Do lanes have to be uniform both sides?

veryangryman

Just reading one of the threads about not enough space to add a lane both sides and it got me wondering...

Is there anything to stop a road having more lanes one way than another. Like the extra lane will still benefit everyone as we all (on average) go back the way we came.

So lets say they find space on the M50 to add another northbound lane...why not?

blindside88

I imagine there would be nothing stopping them putting more lanes one direction over the other. You see “climbing lanes” in certain parts of the country. Fair enough they don’t go on for miles but they do exist

doolox

This road has two lanes in one direction and then changes to two lanes in the opposite direction half along it length from the N11 to the big traffic lights under the Luas overpass.

It is an absolute abortion of a road as people take the outside lane to overtake, then realise they will be trapped into going into the Sandyford Ind Est and try to barge into the left hand land to get on to the M50 and FREEDOM.

L1011

Absolutely no requirement. We'd be here all year finding examples. Most importantly, there were multiple trial schemes of 2+1 road where the sides switched.

highwaymaniac

veryangryman wrote: »

Just reading one of the threads about not enough space to add a lane both sides and it got me wondering...

Is there anything to stop a road having more lanes one way than another. Like the extra lane will still benefit everyone as we all (on average) go back the way we came.

So lets say they find space on the M50 to add another northbound lane...why not?

If the space was there, then no issues. Whether it would be of any use is another matter!

L1011

L1011 wrote: »

Absolutely no requirement. We'd be here all year finding examples. Most importantly, there were multiple trial schemes of 2+1 road where the sides switched.

I think they're great roads. Going from Drogheda to Monaghan I often end up on one of them somewhere along the way (where exactly, I don't know).

It's a great opportunity to get the boot down to get by trucks and speed-limited vans and the likes. You just have to merge in every now and again when the other side of the road gets it's turn to overtake.

If you have space for 3 lanes, I think they're a great idea.

Just sickens the hole of me when you see a climbing lane appear, and a speed van camps at the end of it. But that's a whole different thread, I suppose..

Cookiemunster

Deleted User wrote: »

I think they're great roads. Going from Drogheda to Monaghan I often end up on one of them somewhere along the way (where exactly, I don't know).

It's a great opportunity to get the boot down to get by trucks and speed-limited vans and the likes. You just have to merge in every now and again when the other side of the road gets it's turn to overtake.

If you have space for 3 lanes, I think they're a great idea.

Just sickens the hole of me when you see a climbing lane appear, and a speed van camps at the end of it. But that's a whole different thread, I suppose..

They're not a good idea and they've been dropped by TII as they are dangerous. Drivers accelerate to try and pass traffic just before the double-lane section switched and that is seen as a hazard. They now build 2+2s instead. What surprises me is that they haven't been removed a decade after the decision was made.

wotswattage

Or the slow moving traffic accelerates from 75km/h to 110km/h for the dual part and you really have to dog it to overtake them!!

2+2 is definitely better though I'm not sure how much more it costs..

prunudo

wotswattage wrote: »

Or the slow moving traffic accelerates from 75km/h to 110km/h for the dual part and you really have to dog it to overtake them!!

2+2 is definitely better though I'm not sure how much more it costs..

Have seen this over the years and its generally not commercial vehicles either, usually nervous Norman, day dreaming Doris or farmer Fred.

L1011

The Monaghan one is also built with the dual section downhill in some places, meaning no climbing lane and people inadvertently speeding up coming down causing the inability to overtake them. Poor format badly implemented.

They are used in Scandinavia on roads with much lower traffic than here. The type 2 dual carriageway standard that replaced them is barely more expensive to build and can be cheaper to maintain depending on the barrier type used

OldMrBrennan83

On some levels there was probably a good case for the new M7 works to be 2-in and 4-out.