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How to use the new Kirwan junction

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  • Registered Users Posts: 732 ✭✭✭ VanWildcard


    I wonder how long it'll take Google Maps to update. I see they have the new Menlo road added.




  • Registered Users Posts: 732 ✭✭✭ VanWildcard


    Wait, do the cycle lanes not go through this new junction..?

    Bit late to be looking at the details (I know!) but they appear to be routed onto the footpath to dismount and cross at pedestrian crossings. Surely not??




  • Registered Users Posts: 1,011 ✭✭✭ Greentree_uk


    interesting disaster, it all worked without any traffic lights on the roundabouts. best day in Galway was when none of the traffic light controlled roundabouts were working.. actually how roundabouts are supposed to work. that said I still remember people parking on roundabouts and using them the wrong way round... glad to be out of there I hope you get a bypass soon! not a bad video..



  • Registered Users Posts: 113 ✭✭ Perfect Contrast


    It's proven that roundabouts are only effective up to a certain level of traffic, which all roundabouts in Galway now exceed on a regular basis. Lights on roundabouts were removed a long time ago.



  • Registered Users Posts: 4,070 ✭✭✭ what_traffic


    Nope. Will need to cross in a similar fashion to the pedestrian traffic light phases (Toucan crossing) to go through the junction.

    Will be another very slow junction to navigate if on foot or bike.

    These types of junction design encourage Salmon cycling.



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  • Registered Users Posts: 732 ✭✭✭ VanWildcard


    Will be passing over that way at the weekend, will check it out. Looking pretty blocked up on Google Maps.



  • Registered Users Posts: 4,070 ✭✭✭ what_traffic


    Its 3 days in, it is still NEW to loads of people in the cars, after 3 weeks will be a different story. Similar issues when the other junctions were switched over



  • Registered Users Posts: 651 ✭✭✭ buzz11


    The road to Headford is now a left-turn at this new setup and the turn left lane is far too short and doesn't leave enough length for queuing headford bound traffic. Who designed it?



  • Registered Users Posts: 9,939 ✭✭✭ DaCor


    This is only temporary though, right? It doesn't look like the final design. Sorry for what might be a silly question, but I haven't been through that junction in maybe a year at this stage



  • Registered Users Posts: 732 ✭✭✭ VanWildcard


    Does the left turn go green at the same time as Bothar na dTreabh through traffic? Might be no harm as the area is cursed with constant lane/queue jumping.


    Edit: Or is that meant to be a left turn slip road? In which case that'll not work...



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  • Registered Users Posts: 4,304 ✭✭✭ serfboard


    "Does the left turn go green at the same time as Bothar na dTreabh through traffic?". Yes, it does.

    Have to say I'm disappointed so far with how this is working out - came through this afternoon and traffic northbound was backed up as far as the QB. Alright, says you, but it is summertime and Race Week in particular. Yes, but when I got to the Tuam Road junction the traffic wasn't back that far (Glenburren Park).

    I think that the light sequence on the junction is going to have to be changed - whenever I look at it on Google Traffic, it's always red northbound.



  • Registered Users Posts: 10,282 ✭✭✭✭ ben.schlomo


    We went through from Sandy Rd to Headford Rd northbound on a weekday morning last week. The Headford Rd was backed up and caused a tailback on the junction because the lights at the Menlo/Headford Rd part of the junction stayed red for at least three solid minutes. We've gone through at other times from the Headford Rd to BnaT and it was fine just taking the left lane.



  • Registered Users Posts: 732 ✭✭✭ VanWildcard


    I passed through a few times at the weekend. The left turn towards Headford went green about 10sec after the straight (BnT) green. Since the left turn lane is only about 5 cars long, it blocks the left straight-ahead lane for a lot of the sequence.

    The sequencing will need some work.



  • Registered Users Posts: 1,492 ✭✭✭ jkforde


    did they not model traffic flow based on the real world data they collected? genuinely surprised but I guess real world land constraints, etc. have a crunch part in final design.



  • Moderators, Science, Health & Environment Moderators, Social & Fun Moderators Posts: 55,145 Mod ✭✭✭✭ Gremlinertia


    The area is now on the traffic updates of one national radio station every morning since going live, never heard it mentioned so consistently



  • Registered Users Posts: 95 ✭✭ ballinadog


    Same thing happened at Moneenageisha, was on the AA updates every morning for the best part of 6 months after opening in 2009. Similarly Bodkin in 2013. This is no different. Give it time. It'll be grand in time.



  • Registered Users Posts: 5,163 ✭✭✭ pg633


    Those lights weren't in the original plans as far as I can remember - it was originally just a yellow box.

    The lights were added in after local opposition - people thought they wouldn't be able to get into traffic.



  • Registered Users Posts: 113 ✭✭ Perfect Contrast


    I've been flying through there eastbound in the morning and westbound in the evening. Seems to be working.



  • Registered Users Posts: 366 ✭✭ MaxFlower


    Going from the Liosban to N83 (Headford Rd) yesterday at 3pm. Took 15mins to get from the car dealership (Motorpark?) to the lights. Reason was they were green for 8 seconds and red for 2min20secs. Can't get much through in 8 seconds. ~80% of cars seemed to be going onto the N83.


    My impression so far is that the roundabout was better for N83/ users. The new junction seems poor for anyone heading that direction.



  • Registered Users Posts: 6 Sapient




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  • Registered Users Posts: 4,070 ✭✭✭ what_traffic


    Ya you are probably right but after all they wanted to give priority to the N6 corridor.



  • Registered Users Posts: 6 Sapient


    I said citations: plural not singular. And the one research paper you did cite is from 2014 and a paltry four research papers, of dubious quality, have cited it in their research to-date. However, even accepting this research paper, it invalidates your argument. You either didn't read the research or didn't read the data or lethal combination of both, because the paper recommends roundabouts for the traffic volume of under 3,000 vehicles hourly and only signalized when it is over 4,000. According to Transport Infrastructure Ireland, the N6 has a volume of 1,800 at its peak and the N84, 800 at its peak; so, unless that there is 1,400 vehicles swinging left coming out of the city into Castlelawn Heights, the criteria for the paper you cited invalidates and utterly debunks your argument rather than supports it.

    The notion that it's proven that roundabouts are "only effective up a certain level of traffic" and signalized intersections are the answer is entirely ignorant of the entire body of research on this subject and also of basic common-sense. Here is a recent paper published in May 2021, which claims, when traffic volume is large (8,784 vehicles per hour), roundabouts are 1/3 faster than the most efficient signalized intersections and twice as fast as the most inefficient one. Please read the research before swallowing it whole whatever someone else told you.

    And, also, the lights on the roundabouts were not removed and definitely not "a long time ago". One of the problems, one of many, with that intersection was that there was a signalized pedestrian crossing at the entry to and exit of N6. Signalized entry and exit of a roundabout defeats the purpose and efficiency of a roundabout.

    I hope that you don't work for whomever the council paid for this conversion, because you're not very good at defending them. Whoever is in charge of the planning the traffic network in Galway is a dolt(s).



  • Registered Users Posts: 732 ✭✭✭ VanWildcard


    "According to Transport Infrastructure Ireland, the N6 has a volume of 1,800 at its peak and the N84, 800 at its peak; so, unless that there is 1,400 vehicles swinging left coming out of the city into Castlelawn Heights, the criteria for the paper you cited invalidates and utterly debunks your argument rather than supports it."

    There's a flaw in your assertion that the volume on the N6 is too low. The current measured throughout is throttled by roundabouts along the route and poor light sequencing at the junctions. You can't measure the volume as the demand when the road is choked up - when the capacity is reached the peak volume gets spread over a longer time (= traffic delays at rush hour(s)).



  • Registered Users Posts: 6 Sapient


    First, there is no such assertion that the volume on the N6 is too low in the post. I think you're either confused, or you disingenuously created a strawman argument. Based upon the assertion of criteria by the authors of the paper he cited and based upon the assertion of data by Transport Infrastructure Ireland, the criteria posited by the paper is not met based upon the data. Neither assertion is attributable to me. If you had actually read and comprehended the post, the research paper was accepted for argument's sake and purely to demonstrate his self-defeating argument, period.

    Second, unless the duration of navigating through that particular section is more than an hour (at rush hour PM, and it would never be, because it is throttled by several signalized intersections from Headford Road), the data on the volume of vehicles per hour will be more or less equal to demand for that particular section. Based upon the data from the new junction, there is no statistical significant change in the pattern of volume per hour.

    Remember, the argument is the capacity of a roundabout for the vehicles which approach and exit it more efficiently than a signalized intersection. The argument is not capturing how many vehicles ought to pass through it if there was no signalized intersections, halting, or congestion for each vehicle's journey before they entered the roundabout and judging its capacity based upon that. That's idiotic: that's comparable to judging how fast Usain Bolt runs a 100m based upon his team's 400m relay time. You agree that doesn't make sense, right? I hope so.

    And for argument's sake, even if there was a two-hour delay through that intersection, it would barely meet the spurious criteria set by the research paper cited by the 'Perfect Contrast', and if it did, you'd have to meet the criteria in the paper I cited, which is double the capacity. Do you really think that there was more than 8,784 vehicles per hour hitting that roundabout?

    One last question, was 'roundabouts the root of all evil' on the school curriculum in Galway?



  • Registered Users Posts: 732 ✭✭✭ VanWildcard


    "Based upon the assertion of criteria by the authors of the paper he cited and based upon the assertion of data by Transport Infrastructure Ireland, the criteria posited by the paper is not met based upon the data. Neither assertion is attributable to me."

    You were using TII data to try dismiss the recommendations in Perfect Contrast's linked paper as not applicable. The volume of traffic in TII's data is severely limited to the current capacity of the N6 with roundabouts and poorly sequenced junctions so it's not a valid data source for your assertion.

    It's like saying there's no need to open a second till in the supermarket because the data shows only 1 person per minute is going through the tills. One till can handle 1 person per minute. Ignoring the big queue waiting to get through the till.



  • Registered Users Posts: 4 Greyhound_


    Living in the area for more than 15 years I am very unhappy (saying mildly) with the new layout. It used to take me 10 - 12 minutes to drive from home to Dunnes and back to buy a product. Now, it is more than a half an hour and I simply do not bother. To get out from the Dunne's carpark is impossible. I am actually seriously considering moving from this area as it became uncommutable and road zig-zag's are pathetic.

    Instead of city governors doing what needs to be done for the city, which is a proper by-pass, money are spent for this type of nuisance. The tea does not get sweeter from a simple act of stirring.



  • Registered Users Posts: 6 Sapient


    Yes, I used the data against the linked paper to undercut Perfect Contrast's assertion, his assertion. That's not an assertion: it's attacking his assertion. If you cannot understand the difference between those disparate acts, you cannot continue in this discussion.

    Your repeating of the same erroneous statement isn't going to magically correct it. Your ignorant and naïve appraisal of traffic dynamics was refuted and so, you must respond or concede the point, not parrot the appraisal. As I've already said, and you ignored acknowledging or refuting it so I'll repeat, unless the duration of navigating through that particular section is more than an hour (at rush hour PM, and it would never be, because it is throttled by several signalized intersections from Headford Road), the data on the volume of vehicles per hour will be more or less equal to demand for that particular section. Again, if you cannot understand this, then you have no right to participate in this discussion.

    Your analogy doesn't fit, because all those customers have no impediment before queueing for the till; the analogy would only be correct if for each product a customer wanted, a staff member had to retrieve it from the storehouse for the customer, and after going through the till and before leaving, a staff member has to check the items in their grocery bags against their receipt. Wouldn't it be stupid to state that the tills cannot handle the capacity because the time between a customer entering and leaving the supermarket is too long ignoring the other impediments? And wouldn't it be stupid to state that the tills cannot handle the capacity because of the volume of customers and entering and leaving the supermarket even though the volume does not meet the criteria in two research papers for another till?

    Look, I only want you to answer one question, which you conveniently ignored in your previous post, do you really think that there was more than 8,784 vehicles per hour hitting that roundabout?



  • Registered Users Posts: 732 ✭✭✭ VanWildcard


    "do you really think that there was more than 8,784 vehicles per hour hitting that roundabout?"

    I'm not going to explain it a third time.

    "you have no right to participate in this discussion"

    Nice!



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  • Registered Users Posts: 6 Sapient


    OK, I'll concede that was harsh, but you're not participating in the discussion anyway, and arguing in bad faith?

    You won't answer a simple question. You won't respond to any of rebuttals of your argument or concede your mistakes/errors. You won't argue or concede that unless it takes an hour through that particular section the data on the volume of vehicles per hour will be more or less equal to demand (it's simple math), or concede that the demand from other signalized intersections and sections of the road has zero relevance to the capacity of a roundabout section to handle its volume of traffic, not the overall traffic in the city (simple common sense).

    Just answer the simple question, do you think that there was more than 8,784 vehicles per hour hitting that roundabout? So, what was the demand for that roundabout per hour? 5,000, 10,000, 15,000, or all 36,000 vehicles that daily travelled through those roads into the city in 2019?



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