If you have a new account but are having problems posting or verifying your account, please email us on hello@boards.ie for help. Thanks :)

Hello all! Please ensure that you are posting a new thread or question in the appropriate forum. The Feedback forum is overwhelmed with questions that are having to be moved elsewhere. If you need help to verify your account contact hello@boards.ie

Hi there,
There is an issue with role permissions that is being worked on at the moment.
If you are having trouble with access or permissions on regional forums please post here to get access: https://www.boards.ie/discussion/2058365403/you-do-not-have-permission-for-that#latest

N24 - Cahir to Limerick Junction [design and planning underway]

marno21 · 2017-07-04 23:38:54

Due to the dearth of "pipeline" national road schemes, TII & DTTAS are planning on developing a series of schemes to be advanced when the current funded schemes are completed in the next 5-7 years. Bar the three Donegal schemes, we got first mention of one scheme today when Alan Kelly asked Shane Ross about any prospective…

Comments

#352 21-12-2024 10:54pm

KrisW1001

Registered Users, Registered Users 2 Posts: 2,069 ✭✭✭

Join Date: August 2020

Posts: 2009

https://www.boards.ie/discussion/comment/122981231#Comment_122981231

Yes, 2+1 was withdrawn from the set of standards.
The 2+1 pilot schemes, particularly on N20 south of Mallow, showed an increased risk of accidents at the end of the 2-lane sections. Obviously, it was still deemed safer than the single carriageway it replaced, because the 2+1 has not been removed.
(I always thought that that N20 scheme was an innapropriate use of the road type: in its native Sweden, 2+1 was only used on lightly trafficked rural routes where the main danger was from cars unsafely overtaking slower agricultural vehicles, but on N20 they tried to use it as a cheap capacity fix. N2 Castleblaney-Clontibret is much closer to the intended use case)
As for cost, Type 3 (2+1) was significantly cheaper, because unlike a Type 2 (2+2), the original Type 3 DC specification did not require grade separation or roundabouts for all junctions: for minor junctions, it was permitted for right-turning traffic to cross the median. This was a big cost saving compared to 2+2, especially when retrofitting existing wide single carriageway, but of course it wasn't as safe as the stricter junction policy for Type 2 DCs.
On a new-build road like this one, though, where there are few junctions, 2+1 wouldn't save a lot of money compared to 2+2... why bother for the sake of saving 2 metres of paved width? .

2