How many signal heads is "enough"?

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Bryn666
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Re: How many signal heads is "enough"?

Post by Bryn666 » Mon Nov 29, 2021 23:50

Have "more to be sure" seems to be a prevailing mantra, of course they always just end up being flattened by a numpty driver anyway.
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Chris Bertram
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Re: How many signal heads is "enough"?

Post by Chris Bertram » Tue Nov 30, 2021 09:34

traffic-light-man wrote:
Sun Nov 28, 2021 14:46
10?

IMG_20211124_124610.jpg


Ultimately, the only actual regulation is that each signalised movement (full phases for motor traffic) has two signal heads, as per TSRGD. The actual amount of signal heads used is a decision taken by the designer which will be based on a variety of influences including site conditions, responses to safety assessments and perhaps also a highway authority's policy, amongst other things. There's also a personal judgement call of the designer to factor in, which I think will always vary between designers, naturally.

I generally don't like street clutter, and the over-use of heads and standard-height poles is most definitely a huge contributor to that, but the biggest trend that actually grinds my gears is the use of 6m or 8m poles almost as a matter of routine in some areas where they just don't appear to be necessary. But then again having said that, my idea of over-use might be someone else's idea of not enough...
You can lose three heads there by dispensing with the totem poles on the secondary signals. And then decide how many secondaries are actually needed - do you really need three? You have one on the roundabout plus two closely-associated secondaries, surely you don't need them all?
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L.J.D
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Re: How many signal heads is "enough"?

Post by L.J.D » Fri Dec 03, 2021 00:18

Always found Huddersfield and many other places in West Yorkshire quite excessive

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c2R
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Re: How many signal heads is "enough"?

Post by c2R » Fri Dec 03, 2021 10:13

L.J.D wrote:
Fri Dec 03, 2021 00:18
Always found Huddersfield and many other places in West Yorkshire quite excessive
Yes, it's also a bit confusing that the far side signals seem to show different things from the signals at the junction
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Re: How many signal heads is "enough"?

Post by traffic-light-man » Fri Dec 03, 2021 12:22

c2R wrote:
Fri Dec 03, 2021 10:13
L.J.D wrote:
Fri Dec 03, 2021 00:18
Always found Huddersfield and many other places in West Yorkshire quite excessive
Yes, it's also a bit confusing that the far side signals seem to show different things from the signals at the junction
I wonder if it always runs the right turn after the ahead/left in order to clear the 'filter' on the secondary head, or does the arrow on that one head simply extinguish if the right turn doesn't run? :roll:
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Re: How many signal heads is "enough"?

Post by AndyB » Fri Dec 03, 2021 13:51

Gareth wrote:
Mon Nov 29, 2021 17:56
The modern obsession with totems with two vertically aligned signals is annoying too. That's a big culprit in many of these cases where there's too many signal heads. Often, just a single mast arm would suffice and even then, only on wide roads.

I do feel the UK's almost unique aversion to mast arms is part of the problem.
To be fair, the totem approach is really helpful where the road alignment means you could see an existing signal pole from further back - drivers at or near the stop line get the benefit of the normal signal head, drivers on approach get advance warning.

Here's a good example of the totem approach. No place for masts.

And here's an example of how not to place secondaries. Great if you're short, terrible if you're too tall to be able to see the green on the second secondary pole from the stop line.

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Re: How many signal heads is "enough"?

Post by KeithW » Fri Dec 03, 2021 15:18

Gareth wrote:
Fri Nov 26, 2021 13:55

That's the federal standard but there's still big variations between states. Much of the north east tends to have two signals on a diagonal trajectory over the intersection, either by span wire or a mast arm on each corner. New Jersey tends to do nearside mast arm and farside mast arm, the signal head on the nearside being on the left/offside.

Wisconsin always uses a post-mouted signal at the stop line and even a duplicate offside one on dual carriageways, which looks very British. California's also increasingly tending towards this though it's not mandatory there - a signal at the stop line, farside signals on both opposite corners and a farside mast arm if the exit road has two or more leaving lanes (in California this is more often than not).

I think the key thing, whichever approach you go for, is consistency. I feel we haven't had that in this country for several years now. There may be farside signals, there may not. There may be only two signal heads but there could be as many as five or six etc.
Here is an example from Ohio which I am familiar with which has a suspended wire and a distant signal for each lane.
https://www.google.co.uk/maps/@40.06515 ... 8192?hl=en

This is OK in the burbs but get stuck behind a large truck in the city and it can make things tricky.
https://www.google.co.uk/maps/@39.96520 ... 8192?hl=en

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Re: How many signal heads is "enough"?

Post by L.J.D » Fri Dec 03, 2021 17:02

I know it's only 3 heads but I always found this a little OTT when you take into account the filter arrows too. It was recently refurbished and now only has two heads and they kept the filter arrows which surprised me because around these parts they tend to be scrapping complex stages in favor of more simple arrangements. A little off topic but when they added the arrows (was just RAG before) they disconnected the red light camera behind it. As its just an empty box if you look closer and it's not even listed as a camera location on WY partnership no more. I wonder why that was done? Maybe it was confusing the camera with the added on phase?

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Big Nick
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Re: How many signal heads is "enough"?

Post by Big Nick » Fri Dec 03, 2021 19:35

How about this for a giggle? Or is this the industry standard?
https://goo.gl/maps/Xp8kXbweAWcPNXUB9

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Re: How many signal heads is "enough"?

Post by L.J.D » Fri Dec 03, 2021 21:36

I always thought this one was particularly hideous.

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Re: How many signal heads is "enough"?

Post by Nathan_A_RF » Sat Dec 04, 2021 01:17

If we're talking signal heads - i.e. not just traffic lights - then what about wig-wags? I know that the max you can see at a level crossing in the UK is 7 wig-wags, for example the crossing in Topsham

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the cheesecake man
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Re: How many signal heads is "enough"?

Post by the cheesecake man » Fri Dec 10, 2021 13:02

Here's a recently installed pedestrian crossing in Rotherham. It's a simple crossing on a normal S2. Five signal heads is excessive!
IMG_20211203_175505.jpg

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Re: How many signal heads is "enough"?

Post by Gareth » Fri Dec 10, 2021 17:20

AndyB wrote:
Fri Dec 03, 2021 13:51
Gareth wrote:
Mon Nov 29, 2021 17:56
The modern obsession with totems with two vertically aligned signals is annoying too. That's a big culprit in many of these cases where there's too many signal heads. Often, just a single mast arm would suffice and even then, only on wide roads.

I do feel the UK's almost unique aversion to mast arms is part of the problem.
To be fair, the totem approach is really helpful where the road alignment means you could see an existing signal pole from further back - drivers at or near the stop line get the benefit of the normal signal head, drivers on approach get advance warning.

Here's a good example of the totem approach. No place for masts.

And here's an example of how not to place secondaries. Great if you're short, terrible if you're too tall to be able to see the green on the second secondary pole from the stop line.
Your first example isn't really a totem, as there's no lower signal head. I also see why they did that at that location.

The other two demonstrate the modern tendancy to not use farside signals. The first of the two is a textbook case, along with no less than six signals for a two lane approach. Totems the big culprit again. There should be three, at most four signal heads there - two at the line, one on the roundabout itself and, just maybe, a high up signal (and even then only one) if the need to see the signal from a distance is necessary, as opposed to merely putting up a "signals ahead" sign. Btw, I don't see why there wouldn't be space for a mast arm there. True, the massive over-engineered motorway support type we commonly use here would be a bit awkward but many other countries would manage it. Not that I think a mast arm is needed there. A totem on the right side due to the curvature of the road, just maybe. I'm not wholly against totems but I think guidance should be more specific about their use as they currently play a big part in signal clutter. Discouraging more than one per direction would be a start.

Your final example, again like I said above, demonstrates the increasing trend towards nearside only signals and the poor placement of the secondaries. One farside secondary should do. If it's deemed too far, a mast arm set back from the stop line could actually work well here, otherwise, another nearside secondary on the left side is needed.

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Re: How many signal heads is "enough"?

Post by AndyB » Fri Dec 10, 2021 21:08

When you look at the Balls on the Falls junction (nobody remembers its proper name), you can see why there aren't farsides - on that roundabout, it could cause serious confusion. The secondary is in a good position relative to the Stop line, and yes, I have used it. Often enough.

What would a mast achieve? As an elevated junction, the totem layout is high enough to give advanced warning of the traffic lights around and over high-sided vehicles. A mast would require ridiculous amounts of foundations to counter the cantilever, and drivers would have to crane to see them. Expensive for no good reason.

As for a mast arm at the bottom of the Woodstock, the words that come to mind are... are you kidding? A mast arm set back from the stop line would be even more out of the line of any reasonable driver's eyeline. A nearside secondary on the left would also be in altogether in the wrong place and wouldn't fix the problem. Remember, masts are for approaching traffic, not for traffic at the stop line.

If it's a choice between effective, cheap totems with CLS LED Helios consuming small amounts of power in a reasonable driver's view, and an overengineered mast taking signal heads to unnecessary heights, give me a totem and save masts for where local topography means the engineering is necessary.

(Most of NI's masts are on that road in that direction and most are downhill where the sightlines means a totem has already been tried and been like a chocolate fireguard)

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Re: How many signal heads is "enough"?

Post by Gareth » Fri Dec 10, 2021 23:20

AndyB wrote:
Fri Dec 10, 2021 21:08
If it's a choice between effective, cheap totems with CLS LED Helios consuming small amounts of power in a reasonable driver's view, and an overengineered mast taking signal heads to unnecessary heights, give me a totem and save masts for where local topography means the engineering is necessary.
That's spin. You could as easily say "you could replace all that ugly signal clutter with a single elegant mast arm". There's no reason for mast arms to be such a huge endeavour. Most other countries install them commonly, if not routinely. They don't need to be the chunky "motorway gantry" style we have tended to use in this country. Also, I don't see why mast arms can't be used in a secondary position. Works well in other countries and I've seen them here on occasion too.

Not that I'm advocating mast arms to be used almost universally. Most roads in this country are fairly narrow and I'm only really thinking of wide roads, perhaps three lanes plus. If they spammed them as liberally as they do totems, believe you me, I would not be happy about that either. But when it comes to signal clutter, totems are a frequent culprit, as this thread demonstrably shows.

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Re: How many signal heads is "enough"?

Post by AndyB » Sat Dec 11, 2021 00:58

Except that to be visible at the stop line by any reasonable driver, a mast with an arm 6.5m in the air would have to be on the far side of the junction.

Besides, you can't replace it with a single signal head. Logic says you need an absolute minimum of two in case a safety critical aspect such as the red dies in one, and, again, it has to be one easily read from the stop line so you either set it back several metres from the stop line or you provide signals at conventional heights.

A quick google shows that in these situations, the primaries are either in the driver's view with the cantilever arm being for the sole purpose of advanced warning, or if the primaries are on the cantilever arm, they're well back from the stop line.

One way or another you get considerable visual clutter and not a great saving in signalheads by providing visually intrusive masts when something at a far lower height can provide the necessary advance warning.

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Re: How many signal heads is "enough"?

Post by Gareth » Sat Dec 11, 2021 01:24

Except this, near me, looks far better than your roundabout example and the likes cheesecake has linked too, even taking into account they've used the bulky motorway gantry support...

738 A5058
https://maps.app.goo.gl/ajjMLW7RYoQYXLYm6

... and if you don't agree that it looks better than a six/seven head forest of signals, we'll just have to agree to disagree.

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Re: How many signal heads is "enough"?

Post by AlexBr967 » Sat Dec 11, 2021 12:30

Just found a simple toucan crossing with 7 signal heads here. This is definitely excessive but I wonder if it's required because because of the 4 lanes.

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Re: How many signal heads is "enough"?

Post by Gareth » Sat Dec 11, 2021 17:43

Totems yet again...

...and a mast arm!

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Re: How many signal heads is "enough"?

Post by traffic-light-man » Tue Dec 14, 2021 11:18

Gareth wrote:
Sat Dec 11, 2021 17:43
Totems yet again...

...and a mast arm!
At least it looks neat. Without knowing the area, I can understand the mast arm here, especially looking at the lane allocation. Perhaps the 8m poles are a bit over the top, I'd probably look at putting two signal heads on the rotating mast arm seen as it's there anyway, and just sit one over lane two and one over lane three, a bit like this one.

I notice the discussion of 'chunky' mast arms coming up again. I think I've probably noted this before, but when it comes to 'standard' mast arms, these ones that TfL used to use get my vote. They're not much thicker than some of the street lighting columns you see these days and some do have quite a long outreach as well. This type isn't too bad either, I've seen them around the West Midlands as well as this one in Halewood. No sure who manufactured either of those, though.

With the tools on offer, it is cheaper to plant a high pole in a NAL socket than install a mast-arm of course, which is likely one of the reasons high poles have become the go-to if some extra height is deemed necessary in a lot of situations. What I don't subscribe to is the idea that they do the same job, particularly when it comes to the 'canyoning' effect of high-sided vehicles. The angles just don't balance out from the driver's seat of your average family car, and so if it's a genuine regular problem, a mast-arm is the only real cure in my opinion. Although I don't think the 6m mounted heads are particularly to do with canyoning, Switch Island is a great comparison (more so in person) between the two, particularly as the mast arms do carry a lot of weight (not literally) with combatting the canyoning, while the 6m mounted heads regularly just disappear behind heavies.
Simon :driving:

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