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Sensor Controlled Traffic Signals in Dublin

  • 15-04-2019 10:08pm
    #1
    Registered Users Posts: 46 LPC786
    Registered User


    I have noticed most the Traffic signals in Dublin are controlled by sensors. As soon as a vehicle comes in the range of the sensor it turns the signal to green and the vehicle can move. Thats why you will find most of the signals on green at night when there is less traffic

    Where i live in tallaght there is a toad which says buses only. Sometimes after entering the lane most of the drivers realise they have entered a wrong lane and stop well short of the white line and not coming within the range of sensor. Consequently the signal remains red and it causes huge built up of cars behind. Its only after waiting for sometime in frustration or if someone from behind honks the horn that the front car moves a little and traffic starts flowing smoothly again. In order for a smooth flow of traffic RSA must start a guidance programme for drivers to at least reach up to the white line


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Comments

  • Moderators, Sports Moderators Posts: 43,494 Mod ✭✭✭✭ magicbastarder
    Moderator


    LPC786 wrote: »
    RSA must start a guidance programme for drivers to at least reach up to the white line
    if you ask me, the RSA need to start a campaign for drivers to *stop* at the white line.


  • Registered Users Posts: 5,193 ✭✭✭ DaveyDave
    Registered User


    In my experience the sensors are 2-3 car lengths before the line, so the car doesn't have to sit on it. It just has to pass it so the light knows it's approaching, I've noticed a few lights near me in Lucan will change as I'm approaching. It's odd that the road you mentioned is long enough for a line of traffic but they put the sensor close to the line.

    Maybe contact the council or local politician to let them know it's an issue? Maybe the sensor could be moved in the future.


  • Registered Users Posts: 13,999 ✭✭✭✭ AlekSmart
    Registered User


    On the subject of sensors,Leeson St Bridge junction has a brace of new pole mounted devices at each corner...but they could be related to Brexit I suppose ?? ;)


    Men, it has been well said, think in herds; it will be seen that they go mad in herds, while they only recover their senses slowly, and one by one.

    Charles Mackay (1812-1889)



  • Closed Accounts Posts: 1,452 ✭✭✭ Twenty Grand


    if you ask me, the RSA need to start a campaign for drivers to *stop* at the white line.

    Have them near my house on a junction.

    You get the usual eejits pull way past the line, then get stuck as the light won't change until a second car comes behind them and sits on the sensor.


  • Registered Users Posts: 24,647 ✭✭✭✭ coylemj
    Registered User


    People turning right who wait at the white line in the right turning lane when the green light is solid is what gets my goat. They fail to notice the white square painted in the middle of the junction where there is a sensor to detect people waiting to turn right. At Deansgrange Cross, people coming from Clonkeen Road and turning right to go up to Baker's Corner do this all the time whereas people coming from Blackrock turning right for Foxrock Church almost always scoot out into the middle of the junction as soon as the light goes green.

    I was once at the top of Kill Lane at Foxock Church waiting for the lights at the N11 junction to change and they were on red for an age. It eventually occurred to me that the two cars at the head of each lane had stopped short of the sensor. The second car to arrive probably reckoned that the first car was already at the line so she stopped beside her.


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  • Registered Users Posts: 25,633 ✭✭✭✭ GreeBo
    Registered User


    coylemj wrote: »
    People turning right who wait at the white line in the right turning lane when the green light is solid is what gets my goat. They fail to notice the white square painted in the middle of the junction where there is a sensor to detect people waiting to turn right. At Deansgrange Cross, people coming from Clonkeen Road and turning right to go up to Baker's Corner do this all the time whereas people coming from Blackrock turning right for Foxrock Church almost always scoot out into the middle of the junction as soon as the light goes green.

    This can be confusing if you dont know the junction as sometimes the arrow is first and sometimes last, so you risk getting stranded.


  • Registered Users Posts: 1,025 ✭✭✭ bikeman1
    Registered User


    A classic example of the OP is on Philipsburg Avenue heading towards Fairview at the narrow single vehicle section. The sensor is close to the line and every day cars stop way short of the sensors. I've seen cars sit there for 3 minutes until someone tells them to move forward!

    Worse still, one time someone kept beeping which caused the lead driver to hurtle through the red and then nearly into an oncoming vehicle!


  • Registered Users Posts: 24,647 ✭✭✭✭ coylemj
    Registered User


    GreeBo wrote: »
    This can be confusing if you dont know the junction as sometimes the arrow is first and sometimes last, so you risk getting stranded.

    That applies to junctions where traffic going straight ahead gets an 'up' green arrow and people turning right are supposed to wait at the stop line for the filter.

    If the green light is solid, you are never wrong driving into the middle of the junction to wait, either for a gap in the oncoming traffic or when you get a filter light.

    Whether you know the junction or not is irrelevent. The rule is simple for people turning right - solid green means you can drive into the middle of the junction (even if that means stopping in a yellow box) but if the green light is an up arrow, you wait at the stop line for the filter.


  • Registered Users Posts: 24,752 ✭✭✭✭ Wishbone Ash
    Registered User


    The sensors can be a pain in the arse when cycling. At very quiet times, it often means waiting around until a heavier vehicles arrives to get a green. The traffic lights nearest my house are like that.
    LPC786 wrote: »
    ... Thats why you will find most of the signals on green at night when there is less traffic...
    Most lights are not green. They may be green in your direction of travel but for every green light, there must also be a red. Otherwise there would be no need for the green.
    GreeBo wrote: »
    This can be confusing if you dont know the junction as sometimes the arrow is first and sometimes last, so you risk getting stranded.
    Once you have entered the junction you may exit the junction regardless of the light colour. Motorists coming from the other direction must not 'go' on green if their way is not clear.

    Unfortunately most motorists think green simply means 'go'.


  • Registered Users Posts: 24,752 ✭✭✭✭ Wishbone Ash
    Registered User


    coylemj wrote: »
    ... The rule is simple for people turning right - solid green means you can drive into the middle of the junction (even if that means stopping in a yellow box)...
    But only if the road you intend to enter is clear. If traffic is backed up on that road, you must wait before entering the junction.


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  • Closed Accounts Posts: 26,661 ✭✭✭✭ OldMrBrennan83



    Once you have entered the junction you may exit the junction regardless of the light colour. Motorists coming from the other direction must not 'go' on green if their way is not clear.

    Unfortunately most motorists think green simply means 'go'.

    Doesn't work like that in reality though as people would just block every junction. Once the light is green you should be able to go.


  • Registered Users Posts: 36,084 ✭✭✭✭ ED E
    Registered User


    The sensors can be a pain in the arse when cycling. At very quiet times, it often means waiting around until a heavier vehicles arrives to get a green. The traffic lights nearest my house are like that.

    Only because the LAs (their contractors) dont bother to calibrate the damn things.

    And yes, thats on carbon bike. The inductive loops can see you but they're not being set to. DCC have decided to go IR/Thermal now for their new installs though.


  • Registered Users Posts: 953 ✭✭✭ railer201
    Registered User


    If it's of any assistance to other cyclists here, I cycle directly along over that portion of the induction loop that's in line with the direction of travel. This will trigger the lights. I don't know about carbon wheels, mine are aluminium.


  • Registered Users Posts: 25,633 ✭✭✭✭ GreeBo
    Registered User


    coylemj wrote: »
    If the green light is solid, you are never wrong driving into the middle of the junction to wait, either for a gap in the oncoming traffic or when you get a filter light.

    Whether you know the junction or not is irrelevent. The rule is simple for people turning right - solid green means you can drive into the middle of the junction (even if that means stopping in a yellow box) but if the green light is an up arrow, you wait at the stop line for the filter.
    Once you have entered the junction you may exit the junction regardless of the light colour. Motorists coming from the other direction must not 'go' on green if their way is not clear.
    Only the first car can drive into the junction, everyone else should be waiting behind the stop line for either an arrow, or for the first car to move.

    The single car "caught" in the junction when the lights change is entitled to complete their maneuver, but no one else is, and this car shouldn't enter the junction unless there is somewhere for them to exit to, otherwise you are asking for deadlock.


  • Moderators, Category Moderators, Entertainment Moderators, Sports Moderators Posts: 22,583 CMod ✭✭✭✭ Steve
    Life is hard, deal with it.


    coylemj wrote: »
    People turning right who wait at the white line in the right turning lane when the green light is solid is what gets my goat. They fail to notice the white square painted in the middle of the junction where there is a sensor to detect people waiting to turn right.

    There is a junction near me like this.

    If you want to go right and arrive at a red, fine, when the lights turn you go into the box and the sensor eventually gives you a filter light.

    However.

    If you are late, you go into the box, the lights go amber - red and you think that you are free to complete the turn but the opposite side still has a green...

    I would very much like to meet and ......... not going to say....... express my displeasure with whoever the incompetent asshat who wrote the logic and also his boss who signed off on it. If I had done it - I code stuff like this for a living - I would fully expect to be fired.


  • Moderators, Category Moderators, Music Moderators, Politics Moderators, Society & Culture Moderators Posts: 22,315 CMod ✭✭✭✭ Dravokivich
    Category Moderator


    LPC786 wrote: »
    I have noticed most the Traffic signals in Dublin are controlled by sensors. As soon as a vehicle comes in the range of the sensor it turns the signal to green and the vehicle can move. Thats why you will find most of the signals on green at night when there is less traffic

    Where i live in tallaght there is a road which says buses only. Sometimes after entering the lane most of the drivers realise they have entered a wrong lane and stop well short of the white line and not coming within the range of sensor. Consequently the signal remains red and it causes huge built up of cars behind. Its only after waiting for sometime in frustration or if someone from behind honks the horn that the front car moves a little and traffic starts flowing smoothly again. In order for a smooth flow of traffic RSA must start a guidance programme for drivers to at least reach up to the white line

    This has nothing to do with sensors. Drivers not paying attention to road markings and signage, won't likely listen to the RSA. What you need is Garda presence at that junction when those issues occur predominantly.


  • Registered Users Posts: 77,620 ✭✭✭✭ Victor
    Registered User


    LPC786 wrote: »
    I have noticed most the Traffic signals in Dublin are controlled by sensors. As soon as a vehicle comes in the range of the sensor it turns the signal to green and the vehicle can move. Thats why you will find most of the signals on green at night when there is less traffic
    At quiet times, the main road gets a constant green light, side roads get red. The side roads will only get green when traffic triggers the sensor.
    The sensors can be a pain in the arse when cycling. At very quiet times, it often means waiting around until a heavier vehicles arrives to get a green.
    As mentioned, cycle exactly over the tar markings on the road where the sensors are.


  • Registered Users Posts: 1,915 ✭✭✭ dashcamdanny
    Registered User


    Are you referring to the bus gate in Tallaght village?


  • Registered Users Posts: 22,037 ✭✭✭✭ AndrewJRenko
    Registered User



    Once you have entered the junction you may exit the junction regardless of the light colour. Motorists coming from the other direction must not 'go' on green if their way is not clear.

    Unfortunately most motorists think green simply means 'go'.


    GreeBo wrote: »
    Only the first car can drive into the junction, everyone else should be waiting behind the stop line for either an arrow, or for the first car to move.

    The single car "caught" in the junction when the lights change is entitled to complete their maneuver, but no one else is, and this car shouldn't enter the junction unless there is somewhere for them to exit to, otherwise you are asking for deadlock.

    Are these practices set out in law? They weren't mentioned in ROTR last time I looked.


  • Registered Users Posts: 3,205 ✭✭✭ Hoboo
    Registered User


    At night time, if there's no one about, flash your lights or put on full beams coming up to lights. Goes green pretty much immediately.


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  • Registered Users Posts: 77,620 ✭✭✭✭ Victor
    Registered User


    Hoboo wrote: »
    At night time, if there's no one about, flash your lights or put on full beams coming up to lights. Goes green pretty much immediately.
    Only at junctions where optical sensors are used.


  • Registered Users Posts: 7,702 ✭✭✭ blackwhite
    Registered User


    Are these practices set out in law? They weren't mentioned in ROTR last time I looked.

    You pretending not to understand doesn’t mean it isn’t there.
    If you wish to turn right at a set of traffic lights that has an arrow to the right (or white rectangular box with white arrow), drive into the junction when you see a green light. Take care not to block any oncoming traffic. Then, when it is safe, finish your turn.

    So if light is green you move into the junction.
    Once safe, you turn right - no restriction on whether the light is stilk green or not.


    It’s the only instance where its permitted to enter a junction that you cannot immediately exit.


  • Registered Users Posts: 3,205 ✭✭✭ Hoboo
    Registered User


    Victor wrote: »
    Only at junctions where optical sensors are used.

    So I'm not completely mad :)


  • Moderators, Category Moderators, Music Moderators, Politics Moderators, Society & Culture Moderators Posts: 22,315 CMod ✭✭✭✭ Dravokivich
    Category Moderator


    Are these practices set out in law? They weren't mentioned in ROTR last time I looked.

    I recall reading in the legislation a statement along the line of once you are in the junction the lights no longer apply to you. You are required to clear the junction unhindered. The issue lies with other road users who are unaware of it. On phone at the moment, will look it up later.


  • Closed Accounts Posts: 9,700 ✭✭✭ tricky D


    It isn't just lights, but also junctions and in general. Above all else, you are not permitted to crash into some one or thing no matter what the circumstances, even if you should have the right of way. If your right of way means crashing, you actually do not have the right of way. Simplest example is infirm people who are unable to make a pedestrian crossing in time. Lights will go green but the person has right of way until clear.


  • Registered Users Posts: 22,037 ✭✭✭✭ AndrewJRenko
    Registered User


    blackwhite wrote: »
    You pretending not to understand doesn’t mean it isn’t there.



    So if light is green you move into the junction.
    Once safe, you turn right - no restriction on whether the light is stilk green or not.


    It’s the only instance where its permitted to enter a junction that you cannot immediately exit.

    Except that it says elsewhere that red light means stop.


  • Registered Users Posts: 7,702 ✭✭✭ blackwhite
    Registered User


    Except that it says elsewhere that red light means stop.

    You need to go and read the RTAs and the rules of the road again.

    A red light means that you cannot pass the light - or the line indicating the stop point where lines are provided. In cases of turning right, the car will have already passed the light or line when they move into the junction. If there is a light on the opposite side of the junction there is a requirement for a stop line to be marked on the side where the driver is supposed to stop. Once they've passed that line, they are supposed to then exit the junction once it's safe to do so.

    I've often seen idiots who turn left or right at a light-controlled crossroads and suddenly jam on the breaks because they've seen the lights for traffic from the opposite side, and for some brain-dead reason think that they should stop at them. Do you think that they're right to stop there as well?


    The legislation refers to junctions with yellow boxes and traffic lights, but the same principle applies.

    http://www.irishstatutebook.ie/eli/1997/si/182/made/en/print#article29
    29. (1) Subject to sub-article (2), where traffic sign number RRM 020 [yellow box] is provided at a junction (whether controlled by traffic sign number RTS 00I, RTS 002 or RTS 004 [traffic lights], or otherwise], and notwithstanding any indication to the contrary that may be given by such traffic signs, a driver of a vehicle shall not enter, either partly or wholly, the crosshatched area unless the vehicle can clear the area without stopping.

    (2) Sub-article (1) shall not apply where a driver of a vehicle intending to make a right-hand turn at a junction enters the crosshatched area for that purpose.

    So if the car is allowed to enter the junction to wait for a gap - do you propose they sit there if the light turns red and completely block the junction for a full cycle of the lights?


  • Moderators, Category Moderators, Music Moderators, Politics Moderators, Society & Culture Moderators Posts: 22,315 CMod ✭✭✭✭ Dravokivich
    Category Moderator


    Except that it says elsewhere that red light means stop.

    I've been searching all morning and can't find the statement I mentioned earlier. But once you are within the junction, the lights no longer apply to you. My inability to find it again, doesn't mean it's not there. It's just a pain to find this stuff again when unfamiliar with referencing legal documentation.


  • Registered Users Posts: 7,702 ✭✭✭ blackwhite
    Registered User


    I've been searching all morning and can't find the statement I mentioned earlier. But once you are within the junction, the lights no longer apply to you. My inability to find it again, doesn't mean it's not there. It's just a pain to find this stuff again when unfamiliar with referencing legal documentation.

    S.30 of the 1997 Act

    Relates to traffic lights where "traffic sign number RRM 017 [stop line]" is provided. In those cases, the traffic light indicates whether or not you are permitted to proceed past the line.

    Once you are past the line, you proceed when safe to do so.


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  • Moderators, Category Moderators, Music Moderators, Politics Moderators, Society & Culture Moderators Posts: 22,315 CMod ✭✭✭✭ Dravokivich
    Category Moderator


    blackwhite wrote: »
    S.30 of the 1997 Act

    Relates to traffic lights where "traffic sign number RRM 017 [stop line]" is provided. In those cases, the traffic light indicates whether or not you are permitted to proceed past the line.

    Once you are past the line, you proceed when safe to do so.

    Which points to this statement:
    (3) ( a ) A driver of a vehicle facing traffic sign number RTS 00I, RTS 002 or RTS 003 in which the green lamp is illuminated may proceed beyond the traffic lights, or beyond traffic sign number RRM 017 [stop line] if such traffic sign is provided in association with the traffic lights, provided no other road user is endangered and subject to compliance with the relevant provisions of articles 8 and 29.

    But this doesn't match what I wrote above and I'm pretty sure there is one I've seen previously, that stated something much more closer to the comment I made earlier.


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