M20 - Cork to Limerick [preferred route chosen; in design - phase 3]

KrisW1001

Isambard wrote: »

a dual track line on ten minute headways could handle 6 trains an hour, tighter headway than that possible with modern computer signalling. Modern electric trains take very little time to stop and restart , how many trains per hour were you envisioning? Surely there would not be demand beyond a half hourly service Mallow/Cork with one fast and one stopper, there would be plenty of capacity.

Adding an extra track on any line and this one in particular would increase the costs astronomically, most of it is on embankments or in cuttings and extra land would be needed too. (you do realise this is already twin tracked?)

Good points. Yes, I did know it’s twin-tracked, but I forgot how deep some of the cuttings are until you reminded me; I was looking ahead to a situation in future where we get higher-speed trains on inter-urban services (2h30 Cork to Dublin is at least 40 minutes too long). At the very least, the new intermediate stations should not be built by just putting a platform either side of the main-line without allowing some way for through services to pass. Without this, commuter trains going at 70 km/h average (including stopped time) means that any long-distance service needing to use that section is also limited to that speed: it’s not so much about trains per hour as overall travel time for inter-city services. But this is getting far off the topic, so I’ll stop.

-

Regarding the standard of road built as motorway, I think we’re very much in the middle of the European pack. The UK has a very high width requirement for motorways (but also ignores it sometimes: the M4 west of Cardiff, for instance). We initially copied for a while, while land was still cheap and easy to CPO, but the kind of narrow motorway we have now is par for the course across Europe, even in countries that built their networks a long time ago when land was cheaper.

But any roads that get designated as "Motorway" here are still built to fairly strict standards regarding gradients, curve radii and sight lines. Straight motorway sections are not built anywhere anymore, as they’ve been shown to contribute to loss of concentration in drivers.

Expressway (2+2) are something we’ve needed for a long time, for roads that need access-control for safety, but whose traffic does not justify the cost of a motorway. There is a large section of the N20 route whose traffic volumes really do not justify a motorway: that was the starting-point for my “pessimistic” prediction above.

For what it’s worth, I think it’s more likely that N20 will be upgraded as motorway-standard road for its whole length, but only because it’s hard to make a case for a lower standard when M17/M18 was similarly over-provisioned.

Isambard

where are these narrow motorways?

BelfastVanMan

Isambard wrote: »

where are these narrow motorways?

All of them, except M1, M4 as far as Kilcock, M7 as far as Newbridge,M9 as far as Kilcullen and the Portlaoise bypass, M11 Bray Bypass, and the M50.

All others are a lower, narrower spec.

Leonard Hofstadter

BelfastVanMan wrote: »

All of them, except M1, M4 as far as Kilcock, M7 as far as Newbridge,M9 as far as Kilcullen and the Portlaoise bypass, M11 Bray Bypass, and the M50.

All others are a lower, narrower spec.

I think the M7 Portlaoise bypass is wide median as well.

AugustusMinimus

Leonard Hofstadter wrote: »

I think the M7 Portlaoise bypass is wide median as well.

M8 from Cork city to Watergrasshill.

Pete_Cavan

BelfastVanMan wrote: »

All of them, except M1, M4 as far as Kilcock, M7 as far as Newbridge,M9 as far as Kilcullen and the Portlaoise bypass, M11 Bray Bypass, and the M50.

All others are a lower, narrower spec.

I don't think it is true to say that they are a lower spec, they are built to the same standards from a driving/safety perspective. The motorways on approach to Dublin were built with a wider median to allow an additional lane be added in the future to accommodate increased demand. That wasn't necessary on the rest of the motorway network where usage is well below max capacity.

I don't think it is really relevant to the M20 either, it is already up against it to get built without making it more difficult than it needs to be. Also the days of accommodating huge numbers of people driving cars into cities are gone, viable alternatives need to be put in place instead.

Limerick74

Article on the NM20 public consultation in the Echo https://www.echolive.ie/corknews/arid-40313939.html

E36Ross

Route chosen for Mallow bypass,
https://www.irishexaminer.com/news/munster/arid-40319795.html?fbclid=IwAR3aLaTRr3qkIhzMiMytpg33DjRwlLph3PP2cP9-h-aJAGdXnBIT7eS3awg

Whats this means for a Motorway or will this eventually form part of the M20?

marno21

E36Ross wrote: »

Route chosen for Mallow bypass,
https://www.irishexaminer.com/news/munster/arid-40319795.html?fbclid=IwAR3aLaTRr3qkIhzMiMytpg33DjRwlLph3PP2cP9-h-aJAGdXnBIT7eS3awg

Whats this means for a Motorway or will this eventually form part of the M20?

This is east/west, part of the N72. It'll link in with a future M20 interchange at its eastern terminus.

Limerick74

A close call https://www.echolive.ie/corknews/arid-40322510.html

Limerick74

Trying to influence current route selection processes through the media https://www.independent.ie/irish-news/politics/we-will-build-bypasses-instead-of-motorways-from-now-on-to-save-dying-irish-towns-eamon-ryan-40579975.html

KrisW1001

Limerick74 wrote: »

Trying to influence current route selection processes through the media https://www.independent.ie/irish-news/politics/we-will-build-bypasses-instead-of-motorways-from-now-on-to-save-dying-irish-towns-eamon-ryan-40579975.html

After N20, there are no more routes in the State that justify a motorway, so the Greens have not changed anything, really. The retreat from the policy of ”motorways everywhere” happened in 2009-2010 when the government ran out of cash.

The future is indeed in bypassing the remaining towns on the National Primary and secondary network, but consider what the current bypasses of Macroom and Castleblaney look like, and you’ll get a better idea of what that means.

Isambard

Limerick74 wrote: »

Trying to influence current route selection processes through the media https://www.independent.ie/irish-news/politics/we-will-build-bypasses-instead-of-motorways-from-now-on-to-save-dying-irish-towns-eamon-ryan-40579975.html

dumb sort of plan. How does that help a dying town , re-routing the traffic? Same effect as a Motorway would have without the benefits!

Aontachtoir

Limerick74 wrote: »

Trying to influence current route selection processes through the media https://www.independent.ie/irish-news/politics/we-will-build-bypasses-instead-of-motorways-from-now-on-to-save-dying-irish-towns-eamon-ryan-40579975.html

Bypass good, motorway bad? I'm not sure if I understand how this works. Both divert traffic away from congested town centers and allow those areas to be decompressed from a traffic standpoint. Is the difference that motorways make travelling by road across wider regions just too easy and safe?

veryangryman

Just wondering about precidents to this...

Didn't other roads have loads of crusties objections that were ploughed through if not downright ignored. What makes these ones special?

Looking forward to zooming along on this road in the coming years.

windy shepard henderson

veryangryman wrote: »

Just wondering about precidents to this...

Didn't other roads have loads of crusties objections that were ploughed through if not downright ignored. What makes these ones special?

Looking forward to zooming along on this road in the coming years.

the green party are often quietend by the talk of money , but usally its all down to the politicans in the area and how much a say they have , for example every road in wexford is top class . limerick has always lagged behind in the roads department

KrisW1001

Aontachtoir wrote: »

Bypass good, motorway bad? I'm not sure if I understand how this works. Both divert traffic away from congested town centers and allow those areas to be decompressed from a traffic standpoint. Is the difference that motorways make travelling by road across wider regions just too easy and safe?

No, the difference is that motorways are a hugely expensive and wasteful construction for routes that barely scrape above 10,000 vehicle movements a day... which is every National Primary route that is not already built as a motorway. Motorways are not there to alleviate peak commuter traffic jams - those days were already over, Greens or no Greens.

Consistent wide single-carriageway road with no residential entrances is all that’s needed for the rural sections of the remaining network, rising to a 2+2 construction in more densely-populated areas.

There’s zero justification for any further motorway sections after N20 is built.

Aontachtoir

KrisW1001 wrote: »

No, the difference is that motorways are a hugely expensive and wasteful construction for routes that barely scrape above 10,000 vehicle movements a day... which is every National Primary route that is not already built as a motorway. Motorways are not there to alleviate peak commuter traffic jams - those days were already over, Greens or no Greens.

Consistent wide single-carriageway road with no residential entrances is all that’s needed for the rural sections of the remaining network, rising to a 2+2 construction in more densely-populated areas.

There’s zero justification for any further motorway sections after N20 is built.

I thought the national standards had moved on from wide single carriageway like the Croom bypass to preferring 2+2. I really don't understand the benefit of building wide single carriageway - creating a chaotic traffic flow in busier areas and dangerous overtaking patterns - when you could make it a much more comfortable 2+2 with very little extra effort.

Bass Reeves

Aontachtoir wrote: »

I thought the national standards had moved on from wide single carriageway like the Croom bypass to preferring 2+2. I really don't understand the benefit of building wide single carriageway - creating a chaotic traffic flow in busier areas and dangerous overtaking patterns - when you could make it a much more comfortable 2+2 with very little extra effort.

There is a different between a single protected carriageway and the likes of the he Croom bypass. Entrance to it and exits from it are controlled and similar in distances between them the same as motorway's.

Take it that a new single carriageway was build to upgrade the Limerick to Rosslare route. From Limerick you might only have 5 entrances/exits between Limerick and Waterford

Say at Oola, Tipp town, Cahir, Clonmel and Carrick-on- Suit. It would also be a purpose build road separate to existing road. With good long stretches., Slow climbing lanes, lane and a half sections it would be totally different to existing single carriageway's

Isambard

Bass Reeves wrote: »

There is a different between a single protected carriageway and the likes of the he Croom bypass. Entrance to it and exits from it are controlled and similar in distances between them the same as motorway's.

Take it that a new single carriageway was build to upgrade the Limerick to Rosslare route. From Limerick you might only have 5 entrances/exits between Limerick and Waterford

Say at Oola, Tipp town, Cahir, Clonmel and Carrick-on- Suit. It would also be a purpose build road separate to existing road. With good long stretches., Slow climbing lanes, lane and a half sections it would be totally different to existing single carriageway's

rather like the 2+1 south of Mallow then? Absolute disaster and they aren't building more. The problem is you're all limited to the speed of the slowest which brings long tailbacks and mad over-taking when the 2 lane section is reached.

KrisW1001

An older design standard called "Wide Single Carriageway" has been retired in favour of 2+2.

But there is still a design standard for wide single-carriageway roads in general: it’s called "Type 1 Single Carriageway", which would be perfectly suitable for upgrading the remaining rural sections of the National Primary route network that don’t see high traffic volumes. (There are stretches of primary routes that don’t even hit 5,000 AADT; for contrast, the 2+2 road type is recommended from 12,000 upwards)

Bass Reeves

Isambard wrote: »

rather like the 2+1 south of Mallow then? Absolute disaster and they aren't building more. The problem is you're all limited to the speed of the slowest which brings long tailbacks and mad over-taking when the 2 lane section is reached.

Different concept completely. The road out side mallow was where a lane and a half strategy was implemented on an old single carriageway without any hard shoulders, traffic coming onto it from by roads and lanes are too narrow. As well road has too much traffic for that strategy.

There is a section outside Cahir but it is quite a short section. Even existing single carrigeway improvement follow existing alignment and app by roads are allowed access.

A protected single carrigeway is a totally different concept. Ennis to Tuam should have been protected single carrigeway with just motorway access Galway and from Ennis into Limerick

jackrussel

Bass Reeves wrote: »

Different concept completely. The road out side mallow was where a lane and a half strategy was implemented on an old single carriageway without any hard shoulders, traffic coming onto it from by roads and lanes are too narrow. As well road has too much traffic for that strategy.

There is a section outside Cahir but it is quite a short section. Even existing single carrigeway improvement follow existing alignment and app by roads are allowed access.

A protected single carrigeway is a totally different concept. Ennis to Tuam should have been protected single carrigeway with just motorway access Galway and from Ennis into Limerick

What part outside Cahir are you referring to?

Bass Reeves

jackrussel wrote: »

What part outside Cahir are you referring to?

I think it may be part of the bypass if you do not enter Cahir if I remember right it goes from lane to two lane. And back again. It not very long only a mile or so

L1011

There is zero chance of any form of 2+1 being built again. Doesn't save enough money and the merge sections are lethal due to poor driver behaviour.

2+2 will always be built instead

Wide singles also suffer from poor driver behaviour and potentially huge closing speeds in head on collisions

Aontachtoir

Bass Reeves wrote: »

A protected single carrigeway is a totally different concept. Ennis to Tuam should have been protected single carrigeway with just motorway access Galway and from Ennis into Limerick

That sounds desperately short-sighted. There has to be at least one convenient way for traffic to travel through the west without getting stuck behind a tractor every two kilometres. Unless you're proposing banning tractors from a "protected single carriageway", in which case we would just get stuck behind the next-slowest drivers instead. Just build the second lane.

Isambard

Bass Reeves wrote: »

Different concept completely. The road out side mallow was where a lane and a half strategy was implemented on an old single carriageway without any hard shoulders, traffic coming onto it from by roads and lanes are too narrow. As well road has too much traffic for that strategy.

There is a section outside Cahir but it is quite a short section. Even existing single carrigeway improvement follow existing alignment and app by roads are allowed access.

A protected single carrigeway is a totally different concept. Ennis to Tuam should have been protected single carrigeway with just motorway access Galway and from Ennis into Limerick

Lane and a half? what's that? The 2+1 section has no roads joining, the junctions are between the 2+1 sections. The lanes are not narrow and for the most part there are hard shoulders. The road you're advocating would be far worse with only 5 junctions between Tipp and Waterford, a slow driver would cause mayhem!

Bass Reeves

Protected road have the same rules as motorway. No Tractors, mopeds, cyclists or L drivers.. These drivers are supposed to use the old road network. As well you are much less likely to have slow drivers on them for a number of reasons. Most slower drivers are older people. Generally they are completing shorter journeys to access nearby towns or villages they tend not to be makeing journeys that necessitate them accessing these types of roads. As well many will avoid these roads and stay on the older road network even if travelling the equivalent of a section or two of it.

Limerick- Waterford would require dual carriageway for first 15-20 km from Limerick, then high class single carrigeway to beyond Carrick-on-Suir and Dual carrigeway for last 10-15 KM into Waterford

Isambard

Bass Reeves wrote: »

Protected road have the same rules as motorway. No Tractors, mopeds, cyclists or L drivers.. These drivers are supposed to use the old road network. As well you are much less likely to have slow drivers on them for a number of reasons. Most slower drivers are older people. Generally they are completing shorter journeys to access nearby towns or villages they tend not to be makeing journeys that necessitate them accessing these types of roads. As well many will avoid these roads and stay on the older road network even if travelling the equivalent of a section or two of it.

Limerick- Waterford would require dual carriageway for first 15-20 km from Limerick, then high class single carrigeway to beyond Carrick-on-Suir and Dual carrigeway for last 10-15 KM into Waterford

wow generalisations much? (won't be happening).

Cookiemunster

Bass Reeves wrote: »

Protected road have the same rules as motorway. No Tractors, mopeds, cyclists or L drivers.. These drivers are supposed to use the old road network. As well you are much less likely to have slow drivers on them for a number of reasons. Most slower drivers are older people. Generally they are completing shorter journeys to access nearby towns or villages they tend not to be makeing journeys that necessitate them accessing these types of roads. As well many will avoid these roads and stay on the older road network even if travelling the equivalent of a section or two of it.

Limerick- Waterford would require dual carriageway for first 15-20 km from Limerick, then high class single carrigeway to beyond Carrick-on-Suir and Dual carrigeway for last 10-15 KM into Waterford

And what about the buses and lorrys that are limited to 80km? How do you propose safely overtaking them on a single carriageway road?

2+2 is the only logical answer here. It's the same width as the single carriage way you're proposing, but it allows safe overtaking and has a central barrier stopping head on collisions.