Pedestrianise London

Let's make London a more liveable city

How To Fix Our Streets: Traffic signal reform

In this series of posts I will look at quick and easy things local councils can do today to make their streets nicer places for people rather than machines.

This is the third post in the series, catch up on the previous posts on parking reform and rat-runs.

Traffic signal reform

In the next few paragraphs I’m going to try to convince you that traffic signals are the big mistake of urban traffic control.

Traffic lights are a way of controlling traffic flow at an intersection so as to remove the conflict between traffic flowing in opposing directions that would otherwise force the vehicles to negotiate safe passage across the intersection.

This is a sensible thing when vehicle speeds are high and throughput is a priority, so on out of town A roads and major traffic corridors where speeds exceed 30mph. Somehow however, these devices have moved into our cities and infected roads with high volume but low traffic speed where other measures may be preferable.

"We only want traffic lights where they are useful and I haven’t found anywhere where they are useful yet" - Hans Monderman, traffic planner extraordinaire

I’ve mentioned Martin Cassini and his Equality Streets campaign before here on this blog, and I’ll now shamelessly pluck the argument against traffic signals directly from Martin’s brain:

Competing for green time

Traffic lights makes us compete for gaps and green time, encouraging speeding to reach the lights and through the junction, whereas any sane road planning scheme where pedestrians are present would try to reduce vehicle speeds at places of conflict.

They also make us stop when it’s safe to go, a recipe for rage.

The removal of lights and alternative junction treatments stimulate empathy and encourage drivers to see pedestrians and cyclists as fellow road-users.

Zombie attack

Traffic lights take our eyes off the road, just at the moment we are at the most dangerous parts of the network. If you treat road users as idiots, try to protect them from having to pay attention, you end up with dangerous zombies blindly following the signals no matter what road conditions are presented in front of them.

The classic example is that of the satnav user driving into a field.

Stacking

Stacking is a term used in the UK to mean having multiple lanes for a single direction at a set of lights so as to be able to “stack” more vehicles in front of the lights on red and this increase the throughput of the green part of the cycle.

This works by allowing multiple lanes of vehicles across the intersection in one go, but has the negative effect of creating conflict between vehicles as the multiple lanes are merged back together after the lights.

In the UK, we seem to provide road users with little help during this merge procedure, usually simply with lane definition lines vanishing and road space for multiple vehicles running out. This is not only a stressful procedure for motorists, but a potentially dangerous situation for cyclists to find themselves in as cars jostle for position in a rapidly narrowing roadspace.

Solutions

So what are the alternatives?

The quick fix is simple. Identify pointless traffic lights and turn them off. We’ve all seen it, the usual queue of traffic isn’t present, you get to the traffic lights that cause the delays and they’re broken, but instead of chaos, the traffic is flowing smoother than usual. Switch them to always flashing amber if necessary, or bag them up and cover them with give way signage.

Too extreme? A simple change that makes all the difference to pedestrians and cyclists is the removal of secondary lights, otherwise known as repeater lights, you know, the ones that sit opposite the junction and invite drivers to creep across the stop line and into the cycle box or pedestrian crosswalk.

Longer term heavy engineering solutions include the greatest British addition to road planning, the mini roundabout. Priority is clear to everyone, tight entry/exit angles encourage slow speeds, and zebra crossings can be added to each exit to empower pedestrians if needed (no traffic islands please, bad for cyclists).

Also the removal of stacking lanes, make one lane go in one direction to remove the conflicts that occur after the junction and to free up street space for other uses. The junction may lose capacity, but this street isn’t about throughput and so it might encourage vehicles to stick to the main roads.