Failure Behaviour of Temporary Traffic Lights

[tom66]

Today marks the fourth or fifth time in recent memory that I've been at a set of temporary lights stuck on red. I understand this happens if the controller cannot verify that all of the lights are functioning. Likely in this case one of the lamps has a dead battery pack or some other fault. The controllers are networked wirelessly and a robust system is required to ensure the lamps never show a conflicting signal; if the alternate signal cannot be communicated with, then it is impossible to (safely) set a green signal. This even applies if a pedestrian crossing signal has a dead battery. Of course, a signal on red cannot be legally passed unless a police or traffic officer directs you to do so.

However, this seems quite distinct to the failure mode of fixed traffic signals. When they fail, I've noticed they usually turn off in their entirety. At this point, the road user is left to navigate their way through the junction, and no priority is indicated.

The result is that when permanent signals fail, the traffic seems to flow with caution, but when temporary traffic lights fail, the junction can often end up gridlocked as drivers (quite rightly) do not want to pass the red signal. Besides a few cars in front of the stopped vehicle, people are rarely wise as to what has happened. Eventually, one or two cars pass the signal, but the flow of the junction is reduced to a trickle.

It strikes me that these signals either need to fail in the 'off' state (though that has other consequences, as it may not be readily apparent there is a managed junction) or perhaps the UK needs to introduce the 'blinking red' signal that is seen in the US and other countries, which means 'proceed if clear, after full stop', in other words, it becomes identical to a multi-way stop which the Americans really love using. If the signals went into a blinking red state in case of a fault, most of the junction would still flow.

[Mark Hewitt]

Yes; traffic lights near me where they are converting a give way t-junction to be light controlled. Apparently someone ran over the lights on the opposing side, so they are missing and the other two stuck on red.

Second time in a few months this has happened with works in exactly the same place. They never seem in a big rush to fix them.

As someone pointed out in the local facebook groups even though they are now working there will be people who have seen the posts and assume they are still broken and go through on red.

[wallmeerkat]

I remember a set of temporary lights near me, than slightly down the road another where there were seperate pieces of work going on.

One finished before the other, but the contractor put the lights beside each other at the first one, I approached it and one light was red and the other green. Very much proceeded with caution, especially as it was on a blind bend.

[FosseWay]

This is one of the areas where the law needs tightening so that there is reciprocity in duty/responsibility between those imposing the restriction and those expected to obey it. If it is so desirable that everyone stop at red lights that we make it a blanket legal requirement, then the same strict liability to ensure the signals themselves behave as intended should be laid on the entity erecting the lights. In other words, there is no more excuse for lights to give false information than there is for a road user to jump a red, and the penalties should be similar. Note that I am talking about directly wrong information, such as lights stuck on red or giving green at both ends. If the lights just don't work at all, then road users need to proceed as if they weren't there.

The same should be true regarding signage, road markings and so forth for any strict liability offence. If it's a criminal offence to jump a red, speed, drive the wrong way down a one-way street etc., then it should be a criminal offence to fail to provide the signals and signs that tell drivers what they need to know in order to obey the law. A "we'll get round to fixing it sometime" attitude isn't good enough.

[traffic-light-man]

I've mentioned this before, and although I see why they fail to all-red, I think they should be as per regular signals and fail to all out. At least with an all out you have an indication that something is wrong, as tom66 suggests.

When Liverpool (or perhaps still Amey at that point) were going full steam ahead with their cycle track plans to connect Tithebarn Street with Lime Street via the flyover they were simultaneously demolishing, they switched off 3 or 4 (IIRC) sets of signals and put them on portables (without any further work ever happening - eventually one site got a bit of a refurb and the others just got switched back on without any changes). Given the portables were the for so long, across the various sets they would frequently fail to all red and cause significant disruption. The usual response was for a bobby to turn up and simply turn all the heads around away from the carriageway and leave it as uncontrolled.

I've actually got a video of one failing to all-red while I was using the junction. I was just passing the signal head and it can just be seen within the shot to snap from green to red and the peds all locking out (wait indicators lit).

Funnily enough, I think I've only ever seen this happen with SRL signals. Perhaps an indication of their equipment, on-site support or perhaps just a case of confirmation bias because they're so common in this area.

[tom66]

The failed set in this case (in Rushden, Northants) was indeed an SRL system. They use 458MHz RF to communicate according to a datasheet. It does seem to be a public, unlicenced RF band, with the only restriction being devices may not be airbourne (I suppose traffic lights in a tornado would present a compliance issue )

I also expect the light systems are based on a mesh network, and that there is no central coordinator. One issue we had with this in engineering an unrelated product was that the coordinator role had to either be mains powered, because it would do so much more work (constantly transmitting whereas others were mostly receiving), or it would need to move around the network to distribute the battery load across all devices. This creates a real nightmare "two general's problem" where you had a network where half the nodes had successfully moved to one coordinator, whereas the other half hadn't. The network could easily split into two, and since our product was an alarm with distributed sounders, it was easy to get half the network to go into alarm independently of the other half. I assume that the signals detect that one or more nodes are no longer reachable, and determine that they must go into the fault state.

[the cheesecake man]

I encountered a set stuck on red last night. Eventually everyone gave up and went through the roadworks anyway. No doubt technically illegal. But what are the alternatives?

phone the police and ask them to authorise you by phone to proceed? It seems unlikely they'd do that, and they'd quickly get annoyed if everyone did so.
phone the police and request they attend to investigate? Unless it was causing a danger (which it wasn't as it was a short section on a straight low-speed road) it's unlikely they would, although they might at least be able to report it to the relevant operator.
phone the police to report, and go through? Phoning the police to admit a traffic offence doesn't sound clever.
turn round and find an alternative route? Seems a bit of an overreaction.
get out and trash the lights? Satisfying and avoids a traffic offence, but may involve committing criminal damage.

[avtur]

Here in Mid Sussex we seem to have and extraordinary number of temporary traffic lights in use. With most of our local roads being quite narrow even the most minor obstruction of the road (by works) reduces capacity to alternate single line working and so out come the traffic lights.

What I've noticed is that when these lights are used on what you might call local main roads there always appears to be an operator with the lights during the 'normal' working day. The operator is usually tucked up in their car at one end of the works or the other, this means there is always someone on hand if there is a failure, well at least through the busier part of the day. Is there some sort of requirement for an operator to be on hand when temporary lights are deployed on certain types of road?

For all the widespread use of temporary lights, and driving over 100 miles per day in the local area I see lots of them, I can't think when I last saw a set that had failed.

'Sunbelt Rentals' and 'Amberon' appear to be the operators of choice in the area.

[tom66]

get out and trash the lights? Satisfying and avoids a traffic offence, but may involve committing criminal damage.

What would the consequence of getting out and turning the traffic signal away from the lane so that drivers cannot see it?
I suspect that's all police would do, if it's quiet enough.

[Chris5156]

Hmmm....

phone the police and ask them to authorise you by phone to proceed? It seems unlikely they'd do that, and they'd quickly get annoyed if everyone did so.

Assuming you could get through to someone who had some sort of authority, rather than just a call centre, I don't see how they could authorise you if they're not at the scene. They'd have no way of knowing what the situation was, beyond your account which would be incomplete, so on what basis would they be telling you to go ahead and break the law?

phone the police and request they attend to investigate? Unless it was causing a danger (which it wasn't as it was a short section on a straight low-speed road) it's unlikely they would, although they might at least be able to report it to the relevant operator.

They could get a patrol to attend at some point in the future when one was nearby and not engaged on any other more important job, but that wouldn't help your immediate situation and while it would help other people in the future, it wouldn't help you get through.

phone the police to report, and go through? Phoning the police to admit a traffic offence doesn't sound clever.

You could report it stuck on red and then go through without telling them the second part, I suppose.

turn round and find an alternative route? Seems a bit of an overreaction.

I think that is the only legal and officially sanctioned thing to do.

[ForestChav]

I've seen a fair amount of traffic lights where there is a contact number to ring if there are any issues with the lights.

Though the other day I saw a 4-way control where the lights were all completely switched off but still in place along with the roadworks, which is presumably a different situation to going through on red - as it was dark enough for traffic to be lit and it was a relatively quiet junction anyway (which I'm not sure ever needed that level of control) it seemed safe enough to go through with caution.

[Lockwood]

I've seen a failed set of temporary lights at a T junction with a roads policing officer controlling traffic.

I've also had some failed permanent lights, controlling a narrow bridge on a bend. Stuck on red. Phoned 101 on hands free , told them where I was, what was going on (it's 3am, there's no other traffic), got told to proceed with caution. I asked them to confirm they were authorising me to pass a red light. They told me to wait a moment, checked with a supervisor and then stated for the recording that I was allowed to do that and that they'd notify the council.

[the cheesecake man]

What would the consequence of getting out and turning the traffic signal away from the lane so that drivers cannot see it?
I suspect that's all police would do, if it's quiet enough.

That's an interesting one. It's illegal to pass a red light, there's a red light, I know it's there, I've passed it. That sounds like it's still illegal for me, even if it wouldn't be for later drivers who wouldn't know it was there.

Hmmm....

phone the police and ask them to authorise you by phone to proceed? It seems unlikely they'd do that, and they'd quickly get annoyed if everyone did so.

Assuming you could get through to someone who had some sort of authority, rather than just a call centre, I don't see how they could authorise you if they're not at the scene. They'd have no way of knowing what the situation was, beyond your account which would be incomplete, so on what basis would they be telling you to go ahead and break the law?

If they told me to proceed I wouldn't be breaking the law, but I agree it's very unlikely they'd just believe me and authorise it by phone.

You could report it stuck on red and then go through without telling them the second part, I suppose.

I could, but if they did turn up and I wasn't there I still seem to have incriminated myself.

turn round and find an alternative route? Seems a bit of an overreaction.

I think that is the only legal and officially sanctioned thing to do.

I do too, unless I'm on a one-way street, then that isn't legal either. Zugzwang!

[Fenlander]

We've had gas pipe replacement works going on down our street for the last 3 weeks, this morning the 4way temporary traffic lights failed. It's a main route into town and suffers at the best of times from traffic backing up from a level crossing causing the queue one way to back into the works area, which prevents the other direction from going anywhere. Heading in to town you can't see the problematic queue as it's round the corner and by the time you've gone part way along the restriction it's too late to do anything other than block the road.
This morning the lights were all red, I woke up at 7AM to the sound of car horns as everyone tried to work out what to do. Not having a contact number I tweeted Cadent, the local police and both local newspapers for a bit of awareness, 3 hours later Cadent replied saying they'd get their contractor to have a look. No response from the police but the papers retweeted and I see from google maps live traffic it's no better this afternoon.

[Chris5156]

You could report it stuck on red and then go through without telling them the second part, I suppose.

I could, but if they did turn up and I wasn't there I still seem to have incriminated myself.

No, they'd have no evidence of what you'd done. You could have turned round and left in the other direction, or you could have been reporting it as a pedestrian.

turn round and find an alternative route? Seems a bit of an overreaction.

I think that is the only legal and officially sanctioned thing to do.

I do too, unless I'm on a one-way street, then that isn't legal either. Zugzwang!

This is true - I don't know what the official advice would be if you find a stuck red light on a one way street. Pray for divine intervention, presumably, or register your car as your new permanent address

[Burns]

Here are the official rules: Let's say Clancy Docwra turn up on a Friday afternoon, dig a small, pointless hole then bugger off for the weekend, as long as you can see from one end to the other, the temporary traffic lights are permissible and its legal to ignore them.

[traffic-light-man]

Here are the official rules: Let's say Clancy Docwra turn up on a Friday afternoon, dig a small, pointless hole then bugger off for the weekend, as long as you can see from one end to the other, the temporary traffic lights are permissible and its legal to ignore them.

Interesting rule, do you have a reference for that?

[multiraider2]

At the moment there's roadworks on the A215 Spring Lane at its junction with the A222 Lower Addiscombe Road/Long Lane. Yesterday evening had to go to Tesco. Very slow progress including lots of time stopped. I eventually got to Longhurst Road and was able to cut the corner round the estate so didn't properly see the state of the lights. I suspect three directions showing red, of which more later. On the way back the lights were out and the queues much reduced. Traffic was being it's normal sensible self in these situations and even though the bottom of Spring Lane was reduced to a s1 because of the road works there was the same mostly sensible stuff you get on a genuine s1. I stopped in the right turn lane here and let a double decker 312 bus and a SUV out of the wrong side lane and then went round.

Today I went on foot to Addiscombe and I saw the lights for myself. All reds showing and I suspect that was as it was last evening. So traffic sits there until it gets fed up. From the Cheesecake Man's earlier post. Most people did what he saw. So rather than phoning the police or turning around, everyone gave up and went through the red light anyway. Not always the first car in the queue though. Until we got a car from the one direction that decided to move that was so far back he or she didn't notice everyone else going through the red and stops and then one of the other directions realises it's red forever and takes the same action. However, altogether much slower than when all blank and everyone crossing did so illegally. Traffic was queued back all the way into Addiscombe Centre and people were turning around there because they couldn't see the issue.

I was tempted when I got back from Addiscombe to push all the lights over/turn them around (they woudn't have my numberplate. "Who was that guy?") But I resisted and left the drivers to their own travails.

[Bendo]

Here are the official rules: Let's say Clancy Docwra turn up on a Friday afternoon, dig a small, pointless hole then bugger off for the weekend, as long as you can see from one end to the other, the temporary traffic lights are permissible and its legal to ignore them.

Official rules from where? Certainly not in any legislation I've read so the actual bit of legislation that covers the would be good to know. I suspect it doesn't exist however.

[AndyB]

A red traffic light, unfortunately, is a red traffic light whether it is a temporary or permanent installation, and it is always technically an offence to disobey it.

If someone approaches two way TTLs at red, waits for two clear cycles of traffic to come the other way with no green, proceeds with caution after the next wave the opposite way, and someone comes the other way on green and crashes into them, then their dashcam is evidence that the lights appeared to be stuck on red. Sufficient doubt for it never to go for prosecution.