Getting the hump: Why is Greenwich Council’s rollout of 20mph zones so slow?

Verdant Lane, Catford
Lewisham Council imposed a 20mph speed limit on all its roads in September 2016 – without a widespread rollout of speed humps

Greenwich Council decided to introduce a 20mph speed limit on all its residential roads in 2012. Six years on, the programme is still being rolled out. Yet in this time Lewisham has approved and implemented plans for a speed limit which now applies on all council-run roads. Eltham North’s Conservative councillor SPENCER DRURY says Greenwich is using out-of-date criteria which is holding the scheme back.

I have two questions for Greenwich Council. Why is it that six years after the decision to introduce a 20 mph zone for all residential roads in Greenwich, it has not happened? And why does every single 20 mph zone proposed include speed humps on almost every road?

In 2017, my ward, Eltham North, had two 20 mph zones introduced and in both of them almost every single residential road was carpeted in speed humps of some kind in the Council’s initial proposals.

I’ve now established that this is because the council is using out-of-date criteria, meaning that while Lewisham has introduced a 20 mph zone for its whole borough in a few years, six years after its initial decision Greenwich still has a patchwork of 20 mph zones, which seem inevitably to be based on expensive, car-damaging and cyclist-disrupting speed humps.

Lewisham/Greenwich borough at Lewisham Road
The borough boundary at Lewisham Road: Lewisham (right hand lane) is using signs and roundels on roads rather than a big roll-out of humps

What is Greenwich’s policy?

In 2012, Greenwich’s cabinet decided to introduce a 20 mph zone for the whole borough. This was based upon some work done by backbench councillors, including Conservatives, who were broadly supportive of the proposal.

The 20 mph zone seemed more achievable in 2012 as the Coalition Government had loosened up the restrictions on 20 mph zones so that they did not have to contain speed humps every few yards, but could also be imposed through signs, roundels painted on roads or even through residents measuring speeds themselves.

The cabinet report report noted this change and accepted the recommendation that speed humps should only be used where the quickest drivers (85th percentile) were travelling at speeds of greater than 30 mph.

A year later, the Department for Transport acknowledged the change in ways 20mph zones could be enforced and published official guidance which suggested that you only needed speed limits where the average (mean) speed was greater than 24 mph.

It is this guidance which Lewisham is using when deciding where to place speed humps to help enforce its borough-wide 20 mph zone.

From a personal point of view, I think these two criteria are broadly similar and Greenwich can reasonably claim that the 30 mph for quicker drivers is roughly the equivalent of the 24 mph for average travellers.

Castlewood Drive, Eltham
Castlewood Drive: Due for humps, despite not attracting speeding drivers

So why are Greenwich proposing speed humps everywhere?

Having established Greenwich’s policy, I asked for access to the speed data collected when the proposals were drawn up for the Arsenal Road 20 mph zone in Eltham, which was consulted on in December 2017.

As the ward councillor, I was aware that residents of certain roads, such as Crookston Road and Arsenal Road, had expressed concerns about the speed of cars outside their homes. But for the vast majority of roads, there had been no speed concerns which had made it to me.

The data (which showed only the 85th percentile speeds) reflected my understanding, with Crookston Road having speeds of over 30 mph at a couple of points and others – such as Arsenal Road, Dairsie Road and Congreve Road – also having some speeds quite close to 30 mph on some stretches of the road.

These roads are often used as cut-throughs when the traffic is bad and so this was not a surprise. But all of the other roads had the overall speeds of the quickest cars at less than 26 mph, which would suggest to me that they did not qualify for speed humps under either the council’s or government’s criteria.

Then the proposals for the area were published. Lo and behold, there were speed humps in every single street (except Cornwallis Walk, which contains only 4 houses and is as short as it sounds). Even in Castlewood Drive, a steep, narrow road where people park on both sides of the road so two cars can’t pass and the quickest cars achieved only 21.7 mph, the council thought speed humps were required to reduce speeds.

I simply couldn’t understand this as the proposals seemed to bear no resemblance (as they hadn’t in the previous 20 mph zone in my ward) to the council’s criteria or indeed the conversations I’d had with residents.

Castlewood Drive, Eltham
Humps could drive road users in Castlewood Drive round the bend

Greenwich using 1990s guidance

But after asking quite a lot of questions, I established that Greenwich had decided to apply a quite different set of criteria for placing speed humps when they introduced 20 mph zones.

Greenwich Council’s criteria was based on a 20 year old piece of Department for Transport guidance (Traffic Advisory Leaflet 9/99 in case you wanted to look it up) which suggested that speed humps were needed whenever 85th percentile speeds were greater than 24 mph. However, the council wasn’t even consistent in using this criteria, as it then decided that it made sense to place speed humps in the four roads where traffic speeds didn’t reach 24 mph for the quickest cars.

The effect of this hidden change in the council’s criteria for adding in speed humps has been to:

  • Slow down the introduction of the 20 mph zones (as every zone becomes much more expensive due to the number of speed humps required – 220 are being constructed in 2017-18 alone).
  • Cover the borough in speed humps which simply aren’t necessary to reduce the speeds of cars according to the council’s own published criteria or the government’s more recent guidance.
  • Disrupt other forms of transport around the borough like cycling because it is harder to negotiate the inconsistent heights and widths of the speed humps.

I just want to confirm that as Leader of the Opposition, we supported 20 mph zones with minimal speed humps to enforce them. But I remain firmly of the opinion that the decision to introduce speed humps is a matter for residents on individual roads or sections of roads.

Arsenal Road, Eltham, 9 January 2018
Arsenal Road: Residents should have the final say on speed humps, Drury says

It may well be reasonable to question whether 20 mph zones like the one in Lewisham are effective, but Greenwich Council has completely ignored its own, democratically decided, policy in favour of a completely different set of criteria, which simply can’t be right.

I would also argue as I drive along the pot-holed, damaged road surfaces between the speed humps that maybe the council would be better advised to maintain the roads we have rather than spending the funds available on extra features.

Of course, maybe the potholes are the alternative to speed humps for a council which wants to slow traffic down – is this another hidden policy that Greenwich hasn’t told anyone about yet?

  • Spencer Drury is the Conservative councillor for Eltham North.
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    15 comments

    1. Agreed about spending more money on potholes, as a commuting cyclist those are the biggest problem, humps I find easy to negotiate, the large amount of poorly maIntained and poorly patched surfaces are the danger to me. So spending less on humps and more on that would make sense. My worry about the 20mph limit is enforcement. Its an important step, in fact crucial step, in the right direction to reducing pedestrian injuries and fatalities, but there aren’t the officers to enforce, they’re all too busy raising funds from parking offences.

    2. While it is difficult to imagine anyone speeding along Castlewood Drive it would be impossible along Granby Road where it is even narrower again with cars ( and vans) parked on both sides. Living on the Progress Estate I have seen very few speeding drivers going through it. There maybe a need for speed bumps on Arsenal and other roads if the locals request them but otherwise it is a waste of valuable resources.

    3. As I have a disabled wife with severe back pain I have to come to a near standstill to negotiate any speed humps.
      Consequently air pollution is increased due to the slowing down and speeding up.
      New traffic calming measures should be introduced I e chicanes.

    4. I agree with pretty much all of this article.

      As a cyclist I found it appalling that money was spent on speed humps for Wricklemarsh Road and Farjeon Road but the mini-roundabout that joins them was left with huge and dangerous (especially for cyclists) potholes. Going round a mini-roundabout with huge potholes is not fun.

      Also (to add insult to injury), yet more money was wasted in Broad Walk, Canberra Road and many other Roads by digging up existing speedhumps and building new ones in between them (presumably to space them out nicely).

    5. Speed humps definitely add to pollution as Scroggs has noted. The fact is, if someone wants to speed they will.

      We had speed humps installed in our area a time back. Since then, just in our road, we have had three garden walls demolished, two accidents where ambulances were needed and the death of an unborn child in one incident at the end of the road where the car ended up on it’s roof. I can’t recall any serious incident in the years preceding the installation of the humps.

      And hands up those who do 20 across Blackheath in the evening! Some of speed limits are just plain daft!

      I fully accept I will be in a minority with these views!

    6. Well, you only live around the corner from me, I can show you the re-built walls. The really obvious one is within two or three hundred yards of you if I have sussed your approximate address correctly. The car stayed in the garden for three or four days and was pretty obvious! I can introduce you to a witness of the ‘car on roof’ incident which led to the death of the unborn child. He knows other witnesses.
      Happy to take this offline.

    7. I probably should have been clearer, Chris – where is your evidence for “speed humps definitely add to pollution”?

      Drivers speeding up and slowing down rather than keeping a constant speed add to pollution – this can happen in streets with speed humps, but that’s the driver’s responsibility. (I’ve opted not to publish some comments making nonsense assertions in this regard too.)

      I’m not going to divulge where I think anybody commenting lives, but if you are in a street used as a rat-run. then that street clearly needs the rat run to be blocked more than it does speed humps. And if somebody is killing people because they are incapable of driving a motor vehicle properly, then speed humps are the least of your worries.

    8. Ah, sorry. Speed humps add to pollution as you quite rightly point out that drivers slow on the approach to them and then accelerate away. With some of the ‘hump’ sleeping policemen you have to slow to walking pace to take them. You can’t maintain a constant speed. I speak as someone who has a ‘square’ hump outside my house and the same happens, but not nearly as often. BTW the fatal accident involved a group of youths in a car being chased by another group.

    9. Greenwich loves speed humps, and even installs them against emergency service advice.

      While I totally agree with 20mph limits in residential roads, even cars doing a steady 20mph do about 8%- 10% more pollution than ones doing 30. So is a “borough blanket 20mph, 24 hours a day” the right answer? Keeping roads outside the residential areas at 30 will move traffic towards them, especially given modern satnavs. That reduces overall pollution and rat-running, and you can concentrate segregation safety measures there. Drivers also accept variable speed limits now, and 20 during school and rush hours, 30 outside it is not “too complicated”. All evidence is people observe limits better when they seem appropriate.

      But it is much easier for councillors to support local limits, because accidents are “on their patch” and so directly their target, but pollution is diverse.

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