Going Dutcher

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Going Dutcher

Interesting post from our own Paul James on the LCC  plans for Parliament square and what the true Dutch equivalent would be


What do people think? We could use this as a basis for crossroad junctions in the book ...

pete owens

ASLs are not a problem. It is the cycle lanes that cause the left hooks by encouraging cyclists to undertake (whether or not they lead to an ASL) - thought this is a mistake we copied from the Dutch who invented the things in the first place. The cycle lanes would be particularly bad in this case as they actually arrange for right turning cyclists to approach to the left of left turning motors - which is asking for trouble at the point where they cross over: http://www.warringtoncyclecampaign.co.uk/facility-of-the-month/August2001.htm

 The advance stop lines themselves are good in that it places cyclists waiting at the lights well in front of the rest of the traffic - far enough for a truck driver to see beyond their blind spot. Fortunately the latest signing guidelines allow cyclists to legally enter ASLs from a safe direction and also for engineers to not include the lanes. Now if you arrange for off road cycle paths to approach the junction they will each need their own phase in the signal cycle which will drastically reduce the capacity of the junction. I'm not saying that that is a bad thing, just that if you are going to start from the position that you are only going to designing for half the volume of motor traffic then you could achieve something far more people freindly than either of those proposals. (and the pedestrianizelondon phase diagram looks like a recipe for gridlock - with queuing E-W traffic permanently blocking the cycle path and pedestrian crossings - even if they avoid blocking the box junctions)

I should point out that the blind spot of an HGV extends to the area immediately in front of the cab (although some are fitted with mirrors that cover this area).

Cycle paths could be phased in various different ways, including in combination with an all red phase for motor traffic (which seems to happen anyway at many junctions incorportating pedestrian crossings lacking filter lanes), or in parallel with motor traffic and / or pedestrians making the same movement with conflicting movements held at red. It would be legally possible for multiple cycle crossings to have a green signal at the same time in the configuration shown, as the cycle paths cross each other at what could notionally be considered a seperate intersection to the cycle crossing and could simply have give way lines.

Obviously there is the risk that cyclists would not be given enough green time (if, for example, the timings for an all red phase were the same as for a minor junction somewhere in Ealing), but as well as being able to make left turns at any time, the two sides of the square closed to motor traffic would not have traffic lights on them.

David Hembrow

Who invented ASLs, or feeder lanes to ASLs, is a moot point. It is Britain that is still installing this outdated infrastructure, and some subset of British campaigners who are still asking for them.

There is a certain type of cycling campaigner in the UK who looks at the Netherlands and instead of seeing what actually works, manages to concentrate on, and ask for Shared SpaceASLsStrict Liability, Trixie Mirrors and all sorts of other things which are either irrelevent, outdated, or just plain bad.

ASLs are not that common the Netherlands. While there is a vast amount of cycling infrastructure around where we live in the Netherlands, the closest ASL is 30 km away in Groningen, where a few older things like this have managed to survive. They're not on the busiest streets, and I'd ridden to and around Groningen a few times before I found one. When I wanted to write about ASLs recently, due to not wanting to make a 60 km round trip to take a few photos I had to make do with a junction in Assen which is almost an ASL, but not quite, and at which all the conflict has been removed.


You won't find ASLs being proposed as new infrastructure in the Netherlands, as they are in the UK, and you certainly won't find them at the sort of busy junctions that the LCC seems to think they are ideal for in London.

Dr C.
Dr C.'s picture



I see Paul has added a second post regarding traffic flow and light phases 


AKA TownMouse

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