Is there a minimum red phase time?

[SussexMan]

A set of traffic lights have just been replaced locally. It's a simple junction where one set of lights goes through the following sequence.

Red
Red/Amber
Green
Green with green filter to the right
Amber
Red

If we ignore the pedestrian crossing element, there is no need for the red phase, its only purpose is to remove the green filter arrow.

Since the new lights have been installed the red phase is about 0.1 seconds long. Blink and you miss it!

Is there a requirement for a minimum red phase? It used to be about 2 seconds before they were replaced.

The local authority have told me it's fine.

[jervi]

Where is this?

In the Traffic Signs Manual Chapter 6 there is no mention of how short a red light can be, or any mention about this sort of situation.

Some what related is this situation here:
https://www.google.co.uk/maps/@50.90604 ... ?entry=ttu
The left turn has no conflicting movement, but when the ahead movement goes green the left filter has to turn off. Then when it goes Green -> Red/amber -> Red, then waits a few seconds before the left filter turns on.

[SussexMan]

It's here.

The road emerging from the right is left turn only so there is never a conflict with traffic heading in the direction which the street view link shows. Something just seems wrong with a red phase lasting about 0.1 of a second.

[tom66]

Where is this?

In the Traffic Signs Manual Chapter 6 there is no mention of how short a red light can be, or any mention about this sort of situation.

Some what related is this situation here:
https://www.google.co.uk/maps/@50.90604 ... ?entry=ttu
The left turn has no conflicting movement, but when the ahead movement goes green the left filter has to turn off. Then when it goes Green -> Red/amber -> Red, then waits a few seconds before the left filter turns on.

A similiar setup here; the green arrow turns on as soon as the red light illuminates, and turns off as soon as the green light illuminates. This means there is a short period of time (2-3 seconds) where only the yellow lamp is illuminated, but there is no actual conflict. (Assuming there is no pedestrian call to service.)

https://www.google.com/maps/@52.2340116 ... ?entry=ttu
https://www.google.com/maps/@52.2340192 ... ?entry=ttu

[Big L]

These straight-on lights will sometimes have a momentary red phase.

If there is a green right-arrow phase in this direction only, so the straight-on/left green light stays lit, and then the detectors don’t see anything on either of the side roads, all of these lights go back to red then the red-amber for straight ahead/left comes back almost immediately.

The same happens in the other direction.

[traffic-light-man]

A set of traffic lights have just been replaced locally. It's a simple junction where one set of lights goes through the following sequence.

Red
Red/Amber
Green
Green with green filter to the right
Amber
Red

If we ignore the pedestrian crossing element, there is no need for the red phase, its only purpose is to remove the green filter arrow.

Since the new lights have been installed the red phase is about 0.1 seconds long. Blink and you miss it!

Is there a requirement for a minimum red phase? It used to be about 2 seconds before they were replaced.

The local authority have told me it's fine.

There is no legal maximums or minimums associated with anything other than the appearance of the amber aspect (two seconds when its with red proceeding green, three when it's on its own following green). However, I can see an argument that if the signal moves from amber directly to red with amber, it isn't completing the prescribed sequence.

The practice of closing down the indicative arrow via a short all-red is a very common one, or else the arrow would simply extinguish in the style of a late start arrangement, which is frowned upon in most places (separate topic there!).

Due to the way UK signals are arranged, unless you have a phase within a stage (a stage being a collection of phases showing green), the stage has no timings. The standard timings typically belong to phases.

The phase can be a 'dummy', i.e. it has no signals attached, and dummy phases are often used specifically for setting timings in stages where the stages might otherwise not really appear.

It's difficult to ascertain what's going on without looking at the controller's specification, but what I suspect is happening here is that the arrow is cleared down by use of an all red stage which has no phase assigned to it and thus no timings, and as a result is running to something almost conceivable as nothing. Or similarly, there's a possible situation where there is a phase in the stage, but the timings associated with it are such that it never actually has chance to run for a conceivable length of time.

It sounds like very poor practice, either way.

[nowster]

The fix would be to change the head so that it shows an "ahead" green at all times: https://maps.app.goo.gl/nsf41yqMdEGCFo7R9

[MotorwayGuy]

Reminds me of this junction. The original Mellors were setup so that the green arrow lit up as soon as the green went to amber, effectively meaning there was never a need to stop when turning left. They were replaced in the mid 2000s (and again a few years later), after which the arrow now lights up a few seconds after the signals turn to red, creating an an brief unnecessary stopping time. I've also seen junctions where the left arrow stays lit all the time, even with the green ball. I can't recall where, but this one used to in the mid 2000s despite it not being always on.

Most of these left-turn examples could be solved with having separate RAG heads for the left movement, but if the movement has no conflicts it would result in the red and amber aspects never being used (like this thing).

[traffic-light-man]

The fix would be to change the head so that it shows an "ahead" green at all times: https://maps.app.goo.gl/nsf41yqMdEGCFo7R9

Except there's only one lane on the approach.

The current arrangement allows gap-accepting right turns in one stage, which you wouldn't get with an ahead filter.

It must also stop traffic on this approach at some point anyway in order to run a stage in which that pedestrian phase can show green when demanded.

[multiraider2]

Unless the pedestrian crossing element of the lights is pressed, the lights at the junction of the A222 and A215 also have a one second red between the green ball and the green left filter. As here. If you take one step back from that shot, it is on a longer red as the pedestrian crossing (with timers) is in operation. This has been the same for a considerable length of time.