Pedestrianise London

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The TFL 2-stage turn

Something new turned up from TFL yesterday, an animation of the design of an “innovative” new right turn layout. In Copenhagen they have “the jug handle”, the Dutch have “the curb protected junction”, now in the UK we have “the confusing mess”.

Mark Treasure has a good look at what’s wrong with it here and I think it’s easy to see the faults in this poor implementation, but more interesting than the “what”, in my opinion is the “why”. How did this solution even get onto the table? Let me hazard a guess.

The problem that TFL are trying to solve is how to enable cyclists to turn right without having to cross two lanes of fast moving traffic by introducing a two stage turn. In other words, how can we get bikes from the cycleway into the ASL box for the perpendicular direction?

The easiest way is to simply allow cycles to pull left from the cycleway into the ASL, the problem with this idea is that missing from the TFL animation is the pedestrian crossing that will exist between the cycleway and the ASL. When the bikes are on the cycleway and wanting to pull into the ASL, pedestrians will have a green man to get into the pedestrian cage in the middle of the road.

DfT rules don’t allow sub-conflicts at a light controlled intersection, that is you can’t give a go signal to pedestrians at the same time as allowing bikes or cars to turn through them for example.

So we can’t possibly allow bikes to just pull through the pedestrians green man into the ASL, we must find another way.

Since the pedestrian crossing on the other side of the road will be red unless activated by a pedestrian, we can allow bikes to turn left and then immediately right through the central reservation straight into the ASL.

Better, but again we’ve introduced a sub-conflict, a minor one but one that could be considered a problem. To get through the central reservation bikes have to swing right, a movement that drivers wouldn’t be expecting and something probably decided as being too dangerous.

So on to option C, the TFL option. Using the DfT’s cycle provision get out clause, the “shared use pavement” to get around the disallowed sub-conflict between bikes and pedestrians. Job done.

Although I’d like to have cheerier news, as far as I can tell, this mess of a design isn’t really the fault of TFL. They’ve tried to do something like the CPH jug handle but due to the rules have ended up tied in knots. The real issue is not how poor this design is, but how to get the DfT to review the rules around sub-conflicts.

That said, I’m not entirely sure why the Southampton jug handle design wasn’t considered, it doesn’t have any of the sub-conflict issues. Maybe the extra space required for it isn’t easy to come by, after all two pieces of drop curb are cheaper than moving pedestrian crossings around.

Of course, the best solution would be a full Dutch style junction.