I came across this article on Auto Express today:

I'm all in favour of 20 mph speed limits being just that, a limit posted by a roundel, much like in Germany where one finds 30 kph limits. However, I was under the impression that any speed limit under 30 mph had to be self-enforcing, hence the proliferation of speed humps and chicanes. Is it possible to create a 20 mph zone without an outbreak of vast quantities of signage and pretty coloured tarmac?

Incidentally, here in Switzerland the approach is just to put ruddy great plant-pots and trees in the middle of the road, stick a couple of reflectors to them and hope for the best.

Cheers,
Nick

Well, in the good old days, there was the perfect hard-wearing urban road surface, suitable only for appropriately low speeds: Belgian blocks.

Right now the Scottish Executive have given blanket authorisation for the installion of part-time 20 mph limits indicated by flashing orange lights on appropriate signage.

These do not usually use any form of traffic calming.

This suggests to me that permanent 20mph limits with no traffic calming would be permissable. If not the Scottish Executive can use their delegated powers under the various road and traffic acts to issue the necessary statutory insrtuments or blanket special authorisations.

I noticed a speed limit sign when going around Perth just outside a school, it was the usual 20 sign with "20's Plenty" underneath it, however the roundel was green rather than red. Presumably this would be unenforceable?

Yes it would. All schools in South Lanarkshire now have advisory 20 limits outside them - because they're advisory there's no 30 sign where they end. There are also 20 roundels painted on the road, which again mean nothing.

Most South Lanarkshire councillors probably think these limits are actually enforceable speed limits.

I much prefer the idea adopted for Glasgow's schools whereby an enforceable 20 limit is in place when the lights are flashing.

The strange thing is, that the cheapest way to slow traffic down would actualy cost nothing. Just let the road surface deteriorate with time, poorly filled roadwork holes and potholes will do the job nicely. One of the residential roads in Cardiff (Princes Streeet, Roath) is in pretty poor condition, and no-one goes fast down it, despite it being straight and wide besause the surface is so rough. A road that leads onto it was resurfaced last year, and humps were added. Seems a waste of money when wear and tear will do the same job. There's also a rat-run in Graayshott, Hampshire (Boundary road) that has deliberately left unsurfaced except for a short section at one end nearest the doctors surgery. This form of traffic calming works very well. ps this road is owned by the council, not private.

This is another one that seems to come up regularly.

The legal position is explained on the DfT website in the document entitled 20 mph speed limits and zones.

Basically, you can either have a normal 20 mph limit, which does not need any traffic calming measures, but has to have repeaters, or a 20 mph zone, which has different terminal signing and does not need repeaters, but has to be effectively self-enforcing through the use of traffic calming measures.

In my view this is a confusing and pointless distinction, and all 20 mph areas should have repeaters, but it is the way the regulations stand.

Recently, a number of residential estates in Stockport have been given 20 mph limits, because the locals objected strongly to humps, as shown in this example:




I suppose if councillors want to be seen to be doing something, this is the lesser of two evils.

does this mean they will start removing them soon? or that they just won't install any more and will remove them next time each road is resurfaced?

Permanent 20 limits round schools are crazy. They should either be green signs (advisory limits) or the "20 when lights flash". Anyone travelling more than 20 near a school when the kids are going in or coming out is crazy anyway (and if involved in an accident would probably be charged) so an advisory limit should be fine. There is no need at 2am to be travelling at 20 along a straight wide road near a school. Let's see some common sense used.

Interesting. The centre of Goring in Oxfordshire introduced a 20mph limit some time ago, without traffic calming measures, but I don't remember it having repeaters either. It's certainly not signposted as a zone. I'll take a detour round that way sometime soon to check.

One effect this is likely to have is to discourage people from trying to ride bicycles on a road. Humps are usually designed not to affect them.

I went that way on Friday. Looking at the map, the 20mph limit is on the High Street between the junction with Wallingford Road and about halfway across the river.

You get a 20 sign and a 20 roundel on red tarmac at each end of the zone, but nothing else.

Does that make the 20mph limit unenforceable?

20 limits around the Schools in Leek would be pointless as the school traffic speed is self-regulating due to the bottleneck created by parked cars.

Trouble is,it's not the vast majority of drivers who cause the problem, but rather the small number of idiots to whom a 20mph sign means nothing.

This small number of idiots is who we need protecting from which is why streets need to be made impossible to go fast in. I like speed bumps, we've had them now for a couple of years and the difference is amazing, I would fight tooth and nail to keep them as well.

Derek

I'd like to see you try to justify that to someone with chronic back pain for whom they make travel at any speed utter agony.

And to add another spin on it, joyriders don't care about speed bumps - they "add to the excitement".

There was a case locally where idiots were racing over speedbumps in a stolen car, and lost control over one of the humps. The car took off and narrowly missed a bunch of kids playing on the pavement on the street corner.

I think in terms of physical speed reduction systems, chicanes are better than humps, as they do less damage.

The only problem with chicanes is that thay take up road space - basically having the effect of two permamently parked cars - which is the cause of a lot of problems in the first place.

Meanwhile here in Ilfracombe - we were relativey traffic calming free until a couple of years ago, when a new 20 limit and speed bumps were introduced along the High Street (aka the A361). Now they're everywhere. New square speed bumps have been introduced along a road between two schools - which also happens to be a major bus route . There is to be a new 20 limit installed - but the space that they have left for the '20' signs (i.e. between the speed bumps sign and the top of the signpost) seems to be very small - only just big enough for a normal roundel (like the example in Stockport) and certaintly not big enough for a '20 Zone' sign. If a normal roundel does appear, then why didn't the council just make one sign instead of two and have a '20 Zone'?

Surely that's the point? I thought the point of 'traffic calming' was to slow cars down, not to reduce congestion. Congestion, of course, is a brilliant way of slowing cars down. In fact, it's the only thing I can think of that forces people to drive slowly. You can ignore a speed limit, you can go flying over speed humps, but you can't drive quickly when there's heavy traffic.
That all may be slightly tounge-in-cheek, but it does express an essential truth. Traffic crawls past schools in Leek because the roads are thoroughly snarled up. You could have a 10mph or a 100mph limit past the schools and it wouldn't make one scrap of difference at 3:30 as the parked cars on either side make the roads too narrow for people to pass without slowing to a crawl.

Humps slow traffic down. Chicanes often stop it altogether. This means that there are more people who are sufficiently inconvenienced by the latter to complain about it, and that the one in Northop Hall only lasted a few months before the council dug it up and put a few speed bumps in its place.

Glasgows '20 when lights flash' signs are good, however they are shoddily implemented so legallity of some (Berryknownes Road) is dubious. However they are worthless without inforcement.