Sunday, 1 May 2011

Smoothing traffic flow

There are many reasons to cycle, even with the roads sometimes deeply hostile to anything other than the combustion engine. One of the very good reasons to cycle is well illustrated in the video below

This was taken at the same time as the other video (just didn't get around to editing it) and is immediately after the Stratford one way system (the bit where I got close passed by a chap reading a map and another motorist who seemed incapable of moving to the second lane which was free - both got immediately caught in this jam).
As can be seen by the video, the jam stretched for a very reasonable distance; I imagine the motorists were stuck here for a while. And the problem?

The temporary traffic lights which directed traffic through a very short narrowed piece of road where some road-works were being done. The actual issue was that traffic going towards Stratford was also in a queue and were queuing across the road-works, thus restricting the other lane of traffic when their lights went green. Gridlock ensues.

This was a very minor roadwork. It neatly illustrates why I had to give up driving everywhere for sake of my health and sanity. The average car journey is very unpredictable these days - one slight restriction to the road adds on 30 minutes to a 10 minute journey.

TFL and the government's solution to this is to prioritise "smoothing traffic flow" over everything else. Hence we have the situation where a bridge (which are generally difficult for cyclists anyway) is being re-worked to increase traffic lanes and decrease pedestrian and cycling space. And Blackfriars Bridge actually has more bicycles crossing it at rush hour than private cars. If this situation still merits more space given to cars, then it is highly unlikely that those in charge of highways will consider places such Tottenham Hale or Stratford as requiring more cycle friendly planning.

The fundamental problems with the "smoothing traffic flow" are obvious. Traffic reaches its own level - increased capacity increases car usage,  the M25 should teach us this. But also, the traffic flow is trying to be re-worked in London which is dominated by streets singularly unsuitable for large volumes of traffic. In the Tottenham Hale gyratory for instance, traffic generally moves quickly around the multi-lane racetrack in the one way system to come to a grinding halt either side on the A10 as they then filter down onto ancient roads through local centres.

From my experience as a cyclist and driver, the average junction design is to have as many traffic lanes as possible entering it - even if the other side is too narrow to accommodate - in an effort to push as much traffic through the junction as possible. This is uncomfortable for a motorist as the lanes disappear and everyone ends up jostling for position. For a cyclist is a down-right horrible as car drivers are too busy concentrating on claiming their road-space to worry about a bicycle in the middle of it all.

The very act of "smoothing traffic flow" makes junctions and roads more hostile to pedestrians and cyclists than they could be. And then more people decide to drive because the roads are more attractive to cars and much less attractive to anything else. And then the road becomes congested so it is redesigned to "smooth traffic flow", again at the cost of other modes of transport. And so on, and so on, presumably until all space between the buildings in London is one huge traffic smoothing exercise.

What should be accepted is that "traffic smoothing" involves all modes of transport - cycling, walking, bus user and motorists, and that to accommodate everyone traffic flow is going to be between 10mph and 20mph on average. This also humanises the road-space - at the moment traffic is allowed (some may say the road design encourages) to "put their foot down" in the multi-lane free-for-alls to only be snared in the inevitable jams either side. Places like Stamford Hill have traffic lights at the bottom and top - normally with considerable queuing traffic, but the road design in between has two lanes with a lane width of hatching between opposing traffic. It is deeply unpleasant to cycle on - which maybe why I see many cyclists jumping onto the pavement at this point - something which helps out the motorist but hinders the other group of people most affected by this car-culture - the pedestrian.

One day people will realise that their urban spaces are too important to use by seeing how much traffic can be squeezed through it. I think this is already happening - 20mph zones are widely accepted (even if they are not widely respected by motorists), "home-zones" in places have been designed to enhance living space. But our town planners and local government, instead of leading, appear to be trying to pull the other way.

1 comment:

  1. Great post.

    It is incredible to me that a policy of increasing levels of cycling and walking does not seem to be considered as a way of 'smoothing traffic flow'. Traffic planners do not seem to understand that a motorist could be a potential cyclist or walker - the modes are considered completely in isolation, when in fact greater levels of walking and cycling would massively alleviate the kind of congestion you describe in this post.

    "From my experience as a cyclist and driver, the average junction design is to have as many traffic lanes as possible entering it - even if the other side is too narrow to accommodate - in an effort to push as much traffic through the junction as possible."

    I think the more general rule is 'let's get as many traffic lanes in, wherever we can' - it's not just at junctions. Take London Bridge, for example - there's only one lane leading onto it southbound, yet it immediately opens out into a three lane motorway.