty points/accident rate?

 

[roversfan2001]

Is there a correlation between desire for higher limits and penalty points/accident rate?

In my case there's a definite correlation between having a telematics insurance policy and desire for 'higher' (more suitable) limits. Having to do 30 on a road that should clearly have a higher limit, and that everyone else around me is going faster than me, feels quite dangerous.

My hatred of smart motorways is entirely related to the three penalty points on my licence though...

 

[JamesT]

I'm not sure what you are saying. Now, there is a common set of stopping distances for all vehicles, but there's been a suggestion here that those figures were derived from what cars in the 1940s could achieve. Although heave goods vehicles have much improved braking systems and tyres to match, their weights have also increased fourfold, and they are capable of reaching the road speed limit a lot quicker than the immmediate post war trucks did. Thus they are more likely to be travelling at similar speeds as cars in urban areas.

As there are separate tests for classes of vehicle, given their likely different performance it may be worth specifying different distances for each class?
My argument is that the stopping distances should reflect reality, rather than some made-up formula from decades ago. From the article I linked it looks especially suspicious that the thinking time component lines up to distance in feet = speed in mph.
Have TRL test a representative sample of the vehicles on the road today in varying conditions (wet is easy to replicate, ice might be trickier) and see how they perform. Also get in a sample of drivers and test reaction time. Use the results to inform new stopping distances to be used in the highway code and the theory test.

 

[GusB]

I'm definitely in favour of there being more 20mph speed limits. There's one 20mph limit in my village, and that's on the streets leading towards the school. I'd be in favour of a blanket reduction on every street, barring the main road along the top of the village which should remain at 30mph (once upon a time is was 40mph, which would be unthinkable nowadays).

Having said that, I wouldn't be in favour of a blanket 20mph imposed nationwide. It should really be down to local councils to decide, with sufficient input from local residents. If necessary it could be devolved down to community council / parish council level.

 

[AM9]

As there are separate tests for classes of vehicle, given their likely different performance it may be worth specifying different distances for each class?
My argument is that the stopping distances should reflect reality, rather than some made-up formula from decades ago. From the article I linked it looks especially suspicious that the thinking time component lines up to distance in feet = speed in mph.
Have TRL test a representative sample of the vehicles on the road today in varying conditions (wet is easy to replicate, ice might be trickier) and see how they perform. Also get in a sample of drivers and test reaction time. Use the results to inform new stopping distances to be used in the highway code and the theory test.

What is there to lose by havimg conservative stopping distances stated?

 

[bramling]

I'm not sure what you are saying. Now, there is a common set of stopping distances for all vehicles, but there's been a suggestion here that those figures were derived from what cars in the 1940s could achieve. Although heave goods vehicles have much improved braking systems and tyres to match, their weights have also increased fourfold, and they are capable of reaching the road speed limit a lot quicker than the immmediate post war trucks did. Thus they are more likely to be travelling at similar speeds as cars in urban areas.

Is that not for the driver to manage? If they can’t, they shouldn’t be driving in the first place.

 

[AM9]

Is that not for the driver to manage? If they can’t, they shouldn’t be driving in the first place.

It's not just the driver that it affects. There's other vehicles and pedestrians at risk here.

 

[bramling]

I'm definitely in favour of there being more 20mph speed limits. There's one 20mph limit in my village, and that's on the streets leading towards the school. I'd be in favour of a blanket reduction on every street, barring the main road along the top of the village which should remain at 30mph (once upon a time is was 40mph, which would be unthinkable nowadays).

Having said that, I wouldn't be in favour of a blanket 20mph imposed nationwide. It should really be down to local councils to decide, with sufficient input from local residents. If necessary it could be devolved down to community council / parish council level.

The trouble with leaving such decisions to local residents, is it’s like parking - people don’t like people parking outside their own house, but when they themselves drive somewhere then different rules apply.

 

[tomuk]

What is there to lose by havimg conservative stopping distances stated?

Nothing but I don't think there is anything to gain either. As the other poster suggested stopping distances are irrelevant, if you surveyed drivers the large majority of them wouldn't be able to tell you what they are. I have no idea what they are and I haven't been rear ending other cars for 25 years.

I regularly drive three different vehicles a Transporter Van, a large high performance VW Touareg 4x4 and a smaller Nissan Qashqai Crossover which have varying levels of braking performance I adjust accordingly. I don't approach a roundabout trying to remember what the back cover of the highway Code says. In reality the only noticeable difference is the weight of the clutch between the Transporter and Qashqai.

The biggest braking 'shock' I've had was when I test drove my brothers first car, it was an 850cc old Mini with drum brakes all round and no servo assistance, probably not to far removed from the TRL test vehicle. I had to nearly stand up in the car to push the brake pedal down to get it to stop it a set of lights I'd driven through hundreds of times before.

 

[GusB]

The trouble with leaving such decisions to local residents, is it’s like parking - people don’t like people parking outside their own house, but when they themselves drive somewhere then different rules apply.

Why is that a problem? Those who don't like others parking outside their own homes should be more considerate about where they themselves park.

Let's have a residents-only parking scheme, with incentives to use park and ride, for example?

 

[Eyersey468]

I think 20mph speed limits in certain settings such as near a school, on a narrow residential road etc are fair enough however I don't agree with a blanket 20mph speed limit in all built up areas.

 

[cactustwirly]

As a utility cyclist I dislike 20s. I don't typically cycle at 20mph (unlike the Lycra-wearing campaigners), and so 20mph means the threat (overtaking car) is alongside me for a third longer than otherwise.

As a driver I don't overly mind them in the right setting, I put it in third gear and set the limiter. However I prefer "20 zones" i.e. where the road is designed such that 20 is a comfortable speed to drive by placing chicanes, "natural chicanes" (parking, planters etc) and table junctions etc in strategic locations.

I suspect that's not the way round they wanted and thus I don't support this proposal.



As a slight aside I support changing NSL to 50-60-70 single-dual-motorway for all vehicles (other than where mandatory limiters reduce it, so for lorries in practice it'd be 50-56-56 and coaches it'd be 50-60-62). It near enough eliminates single-carriageway overtaking (other than of cycles and tractors) which is a significant safety benefit, and having driven on plenty of 50-signed singles in places like the Peak District you lose hardly any time driving at 50 and get a far more relaxing experience, plus less pollution from braking and accelerating frequently. (You can of course choose to drive at 50 in a 60, but that frustrates people and causes dangerous overtakes, so the lower limit is better). 60 on non-motorway duals also reduces risk (driving at 70 on many of them is like a roller coaster, e.g. the A1 where they've kept the old single as one carriageway and added another), and I'd apply 60 to any non-hard-shouldered motorways too.

I hate those chicanes as they make traffic worse.
There's a hilarious one in reading. It caused both directions to become gridlocked as you couldn't pass the chicanes as the opposite side of the road had a queue for some traffic lights. So you have to wait for the traffic lights that you've just gone through to turn green before you can pass the chicane

Pretty much every modern car does that automatically unless the auxiliary load is too high or the battery is in poor condition.

Mine has stop start, but it's very fussy.
It only works half of the time.

This is despite having a new battery.

 

[ABB125]

Mine has stop start, but it's very fussy.
It only works half of the time.

This is despite having a new battery.

I have stop start too - it's called "turning the key"