Lack of Filter Lights / Odd sequences causing traffic : Dublin and possibly elsewhere

flaneur

I have been driving around Dublin for the last few days having spent some time abroad and the one thing that is striking me as really problematic is the way filter lights are either non-existent or not setup correctly.

For example, the majority of junctions I am encountering have no filter lights at all and seem to end up causing cars to get stuck in the middle of junctions as there's sequence programmed to ensure that the traffic is held for a few seconds to allow cars to turn.

Where there are filter lights present, they seem to flip from full green to full red without filter and weirdly put on the filter during the green only. Again, the result is that cars are being caught on the junction and there's a huge tail back.

The filter should be used to avoid this by giving a short filter light sequence with full red to ensure cars can escape from the junction.

It looks to me like with a bit of a more sensible and logical approach taken to traffic light planning, you could radically reduce the amount of congestion in central Dublin. The sequences of the lights just seem to be totally out of whack.

I've even spotted a few where the traffic, or in some cases the pedestrians were being shown a red signal when it was clear that all the other junction elements were also held red, so nothing was moving for no particular reason.

There also seem to be quite a few ludicrously short sequences on some junctions where almost nothing moves because cars can't react quickly enough / some Irish drivers take so long to pull away at lights.

It seems like there's scope to outsource traffic planning to a company that knows what it's doing rather than trying to do it with limited resources in house, which is what I assume is happening in Dublin?

Even this morning, I was driving about 5km though the city centre from Dublin 7 to Dublin 4 and it took way too long. It was nothing to do with traffic volumes either. Traffic was pretty light. It was just badly laid out junction after junction with weird light sequences.

HonalD

Do you have specific examples to help visualize the issues?

Dravokivich

From Ballybough into Fairview / Richmond Rd is badly done.

In the opposite direction heading into Summerhill, it's not so much the sequence that's off, but the position of the lights are skewed. So if unfamiliar with the junction, can cause a bit of confusion.

In general, it's more so bespoke junctions that really stand out more as poorly designed. Such as Long Mile Rd and Naas Rd. Rules of the road advise us to keep left, but if you're heading from Long Mile Rd to Nangor Rd, you're better off keeping right as the first 2 lanes merge into it.

flaneur

I don’t have specific examples as I’m unfamiliar with the street names and most of them seem to have no signs that you can see from a car, so it’s very hard to distinguish.

I’ve just spent a day going around chasing office viewings with directions like:

12A Blahblah Court
Dublin 2

Which subsequently turns out to be a unit within an office building that has no building number.
Total waste of a day driving around in circles with traffic systems that don’t work!

HonalD

Dravokivich wrote: »

In general, it's more so bespoke junctions that really stand out more as poorly designed. Such as Long Mile Rd and Naas Rd. Rules of the road advise us to keep left, but if you're heading from Long Mile Rd to Nangor Rd, you're better off keeping right as the first 2 lanes merge into it.

That’s a fairly unique junction, it was the first “hamburger” type of junction in Ireland. The concept is that you keep left to turn right on the Naas Road, which as you say is counter intuitive. Advance warning signage is key to the success of such junctions as people are fairly obedient of overhead gantry signage and if the lanes are marked correctly then this helps users.

flaneur

They need to mark out the lanes much further back at most of the junctions as you end up in the wrong lines when there’s heavy traffic.

HonalD

flaneur wrote: »

I don’t have specific examples as I’m unfamiliar with the street names and most of them seem to have no signs that you can see from a car, so it’s very hard to distinguish.

I’ve just spent a day going around chasing office viewings with directions like:

12A Blahblah Court
Dublin 2

Which subsequently turns out to be a unit within an office building that has no building number.
Total waste of a day driving around in circles with traffic systems that don’t work!

If you believe the AA, then it is done deliberately to reduce the amount of motorists, who give up due to frustration.

quadrifoglio verde

I have noticed this op. Not in Ireland however but when I was walking down the champs elysees one night. They all turned green at 30 second intervals or so. Net result was that all the traffic ended up moving a significant distance.
In Dublin it's my light turns green, but the light in front is red and I can't move due to traffic build up.
Then my light turns red. Light in front turns green but only one or two cars get through because cars stuck at the red light in front of them.
Very very annoying.
I'd also like to see a left turn on red being brought in. It's incredibly annoying waiting at a traffic light to turn left when there's neither traffic or pedestrian's coming.
Right on red works brilliantly in the state's

jimmycrackcorm

flaneur wrote:

I've even spotted a few where the traffic, or in some cases the pedestrians were being shown a red signal when it was clear that all the other junction elements were also held red, so nothing was moving for no particular reason.

Coincidentally seeing this thread I was cycling through Ballyfermot this evening stopped at lights where every light was red. I've a video recording I must put up where I'm looking around at all the lights wondering why the hell nothing was being allowed to move for ages.

Surely there must be a market for more intelligent traffic light sensors that are effective at quicker changes by detecting that pedestrians aren't going to cross etc.

HonalD

jimmycrackcorm wrote: »

Surely there must be a market for more intelligent traffic light sensors that are effective at quicker changes by detecting that pedestrians aren't going to cross etc.

The technology is deployed by some Council’s in Ireland, but it is extremely expensive and you need one for every push button location so the cost mounts up. I don’t think DCC uses them but I don’t know for sure.

HonalD

quadrifoglio verde wrote: »

I have noticed this op. Not in Ireland however but when I was walking down the champs elysees one night. They all turned green at 30 second intervals or so. Net result was that all the traffic ended up moving a significant distance.

Enjoy it while it lasts

http://www.independent.co.uk/news/world/paris-copenhagen-oxford-ban-petrol-diesel-cars-emissions-pollution-nitrogen-dioxide-a8000596.html

StreetLight

Still waiting for the 'green wave' that was supposed to have been introduced when the speed limit on Dublin's Quays was reduced to 30km/h.

HonalD

StreetLight wrote: »

Still waiting for the 'green wave' that was supposed to have been introduced when the speed limit on Dublin's Quays was reduced to 30km/h.

In fairness, I don’t think that was ever going to happen as we’ve seen, anything to encourage motorists to not use the quays is being implemented so making it attractive to use by introducing a green wave is not on the agenda, no matter what promises were made.

However, sequencing of lights in other areas can be done efficiently, it just takes care and attention in planning......

flaneur

Is that SCATS system they claim to have even up to the job or rolled out properly?

I have noticed definite changes in timing adapting to queues and also instant greens and green waves of sorts wheee it will let you through multiple junctions in sequence in Cork City, using Siemens SCOOT. They claim to have a relatively modern Adaptive Urban Traffic Control System coordinating 195 junctions.

There are also queue length detectors implemented in Cork. You can see the sensor loops in the tarmac way ahead of the junctions. I’m not sure if SCATS is doing that?

Some of the pedestrian crossings in Cork City Centre also seem to have a device pointing downwards towards the waiting area (not very many of them but there’s definitely a couple on Patrick’s St and Grand Parade area). Is that a crossing pedestrian detector ?

Victor

flaneur wrote: »

I’ve just spent a day going around chasing office viewings with directions like:

12A Blahblah Court
Dublin 2

Which subsequently turns out to be a unit within an office building that has no building number.
Total waste of a day driving around in circles with traffic systems that don’t work!

Insist on getting an Eircode for the property and put in here: https://finder.eircode.ie/#/ If you don't have an Eircode, put the address in and see what you get.

flaneur

Tried that! They told me nobody uses Eircodes.

HonalD

flaneur wrote: »

Is that SCATS system they claim to have even up to the job or rolled out properly?

I have noticed definite changes in timing adapting to queues and also instant greens and green waves of sorts wheee it will let you through multiple junctions in sequence in Cork City, using Siemens SCOOT. They claim to have a relatively modern Adaptive Urban Traffic Control System coordinating 195 junctions.

There are also queue length detectors implemented in Cork. You can see the sensor loops in the tarmac way ahead of the junctions. I’m not sure if SCATS is doing that?

Some of the pedestrian crossings in Cork City Centre also seem to have a device pointing downwards towards the waiting area (not very many of them but there’s definitely a couple on Patrick’s St and Grand Parade area). Is that a crossing pedestrian detector ?

I suppose you have to consider that if the inputs (detectors) are working correctly and the system (Scats or Scoot) is set up correctly then the chances of the system working correctly are significantly higher. The idea is that the computerized softwares algorithms will change the timings to reflect traffic demand.

What denigrates this is multiple priorities I.e. putting priority for buses, constraints for LUAS, timings for pedestrian crossings, priority for push button activation and the use of manual over ride by humans, based on human opinion. All these reduce the effectiveness and efficiency of the systems.

My opinion is that the general user is the ultimate opinion about whether the system is working or is being managed correctly. Take a look around the area at off peak times, if you are unnecessarily delayed at the majority of junctions and there are no other demands around, then there is something wrong.

Yes, they are called Kerbside pedestrian detectors. They notify the computer that someone who has pressed the button is either still in their “zone” or has walked away/already crossed and then it should cancel the demand. There are some units that are used for pedestrian counting too so they may be those.

Ninap

Many other countries revert to flashing amber lights at junctions at night. We’re not mature enough to cope with such a concept. Instead make people wait at red lights when nothing crossing. Ludicrous.
The junction at Dodder bridge on the Rathfarnham Road has bugged me for years. They made the left lane (going toward Rathfarnham) left turn only whereas it used to be both straight on and left turn. So now there are tailbacks to Terenure every evening. Why the stupidity? It’s not as if there’s a left turn filter. The priority should be getting as many vehicles through the junction as possible.

flaneur

While I agree that the flashing ambers setup can work well in areas with very slow moving vehicles, I don't think they'd work in this situation.

It's a lack of filter lights that's causing the issue from what I can see.

Also there's a lack of coordination of junctions where queues are being allowed to form because of incorrectly sequenced lights. You get a green light with a right turn into block of traffic held by a red and then people become stuck in the junction cue : beeping horns, frustration and aggression.

I think they need to review a huge % of the lights in central Dublin and also ensure they're using queue detection and syncing up junctions to avoid clogs.

Maybe investing heavily in the traffic signals and reorganizing junctions to absolute international best practice levels might to a long way towards reducing journey times in the city.

I get the impression they see traffic control systems as an overhead rather than something that’s absolutely key to the city functioning. A top notch system is as important as a new Luas line and probably a hell of a lot cheaper but should be considered in the same way as absolutely essential infrastructure.

bebeman

Ninap wrote: »

Many other countries revert to flashing amber lights at junctions at night. .

This 100%.
The sad fact is when traffic lights are out of order at most junctions the traffic moves so much better. We would be better off if they where turned off all day, maybe a small roundabout painted on the road.

G-Man

Satisfying motorists is an endless money pit. How about actually adding pedestrian lights and sequences to all traffic lights.

HonalD

bebeman wrote: »

Ninap wrote: »

Many other countries revert to flashing amber lights at junctions at night. .

This 100%.
The sad fact is when traffic lights are out of order at most junctions the traffic moves so much better. We would be better off if they where turned off all day, maybe a small roundabout painted on the road.

There's nothing sad about it. It's obvious that when you forget about safety for conflicting turning movements and pedestrians then motorists can benefit.

flaneur

If the lights were properly sensor controlled they should notice that there’s no traffic.

Again, I see this with SCOOT as implemented in Cork and with whatever system they’re using in several french cities I spend time in.

At night. Drive up to a red light and it will change to green before you get to the stop line as you’ve tripped detectors and it knows there’s no queue.

I think the issue in Dublin is lack of sensors or detection loops that aren’t working due to damage or something.

I’m not convinced about the turn on red and flashing amber as I have been nearly mowed down in France on pedestrian crossings with green pedestrian lights on several occasions because some moron turned on red without yielding.

What does work well though is flashing amber fly lights - there aren’t too many in use in dublin but they’re popping up a lot in Cork. You can then have almos the turn on red situation, except that you can still provide a safe pedestrian sequence by switching off the flashing amber filter light and going to full red.

You can create much more flexible junctions.

Actually in this day and age (and I’ve seen these in France) you should be able to display any arrow symbol on any lens using LED displays. That means you could design much more flexible lights without physically having to have so loads of extra lamp heads.

LEDs can also switch color...