20 mph Zones - Extend or Eliminate?

[bramling]

So if you stop doing what you need to be reasonably safe from law breaking motorists on the public highway, you are being bullied. That's just about summing the situation up. No wonder that so many potential cyclists just don't bother.

So what’s the solution?

* Complete replacement of our failed political system (that seems to be the cause of most of our current problems)?
* Acceptance that we need to cease population growth?
* Reduce availability of cheap credit in order to reduce the availability of cars?
* Sort out the police, who seem dysfunctional in so many areas, and with whom most people seem pretty dissatisfied?

From my perspective cycling has become more dangerous over the last two and a half decades, and a lot of this can be indirectly attributed to government policies and failings. Sticking up a few 20 mph discs isn’t going to address that, nor even start to.

Worth also adding that, like many things, this has all got worse since Covid.

Out of interest, have you cycled / do you cycle on roads?

 

[AM9]

Out of interest, have you cycled / do you cycle on roads?

Frequently since my teens but over the last thre/four years, very little owing to a leg issue. I have however as a motorist, always respected cyclists on the road and despite the attempts of some 'bullying' drivers stood fast in doing so.

Frequently since my teens but over the last thre/four years, very little owing to a leg issue. I have however as a motorist, always respected cyclists on the road and despite the attempts of some 'bullying' drivers stood fast in doing so.

I live in hope of cycling again soon, I have a Brompton and a hardtail hybrid cycle.

 

[DerekC]

So what’s the solution?

* Complete replacement of our failed political system (that seems to be the cause of most of our current problems)?
* Acceptance that we need to cease population growth?
* Reduce availability of cheap credit in order to reduce the availability of cars?
* Sort out the police, who seem dysfunctional in so many areas, and with whom most people seem pretty dissatisfied?

From my perspective cycling has become more dangerous over the last two and a half decades, and a lot of this can be indirectly attributed to government policies and failings. Sticking up a few 20 mph discs isn’t going to address that, nor even start to.

Worth also adding that, like many things, this has all got worse since Covid.

Out of interest, have you cycled / do you cycle on roads?

Cyclists seem to assume that the effectiveness or otherwise of the 20mph speed limit should be determined based on the effect on them. Whether or not we drive a car or cycle, we are all pedestrians. To repeat, the risk of a pedestrian being killed when hit by a car at 30mph is between five and eight times higher than at 20mph. As far as I am concerned that's the end of the argument. In town centres, housing estates and other places where cars and pedestrians are likely to interact, the speed limit should be 20mph. That doesn't mean that all 30mph zones should become 20mph zones, though. The difficult areas are where there are heavily trafficked routes which pass through urban areas. South London seems to be doing real world experiments - applying 20mph to the A24 through Tooting, for example. Hopefully somebody is collecting the statistics so that we can have proper evidence to base decisions on, and not just a lot of social media anecdotes from the motoring lobby.

 

[AdamWW]

Cyclists seem to assume that the effectiveness or otherwise of the 20mph speed limit should be determined based on the effect on them. Whether or not we drive a car or cycle, we are all pedestrians. To repeat, the risk of a pedestrian being killed when hit by a car at 30mph is between five and eight times higher than at 20mph. As far as I am concerned that's the end of the argument. In town centres, housing estates and other places where cars and pedestrians are likely to interact, the speed limit should be 20mph. That doesn't mean that all 30mph zones should become 20mph zones, though. The difficult areas are where there are heavily trafficked routes which pass through urban areas. South London seems to be doing real world experiments - applying 20mph to the A24 through Tooting, for example. Hopefully somebody is collecting the statistics so that we can have proper evidence to base decisions on, and not just a lot of social media anecdotes from the motoring lobby.

I think a lot of people don't know/have forgotten that kinetic energy goes as the square of speed or don't think through the consequences.

I wonder if it would make people more aware if analogue speedometers were arranged so that the needle moved linearly with energy not speed.

I do wonder about your assertion that we're all pedestrians though. You'd think so, but from the way some drivers behave it appears that they've never had to cross a road away from an official crossing in their life. Perhaps because they always park right in front of where they're going even if that means parking in a bus layby or blocking a pavement.

 

[bramling]

Cyclists seem to assume that the effectiveness or otherwise of the 20mph speed limit should be determined based on the effect on them. Whether or not we drive a car or cycle, we are all pedestrians. To repeat, the risk of a pedestrian being killed when hit by a car at 30mph is between five and eight times higher than at 20mph. As far as I am concerned that's the end of the argument.

In general terms it is reasonable to consider that cyclists are rather more likely than any other group to be on the receiving end of an incident that is in no way their fault - and not just from motorists, pedestrians can be just as much of a liability to cyclists.

For pedestrians, it’s all well and good saying that 20 mph is absolutely safer, however like everything in life there is an element of compromise. Pedestrians have to take some responsibility, which means taking care when crossing a road. Obviously roads where there are specific issues merit special measures (which may well be a reduced speed limit, but could also be something as simple as an extra crossing), however like with many things a blanket restriction is not the answer.

Personally as a pedestrian I find 20 mph extremely irritating as it often means waiting longer to cross a road. So it seems to be annoying for pedestrians and drivers, and more difficult for cyclists, lose all round.

 

[Bletchleyite]

and more difficult for cyclists

I don't agree. In central London as a cyclist I love it. I can out-accelerate the cars and ride with them taking the lane (and anyone not fit enough to ride at 20 on the flat has the option of an e-bike, which can at least take them to 15.5* which is good enough for most purposes given how 20 on a car speedo will actually be about 18). Absent full segregation on the Dutch model (which is my preference but not always practical, particularly in an old city like London) it is vastly better than 30 for me.

Plus if anything does hit me I'm considerably less likely to be seriously injured.

I can understand why drivers don't like it, but having tried it I don't understand why a cyclist would not, unless they're the sort of cyclist who wants to get their head down on a £10K road bike and ride at 30 or more, but that sort of cyclist is a small minority and city streets aren't the place for them anyway, to do that you want to get out onto the country lanes which typically have a 60mph limit anyway!

(Before I tried it I thought I wouldn't like it because it would prolong overtakes, but my experience in central London is that people just don't overtake, particularly if you take the lane and ride as if you were a motorcycle rather than in the gutter).

I wonder if maybe compliance is higher in London due to the more intensively policed nature of it compared to the rest of the country? And because cars really are deprecated in central London?

 

[Meerkat]

However, slightly more time spent on journeys through roads that have more restrictions than some drivers would prefer does not simply translate to a direct cost when the full human impact is included.

It is a significant amount of time in total as it affects a lot of journeys for individuals. And in business cases time has a value.

I'm not convinced that additional time is that significant, particularly on some roads in Wales where the actual average speed when a 30 mph limit was nowhere near that figure, and the actual speed was much nearer the new 20mph limit since it was changed.

If that is true for a particular site then there won’t be complaints about it

Then there's the actual speed when a 30mph limit road isn't heavily loaded where speeds are consistently heading towards the 40mph level, effectively invalidating any case for 30mph being as safe as body collision tests indicate

If the road isn’t heavily loaded then the chances of an accident plummet - risk isn’t just severity but also likelihood

and adjust the legal limit to bring that down to the appropriate safety aspirations.

That is a very poor way of making law. Just prosecute the current law properly or engineer the road to have a physical 30mph limit

He shouldn't be sweating after a two mile ride unless it's all uphill.

I did compare it to walking/jogging - you wouldn’t have a shower if you walked (cruised) to work, so don’t jog (thrash it)!

To repeat, the risk of a pedestrian being killed when hit by a car at 30mph is between five and eight times higher than at 20mph.

What’s the risk of them actually being hit, particularly in the disputed 20v30 zones?
PS I have always wondered - is this stat the impact speed or the speed before braking?

I don't understand why a cyclist would not

20mph reduces overtaking - as a cyclist I hate having cars trundling along behind me.

 

[bramling]

I don't agree. In central London as a cyclist I love it. I can out-accelerate the cars and ride with them taking the lane (and anyone not fit enough to ride at 20 on the flat has the option of an e-bike, which can at least take them to 15.5* which is good enough for most purposes given how 20 on a car speedo will actually be about 18). Absent full segregation on the Dutch model (which is my preference but not always practical, particularly in an old city like London) it is vastly better than 30 for me.

Plus if anything does hit me I'm considerably less likely to be seriously injured.

I can understand why drivers don't like it, but having tried it I don't understand why a cyclist would not, unless they're the sort of cyclist who wants to get their head down on a £10K road bike and ride at 30 or more, but that sort of cyclist is a small minority and city streets aren't the place for them anyway, to do that you want to get out onto the country lanes which typically have a 60mph limit anyway!

(Before I tried it I thought I wouldn't like it because it would prolong overtakes, but my experience in central London is that people just don't overtake, particularly if you take the lane and ride as if you were a motorcycle rather than in the gutter).

I wonder if maybe compliance is higher in London due to the more intensively policed nature of it compared to the rest of the country? And because cars really are deprecated in central London?

I think you may well be on to something with the idea that London may not be the same as elsewhere.

Personally I don’t really like having vehicles close up behind. If you come off for whatever reason (for example hit a pothole badly, pedestrian does something, or even a stray animal crosses), you are going to go straight under the wheels of whatever is behind you if they’re not leaving a decent gap - which of course many people don’t. 20 mph isn’t going to offer you much help in that situation.

Personally I’d rather take my chances with 30 mph and have people overtaking properly. 20 mph really seems to bunch traffic up in undesirable ways.

 

[AM9]

It is a significant amount of time in total as it affects a lot of journeys for individuals. And in business cases time has a value.

Ah the cost is everything mentality, - even to the extent of sacrificing safety.

If that is true for a particular site then there won’t be complaints about it

Oh yes there will, - those motorists that would see it as taking away their right to travel at 30mph forever, (or whatever speed over the limit that they think they should get away with.

If the road isn’t heavily loaded then the chances of an accident plummet - risk isn’t just severity but also likelihood

Once again, safety is secondary, let's trade some light injuries for a lower number of KSIs.

That is a very poor way of making law. Just prosecute the current law properly or engineer the road to have a physical 30mph limit

Then listen to the whining of speeding motorists that cameras and enforment is war on motorists and a cash cow. On the other point. Making every inadequate road safe at 30mph is like throwing cash at persistent speeders. If there is violation of limits set to protect pedestrians and other vulnerable road users, reduce the legal limit until the actual speeds meet th safety requirement, (or of course put those inconsiderate drivers off using the roads in question).

 

[Ediswan]

I wonder if it would make people more aware if analogue speedometers were arranged so that the needle moved linearly with energy not speed.

Interesting idea. Against, the scale would be cramped at 20 mph, so harder to read.

 

[Meerkat]

Ah the cost is everything mentality, - even to the extent of sacrificing safety.

Bit childish, and you don’t seem to understand how safety has a value, and time has a value. Shouting ‘but safer so ignore every thing else!’ isn’t a sensible way of debating things.

Oh yes there will, - those motorists that would see it as taking away their right to travel at 30mph forever, (or whatever speed over the limit that they think they should get away with.

Not on a road where the vast majority of them cant do 30 anyway.
There is a good theory that speed limits should be set at the 85th percentile of current speeds. Most drivers know what they are doing.

Then listen to the whining of speeding motorists that cameras and enforment is war on motorists and a cash cow. On the other point. Making every inadequate road safe at 30mph is like throwing cash at persistent speeders. If there is violation of limits set to protect pedestrians and other vulnerable road users, reduce the legal limit until the actual speeds meet th safety requirement, (or of course put those inconsiderate drivers off using the roads in question).

You haven’t proven what the safety requirements are - you are just saying ‘safer’
Lets make all trains go over level crossings at ‘stop on sight‘ speeds - it’s safer!

 

[Bikeman78]

I do wonder about your assertion that we're all pedestrians though. You'd think so, but from the way some drivers behave it appears that they've never had to cross a road away from an official crossing in their life. Perhaps because they always park right in front of where they're going even if that means parking in a bus layby or blocking a pavement.

I rarely walk in my local urban area, apart from taking the kids to school which is a two minute walk. Local journeys are undertaken by bike, car or bus. If I go shopping in the city centre, I cycle or take the bus and rarely have to cross any roads to get to where I want to go.

For pedestrians, it’s all well and good saying that 20 mph is absolutely safer, however like everything in life there is an element of compromise. Pedestrians have to take some responsibility, which means taking care when crossing a road. Obviously roads where there are specific issues merit special measures (which may well be a reduced speed limit, but could also be something as simple as an extra crossing), however like with many things a blanket restriction is not the answer.

Or putting the crossing where people actually want to cross. An example that springs to mind, there are two Pelican crossings very close together by the Hilton hotel. From my observations over 20 years or so, an awful lot of people ignore both crossings and cross the road between them. The one closer to the castle is used so rarely, I reckon I get stopped by it once a year on average.

 

[DerekC]

In general terms it is reasonable to consider that cyclists are rather more likely than any other group to be on the receiving end of an incident that is in no way their fault - and not just from motorists, pedestrians can be just as much of a liability to cyclists.

I don't follow the logic. Pedestrians are regularly hit on the pavement by cars (and cycles sometimes), on pedestrian crossings and by motor vehicles exceeding the speed limit.

Personally as a pedestrian I find 20 mph extremely irritating as it often means waiting longer to cross a road. So it seems to be annoying for pedestrians and drivers, and more difficult for cyclists, lose all round.

Based on a sample of one. Personally, as a pedestrian I find 20mph much better - there is more time to assess whether it's safe to cross, and if I get it wrong the car can slow down a bit without the driver getting hot and bothered. And if applied sensibly in the right places the impact on travel time to me as a driver is minimal.

There is a good theory that speed limits should be set at the 85th percentile of current speeds. Most drivers know what they are doing.

Not sure there is much theory to it. It's just convenient for the highway and police authorities to have it as a rule so that policing doesn't get too strenuous. It's a nonsense when you have a hidden hazard which applies largely to pedestrians and cyclists. I have personal experience of trying to get a 30mph applied at a crossroads with just that problem and the 85% rule is quoted back at you. This was and is in the middle of a village at a crossing with very limited sightlines, on a bend with a 40mph speed restriction on the main road. Although the 85% value over 24 hours was just on 40mph, it was higher in the peaks and early morning and evening at the tail end of the peak saw occasional approach speeds up to 65mph. It simply wasn't possible to cross without real risk of being flattened unless you had good hearing and could run fast if necessary.

 

[The Ham]

Not sure there is much theory to it. It's just convenient for the highway and police authorities to have it as a rule so that policing doesn't get too strenuous. It's a nonsense when you have a hidden hazard which applies largely to pedestrians and cyclists. I have personal experience of trying to get a 30mph applied at a crossroads with just that problem and the 85% rule is quoted back at you. This was and is in the middle of a village at a crossing with very limited sightlines, on a bend with a 40mph speed restriction on the main road. Although the 85% value over 24 hours was just on 40mph, it was higher in the peaks and early morning and evening at the tail end of the peak saw occasional approach speeds up to 65mph. It simply wasn't possible to cross without real risk of being flattened unless you had good hearing and could run fast if necessary.

85th percentiles are a useful tool, however they aren't really used for assessing what the speed limit should be as much as they were.

Car is no longer king, and shouldn't have been due some time now, other factors should be considered. For example, a 40mph 85th%ile may not be an appropriate speed if there's a lot of accidents. Likewise, there's times when the existence of a school, a crossing, or shops may mean that enforcing a lower speed limit could be better.

 

[Krokodil]

With areas with the 20mph limit, nobody seems to give a stuff, even bus drivers.

Whenever I've been on an Arriva Wales bus, the 20 limits have been stuck to religiously. Even in the (few) areas where they probably should be revised. Perhaps Arriva use black boxes.

But what it does mean is we now have a forest of signs all around the town

Which is exactly why the Welsh Government changed the law. Previously the default limit was 30mph in built-up areas (definied as within 200yds of street lighting) and NSL (originally unrestricted, as is still the case in the IoM) elsewhere. Any other limit requires reminder signs. The Welsh law change means that 20mph is now the default for a built-up area and therefore requires no reminder signs, 30 zones now require the reminder signs instead.

It's worth remembering that there was no science behind the choice of 30mph as an urban speed limit. It was a pretty arbitary figure when it was set in the 1930s. Nearly 100 years later, we have much more data.

It is a significant amount of time in total as it affects a lot of journeys for individuals. And in business cases time has a value.

Businesses certainly consider time to have a value. That's why the Irish lorries routinely speed on the A55 (I've been overtaken by one when doing an indicated 70mph), their employers consider the time saving (which over a week would accumulate to enough time to get an extra run in) to be worth more than the cost of the fines when a police officer examines the tachograph.

The average length of a car journey in the UK is 8.1 miles. If that entire journey was driven at an average of 30mph (which it wasn't because it would have encountered junctions, and acceleration is not instant) it would have taken 16 minutes 12 seconds. At an average speed of 20mph it now takes 24 minutes 18 seconds. That's small change, I've spent more than 8 minutes 6 seconds reading this thread. That's a hypothetical worst-case example. Once you consider a few junction stops, plus navigating residential streets or car parks (most car journeys start and/or end on a slow-speed street where you couldn't do 30 whatever the signs said) the average speed never was 30mph in the first place. Then consider that this 8.1 mile average will include both short journeys (which will mostly be on restricted roads) and long journeys (which will mostly be on 60mph roads or 70mph motorways) then the time lost by the change in limits will be even trivially smaller.

Taking some real world average speeds (rather than assuming that everyone averaged 30 and now will average 20), Bristol's daytime average dropped by 2.7mph in the areas where speed limits were reduced. So that 8.1 mile journey (enough to get you from one side of the city to the other) used to take 19 minutes 50 seconds and now takes 22 minutes 18 seconds. What were you otherwise planning to do with the two-and-a-half minutes you've lost?

So what do 20mph limits gain? In Bristol they gain 4.53 lives per year, plus 11.3 serious and 159.3 slight injuries are avoided. In cash terms the speed limit reduction has saved the city more than £15m per year according to the University of the West of England (source: https://www.bbc.co.uk/news/uk-england-bristol-43050841)

 

[Meerkat]

So what do 20mph limits gain? In Bristol they gain 4.53 lives per year, plus 11.3 serious and 159.3 slight injuries are avoided. In cash terms the speed limit reduction has saved the city more than £15m per year according to the University of the West of England (source: https://www.bbc.co.uk/news/uk-england-bristol-43050841)

Lot of estimates there.
the added time for each journey maybe seem trivial but it’s on journeys people do multiple times per day, plus all the business travel.
If small time savings are so trivial why do we bother speeding up trains?

 

[Krokodil]

Lot of estimates there.

If you want to provide your own figures, go ahead. Any estimate of time lost that I have seen from the "20 is not plenty" brigade has been a ludicrous fantasy - for example: "if it took you 2hrs at 30 it'll now take 3hrs". I'd be amazed if there was a continuous stretch of 60 miles of 30mph road (now 20) anywhere in the country with no fast trunk road you could be using instead. So if you can provide examples of just how much time is being lost and convert that into money, I'm all ears.

it’s on journeys people do multiple times per day

If speeding up journeys in built-up areas is the goal then we should look to reduce congestion. 30mph areas are often stop-start, whereas 20mph allows traffic to flow smoother (in a railway analogy it's slow enough to allow more line of sight working rather than relying upon signalled junctions and crossings). 72% of car journeys are less than five miles, 25% less than 1 mile. The latter journeys are often quicker by bicycle than by car, because of the need to find a parking space and park. Remove them and traffic will flow much more freely. How do you encourage more people (particularly parents with kids) to cycle? Make the roads safer.

plus all the business travel

Which is generally doing long distances over trunk roads, not kerb-crawling on residential streets.

If small time savings are so trivial why do we bother speeding up trains?

Trains move lots of people over long distances, mostly isolated from pedestrians (and we are generally working towards elimination of level crossing risk). Cars are occupied by an average of 1.3 people (so are an inefficient use of road space), usually over very short distances (particularly the journeys within the 20mph zones we speak of) which would be more efficiently served using active travel. They account for more than 5,000 pedestrians killed or seriously injured each year. That's why it's important to encourage modal shift from cars to public transport and active travel.

 

[The Ham]

If you want to provide your own figures, go ahead. Any estimate of time lost that I have seen from the "20 is not plenty" brigade has been a ludicrous fantasy - for example: "if it took you 2hrs at 30 it'll now take 3hrs". I'd be amazed if there was a continuous stretch of 60 miles of 30mph road (now 20) anywhere in the country with no fast trunk road you could be using instead. So if you can provide examples of just how much time is being lost and convert that into money, I'm all ears.

I'd go further and suggest that there's probably fairly few places where you could even travel as much as 10 miles at 30mph without there being an alternative route (i.e. higher speed roads) which would reduce the impact of that route was changed to be being 20mph.

Even where they do exist, that's likely through a large urban area and so you're journey time would likely be significantly slower than an average of 30mph (even off peak) due to the number of junctions you've got to negotiate - reducing your average speed.

As there'll be a given amount of time already spent traveling at less than 20mph then the overall saving would likely be lower. Add to that the time spent increasing from 20mph to 30mph which further reduces your average speed (again the more you do this the more it will impact you).

This could mean that for fairly free moving roads with limited junctions the average speed may fall by less than 10mph.

 

[Krokodil]

As there'll be a given amount of time already spent traveling at less than 20mph then the overall saving would likely be lower.

Exactly. In the 30mph roads in Bristol that were later converted to 20 the daytime average speed was only 24.5 before the change (in the peak you'd be lucky to average 10mph on Gloucester Road through Horfield). Now the average is 21.8mph.

 

[The Ham]

Exactly. In the 30mph roads in Bristol that were later converted to 20 the daytime average speed was only 24.5 before the change (in the peak you'd be lucky to average 10mph on Gloucester Road through Horfield). Now the average is 21.8mph.

10 miles at 25.4mph takes 24.5 minutes.

10 miles at 21.8mph takes 27.5 minutes.

However as I said, you'd not find many places where you'd be able to drive for 10 miles without there being an alternative route with higher speed roads which would mitigate at least some of that 3 minutes.

It's also not a journey that is all that commonly undertaken.

The bigger impact would be those trips of 1, 2, or 3 miles which would be about 18 seconds per mile slower. Whilst that's up to a minute slower, there's a fairly good chance that people have to allow more than that for the times when there's more congestion than normal, so they aren't likely to be leaving any earlier or expecting to be home any sooner.

For example at the higher speed, it would take about 7.5 minutes to travel 3 miles, however most people of driving (even off peak) would plan for it take about 10 minutes as that's within normal journey patterns (not even an excessively busy day) chances are with the slower speeds most people would still assume it would be taking 10 minutes.

 

[Meerkat]

If you want to provide your own figures, go ahead.

I couldn’t get the study to load to find their source data

whereas 20mph allows traffic to flow smoother

I doubt that in an urban situation

Which is generally doing long distances over trunk roads, not kerb-crawling on residential streets.

Business travel includes the huge mileage of delivery drivers (both to houses and local shops), buses, police, care workers, etc etc

The bigger impact would be those trips of 1, 2, or 3 miles which would be about 18 seconds per mile slower. Whilst that's up to a minute slower, there's a fairly good chance that people have to allow more than that for the times when there's more congestion than normal, so they aren't likely to be leaving any earlier or expecting to be home any sooner.

On local journeys if delays don’t use your slack you use the time (ie you are home earlier) so this is not a relevant argument.
And it’s the local bit that you do most often - so it’s a little bit of time but multiplied by a lot of examples.

Just to be clear I am not against 20 limits in appropriate places, but a default of making 30 into 20 is just Damaging anti car ideology.

 

[Krokodil]

Business travel includes the huge mileage of delivery drivers (both to houses and local shops),

Delivery drivers seldom care about the law anyway (and I'm not that fussed about Amazon's productivity, it's not like they pay their fair amount of tax). It's not just the vans with iffy driving standards, in a previous life I remember unloading P&H lorries with great difficulty, given what the driving had done to the load. Again, it's not like we're talking a massive change in speed, it was 2.7mph in Bristol. Most lorries weren't at the higher end of the old speeds either.

buses,

The main flaw with buses is that they get stuck in traffic, if you want them to be competitive (rather than just a last resort for those with no choice) then they need dedicated lanes.

police,

I'd be interested to know how much police work (excluding pursuits) is affected by this. Also worth bearing in mind that the £15m/year Bristol saved from having safer roads will include the police as well as the NHS.

care workers, etc etc

Again I'd be interested in a time & motion exercise. My instinct is that urban care workers probably spend an excessive amount of time looking for parking spaces and otherwise crawling around in traffic. They may actually benefit from being able to do their rounds by bicycle. In rural areas there is little impact from 20mph zones, through traffic must briefly slow down while passing through a village and local traffic wouldn't have managed 30 anyway (in pretty much any village I've ever known you'd struggle to do more than 15 anywhere except the main road through it).

anti car ideology.

Pro-safety and pro-environment is not "anti-car". Motorists benefit from modal shift too, every car driver who walks or cycles instead is one less car in the jam.

On the subject of productivity, did you know that in some parts of the US, people spend a quarter of their waking lives either driving to work or working to pay for the car they drive to work? We're not at that extreme, thank goodness but it's important to remember that not all of the money spent is recirculated in the UK economy, several places with dubious human rights records (not to mention one or two openly hostile states) have become rich on the proceeds.

 

[The Ham]

journeys if delays don’t use your slack you use the time (ie you are home earlier) so this is not a relevant argument.
And it’s the local bit that you do most often - so it’s a little bit of time but multiplied by a lot of examples.

Just to be clear I am not against 20 limits in appropriate places, but a default of making 30 into 20 is just Damaging anti car ideology.

Not all local journeys result in you being home sooner.

For example (and whilst not so well be relevant for all people they will be relevant for some) picking a child up from somewhere with a scheduled end time, going to an appointment, going to work, going to catch a train, or pretty much any outwards trip where there's a defined time.

Whilst you may get there up to a minute earlier, it's not time that it's actually going to be saved, as work is unlikely to let you clock off one minute early, the train is still going to arrive when it does, there club/school aren't going to let your child out early.

When coming home, yes the average will be up to a minute faster and so you have that time. However, there's going to be times when there's congestion which would slow down the journey when you can max out at 30mph, however chances are when you can max out at 20 the amount of time saved would be reduced.

Even if an individual did 6 trips a day returning to their home (so there's at least in trip away from home where the time is likely to be lost), at most that's an extra 36.5 hours a year, however that's added to the 22.8 days of time spent driving for making 12 trips of 3 miles day (1 out and one back to your house, assuming no extra delays reducing the time saving).

However, one person making 12 trips a day of three miles is fairly rare, it's more likely that there'll be shorter journeys (reducing the time - at one mile it's 18 seconds, yes i know 3*18≠60, but I've been consistent by saying up to a minute, it would sound petty to say 54 seconds) or there'll be fewer trips or both.

As such the amount of time saved for most people wouldn't be all that much.

 

[Meerkat]

The main flaw with buses is that they get stuck in traffic, if you want them to be competitive (rather than just a last resort for those with no choice) then they need dedicated lanes.

That’s a distraction. Buses will be in 30 zones much of the day - if they have to do 20 it will make a difference.

I'd be interested to know how much police work (excluding pursuits) is affected by this.

They drive around all day. If they have to do 20 for much of it then they will cover significantly less area. And the plod are now very centralised - they do a lot of driving from their base to their work area.

They may actually benefit from being able to do their rounds by bicycle. In rural areas there is little impact from 20mph zones, through traffic must briefly slow down while passing through a village and local traffic wouldn't have managed 30 anyway (in pretty much any village I've ever known you'd struggle to do more than 15 anywhere except the main road through it).

Have you seen how much stuff care workers lug about! Suburbia is full of miles and miles of 30 limits on which you can easily do 30 for much, if not all the day.

Pro-safety and pro-environment is not "anti-car". Motorists benefit from modal shift too, every car driver who walks or cycles instead is one less car in the jam.

It is anti car if the aim is to slow down cars on a blanket basis, without a business case for it at a road by road level.

As such the amount of time saved for most people wouldn't be all that much.

In suburbia there are miles of 30 limits on which you can do 30. All that will now take 50% longer.
it will add up. Why does time not have a value for speed decreases when it does for all other things?

 

[Krokodil]

In suburbia there are miles of 30 limits on which you can do 30. All that will now take 50% longer.

Except that there generally aren't miles of roads in suburbia where you can safely do 30. There are some feeder roads which if properly designed would be equipped with protected cycle lanes and proper pedestrian crossings can remain at 30. Often roads where there is some sort of spacer (usually grass but increasingly wildflowers) between the pavement and the road. Streetview link of an example, not a perfect one but along the right lines:
https://maps.app.goo.gl/ZnZEQLtWWumKmA5C8?g_st=a c

The rest are twisty, windy residential streets which are often clogged with parked cars. No one should be doing 30 on these, even if the limit technically allows it. These should remain 20, even if some also happen to function as distributor roads (such as in an older development designed without the benefit of modern planning theory). Speed limits exist to ensure safe conditions for vulnerable road users, convenience is not a consideration.

 

[The Ham]

In suburbia there are miles of 30 limits on which you can do 30. All that will now take 50% longer.
it will add up. Why does time not have a value for speed decreases when it does for all other things?

As I've said there's very few places where you can drive for 10 miles in a 30 limit without there being an alternative route would reduce the impact.

Also, due to junctions, crossings and the like, you can rarely average 30mph in a 30 limit, whilst the same is true if a 20 limit, a lot of the time spent sorting down and speeding up will be between 30 to 20 and from 20 to 30, so it's almost never 50% more time.

Even if it were to be, given that most people would need to add in a buffer for congestion (stopping at a crossing to allow a pedestrian to cross, stopping at a red light at a junction, having to give way as there's a stream of traffic on the main), so they will have wasted time built in. Changing to a 20 limit for a noticeable distance isn't likely to alter that buffer by very much (if at all), as the days they need it they'll be going far slower than 20mph anyway.

 

[yorkie]

...In suburbia there are miles of 30 limits on which you can do 30. All that will now take 50% longer...

I find this implausible.

Can you link to an example journey on Google Maps where you think this might apply?

 

[signed]

Unless proper enforcement of any existing rule is done, compliance will never happen and non-compliance ruins any rule.

In Paris, being at 30kph (as required) can sometimes be dangerous as everyone, including taxis, buses..., drives at 50kph. If everyone complied, danger would probably be a LOT lower... The ring road down to 50kph (from 70, while everyone drives 90) after the Olympics is gonna be a massive **** show as compliance will probably not pass 10%.

Keep the roads at whatever they are now, concentrate on making the penalties for non-compliance actual proper detterants (I like the concept of income-based fines like in Nordic countries. suspension/penalty points on DL don't do anything, more and more people are driving without a license and that is not gonna stop anything) for anyone and then, and then only, act in regards for the rest of the populations.

 

[Krokodil]

Unless proper enforcement of any existing rule is done, compliance will never happen and non-compliance ruins any rule.

The Dutch police spend very little time enforcing speed. If a street has a speed problem then it's viewed as a design failure, and the engineers look for ways to encourage drivers to self-regulate their speed. Narrower lanes, uneven surfaces, chicanes etc.

 

[Bletchleyite]

The Dutch police spend very little time enforcing speed. If a street has a speed problem then it's viewed as a design failure, and the engineers look for ways to encourage drivers to self-regulate their speed. Narrower lanes, uneven surfaces, chicanes etc.

The UK has a similar thing in 20 Zones - the idea is that they aren't really enforced but rather traffic calming ensures that is a comfortable speed that people will tend to do naturally.