Traffic Lights

chamar

This is a rather banal question, but has any attempt ever been made in Dublin to time traffic lights to change in sequence? I'm always amazed, that no matter how much traffic there is, coming into dublin off the M11 that there seems to be no pattern to the lights. I remember in Manhattan, taxi-ing up and down the island was such a breeze because the lights would go green one after the other after the other. Granted Manhattan is quite small, but I'm just curious if they have ever even tried in Dub?

Hagar

It's much easier to do that on a grid layout road system.
That said I'm always amazed at how well traffic flows in certain areas if the traffic lights are off due to power disruptions or whatever. The light sequences could certainly do with some work. I'm not sure how lights changing via transponders on buses effect linked sets of lights either. I suspect it messes them up. But that's only a guess on my part.

chamar

Yeah - I know a grid system facilitates this - I am more thinking of certain sections of Dublin - like there is about 10 or more sets of lights from cabinteely into Donnybrook - and I am almost sure they just change randomly.

stooge

At Kylemore crossroads on the naas rd coming into town there is a set of filter lights to go towards walkingstown, i used to work out there and use them every day and I have to say they are the worst lights in the world. Preference is first given to the luas, then to traffic going into/out of town and then traffic going down the kylemoreroad. I timed the lights one day and I was there for almost 8mins. f'ing ridiculous.

HelterSkelter

I read an interview before with the director of traffic and he said that the traffic lights were timed in such a way as to slow traffic down as they wanted to discourage people from using their cars.

godtabh

HelterSkelter wrote:

I read an interview before with the director of traffic and he said that the traffic lights were timed in such a way as to slow traffic down as they wanted to discourage people from using their cars.

Traffic lights are usual desgined in order to make sure that junctions have capacity to deal with flow.

Engineers use OSCADY or TRANSTY to desgin signal controlled junctions. TRANSTY would be used to modle big networks while OSCADY would be used to modle smaller situations such as an entrance to a supermarket or school or some such

chamar

Well, whatever they use doesn't work. I take the previously mentioned routes very frequently in heavy traffic, light traffic, in the middle of the night & at rush hour. There is no way the lights are synchronised.

silverharp

One thing I have noticed is that at a 4 way junction and the lights are red, the pedestrian light stays red as well, why doesn't the pedestrian light go green everytime the traffic light is red, eg the junction before tara st going down from O'Connell Bridge.

Red Alert

yes it's idiotic alright that unless someone hits the button it stays red. could be that the pedestrian minimum green time is higher than the road, so if there's only one car there it won't be holding up the other road unnecessairly long.

i find it bizarre they'd want to cause traffic disruption. but this being ireland and all the looneys who find themselves in high places i wouldn't be surprised.

godtabh

chamar wrote:

Well, whatever they use doesn't work. I take the previously mentioned routes very frequently in heavy traffic, light traffic, in the middle of the night & at rush hour. There is no way the lights are synchronised.

Traffic lights can be phased i.e morning rush hour, evening rush hour, school rush hour etc.

Lights can be synchronised but the way things are planned here means that its not set up that way.

silverharp wrote:

One thing I have noticed is that at a 4 way junction and the lights are red, the pedestrian light stays red as well, why doesn't the pedestrian light go green everytime the traffic light is red, eg the junction before tara st going down from O'Connell Bridge.

I dont know what junction your talking about but I assume the reason the pedestrian light is red is because there is traffic coming from different directions i.e from the left or from the right or straight on.

chamar

kearnsr wrote:

Lights can be synchronised but the way things are planned here means that its not set up that way.

I don't accept that. There are lots of individual 'strips' of traffic lights coming in to the city that could and should be synchronised. I drive through them enough to know they aren't.

mike65

Just switch them all to flashing amber and see the difference.

Mike.

jd

Some traffic lights have this sequence

Left feeder Green
Orange (left feeder off)
Full Green.

godtabh

chamar wrote:

I don't accept that. There are lots of individual 'strips' of traffic lights coming in to the city that could and should be synchronised. I drive through them enough to know they aren't.

More often than not Develoment 1 has nothing to do with Development 2 and hence while they could be synchronised they arent

Red Alert

almost all traffic lights apart from some suburban pedestrian crossings are linked into a system, i think it's called SCATS.

also i'm a bit concerned about the LUAS not receiving instant priority. it's really annoying when you're left waiting for a few minutes in sight of stephen's green.

cast_iron

jd wrote:

Some traffic lights have this sequence

Left feeder Green
Orange (left feeder off)
Full Green.

That's a bit odd alright. I assume it's to give extra indication to those that are not going left that they can go.

mike65

jd wrote:

Some traffic lights have this sequence

Left feeder Green
Orange (left feeder off)
Full Green.

I hate that! Green filter should remain on.

Mike.

cast_iron

kearnsr wrote:

More often than not Develoment 1 has nothing to do with Development 2 and hence while they could be synchronised they arent

Did you not answer you own question? The fact that Dev 1 has nothing to do with Dev 2 is exactly the reason they are not sinc'd. Simply put, each junction (Dev) has it's own traffic leading up to it, and each feeder road to the main road don't and can't hold the same priority.
So, junctions are not just biased towards the main road only. Actually, they seem disjointed precisely because that little bit of extra thought went into them.....

silverharp

kearnsr wrote:

I dont know what junction your talking about but I assume the reason the pedestrian light is red is because there is traffic coming from different directions i.e from the left or from the right or straight on.

should have clarified, the street I'm thinking of is one way so when the traffic is stopped, it's stopped

Victor

HelterSkelter wrote:

I read an interview before with the director of traffic and he said that the traffic lights were timed in such a way as to slow traffic down as they wanted to discourage people from using their cars.

Source?

silverharp wrote:

One thing I have noticed is that at a 4 way junction and the lights are red, the pedestrian light stays red as well, why doesn't the pedestrian light go green everytime the traffic light is red, eg the junction before tara st going down from O'Connell Bridge.

Where do you mean? On the quays, between Tara St and O'Connell Bridge the only lights are the pedestrian crossing at Marlborough Street on the northside.

Our man in Havana

What I find annoying is at night lights changing for non existant pedestrians. Why have forced ped phases at night where they are no peds around?

Hagar

They are there to faciliate the non-existant pedestians getting to the non-existant 24 hour buses that run in the 24 hour buslanes.;)

godtabh

cast_iron wrote:

Did you not answer you own question? The fact that Dev 1 has nothing to do with Dev 2 is exactly the reason they are not sinc'd. Simply put, each junction (Dev) has it's own traffic leading up to it, and each feeder road to the main road don't and can't hold the same priority.
So, junctions are not just biased towards the main road only. Actually, they seem disjointed precisely because that little bit of extra thought went into them.....

I didnt ask a question!

In some situations you can have developments working together where all the lights are setup so they work as one unit rather than indivdual units.

Its a chicken and egg situation. Should the junctions be designed before the developments or should they be desgined after the development. Most places have L.A.Ps now so these junctions should be set up before developments go ahead and then fine tuned as they come on line

silverharp

Victor wrote:

Source?
Where do you mean? On the quays, between Tara St and O'Connell Bridge the only lights are the pedestrian crossing at Marlborough Street on the northside.

at tara street station, south side, the road that comes up from Pearse street, where it intersects with the queys is one way , now youll probably prove me a liar, but from memory the pedestrain lights could be red, while the traffic is stopped

Victor

Do you mean where Tara Street (from the fire station to the train station) itself meets the quays?

corktina

In Mallow yesterday I was highly amused to see signs on the only two sets of lights stating that they were being set to flashing Orange during busy times....surely an admission that they are a hinderence to traffic rather than a help, as is the case in many many locations PARTICULARLY on roundabouts. Many of these lights are there solely due to the incompetence of drivers....

In Kanturk, we had a mini roundaboit installed about two years ago and still people stop there and give way to everything in sight.....we had a pedestrian crossing turned on yesterday with no zig-zags installed and no black and white markings on the road.....due the incompetence of Cork co co again.....imho

silverharp

Victor wrote:

Do you mean where Tara Street (from the fire station to the train station) itself meets the quays?

thats the one, the end of tara street before georges quay. Will keep an eye out if I spot this again

gurramok

silverharp wrote:

thats the one, the end of tara street before georges quay. Will keep an eye out if I spot this again

Mostly yeah, i have noticed that too.

Also, most drivers race across the bridge if heading to Gardiner st to beat the lights at Talbot st junction as they always go red when bulk of traffic arrives.
If they speed a bit, they beat them and then all the lights upto Dorset St do be still green.
If they don't beat them, its stop start at next 4 set of lights due to always red light at each junction when the one before goes green!

Its actually encouraging speeding than deterring it.