Sunday, 18 September 2011

The Mayor's attempt to speed up traffic using the traffic lights has a significant impact on everyone else. And it doesn't even work for drivers - in response to Dave Hill at The Guardian




Traffic lights at Cedars Road, Clapham Common


This weekend, Dave Hill at The Guardian posted an excellent piece about Boris Johnson's transport strategy. He talked about how the Mayor is prioritising the streets for more and more people to drive through and how the city is straining under that policy.


Dave Hill is one of the few mainstream journalists to successfully  have grasped the true nature of Boris Johnson's election commitment to 'smooth the traffic flow' and I urge you to read his article. 


At one point, Hill describes how the smoothing traffic flow policy means "a great deal of attention being lavished on traffic lights to no great effect".


I think there is one traffic light that exemplifies everything about the Mayor's obsession with pumping more motor vehicles, more rapidly through London's creaking infrastructure.


In 2009, Transport for London decided to change the traffic light sequence at Cedars Road where it meets Clapham Common. The offending lights are pictured above.


Cedars Road is a signed cycle route and people can cycle straight ahead over Clapham Common to head towards Wandsworth or south Lambeth.


At the time, TfL stated:


"The objective of the scheme is to reduce delays for left turners from the CedarsRoad approach to the junction by introducing a left turn filter phase that can fit within the existing signal staging. The primary driver of the scheme is reducing delays to the eastbound Route 345. However the proposal wouldbenefit all traffic on this approach equally."


The report went on to estimate the impact on cyclists and pedestrians. "Neutral impact on both," it declares. 


Sounds sensible, doesn't it? Fiddle around with some traffic lights and people on the bus can get through the lights faster. And, according to TfL, everyone's a winner because there's no impact on anyone else. 


Except, that's not strictly true. 


For starters, pedestrians get less time to cross Cedars Road because the signals are changed in favour of motor vehicle green phases and less time for pedestrians to cross the road. 


But for people on cycles, TfL has added an extra danger. The overwhelming majority of people cycling through this junction are heading directly ahead, over the Common. The design of the advanced stop box very clearly shows that you are supposed to cycle to the lights and enter the advanced stop line from the left hand side. In other words, the street is designed to make you think you should cycle into the advanced box and wait on the left hand side to continue straight on. But if you do that, you'll find the left-filter now turns green well before the lights to go straight on.


Net result: lots of motor drivers honking lots of people on cycles who are then surprised by drivers behind them trying to turn left directly through the space that is reserved for them. What's more, if you're on cycle, you can't see the left filter from the advanced stop box and there's no signage to warn you not to wait in the box where you would naturally think you should wait.


Transport for London has corresponded at length with Lambeth Cyclists about this junction. After some initial correspondence a Transport for London review did acknowledge that “the potential safety issue for cyclists as a result of this change must be addressed” and some very minor tweaks were made. But nothing that gets rid of the basic problem - Transport for London is adamant that the scheme is staying. 


All of this got me wondering: Why would TfL be so wedded to this particular traffic light scheme? The plan was to shave 11-19 seconds off bus journey times. Except TfL has apparently conceded in correspondence that the time saved by buses at this junction is - wait for it - a maximum of four seconds but probably as low as ONE SECOND.


In other words, Transport for London has:


a) made this junction less pedestrian-friendly by reducing pedestrian green phases
b) made this junction much more dangerous for cycling by adding the left filter
c) to save one second on average bus journey times


But there's also something massively revealing in the correspondence between the teams at Transport for London about this traffic light.


In September 2009, an FOI request reveals an internal email that points to what's really going on here: "this proposal could be seen as one that would help to 'get traffic moving'"says one TfL official to another.


TfL is supposed to regard traffic as meaning everyone on London's streets. It is supposed to make it safe and convenient for people to get around London by foot, by cycle and by motor vehicle. This traffic light works to save one second for the average bus journey at the cost of much longer journey times for pedestrians and more dangerous journeys for people who cycle.


Dave Hill is right to point out how the Mayor is obsessed by traffic lights. But he's not right to say that has  'no great effect'. It would be more accurate to say, the tinkering with traffic lights is being done to give the impression of faster journey times to motor drivers while creating significant new risk, slower journeys and more inconvenience to other road users.


Lord Donaldson of Kingsbridge understood
what Boris Johnson hasn't yet worked out.
Traffic lights won't sort the congestion out.
http://bit.ly/oMcgRN
Back in 1982, there was a debate about traffic lights in the House of Lords. The Earl of Avon reviewed the then Greater London Council's new 'spilt-cycle offset optimisation technique system'. To you and I, that means traffic light sequencing. At least he was honest enough to say what the new traffic light configuration meant:

"The GLC's decision to make a substantial investment in the [system] is to be welcomed, and it is hoped that it may lead to significant improvements in traffic speeds in the central area."



The same thing is happening now. But it didn't work in the eighties. And it won't work now. 


Lord Donaldson of Kingsbridge was very clear in the same debate when in realising that the GLC's traffic light magicking wouldn't work any more than TfL's smoothing the traffic flow isn't going to work: "When it comes to too many cars and solo drivers, there is only one way to deal with that; namely, to make motoring short distances in London so disagreeable and expensive that people stop doing it."


In recognising that fact, Dave Hill, your article is completely spot on.