N40 - Cork South Ring Bandon & Sarsfield Flyovers

AugustusMinimus

IIRC, that eastbound carriageway is to be straightened up a bit so that would require resurfacing. Would be stunned if they didn't resurface it given how little work it would entail.

alanucc

AugustusMinimus wrote: »

Went through Sarsfield's Roundabout last night though. First time I've driven along side an artic. The roundabout at both ends is simply too tight. Will have to be changed I'd imagine.

My impression is that artics won't often need to pass through Sarsfield roundabout on the "short axis" once the mainline is complete, so maybe it won't be too bad?

phatmanwc

alanucc wrote: »

My impression is that artics won't often need to pass through Sarsfield roundabout on the "short axis" once the mainline is complete, so maybe it won't be too bad?

I agree that there will be less HGV movements on the roundabout once the mainline is open, but a certain amount will be inevitable, especially with traffic from the industrial estates heading eastward. I'm not sure anything can be done it about it either, due to the locations of the support columns . Oh well, just have to wait and see how things work out...

alaimacerc

Yes, it's the artics doing right turns in either direction that'll be the real pain, but the loss of the through traffic treating it like a chicane is devoutly to be wished. Hopefully the radius will be OK for people taking it at a more temperate speed.

Was out past Bandon Road this evening, and that end really does look pretty much all over bar the politico with a pair of scissors. Just a polite little moveable fence barrier keeping traffic off the west end of the flyover, it looks like. (Only had my phone with me, and too dark for decent snaps with that, so I won't join the camera club just yet.)

mydiscworld

Are both flyovers likely to open some time in July so?

AugustusMinimus

They are still saying the end of July. Anyone's guess at this stage. By the looks of it, they shouldn't be too far off. Might be a bit of landscaping and bits to finish off after the opening though.

sheff_

phatmanwc wrote: »

I agree that there will be less HGV movements on the roundabout once the mainline is open, but a certain amount will be inevitable, especially with traffic from the industrial estates heading eastward. I'm not sure anything can be done it about it either, due to the locations of the support columns . Oh well, just have to wait and see how things work out...

Looking at OSM it would seem the radius at north and south ends of the roundabout is similar to that up the hill at Wilton Road and wider than others around the city. You'd imagine that should be sufficient?

AugustusMinimus

sheff_ wrote: »

Looking at OSM it would seem the radius at north and south ends of the roundabout is similar to that up the hill at Wilton Road and wider than others around the city. You'd imagine that should be sufficient?

Trust me, the radius is a lot lot smaller. I drive through both regularly.

moyners

Does anyone know why they made the shape so elongated? Driving through there the last few days I reckon there's enough space towards the flyover part to bring in the ends slightly (might require some more piles) thus making the curve at each end less sharp. What do others think? Was it ground conditions that made them bring the ends out so far from the centre?

AugustusMinimus

Due to asymmetrical slip roads leading onto and off of both roundabouts, it means that the Sarsfield Roundabout will see more traffic than the Bandon Roundabout.

Thape of the roundabout (rectangle with circular ends) is being used so that there is more space for cars to queue at the traffic lights on the roundabout while not blocking cars behind from accessing the nearest sliproad.

This was a constant problem with the old roundabout, albeit with higher traffic levels sans flyover.

I can't understand though why they simply didn't make the roundabout wider. There is plenty of space under the flyover to do so. Loads of room in fact.

phatmanwc

sheff_ wrote: »

Looking at OSM it would seem the radius at north and south ends of the roundabout is similar to that up the hill at Wilton Road and wider than others around the city. You'd imagine that should be sufficient?

It's definitely tighter, but I think the fact that there are three 'narrow' (albeit standard width) circulatory lanes on the new Sarsfield Roundabout adds to the illusion, whereas the Wilton Roundabout has two wider lanes, for the most part. I'd imagine HGV movements would be higher on the Sarsfield R/A too.

phatmanwc

AugustusMinimus wrote: »

Thape of the roundabout (rectangle with circular ends) is being used so that there is more space for cars to queue at the traffic lights on the roundabout while not blocking cars behind from accessing the nearest sliproad.

I'd say that's the primary reason, as well as creating an adequate degree of deflection for traffic entering the roundabout from the slip roads, i.e. to avoid traffic shooting straight through the roundabout on a green light, and requiring them to reduce their speed to negotiate the tight radius.

AugustusMinimus

phatmanwc wrote: »

I'd say that's the primary reason, as well as creating an adequate degree of deflection for traffic entering the roundabout from the slip roads, i.e. to avoid traffic shooting straight through the roundabout on a green light, and requiring them to reduce their speed to negotiate the tight radius.

Due to the way the asymmetrical slip lanes have been done, there should be no need to shoot through the roundabout as you say.

alaimacerc

AugustusMinimus wrote: »

I can't understand though why they simply didn't make the roundabout wider. There is plenty of space under the flyover to do so. Loads of room in fact.

As in more lanes? I suppose you could in theory have two northbound and two eastbound lanes (mutatis mutandis, south and west), but I suspect that'd boggle the brain in navigational terms, and the inside lane would be even more "tight" in radius than people are already complaining about.

Ron Scott

Any hope they will improve the westbound lanes(s) outside Dunnes Stores after the traffic lights when all this is done ? Since they added that "merge right" lane there last year, it's a constant source of tension and messing.

AugustusMinimus

No. As in widening the arc itself.



Red represents the flyover lanes. Inner green elongated circle is the current roundabout. Outer is what I think it should be. Black represents the centre pillars and where both ramps start.

As it is, there is huge space to widen the roundabout up against the where both of the ramps start. Absolutely crazy the way they've made the roundabout so narrow, which has lead to very small radius ends.

AugustusMinimus

Ron Scott wrote: »

Any hope they will improve the westbound lanes(s) outside Dunnes Stores after the traffic lights when all this is done ? Since they added that "merge right" lane there last year, it's a constant source of tension and messing.

I cannot fathom why they did this. All it does is cause chaos after the traffic lights with people racing to get ahead of others. There used to be a roundabout there and guess what, it worked with no problems.

phatmanwc

Ron Scott wrote: »

Any hope they will improve the westbound lanes(s) outside Dunnes Stores after the traffic lights when all this is done ? Since they added that "merge right" lane there last year, it's a constant source of tension and messing.

Do you mean on the N71? In which case, the merging lanes have been there for a good few years at this point. The original plan was to build a roundabout out by the new graveyard at Chetwynd, and to upgrade that section to 2 lanes in each direction, but this never happened, hence the merge. I have to agree, it's a bit of a mess, especially if you're not used to it...

hoodwinked

wasn't this supposed to be opened in July?


does this mean they are now behind schedule?

AugustusMinimus

July isn't over yet. Should be open by the end of it.

niloc1951

Ron Scott wrote: »

Any hope they will improve the westbound lanes(s) outside Dunnes Stores after the traffic lights when all this is done ? Since they added that "merge right" lane there last year, it's a constant source of tension and messing.

Until the two lanes after the lights are extended for a greater distance the sensible option here would appear to be to have the merging before the lights , between the roundabout exit and the lights.
The inner lane could be clearly marked ' left turn only' and/or shopping centre/local traffic, with left turning arrows. The outer lane could be marked N71 with straight ahead arrows.
Close off the slip lane into Dunnes and have a straight ahead green light for the outer lane and a left turn green light for the inner lane.

This should do away with the drag start down the N71 from the lights and the barging as the two lane become one. Slow left turning traffic should discourage any chancers trying to get a jump from the inner lane.

Ron Scott

niloc1951 wrote: »

Until the two lanes after the lights are extended for a greater distance the sensible option here would appear to be to have the merging before the lights , between the roundabout exit and the lights.
The inner lane could be clearly marked ' left turn only' and/or shopping centre/local traffic, with left turning arrows. The outer lane could be marked N71 with straight ahead arrows.
Close off the slip lane into Dunnes and have a straight ahead green light for the outer lane and a left turn green light for the inner lane.

This should do away with the drag start down the N71 from the lights and the barging as the two lane become one. Slow left turning traffic should discourage any chancers trying to get a jump from the inner lane.

Makes sense

alaimacerc

AugustusMinimus wrote: »

No. As in widening the arc itself.

Oh, right. Someone made that point earlier, and I thought you were saying something different.

As it is, there is huge space to widen the roundabout up against the where both of the ramps start. Absolutely crazy the way they've made the roundabout so narrow, which has lead to very small radius ends.

There is, especially on the west side:


Bear in mind that it's had this alignment since before the bridge went up, so it may have been necessary to leave a decent bit of room while construction was underway. If they're planning on another realignment, it would likely make sense to wait until the flyover is open before doing that. Which isn't to say whether or not they are... The original plans did specify a quite different one from the current layout, however.


Roadworks out by Curraheen this evening -- not obviously related to the junction, apparently just lights (if a guy in a high-vis is to be believed).

alanucc

Google maps have updated their aerial photos for Cork City within the last few days. Looks like the images were taken just before the bridge beams at Sarsfield were installed, as you can see them scattered around the site.

phatmanwc

alanucc wrote: »

Google maps have updated their aerial photos for Cork City within the last few days. Looks like the images were taken just before the bridge beams at Sarsfield were installed, as you can see them scattered around the site.

Class, seem to have been updated for most of the county! Haven't looked any further, but definitely the last holes seem to have been filled in (Seven Heads area was patchy), and much smoother imagery. That's my afternoon sorted!

neddynasty

There was a line painting truck on the western side of the Bandon flyoer this morning. Things certainly coming to an end. Not sure they'll open in July at this stage but maybe just after the August Bank Holiday weekend. I ranother 4 weeks work after that to tidy up etc.

Prowetod

They were installing the poles for the overhead lighting at the sarsfields flyover late last night.

DerMutt

Passed through yesterday evening, there are lane dividing lines painted on the BRR flyover!

CMP is busy removing existing tarred sections on SRR side of things too. Is this because they need to re-profile or are there quality issues?

On the subject of quality has anyone noticed that whilst there's a lovely arc on the BRR flyover concrete barriers the SRR ones are a little "dippy"?

neddynasty

The lads were working hard today laying Tarmac on the Sarfields flyover.

KCAccidental

neddynasty wrote: »

The lads were working hard today laying Tarmac on the Sarfields flyover.

tough old work in this heat. fair play to them.