Unique Traffic Signals

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L.J.D
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Re: Unique Traffic Signals

Post by L.J.D »

Here is a bit of an odd situation the dead end side road had its own signals to get out at one point evident by the burned away stop line and empty NAL socket next to it. But they later removed the signals and turned it into a give way whilst the rest of the junction is under signal control. I can't think why they'd remove it given its only a small side road so I imagine it didn't cause that many issues. I'm not overly keen on the installation anyway i think it looks quite messy the placement of signal heads isn't great because it's a heavily used double decker bus route so it's easy for signals to be blocked off in busy traffic and missed completely.
tom66
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Re: Unique Traffic Signals

Post by tom66 »

L.J.D wrote: Tue Apr 12, 2022 20:39 Here is a bit of an odd situation the dead end side road had its own signals to get out at one point evident by the burned away stop line and empty NAL socket next to it. But they later removed the signals and turned it into a give way whilst the rest of the junction is under signal control. I can't think why they'd remove it given its only a small side road so I imagine it didn't cause that many issues. I'm not overly keen on the installation anyway i think it looks quite messy the placement of signal heads isn't great because it's a heavily used double decker bus route so it's easy for signals to be blocked off in busy traffic and missed completely.
Isn't it a bit embarrassing as a country when the deliberately erased stop-line is about as clear as the ones that are intended to be present.
Jonathan24
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Re: Unique Traffic Signals

Post by Jonathan24 »

L.J.D wrote: Tue Apr 12, 2022 20:39 Here is a bit of an odd situation the dead end side road had its own signals to get out at one point evident by the burned away stop line and empty NAL socket next to it. But they later removed the signals and turned it into a give way whilst the rest of the junction is under signal control. I can't think why they'd remove it given its only a small side road so I imagine it didn't cause that many issues. I'm not overly keen on the installation anyway i think it looks quite messy the placement of signal heads isn't great because it's a heavily used double decker bus route so it's easy for signals to be blocked off in busy traffic and missed completely.
If you go back through the Streetview history, I can't see any point when traffic lights were ever present on that road. The traffic lights only appeared between May 11 and October 12 but in the first Streetview image after installation, there is no traffic light on that road. So if there was ever a traffic light on that road, it was (very) short lived. I wonder if the socket was installed as future proofing, in case it was ever needed in the future?
Skipsy
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Re: Unique Traffic Signals

Post by Skipsy »

traffic-light-man wrote: Sat Apr 09, 2022 15:53 How many roundabout have filter arrows? Not quite unique because I'm about to list two, but I presume they're not very common at all.

Just a thought prompted by this one I came across on street view, though in this instance I can't quite work out why you wouldn't just give it a full RAGa instead.

This is another one, at a junction should really be a T-junction but instead is a piddly little roundabout that's signalised as if it was a T-junction. It does provide some useful u-turn opportunities, though.

Are there any others kicking around?
There used to be one here before the junction was remodelled into a 5 way junction.
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Re: Unique Traffic Signals

Post by Skipsy »

Bryn666 wrote: Tue Apr 12, 2022 12:02
pjr10th wrote: Tue Apr 12, 2022 00:49 What I imagine must be a very early Signalised roundabout with a filter arrow onto the motorway in Renfrewshire. Leggatston Dr
https://maps.app.goo.gl/P46robfMRjYzj4wa8. Also interestingly uses banned turned signs.
That appears to invite you to turn directly into the path of vehicles already on the roundabout entering the M77. Yikes! Who signed THAT off?
Not really as jnty said but it's one of them interesting places where in this case the middle lane can go left or straight, but the left turn has a filter. So someone waiting for the filter could be stuck behind someone going straight and would have to change lane or wait for the full green
Skipsy
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Re: Unique Traffic Signals

Post by Skipsy »

So this junction on the A4 confuses me, because the light is green for North and South bound traffic here. So my question is, should you treat it like a roundabout and give way to the right, or do they have to give way to you, treating it like a regular right turn?

Is there anything like this anywhere else?
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Big L
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Re: Unique Traffic Signals

Post by Big L »

Skipsy wrote: Fri Apr 15, 2022 19:44 So this junction on the A4 confuses me, because the light is green for North and South bound traffic here. So my question is, should you treat it like a roundabout and give way to the right, or do they have to give way to you, treating it like a regular right turn?

Is there anything like this anywhere else?
Remember the green light doesn't mean go.

The highway code wording is
you may go on if the way is clear.
Make poetry history.

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Add your roads knowledge to the SABRE Wiki.
pjr10th
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Re: Unique Traffic Signals

Post by pjr10th »

Skipsy wrote: Fri Apr 15, 2022 19:44 So this junction on the A4 confuses me, because the light is green for North and South bound traffic here. So my question is, should you treat it like a roundabout and give way to the right, or do they have to give way to you, treating it like a regular right turn?

Is there anything like this anywhere else?
It's bad design as it is unclear.

However imo, you're turning right, so you've got to give way to oncoming vehicles. There's no give way line for joining traffic, so that rule doesn't apply.

There's a similar - yet slightly different - junction near me:
https://maps.app.goo.gl/q22fYTXAEaBpSNXJ6
AlexBr967
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Re: Unique Traffic Signals

Post by AlexBr967 »

pjr10th wrote: Sat Jan 29, 2022 22:41
AlexBr967 wrote: Sat Jan 29, 2022 21:50
pjr10th wrote: Sat Jan 29, 2022 18:52 Can pelican crossings have ahead arrows rather than the full ball?
Yep. Admittedly it makes more sense here.
Is that technically a pelican? It's not got zig zags (or legacy stud markings) - I think it might be linked to the junction up ahead?
That wasn't a pelican but this is. Looking at the PBUs it had a flashing amber stage despite the arrow. This setup is unique in a lot of other ways two. Got replaced with 2 puffin crossings eventually but still a unique setup
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Re: Unique Traffic Signals

Post by WhiteBlueRed »

This is not in Britain (it's in South Africa) but this is really strange.
https://www.google.com/maps/@-25.757638 ... 312!8i6656
I don't understand why would a grade-separated interchange need traffic lights.
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L.J.D
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Re: Unique Traffic Signals

Post by L.J.D »

WhiteBlueRed wrote: Thu Apr 21, 2022 08:13 This is not in Britain (it's in South Africa) but this is really strange.
https://www.google.com/maps/@-25.757638 ... 312!8i6656
I don't understand why would a grade-separated interchange need traffic lights.
Ramp metering in busy periods so traffic can merge when there's a gap to stop congestion on the mainline. UK has plenty of examples as do alot of countries.
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Re: Unique Traffic Signals

Post by jnty »

L.J.D wrote: Thu Apr 21, 2022 10:17
WhiteBlueRed wrote: Thu Apr 21, 2022 08:13 This is not in Britain (it's in South Africa) but this is really strange.
https://www.google.com/maps/@-25.757638 ... 312!8i6656
I don't understand why would a grade-separated interchange need traffic lights.
Ramp metering in busy periods so traffic can merge when there's a gap to stop congestion on the mainline. UK has plenty of examples as do alot of countries.
I think metering wouldn't usually have signals on the mainline though? This looks like a reaction to a short slip road causing problems at peak times. Similar signals can be found on the A90 on approach to Edinburgh.
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Nathan_A_RF
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Re: Unique Traffic Signals

Post by Nathan_A_RF »

There's a plethora of signals on one of the slip roads at Redbridge here
https://www.google.co.uk/maps/@50.92174 ... 384!8i8192
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Re: Unique Traffic Signals

Post by Chris5156 »

jnty wrote: Thu Apr 21, 2022 13:43
L.J.D wrote: Thu Apr 21, 2022 10:17
WhiteBlueRed wrote: Thu Apr 21, 2022 08:13 This is not in Britain (it's in South Africa) but this is really strange.
https://www.google.com/maps/@-25.757638 ... 312!8i6656
I don't understand why would a grade-separated interchange need traffic lights.
Ramp metering in busy periods so traffic can merge when there's a gap to stop congestion on the mainline. UK has plenty of examples as do alot of countries.
I think metering wouldn't usually have signals on the mainline though? This looks like a reaction to a short slip road causing problems at peak times. Similar signals can be found on the A90 on approach to Edinburgh.
It’s a very short merge in what must be an extremely busy location. It’s also an isolated GSJ on a road with signalised junctions either side. In this situation the grade separation removes right turns from the junction, which massively increases its capacity, even if it’s not possible for the merges to be free flowing.

There’s something very similar at Poplar, the northern end of the Blackwall Tunnel, which is a six ramp parclo in which all the merges are signalised. That’s partly because the merges are ridiculously short but also to ration the time each flow of traffic gets - otherwise A12 to A102 would dominate and turning flows would struggle to reach the tunnel.
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L.J.D
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Re: Unique Traffic Signals

Post by L.J.D »

I know it's been mentioned on this forum before but this unique set up always deserves a mention.
tom66
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Re: Unique Traffic Signals

Post by tom66 »

This is a new example of ramp metering on a local road.

https://www.google.co.uk/maps/@53.78316 ... 384!8i8192
jnty
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Re: Unique Traffic Signals

Post by jnty »

tom66 wrote: Sat Apr 23, 2022 09:22 This is a new example of ramp metering on a local road.

https://www.google.co.uk/maps/@53.78316 ... 384!8i8192
I think the definition of ramp metering would demand that the main line is unsignalled? I think this is just a signalised merge.
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traffic-light-man
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Re: Unique Traffic Signals

Post by traffic-light-man »

As jnty said further upthread, it's not a ramp meter if it's directly controlling the conflicts at the merge. It's just a junction.
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Re: Unique Traffic Signals

Post by tom66 »

If the South African example counts as ramp metering then this does too!

Yes, it's just a signalised merge, although the visibility is rather good so I think it was primarily included to improve flow rather than safety.
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Re: Unique Traffic Signals

Post by traffic-light-man »

Yes, and so the South African example isn't a ramp meter either. It even has pedestrian facilities on the slip road approach.
Simon
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