Saturday, February 10, 2007

20mph speed limit for Darlington, article in Advertiser

For the second time in three weeks we made the front page of the Darlingon Advertiser; the free newspaper which is delivered to every home in the town each week: Call for 20mph town speed limit.

For me the key fact to consider is: 90% of people hit by a vehicle at 40mph die, 20% at 30mph and only 2.5% at 20mph. I don't think any other argument is really needed.


Anonymous said...

Can anyone explain the arrival of the ridged beige paving stones that have been installed along with the works to the cycle path adjacent to the ring road opposite the fire station.They seem to be designed and sited to cause maximum damage to both riders and bikes.Is there a potential negligence issue if someone is injured? Were any cyclists involved in the design of this new cycle path?

miketually said...

Hi anonymous,

I've not seen these slabs myself, but I think I know what they are.

Ridged paving stones are used at the start and end of cycle paths, and are supposed to be repeated at specific intervals. They're known as tactile paving and are supposed to show visually impaired (VI) pedestrians which paths are for bikes and which for pedestrians.

You will also have seen these, with raised knobbles at pedestrian crossings, where they're for the same also for VI pedestrians.

On paths which are split between pedestrians and cyclists, the ridges run across the path for the pedestrian side and along the line of the path for the cyclist side.

We've told the council that we don't like these paving stones. Mainly because when they're wet they'll hook the side of a narrower bike tyre if you try to cross them at a slight angle, pulling the wheel in a different direction to intended, like being caught in a rut. My wife dislikes these when walking, and they wake up sleeping babies in pushchairs; in fact, she switches to the bike side when pushing pushchairs over the slabs, somewhat defeating the point of them (she checks for bikes first, obviously).

A council officer told me that the use of these slabs is set out in national guidance, which specifies the depth and width and repeat interval, and that Darlington council policy is to follow the guidelines to the letter. However, the officer also told me that not all councils follow the guidleines quite so rigidly.

The same rigid adherance to guidelines that don't always work in practice is the reason why we don't have any advanced stop lines in Darlington (no room for filter lanes leading to them) and why loads of money is spent on widening paths like the one through Beech Wod from Asda to Barmpton Lane, to meet the guidleines for a shared use path, even though pedestrians and cyclists have been sharing that path since the houses were built with no problems.

miketually said...

Blimey, that was a long reply :)

I'll try to get along to see the path soon, though I think Richard and Tim have already been to have a look at it. We'll see if we can get some photos and a responce from the council.

If you have anymore questions, please comment again. Also, if you're not already a DCC member, please get in touch and we'll add you to the membership list. It's free!

james wishart said...

I am a retired civil engineer. I too am interested in these zones. In a few month's time the Department for Transport will issue guidelines in a new Manual for Streets, specifying that all residential areas should have a 20mph design speed. It may be that your proposal for zones should take this into account. I have a campaigning website which gives details of the proposals at

miketually said...

That's very interesting James, thankyou. I assume this only applies to new residential developments, but it obviosuly signals that 20mph limits are the way the government sees residentail streets progressing.

james wishart said...

No Mike, it doesn't specify new development only and I don't see how the country could be divided between two speed limits, old and new. But it is a complicated issue because the rules already say that there is no need for speed bumps and other traffic calming measures if the *average* speed in an area is already 24mph or below. It just needs the signs. But local authorities seem to ignore this advice and seem always to be determined to build speed bumps. I think that all residential areas *could* have 20mph limits if the government mounted a publicity campaign to educate the public, as it did successfully when it introduced seat belts.

miketually said...

I see. I took "design speed" to mean that roads should be designed to giet that 24mph average.

Thanks for the info.

An Inconvenient Truth said...

Interesting comments, James. The national guidelines you talk about offer 2 ways of introducing 20mph, one with, the other without speed bumps etc. Most councils, including Darlington, choose the second, as they are regarded as "self-enforcing". The police here also prefer this for the obvious reason that it creates no extra work for them.
However, we have now moved into new territory with the council suggesting that legally this is the ONLY option - which is patently untrue. My view is that this is a lazy position - it avoids the need to consider enforcement.

But if you then compare this debate with the existing state of play with the 30mph limit, you begin to realise how politically partial the police and the local authority are with this issue. The 30mph limit is routinely flouted by motorists. Yet it is accepted as a de facto standard anyway.

I strongly believe that there is a significant machismo on the part of the local authority and particularly the police. They would like to think that their laws decide everything, but in the real world, people behave otherwise. Measures that contribute to a psychology of slow driving - including giving cyclists much more visible priority - are equally, if not more important.

james wishart said...

Hi, some more grist for the mill:-

The draft Manual in section 7.9.2 says "All streets whose main function is to provide a residential environment should have vehicle speeds of no more than 20mph." It is significant that it doesn't use the word 'design' nor does it qualify it by saying 'new streets'. This is great news. The least said at this stage the better [!].
'Self enforcing' is not explicitly defined as far as I can see.

The government circular 'Setting local speed limits has the following paragraphs:-

Page 17 of Update of Circular 1/93 Setting local speed limits
“80. Research into 20mph speed limits carried out by TRL (TRL Report 363) showed that where speed limits alone were introduced, reductions of only about 2mph in mean speeds were achieved. 20MPH SPEED LIMITS ARE THEREFORE ONLY SUITABLE IN AREAS WHERE MEAN VEHICLE SPEED ARE ALREADY LOW. (THE DEPARTMENT WOULD SUGGEST WHERE MEAN VEHICLE SPEEDS ARE 24MPH OR BELOW), OR WHERE ADDITIONAL TRAFFIC CALMING MEASURES AE PLANNED...[Emphasis added]

Page 11 of Setting Local Speed Limits says:-
"36. Mean speeds and 85th percentile speeds (the speed at or below which 85% of the traffic is travelling) are the most commonly recorded characteristics of speed. Traffic authorities should continue to routinely collect and assess both, BUT MEAN SPEEDS SHOULD BE USED AS THE BASIS FOR DETERMINING LOCAL SPEED LIMITS. This is a change from the use of 85th percentile speed in Circular Roads 01/93 (DoT, 1993). As explained in paragraph 17, the use of mean speeds is underpinned by extensive research demonstrating the well proven relationship between speed and accident frequency and severity. They also
reflect what the majority of drivers perceive as an appropriate speed to be" [Emphasis added]

Steve said...

To mention the ridged tactiles again, they've been recently discussed in the uk.rec.cycling newsgroup as being very prone to fill up with ice.

Designing psyclepaths? That's an odd way to say 'councillor draws on roads on the OS map with a marker'

An Inconvenient Truth said...

Hi again, just trying to get this clear.

1. National thinking, based on extensive research into mean speeds, suggests that motorists respond to legal measures alone in a limited way (2mph reduction, typically).

2. The only alternatives suggested so far are physical "traffic calming measures" - deemed "impractical" by Darlo council.

3.Motorist psychology is hinted at when James says:

They also reflect what the majority of drivers perceive as an appropriate speed to be.

This raises the obvious question - has research been carried out into alternative measures that cause a reduction in the majority of drivers' perceived appropriate speed? And crucially, what role could cyclist priority play in such measures?

miketually said...

Thar are always Road Witches :)

miketually said...

"Can anyone explain the arrival of the ridged beige paving stones that have been installed along with the works to the cycle path adjacent to the ring road opposite the fire station."

My wife read this last night and said there were paving stones matching this description on the new path at the bottom of McMullen Road and that they weren't textured paving like is usually used. She thought they looked lethal as well.

I'm going to go that way home, to take a look.