Confusing Speed Limit Signs

[phobic3000]

I will stick to 30 along Sydenham Hill thank you very much! Unless someone is doing 20 in front of me, in which case I'll get mildly frustrated and try not to fall asleep behind the wheel...

[mako]

strafer "due to the impatience of people not wanting to drive so slow"

aka criminal activity

Neither impatience nor not wanting to drive so slow are criminal activity, only actually exceeding the limits are.

Wulf-you dont mention who these are costs to. Are they not covered mostly by insurance in which case it is insurance companies profits you are describing not a cost/saving to the taxpayer. All the talk of it is only another x minutes on a journey is time multiplied by hundreds of thousands of journeys so if you are making it a financial debate you have to include this loss of work hours to industry.

and everybody must understand that the average speed currently (influenced by central london not dulwich)includes being able to go at thirty. Make that 20 and congestion increases and travel times will increase dramatically

[mako]

I'm sure those pro 20 limits everywhere merchants cant drive a modern car. modern cars are not suited to long periods of a twenty limit. this means that to avoid speeding you must travel at 15-18 for much of the journey or sit staring at your speedo, neither of which are great options. What gear are you lot driving in?

[StraferJack]

"Neither impatience nor not wanting to drive so slow are criminal activity, only actually exceeding the limits are.

"

never said otherwise

" Make that 20 and congestion increases"

how do you make that out?

[mako]

A simple example would be waiting longer at traffic lights as queues longer. at thirty more cars would have made it through

[mako]

As for 'never said otherwise' it is a direct quote from your post of 8.36

[mako]

As a cyclist i also dont want cars travelling at same speed as me. at 20 there will be busy traffic all driving at 15-20, many cyclist on the inside doing the same and turning left for cars becomes dangerous as there is much more undertaking. now, cars generally have more room for changing speed to accelerate away from potential dangers. as any good driver will tell you the ability to change speed is as useful as to slow down to avoid incidents.

[henryb]

mako Wrote:

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> A simple example would be waiting longer at

> traffic lights as queues longer. at thirty more

> cars would have made it through

Flow rates increase at lower speeds because cars can be closer together.

> many cyclist on the inside doing the same and turning left for cars becomes dangerous as there is much more

> undertaking.

Cyclists are not supposed to undertake at junctions. However most cyclists top speed is about 20 the same as the cars should be travelling - so there should be less overtaking by cars and undertaking should only happen in traffic jams.

[henryb]

mako Wrote:

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> Wulf-you dont mention who these are costs to. Are

> they not covered mostly by insurance in which case

> it is insurance companies profits you are

> describing not a cost/saving to the taxpayer.

Are you actually saying we should not spend public money on saving peoples lives because its the insurance companies that pay out on life insurance?

I can't say I agree with that.

[bawdy-nan]

There's so much evidence in favour of this and countering the assertions made here about journey times and other "dangers". The only "anti" actual evidence I have come across is that without proper enforcement the reduction in actual top speeds is less.

Very happy to listen to proper arguments against my position on this but backed up with evidence. All we're getting on here is a load of "I reckon". It seems like a total no-brainer: evidence shows that it will massively reduce deaths and injuries, especially of children and young people. The perceived increased safety is also much more likely to encourgae people out of cars and onto the streets and cycles at key congested times (ie school in and out). As congestion is the main factor in increasing journey times in urban areas (according the RAC) this can only be a good thing for those who want or need to make their journeys by car as it will reduce congestion and speed up your journeys. Is what I reckon.

[Blah Blah]

Mako does make a very good point about people who drive for a living and the extra cost to industry. Taxis will cost more. Anyone who drives as part of their job will be spending more time on the road and accross the day that could add up to hours extra.

[bawdy-nan]

except that the increase to journey times is tiny. Say, you do 100 miles in the day that's an extra 30 mins...(1t 20 seconds a mile extra)...

[Blah Blah]

Bawdy-nan, the congestion charge was supposed to reduce congestion. Not only is congestion still there, excess congestion was simply displaced to outside the zone. People are far more attached to their vehicles than you might think. Some of the evidence you refer to is anecdotal. The truth is that Southwark doesn't know if and by how many, accidents will reduce until the scheme has been in place for a measure of time. Traffic calming measures already exist in areas where young people are most likely to be at risk, like outside schools, residential areas etc. The only strong evidence is that of the seriousness of injury vs speed, because that can be tested, in a controlled environment. What can't be tested though is how a given driver will behave in a given situation.

[Blah Blah]

Your maths are a bit out there BN. 100 miles at 30mpr takes 3hrs 20mins. 100 miles at 20mph takes 5 hours. That's an extra 1hr and 40 mins.

[bawdy-nan]

No BB - I'm talking about the increase in journey times. The evidence from many local authorities where this has been implemented suggest that per mile the increase in journey time is max 20 seconds (usually less).

The evidence I'm citing isn't anecdotal - see the links I posted earlier in the thread.

Certainly my reckoning that more people will get out of their cars if the roads are perceived to be safer for pedestrians and cyclists is pure I reckon but even if that's not the case the evidence supporting the new limits is very powerful.

On the C Charge who says it didn't reduce congestion - would be interested to read that study.

[LadyNorwood]

wulfhound Wrote:

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> > Wulfhound. You state the arguments for twenty

> are only strong because of the very minimal impact

> on journey times. Yet the only way in which it can

> have minimal impacts on journey times is if it has

> minimal impacts on speeds in which case it is a

> pointless waste of money. A limit 50% higher is

> obviously not minimal but a huge difference.

>

>

> Think about it - most of our journey *time* (as

> opposed to *distance*) driving in Inner London is

> spent waiting at lights, or queuing in slow moving

> traffic (unless you do most of your driving after

> 8pm ish). The journey time average speed for

> driving in London during the day is about 12mph,

> and has been for years. So there's an average

> speed and a peak speed. Bringing the peak down

> doesn't affect the average by much at all, but it

> does greatly reduce the likelihood of *severe*

> collisions, which, for cars/vans/taxis, tend to

> occur at or near peak speed.

>

> The figure quoted by bawdy-nan (10-25 seconds per

> mile) suggests 2 minutes on a 6 mile journey - 32

> minutes instead of 30. Journey time *reliability*

> actually *improves*, because the

> worse-than-average journeys are affected less than

> better-than-average.

>

>

> If so what are these costs?

>

>

> I'm basing on DfT figures, which are approx as

> follows:

> Fatal accident - ?1.7m

> Serious injury - ?200k (AFAIK this means injury

> requiring at least an overnight stay in hospital)

> Slight injury - ?15k (injury requiring hospital

> treatment but not overnight stay)

> ( see

> https://www.gov.uk/government/uploads/system/uploa

> ds/attachment_data/file/244913/rrcgb2012-02.pdf

> for how they figured it out - it appears to have

> been prepared by civil servants with no particular

> axe to grind, not lobbyists )

>

> These figures are averages - individual cases will

> vary enormously.

>

> And LB Southwark STATS19 (police road casualty

> data) for 2013:

> Fatal: 5

> Serious: 82

> Slight: 905

>

> ... which in fact yields a much larger number than

> ?15m. No doubt these figures are debatable, but I

> think they help get a handle on the scale of the

> problem.

>

>

> Croxted Road is 20mph; then increases to 30mph as

> you cross the South Circular; then reverts to

> 20mph on Croxted Road - what a complete and utter

> waste of resources and time for a 10 yard stretch

> of tarmac....

>

>

> Because the South Circular is a Red Route, i.e.

> it's regulated by TfL not LB Southwark. TfL has

> decided that the limit on Red Routes should stay

> 30 for the time being.. you'd have to be pretty

> brave to try and cross that anywhere apart from a

> designated crossing, and they've legalised cycling

> on the pavement along most of it, so it probably

> makes sense for it to stay 30.

I appreciate that, but TfL/Southwark have gone to the trouble of marking the road and putting up speed signs for the width of the South Circular - by the time you've accelerated from 20 to 30 you're back in the 20 zone (if you even have the time to do that) - an utterly pointless jobsworth piece of crap....

[Blah Blah]

BN, on a clear road the journey time will be much more than 20 seconds a mile. So at night it's going to add considerably more time to journeys.

Tfl's own figures for the last ten years show that traffic in the congestion zone has only decreased by 10.2% with no increase in journey times since 2007.

[rodneybewes]

Blah Blah Wrote:

-------------------------------------------------------

> Bawdy-nan, the congestion charge was supposed to

> reduce congestion. Not only is congestion still

> there, excess congestion was simply displaced to

> outside the zone. People are far more attached to

> their vehicles than you might think. Some of the

> evidence you refer to is anecdotal. The truth is

> that Southwark doesn't know if and by how many,

> accidents will reduce until the scheme has been in

> place for a measure of time. Traffic calming

> measures already exist in areas where young people

> are most likely to be at risk, like outside

> schools, residential areas etc. The only strong

> evidence is that of the seriousness of injury vs

> speed, because that can be tested, in a controlled

> environment. What can't be tested though is how a

> given driver will behave in a given situation.

Congestion may still be there but it's miles better than it used to be in central London. With the increase in cars on the road the strategy isn't to make things easier for cars to move about London, that's an incentive to drive. It's to make it more expensive and less convenient, so as to decrease the incentive. Of course the missing piece in this is the god-awful transport system we have which makes the slow, inexorable change in habits excruciating all round.

[bawdy-nan]

Blah Blah Wrote:

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> BN, on a clear road the journey time will be much

> more than 20 seconds a mile. So at night it's

> going to add considerably more time to journeys.

And they do have variable speed limits in France, for example, when wet (ie when road conditions change) but I suppose a variable speed limit is even harder to implement than the blanket 20.

>

> Tfl's own figures for the last ten years show that

> traffic in the congestion zone has only decreased

> by 10.2% with no increase in journey times since

> 2007.

10% reduction seems not bad when you consider the year on year increase in car ownership - low percentage increases between 2007 and 2012 but 1.5% increase between 2012 and 2013

[christgill]

LadyNorwood Wrote:

>

> I appreciate that, but TfL/Southwark have gone to

> the trouble of marking the road and putting up

> speed signs for the width of the South Circular -

> by the time you've accelerated from 20 to 30

> you're back in the 20 zone (if you even have the

> time to do that) - an utterly pointless jobsworth

> piece of crap....

Is this a joke?

The 30mph signs are there so that drivers know that, turning onto the South Circular, the new speed limit is 30mph - not to provide a two second opportunity to floor the accelerator...

[Charles Notice]

Speed will not be the main cause of death and destruction but sitting behind a long line of cars with the front car being PC and letting the speed drop to between 15/20 mph with drivers not being able to move quicker with a empty road ahead.

Frustration and anger will then kick in. Example Sydenham hill then along to CP is a prime example of blinkered thinking on road speed.

It's a pity that people cannot think out of the box.

To test this just drive for a time at 20 with an empty road in front ignoring traffic behind.

Common sense is far more important and relevant.

[mako]

Mr barber may have the numbers of how many have died in southwark that realistically wouldnt have done with a 20 speed limit. Ie if hit by a lorry at 20 still bad, death not a result of speed, speeding car was speeding over 30 so would still speed over 20 etc. take these out and the benefits likely to be zero deaths avoided in a year.

[mako]

Cyclists may only undertake generally when congested at the moment but when cars are driving at 15-20 this will be much more common and will be dangerous.

Please can someone explain that if volatility of speeds comes down from 0-30 to 0-20 how congestion doesnt increase? Surely by definition more cars travelling at the same speed means more congested?

[rodneybewes]

Charles Notice Wrote:

-------------------------------------------------------

> Speed will not be the main cause of death and

> destruction but sitting behind a long line of cars

> with the front car being PC and letting the speed

> drop to between 15/20 mph with drivers not being

> able to move quicker with a empty road ahead.

>

> Frustration and anger will then kick in. Example

> Sydenham hill then along to CP is a prime example

> of blinkered thinking on road speed.

>

> It's a pity that people cannot think out of the

> box.

>

> To test this just drive for a time at 20 with an

> empty road in front ignoring traffic behind.

>

> Common sense is far more important and relevant.

I'm not sure common sense has worked in the history of motoring so far. Hence traffic lights, box junctions, level crossing barriers, speed restrictions etc. And your first sentence doesn't really hold up.

[henryb]

mako Wrote:

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> Cyclists may only undertake generally when

> congested at the moment but when cars are driving

> at 15-20 this will be much more common and will be

> dangerous.

>

Seriously most cyclists don't go over 20. The average speed for the tour de france winner is only 24 mph. If you are cycling that fast on busy London streets and regularly undertaking cars at speed - then I think you need to calm down a bit.

> Please can someone explain that if volatility of

> speeds comes down from 0-30 to 0-20 how congestion

> doesnt increase? Surely by definition more cars

> travelling at the same speed means more congested?

I said earlier - lower speeds increases the flow rate because cars can be closer together. That is why they drop the speed limit on congested motorways. Not exactly the same but the same in principle.