TfL to cut speed limit to 20mph

[Amarillo]

In September 2023 TfL plan to cut the speed limit on much of its single carriageway red route trunk roads to 20mph. Within the central congestion zone the limit is already 20mph. In my part of London this will effect roads such as the South Circular, A20 and A2 - though the single carriageway section of the A2 across the Blackheath plateau will remain a 30mph limit. It appears that later, much of the urban dual carriageway red route in London will see limits cut from 40 to 30mph.

If TfL choose to enforce these new limits with cameras, I expect it will be a nice little earner for them. (It is rumoured that static TfL cameras in 20 zones are calibrated to capture vehicles travelling in excess of 25mph; this rumour does not apply to mobile cameras and average speed cameras where 21mph might be the trigger).

 

[rod_vw]

It's my belief that a vehicle speedometer can legally have a 10% discrepancy. If that is so all cameras must allow the same margin.

Or shall we all employ a man with a flag!

 

[andyinluton]

It's my belief that a vehicle speedometer can legally have a 10% discrepancy. If that is so all cameras must allow the same margin.

Or shall we all employ a man with a flag!

The allowable 10% discrepancy is for over reading, there's no allowance for under.

 

[Lambeth Cali]

TfL have historically been quite keen to keep the North and South Circular at 30 mph as it’s central to their plan to keep traffic moving.

Some of the 20mph stuff is to do with road safety and some I think to do with emissions but I think they recognise that the 406 and 205 need to keep moving at 30mph. In Lambeth we’re already blanket 20mph. I quite approve of it to be honest but we have a stretch outside our house where cars do crazy overtakes because they’re angry at the car in front doing 18mph. Every other month we hear a loud bang and go outside to find another car has clipped a parked car whilst overtaking and flipped over onto its roof. No fatalities yet but I’m told we’re going to be given a speed camera soon.

 

[Amarillo]

TfL have historically been quite keen to keep the North and South Circular at 30 mph as it’s central to their plan to keep traffic moving.

Some of the 20mph stuff is to do with road safety and some I think to do with emissions but I think they recognise that the 406 and 205 need to keep moving at 30mph. In Lambeth we’re already blanket 20mph. I quite approve of it to be honest but we have a stretch outside our house where cars do crazy overtakes because they’re angry at the car in front doing 18mph. Every other month we hear a loud bang and go outside to find another car has clipped a parked car whilst overtaking and flipped over onto its roof. No fatalities yet but I’m told we’re going to be given a speed camera soon.

I don’t think that emissions come into the decision to create 20mph zones. It is all about pedestrian safety:
Hit at 30mph 50% chance of living
Hit at 20mph 90% chance of living

Some details here:

Lowering Speed Limits

The Mayor and Transport for London (TfL) is committed to Vision Zero, eliminating death and serious injury from London’s roads. The Vision Zero Action Plan sets out our ambition and next steps to achieve this. It details our plans to reduce road danger, including proposals to implement safer...

haveyoursay.tfl.gov.uk

The N. Circular and S. Circular are completely different beasts, and other than making a near orbital road, bear little in common.

All (most) of the NCR is purpose built, sometimes grade separated, with properly designed junctions. Little of the SCR is purpose built, it is mostly a hotch potch of pre existing roads and includes delights such as the inaptly named Rushy Green gyratory (you cannot rush it, and the “green” is now an electic mix of businesses including McDonalds, Lidl, a rather good pub, and a now closed down gun shop below a tower block called Eros House).

 

[Camperfamily]

Much of Edinburgh city is now 20mph. It takes a while getting used to initially (coming from blanket 30mph), but I now often feel that 30mph would seem too fast in an inner city setting. Prior to the reduced limits I never thought twice about 30mph being fast. I’m now very much in favour of the 20mph in the inner city setting.

I also can’t say I notice much of a difference in journey times as a result, despite Edinburgh generally not suffering from traffic congestion.

 

[andyinluton]

I don’t think that emissions come into the decision to create 20mph zones. It is all about pedestrian safety:
Hit at 30mph 50% chance of living
Hit at 20mph 90% chance of living

Some details here:

Lowering Speed Limits

The Mayor and Transport for London (TfL) is committed to Vision Zero, eliminating death and serious injury from London’s roads. The Vision Zero Action Plan sets out our ambition and next steps to achieve this. It details our plans to reduce road danger, including proposals to implement safer...

haveyoursay.tfl.gov.uk

Looks like pedestrian education would be better than penalising the innocent motorist again.

Table 5: Contributory factors allocated to pedestrians and vehicles involved in fatal or serious collisions with pedestrian, GB: 2016 to 2021

Pedestrian contributory factor Count
Pedestrian failed to look properly 13,377
Pedestrian careless, reckless or in a hurry 4,918
Pedestrian failed to judge vehicle`s path or speed 4,425
Crossing road masked by stationary or parked vehicle 2,969
Pedestrian impaired by alcohol 2,841
Pedestrian wearing dark clothing at night 1,761
Dangerous action in carriageway (eg. playing) 1,536
Pedestrian wrong use of pedestrian crossing facility 1,399
Pedestrian disability or illness, mental or physical 1,003
Pedestrian impaired by drugs (illicit or medicinal) 497

 

[Corradobrit]

That will make the average cyclist faster than the motorist.

 

[Amarillo]

Looks like pedestrian education would be better than penalising the innocent motorist again.

Table 5: Contributory factors allocated to pedestrians and vehicles involved in fatal or serious collisions with pedestrian, GB: 2016 to 2021

Pedestrian contributory factor Count
Pedestrian failed to look properly 13,377
Pedestrian careless, reckless or in a hurry 4,918
Pedestrian failed to judge vehicle`s path or speed 4,425
Crossing road masked by stationary or parked vehicle 2,969
Pedestrian impaired by alcohol 2,841
Pedestrian wearing dark clothing at night 1,761
Dangerous action in carriageway (eg. playing) 1,536
Pedestrian wrong use of pedestrian crossing facility 1,399
Pedestrian disability or illness, mental or physical 1,003
Pedestrian impaired by drugs (illicit or medicinal) 497

Nice bit of victim blaming going on there. Let us not forget that pedestrians use the road (except motorways and limited other section of road) by right, and motorists under licence.

If you are driving along your local high street it is not unreasonable to do so expecting pedestrians to cross; do so at 11.15pm past a pub and expect people to be stumbling out of the pub; past a school at 3.30 and children will be chasing one another.

 

[Amarillo]

That will make the average cyclist faster than the motorist.

That has been the case in London for a great many years. Cyclist, motorist and public transport user races across London used to be a regular feature on Top Gear. A sweaty Richard Hammond would win by bike, closely followed by a silent Stig on the tube, then a chastened Clarkson in a car, and finally a wet James May in a sailboat on the Thames.

 

[Amarillo]

It's my belief that a vehicle speedometer can legally have a 10% discrepancy. If that is so all cameras must allow the same margin.

Or shall we all employ a man with a flag!

The scrapping of the Red Flag Man was the end of road safety being taken seriously. If every car had a Red Flag Man jogging ahead now pedestrian road deaths would be close to zero.

 

[andyinluton]

The scrapping of the Red Flag Man was the end of road safety being taken seriously. If every car had a Red Flag Man jogging ahead now pedestrian road deaths would be close to zero.

If every car had a red man jogging in front I predict there would be an awful lot of red flag men being run over. ( probably by cyclists)

See my previously presented stats, its pedestrians in the road that are the problem not the speed of cars on the whole. If pedestrians stay on the pavement they don't get run over - pretty simple really.

 

[ArunAlec]

If every car had a red man jogging in front I predict there would be an awful lot of red flag men being run over. ( probably by cyclists)

See my previously presented stats, its pedestrians in the road that are the problem not the speed of cars on the whole. If pedestrians stay on the pavement they don't get run over - pretty simple really.

Trouble with staying on the pavement is they’re going to get knocked down by a prat on an electric scooter!

 

[Amarillo]

If every car had a red man jogging in front I predict there would be an awful lot of red flag men being run over. ( probably by cyclists)

See my previously presented stats, its pedestrians in the road that are the problem not the speed of cars on the whole. If pedestrians stay on the pavement they don't get run over - pretty simple really.

The trouble with requiring pedestrians to remain on the pavement is that pedestrians will either end up walking around in circles or come to an abrupt halt when the pavement ends or their route is barred by a car using the pavement as a parking facility.

 

[SamSara]

In September 2023 TfL plan to cut the speed limit on much of its single carriageway red route trunk roads to 20mph. Within the central congestion zone the limit is already 20mph. In my part of London this will effect roads such as the South Circular, A20 and A2 - though the single carriageway section of the A2 across the Blackheath plateau will remain a 30mph limit. It appears that later, much of the urban dual carriageway red route in London will see limits cut from 40 to 30mph.

If TfL choose to enforce these new limits with cameras, I expect it will be a nice little earner for them. (It is rumoured that static TfL cameras in 20 zones are calibrated to capture vehicles travelling in excess of 25mph; this rumour does not apply to mobile cameras and average speed cameras where 21mph might be the trigger).

Wish was in place Blackheath Road J/W Greenwich South Street last week when someone was intent on catching the lights and nearly took the front off my van!

 

[Velma's Dad]

The allowable 10% discrepancy is for over reading, there's no allowance for under.

At risk of pedantry before my first morning coffee, there's no "10% speedo error allowance" in law. Speeding is a strict liability offence and if you exceed the limit by 1mph you are guilty and potentially liable to prosecution.

In practice it's unusual for a prosecution to be brought for being just over the limit. For static speed cameras most police areas apply a 10%+2mph threshold, ie triggered at 35 mph in a 30 limit, 57 in a 50 etc. But they are not obliged to do so.

Of course in the past most car speedos used to significantly over-read so if you were seeing mid 30s on the needle you were probably still okay. But today's seem to be more accurate, unless of course you have fitted different wheels/tyres.

For our various vehicles I've checked the speedos against the GPS speed reading on Google Maps so I know how roughly how much leeway I've got.

 

[Amarillo]

At risk of pedantry before my first morning coffee, there's no "10% speedo error allowance" in law. Speeding is a strict liability offence and if you exceed the limit by 1mph you are guilty and potentially liable to prosecution.

In practice it's unusual for a prosecution to be brought for being just over the limit. For static speed cameras most police areas apply a 10%+2mph threshold, ie triggered at 35 mph in a 30 limit, 57 in a 50 etc. But they are not obliged to do so.

Of course in the past most car speedos used to significantly over-read so if you were seeing mid 30s on the needle you were probably still okay. But today's seem to be more accurate, unless of course you have fitted different wheels/tyres.

For our various vehicles I've checked the speedos against the GPS speed reading on Google Maps so I know how roughly how much leeway I've got.

Here's a handy table revealed by an early 2019 freedom of information request.

Police force​	Number of cameras	Camera activation threshold
Avon and Somerset	41	10% + 2mph
Bedfordshire	38	Would not reveal threshold
Cambridgeshire	32	Would not reveal threshold
Cheshire	15	10% + 2mph
Cleveland	4	10% + 2mph
Derbyshire	18	10% + 2mph
Devon and Cornwall	98	10% + 2mph
Durham	0 fixed	10% + 2mph
Essex	63	Don't use a standard threshold
Greater Manchester	235	Would not reveal threshold
Gwent	21	10% + 2mph
Hampshire	36	10% + 2mph
Hertfordshire	53	Would not reveal threshold
Kent	109	10% + 2mph
Lancashire	34	10% + 3mph
Leicestershire	30	10% + 2mph
Merseyside	18	10% + 2mph
Metropolitan Police/TfL	805	10% + 2mph
Norfolk	26	10% + 2mph
North Wales	28	10% + 2mph
Northumbria	55	10% + 2mph
Nottinghamshire	48	Refused to confirm if threshold exists
Police Service of Northern Ireland	12	10% + 2mph
Scotland	173	Refused to confirm if threshold exists
South Wales	137	10% + 2mph
South Yorkshire	25	10% + 2mph
Staffordshire	286	Would not reveal threshold
Suffolk	4	10% + 2mph
Thames Valley	294	10% + 2mph
Warwickshire	28	10% + 2mph
West Mercia	23	10% + 2mph
West Midlands	33	Would not reveal threshold
West Yorkshire	402	10% + 2mph

 

[andyinluton]

At risk of pedantry before my first morning coffee, there's no "10% speedo error allowance" in law.

To be even more pedantic, I was not talking about a tolerance on speeding, I was referring to the accuracy of your speedometer. If your Speedometer isn't allowed to under read you should never be speeding if you rely on your speedometer.


Speedometer accuracy: What does the UK law state on how accurate speedometers must be?

Under UK law - which is based on a European Union standard - UK speedometer regulations also outline how accurate speedometers must be.

The regulation states that speedometers must never underreport a vehicle's speed, while it must never overreport by more than 110% of the actual speed + 6.25mph.

So if you’re going 40mph, your speedometer may read up to 50.25mph - but it can never read less than 40mph. In order to stay within the law, carmakers calibrate their speedometers to slightly overreport their vehicles' speeds.

 

[Amarillo]

Wish was in place Blackheath Road J/W Greenwich South Street last week when someone was intent on catching the lights and nearly took the front off my van!

On the A2 coastbound, the proposed 20mph limit ends at the boundary between Lewisham and Greenwich. It doesn't restart when the road re-enters Lewisham. I think this might be because Greenwich is one of the few (only) inner London borough* not to implement a borough wide 20mph limit. The junction in question is just inside the Greenwich boundary.

*By some definitions Greenwich is an outer London borough.

 

[SimonC]

Looks like pedestrian education would be better than penalising the innocent motorist again.

Table 5: Contributory factors allocated to pedestrians and vehicles involved in fatal or serious collisions with pedestrian, GB: 2016 to 2021

Pedestrian contributory factor Count
Pedestrian failed to look properly 13,377
Pedestrian careless, reckless or in a hurry 4,918
Pedestrian failed to judge vehicle`s path or speed 4,425
Crossing road masked by stationary or parked vehicle 2,969
Pedestrian impaired by alcohol 2,841
Pedestrian wearing dark clothing at night 1,761
Dangerous action in carriageway (eg. playing) 1,536
Pedestrian wrong use of pedestrian crossing facility 1,399
Pedestrian disability or illness, mental or physical 1,003
Pedestrian impaired by drugs (illicit or medicinal) 497

How would educating pedestrians help the "Pedestrian disability or illness, mental or physical" category?

 

[66tim99]

Looks like pedestrian education would be better than penalising the innocent motorist again.

Table 5: Contributory factors allocated to pedestrians and vehicles involved in fatal or serious collisions with pedestrian, GB: 2016 to 2021

Pedestrian contributory factor Count
Pedestrian failed to look properly 13,377
Pedestrian careless, reckless or in a hurry 4,918
Pedestrian failed to judge vehicle`s path or speed 4,425
Crossing road masked by stationary or parked vehicle 2,969
Pedestrian impaired by alcohol 2,841
Pedestrian wearing dark clothing at night 1,761
Dangerous action in carriageway (eg. playing) 1,536
Pedestrian wrong use of pedestrian crossing facility 1,399
Pedestrian disability or illness, mental or physical 1,003
Pedestrian impaired by drugs (illicit or medicinal) 497

Is there a motorist contributory factor Count?

 

[andyinluton]

How would educating pedestrians help the "Pedestrian disability or illness, mental or physical" category?

Probably wouldn't.
But in the same way someone that is happy to do 60mph in a 30 limit isn't going to slow down just because they have changed the signs to 20

 

[andyinluton]

Is there a motorist contributory factor Count?

As you asked from the same .Gov publication, just shows that you prove anything with statistics - this shows there's more stationary vehicles contributing to accidents than there are speeding vehicles.




Vehicle contributory factor Count
Driver or rider failed to look properly 7,768
Driver or rider careless, reckless or in a hurry 2,858
Driver or rider failed to judge other person`s path or speed 1,787
Stationary or parked vehicle(s) 1,243
Poor turn or manoeuvre 1,142
Exceeding speed limit 1,057
Aggressive driving 1,011
Loss of control 840
Travelling too fast for conditions 740
Dazzling sun 738

 

[2into1]

Can't help feeling this news reflects more hatred directed towards those successful enough to enjoy the freedom of cars than it is concern for the safety of pedestrians.

 

[Amarillo]

Can't help feeling this news reflects more hatred directed towards those successful enough to enjoy the freedom of cars than it is concern for the safety of pedestrians.

It sounds like you haven’t read TfL’s reasoning for the reduction posted in message #5 above.

The case for 20mph limits in urban areas is stark.
Hit a pedestrian at 30mph, half die.
Hit a pedestrian at 20mph, 1:10 die.