Anyone know if these exist?

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Skipsy
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Anyone know if these exist?

Post by Skipsy »

Are there any examples of these traffic light phases?

1. Left and right turn filter running concurrently.
2. 2 filter arrows going green before the full green (eg: left arrow first, then straight, and then the full green).
3. Right turn filter that turns off and then on again on the same green light.
Jonathan24
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Re: Anyone know if these exist?

Post by Jonathan24 »

Here is an example of the third kind:

https://www.google.com/maps/@54.5904616 ... 384!8i8192

The most common mode of operation is that the right filter turns off when the main traffic light turns to red however, the filter can turn off by itself (by way of the amber light above it) if there is no traffic waiting in the side road.
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Chris Bertram
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Re: Anyone know if these exist?

Post by Chris Bertram »

Jonathan24 wrote: Sat Mar 13, 2021 11:44 Here is an example of the third kind:

https://www.google.com/maps/@54.5904616 ... 384!8i8192

The most common mode of operation is that the right filter turns off when the main traffic light turns to red however, the filter can turn off by itself (by way of the amber light above it) if there is no traffic waiting in the side road.
Those are quite particular to Northern Ireland, however. Never seen in GB.
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traffic-light-man
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Re: Anyone know if these exist?

Post by traffic-light-man »

Skipsy wrote: Sat Mar 13, 2021 10:18 3. Right turn filter that turns off and then on again on the same green light.
I think this one is more of a quirk of permitted stage moves in VA and a lack of certain demands allowing it to happen:



However this one runs intentionally like this depending on the stages served by the previous junction:



I think you'd be hard-pressed to find many examples of this given the lack of early starts outside of certain parts of the North West, and as Chris mentions, the Northern Irish variation.
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Re: Anyone know if these exist?

Post by Rambo »

These don't match the description but there are a couple of late starts local to me within close proximity of each other. This one https://www.google.com/maps/@53.3998438 ... 312!8i6656 only stays on for less than 10 seconds. At least it extinguishes very quickly! This one just down the road https://www.google.com/maps/@53.4003754 ... 312!8i6656 has been changed to one recently although GSV hasn't recorded it yet.
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Chris Bertram
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Re: Anyone know if these exist?

Post by Chris Bertram »

We have, close to me, a junction where southbound traffic on the main road has an invisible early start right turn as it gets a green several seconds before northbound traffic. There is a visible right turn arrow later in the signal sequence, when traffic from the side road has a left turn signalled. Birmingham has never tried out the Tameside right turn with its disappearing arrow.

The principle seems to be that green arrow signals need to be cancelled by (a) a leaving amber, or (b) a filter arrow being overridden by an all directions green ball signal. A disappearing arrow doesn't conform to this principle. But NI shows us the possible remedy, and in operation it's similar to the "doghouse" signals seen in parts of north America with a single red but greens and yellows for straight ahead and turning movements. As ever, a lack of flexibility combined with prejudice against anything not invented here stymies progress
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traffic-light-man
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Re: Anyone know if these exist?

Post by traffic-light-man »

Rambo wrote: Sat Mar 13, 2021 21:36 These don't match the description but there are a couple of late starts local to me within close proximity of each other. This one link only stays on for less than 10 seconds. At least it extinguishes very quickly! This one just down the road link has been changed to one recently although GSV hasn't recorded it yet.
It's interesting to see other areas still installing them. Liverpool still installs them as-new, but I thought it was a heavily dying breed, even in other areas of the North West. Having said that, I'm aware of a new one in Burscough too that was installed recently as part of a brand new site, which was a surprise to see.
Chris Bertram wrote: Sat Mar 13, 2021 22:19 We have, close to me, a junction where southbound traffic on the main road has an invisible early start right turn as it gets a green several seconds before northbound traffic.
That could be a variation in intergreens between a conflicting phase in the previous stage and the two opposing phases in the current stage, leading to what you describe.

There's one without an arrow at all near me, but I think it runs for far too long to be an intergreen causing it, especially given that it's a basic cross roads. I think it's likely to be an intentional late start, but without the arrow for some reason. It had crossed my mind that it might have been artificially created at a later date by extending one of the intergeens without needing to re-config the controller and wire in an extra phase.
Chris Bertram wrote: Sat Mar 13, 2021 22:19The principle seems to be that green arrow signals need to be cancelled by (a) a leaving amber, or (b) a filter arrow being overridden by an all directions green ball signal. A disappearing arrow doesn't conform to this principle.
An arrow phase must be terminated by a full green or a full amber on the associated phase, correct. The late start indicative arrow stretches that by assuming that because the full green is already illuminated, it's ok to extinguish the indicative arrow.

Despite being unusual outside of its namesake area, the back-to-back Humberside right turn filters are actually more in keeping with convention on the basis that they're terminated by the appearance of the full green on the associated phase, in exactly the same way as a common left turn filter would be.
Chris Bertram wrote: Sat Mar 13, 2021 22:19But NI shows us the possible remedy, and in operation it's similar to the "doghouse" signals seen in parts of north America with a single red but greens and yellows for straight ahead and turning movements. As ever, a lack of flexibility combined with prejudice against anything not invented here stymies progress
I'm inclined to agree with the principle of allowing a closing amber for late start indicative arrows, but I'd much rather see an amber arrow used instead of the full ambers used on the island of Ireland.

They'd also be useful in terminating left turn filters running in the 'shadow' of a late start right turn, given the only way to do that currently is to use a full phase for the left turn.
Simon
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