Traffic Lights turned off at night?

[2ndcitysuit]

Evening

Did you hear the interview on BBC Radio Five Live this evening with the chap from Devon Council suggesting that traffic lights (particularly on roundabouts) be turned off after say 8.00pm?

Article on BBC Devon web page here:


http://www.bbc.co.uk/news/uk-england-devon-10955182

He made great mention of the amount of roundabouts in Exeter that now have traffic signals on them. Sounds a reasonable idea?

[scragend]

I don't see any problem in turning off traffic lights on roundabouts at night. After all, there are very many roundabouts which don't have traffic lights at all, and they get away with it OK.

Other junctions would have to be looked at case by case. Some would be fine to turn into give ways at night, others (e.g. restricted visibility) maybe not so suitable.

[stu531]

Around Europe, many of them go to flashing amber (proceed with caution - like on a pelican). GIven that they're half on and half off, do they use around a half of the electricity of continuous-on?

[WHBM]

There is a modern design but signalled roundabout here

http://maps.google.co.uk/?ie=UTF8&ll=51 ... 76,,0,7.21

in London's Docklands which is completely inappropriate for signals, and which must have wasted hours of my time over the years as I wait and wait for nothing to come along the westbond approach. Quite why it cannot function just as a normal roundabout 24 hours a day I cannot imagine. Of course, being London it is on long time intervals, rather than demand-activated.

[Christhebull]

I assume that if traffic lights are turned off, more junctions will become like these part time signals on the A3090 near Hursley, which are the only part time signals I have seen that are not at a roundabout - they are at a T-junction instead. Are there any others like this?

[t1(M)]

This is nothing new - I remember several years ago approaching the Tolworth roundaboutearly one morning with the part-time lights off, to have them go to yellow, and then red on my approach.

The giveaway is a give way line just beyond the stop line

[pjkh]

Around Europe, many of them go to flashing amber (proceed with caution - like on a pelican). GIven that they're half on and half off, do they use around a half of the electricity of continuous-on?

They also do this in the US. A flashing amber means it's off and you have priority, and a flashing red turns it into a stop sign. Sometimes all four directions have a flashing red, which means 4 way stop.
Works well. We should have it here.

Aside from the electricity consumption, they can save on fuel consumption too (not the US flashing reds, obviously) as you don't have to stop when there's no reason to.

[2ndcitysuit]

The sensible use of peak time lights on roundabouts - and switching off at night - seems so obvious Sat waiting for the green light at midnight half way round a roundabout is just plain daft.

By the way, one of the worst decisions Birmingham CC ever made was putting (full time) lights on the Robin Hood roundabout. Talk about making something so difficult to negotiate, and lane changing made particularly difficult when confronted with stationary traffic.

[Beardy5632]

There is a modern design but signalled roundabout here

http://maps.google.co.uk/?ie=UTF8&ll=51 ... 76,,0,7.21

in London's Docklands which is completely inappropriate for signals, and which must have wasted hours of my time over the years as I wait and wait for nothing to come along the westbond approach. Quite why it cannot function just as a normal roundabout 24 hours a day I cannot imagine. Of course, being London it is on long time intervals, rather than demand-activated.

I thought you were on about the Traffic Light Tree for a minute.

[MotorwayGuy]

There's these weird ones near me, which have a "part-time signals" plate below them, which I haven't seen in use for at least seven years, maybe longer - There used to be mellor heads attached to the poles which seemed to be activated around 5pm, but since the heads were replaced I have never seen them used. Not sure exactly what purpose they serve anyway as there are none on any of the other approaches, and never has been since I can remember:

[ Link ]

[Chris5156]

There's these weird ones near me, which have a "part-time signals" plate below them, which I haven't seen in use for at least seven years, maybe longer - There used to be mellor heads attached to the poles which seemed to be activated around 5pm, but since the heads were replaced I have never seen them used. Not sure exactly what purpose they serve anyway as there are none on any of the other approaches, and never has been since I can remember:

[ Link ]

I'd hazard a guess it's a ramp metering system, designed to reduce the flow of vehicles onto the roundabout from that entrance point. Judging by its location it might have been to stop a heavy rush hour flow of traffic coming off the A2, and heading south, from blocking up the other entrances to the roundabout. If there weren't enough opportunities to enter from the eastern arm of the roundabout, for example, you may have ended up with queues onto the A2 westbound carriageway. That's just a guess, though - and if they are no longer used perhaps they weren't all that necessary after all.

[boing_uk]

The reason most roundabouts are now full time signalised compared to part time is due to a CSS report in 1997 which, in my opinion was either:

a) flawed in its conclusions on the issues regarding the safety of part time signalisation
b) traffic signal engineers have read in to it more than what was there.

In essence, it found that at in a sample of 20 part time roundabouts, 7 sites saw a massive increase in off-peak accidents where there was signalisation only for peak hours.

Now, I am of the opinion that during the day, there may very well have been an increase in accidents due to levels of traffic flow and high circulating speeds at the sites concerned.

There was NO investigation in to whether these were night time accidents, whether there were any other factors in play and there has been no other research in to this since 1997. As a profession I think we shoot ourselves in the foot far too often, and using flawed research (small sample, no detail, no investigation in to causes, no follow up) to back up spurious claims on the grounds of safety was something I thought, certainly in signal engineering, was less prevalent than in other traffic engineering fields.

Alas not.

I will certainly be pushing the matter of quiescent flashing amber and irish flashing left turn amber arrows at the next traffic signals global gathering.

[Mark Hewitt]

There are two examples near me. The Angel of the North junction with the A1 has lights on it and has stop lines as well as give way lines, the lights are just part time and this works well. As the primary function of the lights (as far as I can tell) is to prevent traffic taking a short cut to avoid A1 congestion thus bunging up the roundabout too.

But at Chester-le-Street A1(M) J63 the lights are 24hours. I think because the approaches from the A167 have been modified, deflections changed and give way lines removed.

[RoadKill]

I assume that if traffic lights are turned off, more junctions will become like these part time signals on the A3090 near Hursley, which are the only part time signals I have seen that are not at a roundabout - they are at a T-junction instead. Are there any others like this?

Two more examples:

Brands Hatch

Black Pill

[nirs]

I assume that if traffic lights are turned off, more junctions will become like these part time signals on the A3090 near Hursley, which are the only part time signals I have seen that are not at a roundabout - they are at a T-junction instead. Are there any others like this?

And one in Belfast.

I've narrowly avoided an accident here. The lights are immediately after a 90 degree curve, which doesn't help. Since I almost always go through here at off peak times, I barely see them any more. I once nearly went on through a red light here on a rare occasion when I was there at a peak time! Oops.

[Lockwood]

I thought you were on about the Traffic Light Tree for a minute.

I trust that those are not meant to be followed?

[BigToe]

I thought you were on about the Traffic Light Tree for a minute.

I trust that those are not meant to be followed?

Of course not - the signals are the wrong colour but no, it's a modern art installation

[cb a1]

There was NO investigation in to whether these were night time accidents, whether there were any other factors in play and there has been no other research in to this since 1997. As a profession I think we shoot ourselves in the foot far too often, and using flawed research (small sample, no detail, no investigation in to causes, no follow up) to back up spurious claims on the grounds of safety was something I thought, certainly in signal engineering, was less prevalent than in other traffic engineering fields.

I would speculate that the report authors probably had dozens of caveats, recommendations for further analysis, monitoring, reviews, etc., etc. (in their first draft at least which may have then been edited out of the final report).

Do those that hold the purse strings (i.e. politicians) want to hear such things? Of course not. They want nice simple answers at minimal cost and preferably answered yesterday. [/cynic]

[rileyrob]

Did you hear the interview on BBC Radio Five Live this evening with the chap from Devon Council suggesting that traffic lights (particularly on roundabouts) be turned off after say 8.00pm?
He made great mention of the amount of roundabouts in Exeter that now have traffic signals on them. Sounds a reasonable idea?

From someone who is 'in the know':

Facts:

1. http://www.devon.gov.uk/exetcycleguideleaflet.pdf this shows all the toucan crossings in Exeter (the quality is rubbish) with a red C in a circle.

2. There is a similar map for walking which shows the puffin/pelican crossings which make up a lot of the remainder of the junctions being talked about.

3. Exeter is a Cycling Demonstration Town, and quite successful. It is understood that traffic volumes in the city are dropping (which goes against the nation trend)

4. A lot of the signal junctions are there for peds/cyclists, not traffic, these users are harder to see at night, so the provision of a signal for them is an obvious safety improvement for them. Even if they don’t need them it encourages sustainable options by increasing the perception of safety for a ped/cyclist. This perception of safety is especially important when the number of lanes gets to 3 or more.

5. Zebras give priority to peds, so providing a pelican etc actually favours cars, especially in high footfall areas

And Opinions:

6. Flashing Amber/Red etc wouldn’t save much energy as lights are dimmed at night already and the controllers would still have to run. With Bulbs, flashing would probably reduce their life, and LED’s power usage is really small by comparison.

Point 4 and nirs post (above) are probably the main reason why Exeter keep overnight signals.

[DavidBrown]

Exeter's a bit of an odd one - it is a nightmare to drive around with the main A roads being to the same standard as most of the side streets. However, for whatever reason, congestion does seem to be slightly easing whenever I go there. Non-car options are much more attractive now - if I'm off into the city centre I'll take the train from Barnstaple - cheap fares, a journey time shorter than the cars', and trains directly to Exeter Central, a 2 minute walk from the High Street. When I do need to drive in, improvements such as the Monkerton Link and the changes made with the Princesshay development have helped things in their localised areas, which of course have a (positive) knock on effect elsewhere.

On the subject of Exeter, I did notice a couple of weeks ago that there's some significant works taking place along the A379 link from the M5 J30 to the City Bypass - including what looked like a new road being built opposite the on-slip from the Tesco/Retail Park area. Any ideas what this is for? I haven't heard anything about it, and can't find any news on the councils website - it's definately a seperate scheme from the J30 improvements that are currently in their second phase.