Is it time to look again at 70mph Limits?

[Topological]

I did try to find a previous thread, so my apologies if there is one I missed. The latest I could find was about idiots driving on motorways in 2024.

With the discussion on speed limit enforcement in the New Driving Laws thread, I thought it might be worth bringing the speed discussion out.

Two roads to motivate this discussion that are separated by a few metres (and the railway from Port Talbot to Neath)

The A48 in Baglan (National Speed Limit): A48 Dual Carriageway with Bridges for pedestrians
The M4 parallel to the A48 (50mph): M4 showing Speed Limit for Air Quality sign (also see screenshot below)

Hopefully, those two links work to demonstrate some of the inconsistency that exists (Port Talbot has a 50 on the viaduct section, but the linked section is not part of the viaduct)

Should the national speed limit make a distinction between motorways and standard A road dual carriageways? Should there be a re-examination of roads that are close to houses like the A48 example? Is air quality important with electric cars coming?


ALT TEXT: Image shows M4 near Baglan, South Wales. There is a lorry overtaking the Google car and the sign on the left of the carriageway reads "Speed limit to improve air quality". A yellow average speed camera can be seen further along the carriageway.

 

[Noddy]

There are some areas with appalling air quality in south Wales so I think reducing the speed limits in these areas has been a sensible thing to do. However I also agree that with electric vehicles (of all descriptions) coming they’ll either need to ‘rebrand’ or put the speed limit back up because folk will quickly feel conned. Or have different speed limits for ICE and electric vehicles.

 

[Topological]

There are some areas with appalling air quality in south Wales so I think reducing the speed limits in these areas has been a sensible thing to do. However I also agree that with electric vehicles (of all descriptions) coming they’ll either need to ‘rebrand’ or put the speed limit back up because folk will quickly feel conned. Or have different speed limits for ICE and electric vehicles.

Did you check out the proximity to houses of the two roads in that particular case? The A48 with houses on service roads next to it is 70, the M4 with a railway and trees between it and the A48 (and therefore houses has the 50 and the sign).

I realise a map would be helpful for that case:


ALT TEXT: Map of the A48 and M4 in Baglan showing the proximity of the A48 to houses and the lack of proximity of the M4 to houses. The M4 is also shown to be next to an industrial estate.

I fully support the reduction of speed on roads like the A48, where there are houses around and people may want to cross. I just feel there has to be some sensible balancing where roads like the M4 in this case are not restricted. If they have to keep the M4 at 50 over the viaduct, at least that is the part that passes houses, the limit can start a lot closer to the viaduct than it currently does (before Junction 42 on the other side of the River Neath).

We may have to get used to the argument that tyre particulates are a problem with electric vehicles, but that is going to be a hard sell when the exhaust pipe is such a clear ommitter of pollution on ICE cars.

 

[Noddy]

Did you check out the proximity to houses of the two roads in that particular case? The A48 with houses on service roads next to it is 70, the M4 with a railway and trees between it and the A48 (and therefore houses has the 50 and the sign).

I realise a map would be helpful for that case:

View attachment 186504
ALT TEXT: Map of the A48 and M4 in Baglan showing the proximity of the A48 to houses and the lack of proximity of the M4 to houses. The M4 is also shown to be next to an industrial estate.

I fully support the reduction of speed on roads like the A48, where there are houses around and people may want to cross. I just feel there has to be some sensible balancing where roads like the M4 in this case are not restricted. If they have to keep the M4 at 50 over the viaduct, at least that is the part that passes houses, the limit can start a lot closer to the viaduct than it currently does (before Junction 42 on the other side of the River Neath).

We may have to get used to the argument that tyre particulates are a problem with electric vehicles, but that is going to be a hard sell when the exhaust pipe is such a clear ommitter of pollution on ICE cars.

Erm, yes I do see your point re the proximity but this 50mph speed limit was specifically imposed by central government to reduce air pollution. I think the speed limits on the A48 at this location are controlled by the local authority who obviously don’t feel the same need. Im not sure but it may be a liability issue-I think the Welsh Goverment is on the hook for air pollution issues such as this but I don’t believe local authorities are in the same way.

But as an EV driver myself I do wryly smile when I pass these signs. They’re going to have to go or change in the next few years.

 

[Bertie the bus]

It definitely isn't time to review speed limits because "reviewing" always means decreasing.

There is a bypass near me which used to be single carriageway and 60 mph. They dualled it and then reduced the speed limit to 50 mph. There is another dual carriageway bypass near me where the speed limit was 70 mph and they reduced it to 50 mph. Nearly everybody just ignores the new speed limit except when plod have a speed detection van parked in one of the laybys.

 

[Bletchleyite]

I would like to see NSL 50, 60, 70 for all vehicles. 70 would apply only to motorways with a hard shoulder and some motorway standard A roads could also be signed up to 70 eg the A55 in North Wales.

This would obviously be subject to legally required speed limiters.

 

[cactustwirly]

I would like to see NSL 50, 60, 70 for all vehicles. 70 would apply only to motorways with a hard shoulder and some motorway standard A roads could also be signed up to 70 eg the A55 in North Wales.

This would obviously be subject to legally required speed limiters.

Travelling from Winchester to Bicester or Swindon to Gloucester at 60mph would be a massive inconvenience
Same with sections of the A1 etc
I don't think such a policy makes sense at all

 

[Topological]

I think any changes should be more logically based.

Motorways really can go to 80, especially where they are three-lane with hard shoulder. I just got a bit conflicted about what that means for the small sections of 2-lane at junctions such as Junction 32 of the M4 where there are only two lanes between the exit and entry slips.

I think that there needs to be balance when reducing roads like the A48 above to a more sensible 50.

Dual carriageways like the A419, or the A1, or A46 through Leicestershire, etc. are all fine at 70. Likewise, the A449/A40 that runs from Newport to the M50 (except the obvious parts where it already has lower limits)

I do find it slightly odd that the speed limits on these dual carriageways with regular junctions is the same as a motorway with few grade-separated junctions.

 

[gazthomas]

One thing that hasn't been mentioned yet is particulate air pollution from tyre debris which won't be solved by EVs, with some research suggesting this is a bigger problem than exhaust emissions

Car tyres produce vastly more particle pollution than exhausts, tests show

Toxic particles from tyre wear almost 2,000 times worse than from exhausts as weight of cars increases

www.theguardian.com

"Car tyres produce vastly more particle pollution than exhausts, tests show

Toxic particles from tyre wear almost 2,000 times worse than from exhausts as weight of cars increases" (quote from linked Guardian article)

 

[philosopher]

It definitely isn't time to review speed limits because "reviewing" always means decreasing.

There is a bypass near me which used to be single carriageway and 60 mph. They dualled it and then reduced the speed limit to 50 mph. There is another dual carriageway bypass near me where the speed limit was 70 mph and they reduced it to 50 mph. Nearly everybody just ignores the new speed limit except when plod have a speed detection van parked in one of the laybys.

For motorways I think 70mph is appropriate. For A roads dual carriageways I think it depends. For dual carriageways that are in effect quasi motorways such as most of the A14 or A42, 70mph is appropriate. For those in rural areas with a fair number of at grade junctions, 60mph is more appropriate. For those passing through urban areas but will few junctions, or short sections of rural dual carriageway, 50mph is probably appropriate.

Related, the 60mph single carriageway speed limit for rural roads to me has always felt way too high. Perhaps it is appropriate for a few very straight and wide single carriageway A roads, but for the vast majority it is not. Driving at or trying to drive at 60 mph down a windy country lane with hedgerows on both sides is likely down right dangerous.

While I know the Highway Code states drivers should take into account road conditions and visibility, there are bound to be some drivers who view the speed limit as a target and not a max speed.

I would say 50mph would be a more appropriate speed limit for rural single carriageway roads.

 

[Bletchleyite]

Travelling from Winchester to Bicester or Swindon to Gloucester at 60mph would be a massive inconvenience

It wouldn't. The difference would be a few minutes and accidents would reduce in number and severity.

 

[AndrewE]

Motorways really can go to 80, especially where they are three-lane with hard shoulder. I just got a bit conflicted about what that means for the small sections of 2-lane at junctions such as Junction 32 of the M4 where there are only two lanes between the exit and entry slips.
...
I do find it slightly odd that the speed limits on these dual carriageways with regular junctions is the same as a motorway with few grade-separated junctions.

I don't think so, I am sure lots of crashes at junctions happen because speed merchants in the outside lane leave it until the last minute (second) to dive under the front bumper of an HGV to get off the motorway. We don't drive much nowadays but have seen accidents almost happen this way virtually every time we use a motorway. Higher permitted speeds would just encourage them to take more risks.

 

[Topological]

I don't think so, I am sure lots of crashes at junctions happen because speed merchants in the outside lane leave it until the last minute (second) to dive under the front bumper of an HGV to get off the motorway. We don't drive much nowadays but have seen accidents almost happen this way virtually every time we use a motorway. Higher permitted speeds would just encourage them to take more risks.

Isn't that just bad driving though?

I must make a note to avoid motorways if you are on them. I have never seen an accident from such behaviour (though one car did go over the diagonally hatched bit once). The best I saw was one try it to get into Cardiff at Junction 33, but the car in front of me was going for the right lane of the two on the slip and headed the latecomer off so that car had to stay on the M4.

 

[Bletchleyite]

Isn't that just bad driving though?

Speed limits in part exist to mitigate bad driving by reducing the severity of the accidents caused by it.

 

[Topological]

Speed limits in part exist to mitigate bad driving by reducing the severity of the accidents caused by it.

True to an extent, but by definition bad driving ignores such rules.

Punishing the majority in the belief that it will cut accidents is thankfully not politically popular.

The 20mph in Wales might not be the greatest policy, but at least it has a rationale and you can see why they thought it was a good idea to go for blanket 20. The motorways are not running through residential areas, do not have pedestrians and are essentially only problematic when people drive badly.

Where most people may believe they could accidentally be involved in an incident in a built-up area with the potential for kids coming running out from behind parked cars (for example), that just is not the case on the motorway.

 

[Bletchleyite]

Punishing the majority in the belief that it will cut accidents is thankfully not politically popular.

I'd suggest that anyone who considers speed limits to be punishment needs to do a bit of thinking about their approach to sharing the roads with others, to be honest.

A speed limit may or may not be justified on safety grounds, but under no circumstances whatsoever is it a punishment.

 

[AndrewE]

Isn't that just bad driving though?

I must make a note to avoid motorways if you are on them. I have never seen an accident from such behaviour (though one car did go over the diagonally hatched bit once). The best I saw was one try it to get into Cardiff at Junction 33, but the car in front of me was going for the right lane of the two on the slip and headed the latecomer off so that car had to stay on the M4.

so weren't both of those near misses? I said that we had seen many manoeuvres that almost caused accidents, and could easily imagine why so many crashes seem to happen at junctions.

Ps: perhaps you have the "It will never happen to me" mentality?

 

[Topological]

I'd suggest that anyone who considers speed limits to be punishment needs to do a bit of thinking about their approach to sharing the roads with others, to be honest.

A speed limit may or may not be justified on safety grounds, but under no circumstances whatsoever is it a punishment.

A speed limit is not a punishment - it is the consequence of the reduction of a speed limit which falls under the definition. Especially where the reduction is motivated because of the actions of others.

The definition of punishment according to the American Psychological Association: LINK

1. a physically or psychologically painful, unwanted, or undesirable event or circumstance imposed as a penalty on an actual or perceived wrongdoer.

This would mean that the imposition of a slower speed limit (and therefore penalty for doing the previously permitted speed) would indeed be an unwanted circumstance. In essence, the act of reducing the limit is to create a potential punishment on those who would otherwise not have faced such a consequence.

It worries me that the current response to the poor behaviour of others seems to be to impose further limitations on the actions of those who did not misbehave.

== Doublepost prevention - post automatically merged: 17 Aug 2025 ==

so weren't both of those near misses? I said that we had seen many manoeuvres that almost caused accidents, and could easily imagine why so many crashes seem to happen at junctions.

Ps: perhaps you have the "It will never happen to me" mentality?

There are such "near misses" all the time on the motorways. Junctions are very much the least of the problems if that is the measure being taken. Watch the way vehicles are weaving all over the place at 4am, or how people pay so little attention to things like weather conditions, or how people slam the brakes on when the matrix signs start putting advisory speeds on rather than slowing down safely, or those who drive in the middle lane.

 

[AndrewE]

A speed limit is not a punishment -

it is an attempt to reduce the incidence of accidents (giving drivers more time to react) and also to reduce the severity of the consequences.

There are such "near misses" all the time on the motorways

Maybe you don't recognise e=mc^2? The enegy to be dispersed rises with the square of the speed... so higher-speed misjudgments are likely to cause far worse damage.

 

[Topological]

it is an attempt to reduce the incidence of accidents (giving drivers more time to react) and also to reduce the severity of the consequences.

Maybe you don't recognise e=mc^2? The enegy to be dispersed rises with the square of the speed... so higher-speed misjudgments are likely to cause far worse damage.

Accidents reduce in severity when safety features are improved.

I do not think anyone believes that cars are still as unsafe as they were when 70mph was selected as an appropriate limit.

My argument is simply that we need reduced speeds where there are external risks (such as those created by cars needing to stop and turn, pedestrians etc) and then that the balance is that we recognise that the motorways can operate perfectly safely at higher speeds.

If the whole aim of law is to prevent harm then we are on our way to a very bad place.

== Doublepost prevention - post automatically merged: 17 Aug 2025 ==

It would probably be helpful to look at the way the Germans handle motorways too:

What is the speed limit on German motorways?​

On the autobahn, there are areas where there are no speed limits, and they are marked with circular white signs with four black diagonal lines. Some of the motorway has a 130 km/h (~80 mph) advisory speed limit for all vehicles under 3.5 tonnes.

Around 30% of the autobahn’s 8000-plus mile roads come with a permanent or variable speed limit, with a further 10% using traffic control systems to regulate traffic.

Unlike many countries, Germany also has minimum speed limits. On a six lane road – the minimum speed for the fast lane is 110 km/h, middle lane is 90 km/h, and slow lane is 60 km/h. If a car cannot maintain these speeds on flat ground, then they are not allowed on motorways in Germany.

Taken from: RAC Guide to German Speed

 

[styles]

From a safety point of view, very unlikely to raise many limits.

The UK is 10th in the world for road deaths per capita (WHO, 2023). Above us is Iceland, Sweden, Norway, Micronesia. We have a better road safety record than Germany when measured per capita or by number of miles driven. Their road-related death rate per capita is 30% higher than the UK's. For all people point at the Autobahn, the limitless sections have a worse safety record than UK motorways, and large parts of it do actually have speed limits applied. Also anecdotally, German drivers just have better lane discipline in my experience. Middle lane hogging and moving without checking blind spots is rife in the UK.

That's not to say there's no work to be done on road safety. Roughly 1600 people a year die on our roads. Speed is a common factor, with roughly half of speed causes being driving above the limit, and the other half being driving too fast for the conditions but under the limit.

In Scotland our government is debating making single carriageways 50mph for all road users. Currently our limit for wagons is a mere 40mph on single carriageways, which is a huge relative difference from 60mph for cars, car-derived vans, etc. If they follow through with it, it'll be interesting to see the results. The logical step if that's successful would be 60mph for all dual carriageway users. Motorways I think are different in that you can have larger speed differentials, as you usually have 2+ lanes, often 3+, hard shoulders or on 'smart' motorways emergency refuge areas, the lanes are a minimum width to meet motorway standard, etc.

In Wales where my family live, built up areas defaulting to 20mph appears to have been successful, but it'll take a bit longer to get a decent set of data to try and isolate the other factors leading to lower collision, casualty, air pollution rates. TfL's data for this in London is stronger and over a longer period of time, and they do find that the greatest reduction in road kills and seriously injured (KSI) stats come from roads changed to 20mph compared to roads not changed. I could see Scotland going for Wales' 20mph approach or similar, given the recent introduction of pavement parking bans, and trying to bring parity to single carriageway speed limits for different vehicle types.

I also think it's time for Ireland to ditch the 45mph restriction on R-plated drivers. Having people limited to 45mph on motorways where even the wagons are going faster is dangerous. I know it's because the R plate restrictions were in place before they actually had motorways, but times have changed and it's time to update the legislation.

If we are to raise the motorway speed limit to 80mph as some suggest, I think we'd have to revise NPCC's recommendation of 10%+2mph enforcement threshold, and the 10%+9mph recommended limit for speed awareness courses. Otherwise you can be doing nearly 100mph and get away with paying £100 for a course. I'd rather just leave that limit as it is at 70mph. The DfT has ruled out increasing the limit to 80mph for years, so unless we get a Reform UK government, who would certainly do it as a cheap vote winner, I can't see it happening anyway.

 

[Noddy]

Currently our limit for wagons is a mere 40mph on single carriageways, which is a huge relative difference from 60mph for cars, car-derived vans, etc.

I think the issue there is to raise the truck speed limit to 50mph, unless it’s a particularly dangerous road/known hotspot. Forty for trucks on an open road is a stupidly low speed limit, even if other vehicles are limited to 50. It’s still a 20% speed deferential and I’m sorry but it just encourages dangerous manoeuvres. While I wouldn’t be in favour of raising any other speed limits (apart from this one) and am massively in favour of more 20s not just in built up areas but also minor rural lanes with a lot other non-motorised road users, I’m also in favour of introducing minimum speed limits on both motorways and dual carriageways. If folks can’t maintain a speed above 50mph they shouldn’t be on it.

 

[styles]

I think the issue there is to raise the truck speed limit to 50mph, unless it’s a particularly dangerous road/known hotspot. Forty for trucks on an open road is a stupidly low speed limit, even if other vehicles are limited to 50. I’m sorry but it just encourages dangerous manoeuvres. While I wouldn’t be in favour of raising any other speed limits (apart from this one) and am massively in favour of more 20s not just in built up areas but also minor rural lanes with a lot other non-motorised road users, I’m also in favour of introducing minimum speed limits on both motorways and dual carriageways.

There is a sort of unofficial minimum speed limit on motorways, in that if the police spot you doing below either 40mph or 50mph (I forget which), they'll likely pull you over. It's referred to a few times on those Traffic Cops type programmes. It's not official, but I'm assuming some forces have made it a policy, formal or informal. I wouldn't object to formalising it, though the legislation would need to be carefully worded so people stuck in traffic aren't committing an offence. Presumably the legislation for minimum speed limits already accounts for this (e.g. as we use for some tunnels).

 

[Merle Haggard]

The national speed limit for goods vehicles on single carriageway roads in the UK was raised to 50 mph some years ago.

Around here we have the '20 mph advisory' signs in former 30mph areas. If you observe it you are likely to be tailgated by a loaded 8 wheel tipper involved in either HS2 or rail terminal construction. Interesting that, in other 30 mph areas, if you drive at 20 mph (with the same result) it could be construed that you are committing the offence of 'careless driving'...

 

[Harpo]

Motorways really can go to 80

Absolutely not! UK driving standards are just not good enough.

 

[jupiter]

80 would be a ridiculous limit in the UK today with the huge traffic density. Comparing with autoroute in France or autobahn in Germany is not comparing like with like.

Frankly I‘d be happy if I could get to and hold 70 more often on UK motorways, they are often choked to death.

 

[JamesT]

The national speed limit for goods vehicles on single carriageway roads in the UK was raised to 50 mph some years ago.

Around here we have the '20 mph advisory' signs in former 30mph areas. If you observe it you are likely to be tailgated by a loaded 8 wheel tipper involved in either HS2 or rail terminal construction. Interesting that, in other 30 mph areas, if you drive at 20 mph (with the same result) it could be construed that you are committing the offence of 'careless driving'...

England and Wales. Scotland didn’t change their limits at the same time. https://www.transport.gov.scot/news/national-speed-management-review/

The consultation runs until Wednesday 5 March 2025. It invites feedback on proposals to lower the national speed limit on single carriageway roads from 60 mph to 50 mph and to increase speed limits for goods vehicles over 7.5 tonnes on single-carriageways to from 40 mph to 50 mph and dual carriageways from 50 mph to 60mph.

 

[fishwomp]

Maybe you don't recognise e=mc^2? The enegy to be dispersed rises with the square of the speed...

I recognise it, and it's the wrong formula: c is speed of light, and this is Einstein and particle physics. The speed of light is not reduced by the average speed limits on the M4.

You mean e = 0.5*mv^2..

However, the point you are making is correct, energy (as dissipated in a crash) is proportional to the square of velocity.

== Doublepost prevention - post automatically merged: 18 Aug 2025 ==

sign on the left of the carriageway reads "Speed limit to improve air quality". ..

Meanwhile, whilst driving in a long 20mph zone yesterday, I noted the decrease in mpg compared to the adjacent 30mph .. that is *increasing* pollution....

 

[Bletchleyite]

In Scotland our government is debating making single carriageways 50mph for all road users. Currently our limit for wagons is a mere 40mph on single carriageways, which is a huge relative difference from 60mph for cars, car-derived vans, etc. If they follow through with it, it'll be interesting to see the results. The logical step if that's successful would be 60mph for all dual carriageway users. Motorways I think are different in that you can have larger speed differentials, as you usually have 2+ lanes, often 3+, hard shoulders or on 'smart' motorways emergency refuge areas, the lanes are a minimum width to meet motorway standard, etc.

To me there's a big difference between a motorway standard or close to motorway standard dual and a normal dual. Most notably acceleration lanes are long enough to join at the prevailing speed of the road (usually 56mph) though there is a big issue with nervous drivers doing so dangerously way below that which could do with being addressed by way of mandatory motorway lessons prior to completing the test, and there is a hard shoulder. I would apply a maximum 60 to a motorway without a hard shoulder just as hard shoulder running on the original Managed Motorways setup did.

You could sign up to 70 duals that did meet that sort of standard.

40mph for any road without a marked centreline (unless urban or signed otherwise) could also be a sensible move. 60 on single track roads is largely silly.

I could be persuaded by 80 on a proper (hard shoulder) motorway in the past but I think I'd now be against on environmental grounds as air resistance is the square of the speed so 80 is significantly worse on fuel consumption and thus emissions than 70, so I think now on balance not.

 

[mpthomson]

Accidents reduce in severity when safety features are improved.

I do not think anyone believes that cars are still as unsafe as they were when 70mph was selected as an appropriate limit.

My argument is simply that we need reduced speeds where there are external risks (such as those created by cars needing to stop and turn, pedestrians etc) and then that the balance is that we recognise that the motorways can operate perfectly safely at higher speeds.

If the whole aim of law is to prevent harm then we are on our way to a very bad place.

== Doublepost prevention - post automatically merged: 17 Aug 2025 ==

It would probably be helpful to look at the way the Germans handle motorways too:



Taken from: RAC Guide to German Speed

It's worth noting that injury and fatalies on German motorways are already higher than the UK on limited sections to start with and significantly higher (more than 20% higher) on unlimited stretches (and that's based on per million km driven, so its a fair comparator). This idea that autobahns are safer than UK motorways is a myth.