Navan Rail Line

Assume it has to go through a CBA?

Whichever way this goes, it's going to involve big bucks, CPOs, ploughing up the countryside, protests, planning objections…

It has to be a 'build right, build once project', something we're not very good at.

Serious consideration and CBA has to be applied to Dunshaughlin, Ratoath and possibly Ashbourne. Future development has to be driven towards the railway line. Not like Ongar where the new town was build a distance from a station that then took years to get open. The railway line should act as a magnate and be a feature to attract housing, etc.

Make it easy to commute and people will use it.

For what it's worth, my view is that it must be double track for the entire length.

4tph to Navan can work with the current D+ plan, which is to have 12tph capacity between Clonsilla and Glasnevin. During peak times that is meant to be 6tph to Maynooth, 4tph to M3 Parkway, as well as a Sligo and a Longford service. So if all M3 Parkway services are extended to Navan that makes 4tph possible, However that would be at the cost of no service starting/teminating from M3 Parkway. I think for the original plan for 2tph to Navan to work with D+, it would have to be as extensions of the M3 Parkway services anyways, so it might make sense to extend all 4 hourly services.

But yes, diverting Sligo trains would allow an extra service from either Maynooth or Navan.

Pardon my ignorance, I'm literally an idiot with a couple of crayons here; but instead of having one alignment trying to do everything, would it not be better to have a separate brand new line in the future, something like the red line below?

There was a Bridge on the R161 over the old alignment, but that road has been upgraded, widened and improved quite recently. I don't see it as a barrier to the line being brought into Navan itself. The old rail yard there south of the Kingscourt-Drogheda line has been empty since 2008/09 as the industrial units there were earmarked for a shopping centre IIRC.

Don't think any line will connect to Navan Central, and there is an old council depot demolished and waiting for development just south of the Hospital that could serve as a station site, slightly west of the Old Navan Junction Station (Where Better Deal are now).

As for the M3, Wasn't there some underbridges built into the motorway at the time as the Rail Line was expected to be rebuilt when that was designed?

Yes, there is an underpass built into the motorway just east of Junction 8. follow the link below and if you look carefully you'll see the walls of the underpass on each side of the motorway, it not very easy to spot.

https://maps.app.goo.gl/Fj5Ed9v53mdeFhSJ9

What's there is more of a culvert than a train underpass. It certainly doesn't have anything like the clearance required for an electrified line. I can see it being more of a hindrance than a help as using that exact location will limit the horizontal and vertical alignment for a distance either side.

Also, a bigger issue along that corridor would be crossing the link road into Navan. That would be an extremely expensive crossing given the width and depth of the cutting that the road is in.

The bigger problem with that alignment is that north of the M3, the corridor has been effectively homesteaded away by private houses. This will not be the approach to Navan unless they want to spend a decade in the courts fighting for CPOs.

Any crossing the M3 will have to be new. That may mean tunnelling below, but I suspect an elevated structure would be cheaper overall, and offer more flexibility around the route of the line.

Interesting. I wonder how they’re going to deal with the houses that are built along the alignment further north.

I've seen photos of it being built its a massive structure and the planning requirement laid out that it must support a twin track electrified railway

Its not a retaining wall, its a box, of precast segments, a bottom piece which is kind of U shaped and top piece which is an upside down U and it all links together, its a common design used for railways passing under motorways

Its about ~40m long and ~13m wide, its +5m tall

The line is on a gradient at this point anyway so going under the motorway is 'easier' from a train point of view

It may be possible to engineer around or CPO if necessary to address issues but that isn't always the best approach. There is always resistance when it relates to private houses and in this case, CPOing and/or major engineering would likely impact on the GAA grounds which would galvanise a lot more support than just those immediately affected.

The Bective road isn't raised by much south of the underpass. The road rises to cross the M3. The top of the underpass is the depth of underpass structure plus motorway build-up below the M3 (at least 1m), the bottom of it is apparently at least 5m further down. That's a big level change from where the rail line crossed the current road. If the rail line has to be below the level of the existing road to use the underpass, there is a lot of work to be done there taking existing houses and GAA club into account.

Crossing the M3 less than 1km further west, beside J8, looks like a better option to me. Could avoid houses both sides of the motorway and the cost of crossing the M3 would be no more than crossing the link road if the rail line went through the underpass. Looks an easier and less contentious solution to me.

I would say the same applies all the way along the old alignment, there is no real reason for choosing that route beyond it was the route choosen in the 19th century. It all has to be CPO'd and reengineered anyway, why not look to see if that can be easier done elsewhere? Chunks are going to have to deviate from the old alignment any, particularly at Kilmessan. I think this intention to stick to the old alignment only makes things more difficult and will be the projects downfall.