Thursday, 22 March 2012

Barton Road Traffic Light Junction

Barton Road Traffic Light Junction is a slightly strange junction in Newnham, Cambridge.

The main route in and out of town turns through a right angle with side roads coming straight in from the other 2 directions. Here's the satellite view from Google Maps (annotated at the end of this link).

Just on a side note, notice the cyclist on the crossing and the red car in the ASL. One of these two is not obeying the law (and my money's on the driver!).

This junction has 4 light phases.
  • The main route both in and out. This is reasonably long because this is the highest amount of traffic
  • The subsidiary route from the east (right) of this satellite view.
  • The subsidiary route from the south (bottom) of this satellite view.
  • The cycle crossing.
It may be that the last three are conditional. There is a button to push for the cycle crossing, and the 2 subsidiary routes may check whether there is a car there.

This junction is complicated by the pedestrian lights around 30m away (to the north/top of this picture). I say this complicates the junction, but it also makes it more dangerous. When lights are this close together it is not unknown for drivers to miss one set of lights and drive through on red. For a pedestrian light or this junction this puts vunerable road users and, to a certain extent, other car drivers at risk.

This clip shows it all really. I'm approaching from the west (left of the above picture).
  1. As I start, the phase for the main route is just finishing. 
  2. At 6 seconds, the car from the east (right on satellite view) goes through. I'm fairly safely presuming that it's green to them.
  3. At 11 seconds, I press the cycle crossing button.
  4. At 20 seconds, the car from the south (bottom on satellite view) passes into town. Again, I'm fairly safely presuming that it's green to them. 
  5. At 22-30 seconds,notice the red light for the main route traffic.
  6. Around the same time I can hear the pedestrian crossing beeping stopping.
  7. At 30-31 seconds, the cycle crossing lights change (although not shown, darn it!), and I move off.
  8. At 32 seconds the camera picks up 2 cars from the lefthand side (or north/top of above picture) just moving through the recently changed pedestrian crossing lights.
  9. At 35 seconds, as I'm crossing, AK60 YEY goes right through the junction red light and pulls into my path.
  10. My first reaction is to get off the road heading straight for the other side. My heart is pounding. I'm thinking what if I'd gone more quickly over the lights, I'd have been under their wheels.
  11. I turn round to get a look at what happened, and at 42 seconds there's a van stopped at the main route lights and the second car coming the other way is nowhere in sight.
  12. At 44 seconds, the van starts to move. Again, I'm fairly safely presuming that it's green to them. 
So, having had a very short moment thinking I might have gone through the cycle crossing when it was red, I quickly followed the logic through. If the main route had been green when AK60 YEY came through, it would have been a main route phase between 30 and 42 seconds only, as the van is stopped. This is hardly time to go through the light changes! So, it's obvious that I was right, the lights were green for me and not AK60 YEY.

On another side note, red light jumping is something that the general public believes all cyclists do, it's just not true. From Tfl, The majority of cyclists (84%) obey red traffic lights. And it's quite clear that the damage done by cars when they do this can be a lot more serious.

So, why are the pedestrian lights away from the junction?

The flow of pedestrians is from the west (left of the satellite view) and into the green space north-east (top right of the satellite view), along the path into town. There is some flow from the north on the west side of the road but it's going south and not turning back on itself (there are no houses or other start points up to the next junction). So, moving the pedestrian lights is not going to effect journey distance at all.

The reason the pedestrian lights are there is probably so that it can be separated from the phasing of the junction lights. And yet, this puts vunerable road users at risk simply to try to improve the throughput of motorised traffic. And with both lights, does it do that anyway?

Surely, pulling the pedestrian crossing down next to the junction and phasing them at the same time as the cycle crossing is the safest option here. It's hardly going to destroy traffic flow.

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