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N52 - Tullamore to Kilbeggan (M6) [route options published]

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  • I often wonder is AADT a bit of a blunt instrument sometimes. Probably gives a better indication on commuter routes where a high volume of traffic is concentrated in one direction in the morning and the other direction in the evening, meaning the road is overloaded. On a stretch of road like this, the traffic is probably spread more evenly in both directions over the day. Roads with a similar AADT would be the N3 Cavan bypass and N80 Carlow bypass but I don't think anyone would suggest dual carriageway on them. Also, the biggest constraints after upgrade on this road (N52) will likely be the roundabouts at either end, not the number of lanes in between.

    Worth noting that the TII document states for this project; Cross-section: Expressway / TBD. Obviously not yet confirmed. It also states Forecast Cost Range: €80-100m which is based on €10m/km for 2+2 as used elsewhere. Given the route will almost certainly encompass the existing relatively recent good quality sections of N52 at northern and southern end, you are talking about ~3.5km of offline new build 2+2 plus just under 5km of single carriageway upgrade. Around €50m is probably a more accurate cost for 2+2 but even that is ridiculous for a minute or two reduction in journey time and no bottlenecks bypassed. I would see something like the recent N52 Turin to Billistown Realignment as what should happen here. That was 6km of mostly offline new build Type 1 Single Carriageway which cost €12.6m. Something similar between Tullamore and M6 J5 would cost less than €20m. Put the other €30m into an upgrade which bypasses a town and gives a meaningful reduction in journey time, plenty of candidates out there.




  • Pete_Cavan wrote: »
    I often wonder is AADT a bit of a blunt instrument sometimes. Probably gives a better indication on commuter routes where a high volume of traffic is concentrated in one direction in the morning and the other direction in the evening, meaning the road is overloaded. On a stretch of road like this, the traffic is probably spread more evenly in both directions over the day. Roads with a similar AADT would be the N3 Cavan bypass and N80 Carlow bypass but I don't think anyone would suggest dual carriageway on them. Also, the biggest constraints after upgrade on this road (N52) will likely be the roundabouts at either end, not the number of lanes in between.

    Worth noting that the TII document states for this project; Cross-section: Expressway / TBD. Obviously not yet confirmed. It also states Forecast Cost Range: €80-100m which is based on €10m/km for 2+2 as used elsewhere. Given the route will almost certainly encompass the existing relatively recent good quality sections of N52 at northern and southern end, you are talking about ~3.5km of offline new build 2+2 plus just under 5km of single carriageway upgrade. Around €50m is probably a more accurate cost for 2+2 but even that is ridiculous for a minute or two reduction in journey time and no bottlenecks bypassed. I would see something like the recent N52 Turin to Billistown Realignment as what should happen here. That was 6km of mostly offline new build Type 1 Single Carriageway which cost €12.6m. Something similar between Tullamore and M6 J5 would cost less than €20m. Put the other €30m into an upgrade which bypasses a town and gives a meaningful reduction in journey time, plenty of candidates out there.

    AADT is one of the criteria used in the design of road upgrades. And as you say this project hasn’t been fully designed yet. In the old NRA days it was to be 2+2.

    The traffic on this stretch is 3 times higher than the Turin section at 14000. While most of it is commuter traffic it is a little different than ones nearer a city. Traffic out of Tullamore to Dublin starts between 6 and 7 am. Then you have the traffic commuting into Tullamore between 8 and 9. With the opposite from about 5pm to 7 or 8pm. There is also a high number of cross country HGV traffic.

    Journey reduction time isn’t the only consideration for a scheme. Traffic safety, local safety and journey reliability are also things to be taken into account.

    This road needs to be improved at some stage and it makes sense for 2+2 to be at least a strong contender. No one is saying it’s the most critical scheme in the country or even on the N52 but it has its merits.




  • AADT is only one measure, and strictly speaking the 20,000 figure is "Maximum AADT to maintain Level of Service class D or better".

    That second bit, Level of Service (LOS), is a rough measure of how freely traffic can flow, rated from Class A to Class F. Ideally, you want class A (all traffic can drive up to the design speed of the road), but in a world without unlimited money and land, you usually have to settle for lower classes of service. D is the last "flowing" traffic class. E and F (the worst) include dramatic slowdowns and (for F) traffic coming to a complete stop.

    Commuter routes will occasionally see LOS E and F, but never for very long (it just seems like it, but really it's often less than 5-10 minutes), and because LOS is usually an hourly average across the whole day, this is compensated for by the higher road capacity allowing much freer moving traffic at off-peak times.

    Rural roads have a different problem to commuter routes: slow vehicles. Suburban commuters drive up (and beyond) to the permitted speed limit if able to, and only slow down due to the high volume of traffic, but on rural roads, slowdowns are mainly from heavy vehicles that are inherently limited to lower speeds. This creates a different kind of congestion, but it all comes out the same way: a lower Level of Service.


    All that said, yes, some routes are being specified at a higher level of service than they might actually need, but there are more factors than just capacity. Dual carriageways avoid the kind of overtaking fatalities that happen regularly on lightly-trafficked rural roads, and there's plenty of evidence that flipping between single and dual carriageway roads increases the risk of accidents.




  • Emerging preferred route due this summer. Date tbc.




  • marno21 wrote: »
    Emerging preferred route due this summer. Date tbc.

    Spoiler: It'll follow the existing route closely.


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  • Prefered route is announced. Making full use of the upgraded bits of the Tullamore bypass and the stretch from the M6 roundabout. (Combining option 2 and 3)


    https://www.offalyindependent.ie/2021/09/17/a-proposed-route-corridor-for-the-new-tullamore-to-kilbeggan-road-has-been-published/





  • The logical choice. Looks like there will only be one junction along 8km of road between the existing roundabouts at either end plus a parallel R or L road all the way for local traffic.





  • This is a 80 to 100 Million projected cost project. The landscape is not very challenging there. Is there any breakdown on possible costing for the various elements e.g. planning, land acquisition, etc... at this stage beyond what is on n52tullamoretokilbeggan.ie.





  • I assume that figure came from the TII update publication? That assumed this project would be T2DC and seemed to value these projects at €10-12m/km. This looks like SC now and a good bit of online reuse so the cost would likely be revised downwards.



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  • If this is single carraigeway then it is only going to improve travel times marginally. Dawdlers and farmers towing livestock trailers on that road even where it is at its best and widest really have a big impact on travel time for others. While I can be patient and tell myself "give it 10 minutes and you'll reach the motorway" most others aren't that patient and take unnecessary risks. The existing road isn't bad quality road, just heavily used and when those ahead of you decide to do 40km then that is the speed you travel too.





  • Where is the SC coming from?

    The online sections are the approach to the roundabout on the M6 side which is paralleled by the old N52 which could be brought back into use, and south of the R421 which is also paralleled by the old N52 with the upgraded part being WS2 built as part of the Tullamore BP.





  • Read the previous posts; this is going to be Type 2 DC.





  • The Preferred Route shows a full movement junction with the R421/L2003 which obviously isn't compatible with DC. North of there could be DC but less than 5km.

    Traffic levels don't justify DC, the existing road will remain and will take local/agricultural traffic. Simply building SC between the existing sections of good road at either end is much more likely to happen then building/upgrading to DC for the full length between the roundabouts.





  • Local/agricultural traffic is negligible on that road IMHO, probably less than 5%. The vast majority of traffic is throughput traffic. Stand at Durrow cross from a hour some day and you will clearly see this in action





  • I disagree with that statement from experience of using the road. While looking for overtaking opportunities I would be making judgements as to whether the cars approaching and travelling behind or ahead of me are local or passing through.

    Irrespective, you will definitely not be reaching 100kmph on that road most of the day even though it is constructed to take cars at that speed.





  • What is a full movement junction? . Is it a junction similar to the current junction where the n52/r421 meet





  • I think the tide has turned against road building. If this is built as 2+2 I'll eat my hat. Single carriageway for sure.

    Post edited by spacetweek on


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  • There is no need for any junction here except to connect the L2003 to the old N52 which will presumably be a continuation of the R421 to Kilbeggan. A simple overbridge would do the job. That would allow the WS2 bit of the N52 to be retrofitted 2+2. Any traffic for the Arden area of town would just use the roundabout where shell of the private hospital is.

    In the old days this would have been built as 2+2 and the traffic levels still justify more than a single but who knows now. For the foreseeable future transport in most of Ireland will be car and truck based. Soon this will be electric or some other means other than internal combustion. Either way we need certain new roads and upgrades outside the cities done. But we shouldn’t be encouraging or facilitating more car based commuting into the cities.



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