Traffic Lights Green on two sides at same time ?

[406V6]

Tonight I witnessed a very close call on a set of traffic lights in sunny Slough where a car on the main road nearly smashed into another just starting out from the side road after the red went to green. Serious avoiding action was taken and through sheer luck there was no crash. I was a couple of cars back on the side road and the lights were definitely green for the first car (nearly t-boned) and then for me as I went through and turned right on to the main road. When I looked back over my shoulder at the light on the main road that had just been run through it was green. As I can't see how the lights on the main road could have been red and then cycled red > red+amber > green after waiting for the light on my road to go green > amber > red, I can only assume that the light on the main road was green throughout. In other words green on two sides at the same time. This would explain why the first car ran through the light at speed. Obviously I can't be certain of this but the whole thing looks very dangerous and I've complained to the council.

 

Has anyone on here experienced a traffic failure like this ? Green on two sides at the same time - a “wrong side†failure in safetyspeak.

[djimbob]

Not quite the same, but my first and only "proper" RTA, was when the sales rep in his astra estate was watching my traffic lights whilst he was stationary on red, and decided in his tired brain that was his cue to steam out and hit my rock solid cossack side car, with my brother in it!

 

We suffered bumps and bruises, and the 250 superdream and cossack sidecar were fucked really, but the insurance paid out in the end, so that was that.

 

Moral of the tale, some road users are taking their cues to proceed from unintended sources, trust no one

[angle]

Technically, that shouldn't be possible. Traffic lights are programmed in 'stages', each of which is a set of movements that can run together - so for a basic crossroads you'd have two or three, the first being the two main road arms, the second is the two side road arms, and then the third is pedestrian crossings, if there are any. These are hard-coded onto the processor that runs the lights in the cabinet by the side of the road. Even the signals running SCOOT (which is where the signals adjust themselves constantly to maximise the amount of traffic they can get through) can only adjust the order they run stages in and how long they run them for, they can't make the lights do anything that isn't pre-programmed.

 

They're also coded to switch everything to red if there's a problem detected - so for example you need a minimum of three signal heads for each approach, one red light out is OK but if there's two out on one approach the whole junction goes red.

 

And yes, I'm a big hit at parties.

[SiC]

Yes, its in the approval docs for this thing to never happen. If a failure like this happens, it should be detected immediately in hardware and cause all the lights to default to red as a failure state. Or might be to switch off... They changed the regs a couple of times over the years and there were arguments on which is the safest failure mode.

 

Contact the local council and ask to speak to the traffic manager to tell him. They usually take these kind of things very seriously.

 

Source: I used to design the vehicle & pedestrian radars and imaging based detectors that you see above most traffic lights.

[SiC]

And yes, I'm a big hit at parties.

You won't (or would) believe how many people refuse to believe me that flashing at the lights doesn't make any difference in how quickly they change! Even though I was involved with the design of many of the damn things...

 

Most of the time people doing it creep up to the lights and so trigger the inductance loops in the road, making the system beleive there is a queue - or that there are no vehicles on other junctions. So thus it changing it quicker because of that.

[HH-R]

Do you know why some pedestrian crossings don't allow enough time for people who walk pretty fast like me time to get over, but some let a snail get two miles down the road before changing from red? It doesn't even seem to be a newer crossing = longer delay thing.

[jon928se]

Iirc from about 20 years + ago, even though the lights may be some form of computer controlled, Scoot or more complex UTC system, there was still hardware interlocks (basically relays) which prevent green on more than phase at a time, irrespective of what the computer is telling the lights to do.

 

 

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[Urko]

There are some near me where it's a very short interval between green to red one way and green the other. I have decided not to mention it to anyone, like the huge potholes in the M1 as I prefer dodging the problem to the 23 years of road closures that fixing it will no doubt involve

[SiC]

Do you know why some pedestrian crossings don't allow enough time for people who walk pretty fast like me time to get over, but some let a snail get two miles down the road before changing from red? It doesn't even seem to be a newer crossing = longer delay thing.

Pelican or Puffin crossing?

 

Pelican crossing is purely time based. Flashing amber is what supposed to stop traffic until the person parses...

 

Puffin has sensors to detect people waiting there and also crossing. Next time loom up and you'll probably see a camera* looking at you, to detect if some is there or not. So in theory, it extends the crossing time if someone is slow. There are minimum times set, so depends on who set it up and how much leeway they gave in it.

 

* Don't worry, those cameras don't record anything in normal use. Apart from there isn't enough storage in them, there is only Bluetooth connectivity for setup. The detector does a huge bunch of processing (especially the 3d based ones) and after all that work, the only wire output is a relay actuated output that states either people are there or not!

[angle]

In Laaaahndan, we've moved over to ped-x crossings with countdown rather than pelican or puffin, which deliberately only give you a few seconds with the green man on to allow the countdown to start from a decent number.

 

Depends on the design of the crossing as well, you'll get more time to cross if there's not an island in the middle of the crossing.

[inconsistant]

There was an accident in Croydon a couple of years ago where a bus hit a tram side on and a passenger died I believe. The bus driver was arrested and charged with whatever because he ran a red light and rammed the tram side on that was crossing the road. A month or so later someone noticed the traffic light on the road was on green as a tram passed across it, and the bus driver was no longer deemed to have caused the accident.

[tooSavvy]

At the end of the Coast Road, Corner House pub, travelling to town I pulled away from a RED > GREEN > into crossing traffic and nearly had RTA

 

Some fuckkwitt had turned the 'opposing' light set 90deg & they were facing me. I appreciate some other light sets (for my flow) were RED.... But looking at the one in line of sight is really a 'subliminal trigger' to pull away!

 

The lights also have a period of 'all traffic stopped' for pedestrians.

 

 

I phoned feds (2 minutes later)!!!!

 

 

TS

[angle]

There was an accident in Croydon a couple of years ago where a bus hit a tram side on and a passenger died I believe. The bus driver was arrested and charged with whatever because he ran a red light and rammed the tram side on that was crossing the road. A month or so later someone noticed the traffic light on the road was on green as a tram passed across it, and the bus driver was no longer deemed to have caused the accident.

George Street? Then not quite, the bus driver claimed his light was green but it turned out he was looking at the next set of lights along the road, he went to prison (after going on the run for a while).

[wuvvum]

Maybe these particular traffic lights are made by Renault?

[inconsistant]

George Street? Then not quite, the bus driver claimed his light was green but it turned out he was looking at the next set of lights along the road, he went to prison (after going on the run for a while).

 

Yes, that's the one, from about 2008... but after a trawl of the internet I can't find anything about the lights being faulty. I wonder where I got that idea from then?

[NorfolkNWeigh]

There's a junction on the A4 Bath Rd near Heathrow Airport that's a crossroads with a slip road coming in at 45 degrees. The lights on the main road have a right turn filter that goes green at the same time as the lights for the slip road also go green, about 75% of the times I've come up the slip road someone has almost wiped me out by going the rough the red light on the main Rd.

There is always debris from collisions swept into the kerb, you'd think the Old Bill or a Highways bod would realise this isn't a good idea.

Some less scrupulous person might keep it in the back of their mind that it would be a good way of getting a knackered car written off , especially as an awful lot of the drivers who make this mistake are foreigners in rentlal cars......

[purplebargeken]

Couple of days ago I approached the traffic lights on the main road round my way. The lights changed to red and then immediately turned back to green and off I went. 

[chaseracer]

Maybe these particular traffic lights are made by Renault?

 

Don't suggest that on the FB page...

[RayMK]

The roundabout on the A5 at Towcester was causing jams, particularly at rush hour and Friday afternoons.  Traffic lights were installed to try to alleviate the problem but it still jams - more to do with volume of traffic than blaming the roundabout.  Drivers unfamiliar with the peculiar road layout with traffic lights all over the place and painted lanes, plus one entry to the roundabout which is not light controlled, often jump the lights because they are looking at the wrong set.  Fortunately, the confusing layout tends to slow people down, so bumps are usually minor.

 

In my experience, temporary traffic lights installed at roadworks are the worst for potential collisions.  Some seem to sit at red for ages despite nothing coming  from the other direction.  If the roadworks do not allow line of sight to the other end, or are at a junction, some drivers get impatient after 5 minutes on a red with nothing coming and storm off.  A 15 minute delay is then caused when they inevitably meet opposing traffic half way in to their time saving bravery.  Also, the red light chancers who make a dash to get through, cause the lights to get out of phase with the traffic flow i.e. chancers continue to come at you whilst you sit there patiently* on a green, then there's time for just one car to go when they're clear, plus the fuming people behind who ignore the light (now red) because it is their turn to go.....  Having calming music in the car is useful....or a Hamlet.

[tooSavvy]

I have been 'bootlid hustled' with revs/horn/lights when (as above) I have stopped @RED when chancers have ffedd up the 'turns each' balance.

 

If its red I stop.....

 

 

TS

[Lacquer Peel]

I've been on work sites where the traffic lights have been on all red because we're felling trees across the road, people still try to jump the lights even if it's clear the road needs to be closed temporarily.

[mat_the_cat]

I've seen both side on green twice. Although this was temporary traffic lights for roadworks, but would have thought the same failsafe measures (should?) apply. Although I suppose on one of those occasions I didn't actually see both ends at the same time, just that I went through on green at around 30 mph, and it was green the other end when I went through!

 

But the other time it was dark, and I could see the green glow from the opposite light. I guess temporary systems are more prone to problems...

[mouseflakes]

I was once confused by one of these...