dragonv480 wrote:OK, that ties in with my own thoughts. Are there any rules about how far beyond the stop line a secondary must be as a minimum? I'm asking as I found a junction with just 2 signal heads per arm, one is on the left side of the road and in line with the stop line, and it has a second head on the right hand side of the road, just maybe a foot beyond the stop line, which makes it tricky to see either signal head when you're actually at the stop line
I'd like to know if there is a maximum as well.
There is a junction in Dundee, where if you turn right, you pass between offside and nearside secondaries which are both at red.
In order to solve the problem, instead of repositioning the secondaries, louvres have been fitted to the red lights.
dragonv480 wrote:OK, that ties in with my own thoughts. Are there any rules about how far beyond the stop line a secondary must be as a minimum? I'm asking as I found a junction with just 2 signal heads per arm, one is on the left side of the road and in line with the stop line, and it has a second head on the right hand side of the road, just maybe a foot beyond the stop line, which makes it tricky to see either signal head when you're actually at the stop line
I'd like to know if there is a maximum as well.
There is a junction in Dundee, where if you turn right, you pass between offside and nearside secondaries which are both at red.
In order to solve the problem, instead of repositioning the secondaries, louvres have been fitted to the red lights.
The advice is:
Primary signals should be a minimum of 1m from stop line.
Secondary signals should not exceed a distance of 50m from stop line and should be within an angle of 30degrees from the drivers direct line of sight.
Other than that a close-associated secondary signal does not have a minimum distance as the question is does it serve it's function as a secondary and be seen from the stop line, if it can't it isn't a secondary in my opinion.
This used to be bad for this - it's a slightly staggered junction, so to go straight ahead, you actually weave left then right, but as you're doing so, you come face to face with a red light - actually the secondary for traffic from the right of you. The number of people who came to a dead stop in the middle of the road was incredible... This wasn't helped by the ped crossing just to the left which might have red lights you needed to obay, actually in-line with the secondary!
It's all been swept away now by the messing upredevelopment of Crescent/Chappel St.. (GSV has yet to catch up though.)
The signal you see at red here sufferes from similar issues.
I think there are a several ways to deal with the issue, as far as I can see:
- Have leading not lagging right turns, thus negating the need for a farside secondary.
- Use a single section arrow - would need approval though.
- Add an additional stop line within the junction and treat it as two t-junctions (even if only for that direction). This allows the conflicting signal (and an additional primary, obviously) to actually be green when it would otherwise be red in the setup seen above.
traffic-light-man wrote:- Have leading not lagging right turns, thus negating the need for a farside secondary.
I assume by "leading right turn" you mean an early start, and by "lagging right turn" you mean an early cutoff?
I wouldn't be comfortable installing an early start without a farside secondary (TBH, I'm not that keen on them anyway). Right turners need to be given warning (via the RTIA extinguishing) that oncoming traffic is about to start.
Member of the out-of-touch, liberal, metropolitan, establishment elite. Apparently.
traffic-light-man wrote:- Have leading not lagging right turns, thus negating the need for a farside secondary.
I assume by "leading right turn" you mean an early start, and by "lagging right turn" you mean an early cutoff?
I wouldn't be comfortable installing an early start without a farside secondary (TBH, I'm not that keen on them anyway). Right turners need to be given warning (via the RTIA extinguishing) that oncoming traffic is about to start.
Yes. Too much time on the American forums, I think!
There are several around Merseyside that don't have farside secondaries but do have long inter-greens. I share the same concern as you, though. In fact, I dislike them on a whole and would gladly see the back of them (unless we were to introduce amber arrows to terminate them!).
Just seen a discussion on SSC about more new traffic lights that have appeared during the Manchester Metrolink extension and one of the guys has taken these photos on the link below: http://www.skyscrapercity.com/showpost. ... ount=27167
Now surely this must be a botch having so many filters and a green ball (before the 2 original arrows extinguishing)? Or is that how it is recommended to be done now? I am no expert on traffic signal positioning so any answers would be welcome
Also, what about the red aspect and filters? I presume that is ok as we have quite a few sets like that in Preston.
Thanks guys!
Last edited by mercer on Mon Jan 14, 2013 23:18, edited 1 time in total.
Following on from the early start/early cutoff debate I'm looking for some advice to avoid ending up with 'botched signals'.
I'm analysing a junction which, due to volume needs to give right-turners an indicative arrow.
At the moment I've got both approaches (Arms A & B) getting a green ball at the same time and right-turning traffic from Arm B looking for gaps. At some point Arm A goes red. Before the right turn indicative arrow comes up for Arm B I'm looking to provide a clearance period. Now the usual 5 seconds you'd provide for a minimum intergreen seems a lot given the junction is fairly compact and I'm not going from a red-amber to green but from a green ball to indicative right.
I'm thinking that 3 seconds would allow for opposing traffic to clear the junction before stating to those right-turners that they're clear to go. Does this seem a reasonable approach? What's the minimum value that 'proper' signals engineers might use on-site, if any clearance time is provided at all?
mercer wrote:Just seen a discussion on SSC about more new traffic lights that have appeared during the Manchester Metrolink extension and one of the guys has taken these photos on the link below: http://www.skyscrapercity.com/showpost. ... ount=27167
Now surely this must be a botch having so many filters and a green ball (before the 2 original arrows extinguishing)? Or is that how it is recommended to be done now? I am no expert on traffic signal positioning so any answers would be welcome
Also, what about the red aspect and filters? I presume that is ok as we have quite a few sets like that in Preston.
Thanks guys!
It's not botched - it's basically another way of providing a protected right turn, without using two different sets of RAG signals.
This setup replaced one similar to the one in your link, however operationally works the same.
It might be that the right turn priority arrow doesn't light up at certain times on day (making it a gap-accepting right turn), however the Red & A+L Greens combination is still required to hold right turners during tram movements. That's a setup which you wouldn't be able to do with a RAG & RAGA combination.
mercer wrote:Just seen a discussion on SSC about more new traffic lights that have appeared during the Manchester Metrolink extension and one of the guys has taken these photos on the link below: http://www.skyscrapercity.com/showpost. ... ount=27167
Now surely this must be a botch having so many filters and a green ball (before the 2 original arrows extinguishing)? Or is that how it is recommended to be done now? I am no expert on traffic signal positioning so any answers would be welcome
Also, what about the red aspect and filters? I presume that is ok as we have quite a few sets like that in Preston.
Thanks guys!
It's not botched - it's basically another way of providing a protected right turn, without using two different sets of RAG signals.
This setup replaced one similar to the one in your link, however operationally works the same.
It might be that the right turn priority arrow doesn't light up at certain times on day (making it a gap-accepting right turn), however the Red & A+L Greens combination is still required to hold right turners during tram movements. That's a setup which you wouldn't be able to do with a RAG & RAGA combination.
Thanks for that! Thinking it through now you have explained it that way makes sense
That secondary has a halogen amber, and LED R&G - very American! I'm yet to find out why some of the Monitron LED Mellors has their doors on sideways. There a similar set in Manc.
mercer wrote:Just seen a discussion on SSC about more new traffic lights that have appeared during the Manchester Metrolink extension and one of the guys has taken these photos on the link below: http://www.skyscrapercity.com/showpost. ... ount=27167
Now surely this must be a botch having so many filters and a green ball (before the 2 original arrows extinguishing)? Or is that how it is recommended to be done now? I am no expert on traffic signal positioning so any answers would be welcome
Also, what about the red aspect and filters? I presume that is ok as we have quite a few sets like that in Preston.
Thanks guys!
It's not botched - it's basically another way of providing a protected right turn, without using two different sets of RAG signals.
This setup replaced one similar to the one in your link, however operationally works the same.
It might be that the right turn priority arrow doesn't light up at certain times on day (making it a gap-accepting right turn), however the Red & A+L Greens combination is still required to hold right turners during tram movements. That's a setup which you wouldn't be able to do with a RAG & RAGA combination.
Theres quite a few around like that, I can think of two on the same road:
The latter is slightly odd in that it has two lanes turning right and only one for straight ahead, and to be honest I'm not sure why the signals here are set up this way. There's more than enough room to provide a standard protected right turn (with a set of signals for ahead movements, and a set for right turns), and it would look a lot tidier IMO.
I'm not sure why this style of setup doesn't just use all-arrows and get rid of the green ball altogether - I think that would make them look a bit tidier.
There's another one here - the only issue is, if traffic arrives on the side road, it has to wait for the signals to cycle on the main road in order to extinguish the ahead filter. Two sets of full RAG (one for ahead and one for right) heads would be more suitable here for flexibility.
traffic-light-man wrote:I'm not sure why this style of setup doesn't just use all-arrows and get rid of the green ball altogether - I think that would make them look a bit tidier.
There's another one here - the only issue is, if traffic arrives on the side road, it has to wait for the signals to cycle on the main road in order to extinguish the ahead filter. Two sets of full RAG (one for ahead and one for right) heads would be more suitable here for flexibility.
Thats a set I was going to post on here a while ago but forgot, mainly for its odd set up of green ball and filter arrows for all directions. That was the main query I had about the ones in Manchester as I had never seen a signal with green ball AND 3 filter arrows all on.
The farside signal, where there are two red-amber-greens (one with a left arrow, one with a straight on) on Streetview, is now a single signal head with two filter arrows at the bottom. Care to guess what the two arrows are?
Yes, of course, two straight ahead arrows
I'm sat there waiting to turn left, nearly ended up jumping the lights when I saw both arrows light up. I expect many have done the same. It just seems utterly pointless and unnecessarily confusing.
I hope they've removed those blue direction arrows telling people they must turn right. It's a pet hate of mine when such signs are used to show which direction of traffic the signal head applies to. It's also more reason why we should have arrows on the red and amber aspects.
