N40 - Cork South Ring Bandon & Sarsfield Flyovers

Bacchus

Traffic heading in towards the tunnel has been crazy in the evenings this past week. I'm going against it (thank God) but today in particular at 5:30, traffic for the tunnel was backed up all the way to the Kinsale road roundabout!! I wonder is this due to all the free flowing traffic coming from Ballincollig/Wilton direction hitting the tunnel at the same time now. It definitely has been heavier than it was before.

JupiterKid

From what I've heard the predicted jams inside the tunnel caused by the traffic reaching Dunkettle faster have indeed come to pass.

Upgrading Dunkettle along with the Macroom Bypass must be the main transport priorities for Cork now.

murphym7

Bacchus wrote: »

Traffic heading in towards the tunnel has been crazy in the evenings this past week. I'm going against it (thank God) but today in particular at 5:30, traffic for the tunnel was backed up all the way to the Kinsale road roundabout!! I wonder is this due to all the free flowing traffic coming from Ballincollig/Wilton direction hitting the tunnel at the same time now. It definitely has been heavier than it was before.

I always believed that the traffic had to get heavier at the tunnel once these flyovers were open, maybe it’s a little early to tell yet, but I still believe it will cause larger tail backs at the tunnel. I never understood the arguments that the flyovers would have little or no impact. As I said, might be too early to tell yet. We will know for sure once September rolls in.

Bacchus

murphym7 wrote: »

I always believed that the traffic had to get heavier at the tunnel once these flyovers were open, maybe it’s a little early to tell yet, but I still believe it will cause larger tail backs at the tunnel. I never understood the arguments that the flyovers would have little or no impact. As I said, might be too early to tell yet. We will know for sure once September rolls in.

I don't think its too early to tell. From what I've seen (heading the other direction) over the past few weeks at between 4:50 and 5:10, traffic is backed up further than before. This week has been particularly bad with yesterday being the worst I've ever seen. Kinsale road roundabout FFS :eek:

When schools come back this is only going to get worse.... blow up the flyovers!

L1011

murphym7 wrote: »

I never understood the arguments that the flyovers would have little or no impact.

I've never understood arguments that they would - and I'm not willing to say they actually have until September.


The same volume of cars will be getting to Dunkettle as before. This is what causes the delays, not the flow form they arrive in. We had two similar schemes in Dublin that didn't worsen issues at the upstream junctions.

Outkast_IRE

There is going to be some angry people come September if the tailbacks don't ease off.

Bacchus

MYOB wrote: »

I've never understood arguments that they would - and I'm not willing to say they actually have until September.

Do you get down to Cork often? Have you seen the tailbacks lately? Not trying to be smart here but they have gotten worse the past few weeks. Maybe there is some other reason for it but Monday and Tuesday this week were the worst tailbacks I've ever seen heading east towards the tunnel. If I was heading that way this evening, I'd rather hang back at work for another hour than face that traffic.

MrDerp

Bacchus wrote: »

I don't think its too early to tell. From what I've seen (heading the other direction) over the past few weeks at between 4:50 and 5:10, traffic is backed up further than before. This week has been particularly bad with yesterday being the worst I've ever seen. Kinsale road roundabout FFS :eek:

When schools come back this is only going to get worse.... blow up the flyovers!

It's a matter of perspective.

4.50-5.10 is pretty early in the peak, and with the improved flow upstream, cars will get to the junction earlier, and therefore the peak at Dunkettle must begin earlier.

I certainly would have expected someone passing at a consistent time, very early in rush hour, to notice more traffic approaching Dunkettle. Similarly, anyone coming from Mahon at 5pm and merging towards the tunnel must be raging now, with far more cars already progressed to this part of the system.

From your perspective, it looks and is worse. Some amount of people will get home a bit later. More will get home a bit earlier.

As a poster said above, the number of cars entering the system is the same. All that has happened is that arrival rate of cars to the final server (dunkettle) is peaking earlier. That means an increased probability of queueing, and increased mean response time (queueing and passing through) for some cars.

Think of the arrival rate in cars/hour, and imagine that plotted in a graph over time between, say, 4pm and 6pm. What has happened is the shape of the curve has changed, with the peak rising closer to 4pm than before. Since the same number of cars will arrive, on average, that change in the peak means the Probability of Waiting (having to queue) will be higher earlier, but the arrival rate will also tail off earlier. The system will continue to process the queue at the same rate (assuming no changes have been made to the light sequence). So now, there is an earlier peak, and possibly a taller narrower one.

But with the system utilization (arrival rate / service rate) passing 1.0 earlier (queue increases) then more cars are being processed earlier.

All in all, some people who used to enjoy beating the queue are now further back. Someone is ahead of them in the queue though. That someone might have always finished work in Bishopstown at 4.15pm, but previously didn't get to Dunkettle until 5.10pm. Now they might be getting there at 4.40pm, and for them, they might even see an improved time at Dunkettle.

Now, where one might see a problem is in the following scenarios:
- 'Tom' used to drive home to Glanmire from work in Bishopstown via Shanakiel, Knocknaheeny, Fairhill, Blackpool, North Ring road, Barnavara hill, but now sees a better overall time on the N40, due to recent upgrades
- 'Sheila' used to drive to work in little island, from Wilton, through town due to congestion at Sarfields Road roundabout, now she enjoys a better overall time on the N40

Examples like these increase the arrival rate of cars to the system, and push up the average response time through the entire system. It happened with the m50 after the upgrade. It was worth dodging the m50 toll when it took 20 minutes to get through. Lots of people happily took alternative back routes and ninja routes, but now those cost 20 minutes so they take the m50, which is now almost as busy (but better moving) at rush hour as before. When it comes to ring roads, if you build/improve it, they most certainly will come.

But long term it's better that they do come, and that the Dunkettle upgrade gets prioritised.

hoodwinked

Outkast_IRE wrote: »

There is going to be some angry people come September if the tailbacks don't ease off.

and some really happy ones heading to Ucc through Wilton! :pac:

Max_Charger

hoodwinked wrote: »

and some really happy ones heading to Ucc through Wilton! :pac:

Or CIT speaking of, is there a new cycle lane between sarsfield and Bandon roundabout? Is it nearly finished or a bit off?

spacetweek

MYOB wrote: »

I've never understood arguments that they would - and I'm not willing to say they actually have until September.
The same volume of cars will be getting to Dunkettle as before. This is what causes the delays, not the flow form they arrive in. We had two similar schemes in Dublin that didn't worsen issues at the upstream junctions.

The idea is that the more freeflow traffic becomes, the larger the bunching effect of a single bottleneck on the network. Therefore Dunkettle could be expected to see worse tailbacks. The same amount of traffic is reaching it but in one group, not spread out over time like before. The flow form is what determines the congestion, not so much the volume, unless lane capacity is an issue. What were the two Dublin junctions?
Ramp metering is essentially this process in reverse. Freeflowing traffic is separated into bundles using traffic lights to prevent too many vehicles joining the flow in one go. This prevents bunching.

Stark

There was a good stretch between the Sarsfield road roundabout and Dunkettle though. Surely that would have smoothed out the bunching effects from the roundabout lights?

hoodwinked

Stark wrote: »

There was a good stretch between the Sarsfield road roundabout and Dunkettle though. Surely that would have smoothed out the bunching effects from the roundabout lights?

i reckon its just more traffic is taking this route as its "quicker" and New.


give it hour long tailbacks and people will go back to their previous routes and traffic will ease up again,

Outkast_IRE

Max_Charger wrote: »

Or CIT speaking of, is there a new cycle lane between sarsfield and Bandon roundabout? Is it nearly finished or a bit off?

It looks like its nearly there just concrete to be poured, i imagine it will just have cycle lane markings. Honestly the cycle lanes in that whole area are so disjointed they are barely worth using. They end and start seemingly at random.

I come from sarsfield rd southside and cross the roundabout on the road with the traffic, and then use the cycle path that runs alongside the ESB and out to bishopstown.

Max_Charger

Outkast_IRE wrote: »

I come from sarsfield rd southside and cross the roundabout on the road with the traffic, and then use the cycle path that runs alongside the ESB and out to bishopstown.

That's prob the easiest thing, even with the new cycle path when you get to the Bandon roundabout you'll have to go through 3 sets of traffic lights compared to 2 at sarsfield. Cheers Outkast.

serfboard

Bacchus wrote: »

at 5:30, traffic for the tunnel was backed up all the way to the Kinsale road roundabout!!

That's a shocking level of traffic alright, but entirely predicatable (and predicted here).

JupiterKid wrote: »

Upgrading Dunkettle along with the Macroom Bypass must be the main transport priorityies for Cork now.

FYP.

Locals will now start pressuring their politicians, who will in turn pressurise the Minister and then the NRA. The result being that Dunkettle jumps massively up the priority list, at the expense of the Macroom bypass (which, AFAIR certain traders in Macroom don't want anyway).

L1011

spacetweek wrote: »

What were the two Dublin junctions?.

Newcastle n4 was predicted to make the kennelsfort junction worse; ditto baldonnell and even kill on the n7 and newlands. In each case you got at worst one tailback of the combined length

Outkast_IRE

Max_Charger wrote: »

That's prob the easiest thing, even with the new cycle path when you get to the Bandon roundabout you'll have to go through 3 sets of traffic lights compared to 2 at sarsfield. Cheers Outkast.

I would recommend tyres which are puncture proof or similar , honestly the whole area is dodgy for broken glass, the path alongside the esb even more so.

I use these on my bike now
http://www.wiggle.co.uk/panaracer-flataway-tyre-liner/

and have not got a single puncture since putting them in. Compared to 3 punctures in 4 months previously.

spacetweek

Outkast_IRE wrote: »

I would recommend tyres which are puncture proof or similar , honestly the whole area is dodgy for broken glass, the path alongside the esb even more so.

I'm just back from Norway and I spotted a narrow manned street sweeping vehicle brushing an offroad bicycle lane. We need that.

AugustusMinimus

I'm one of those people who predicted problems at the tunnel.

Yes, the same amount of traffic should be going through the tunnel. The main difference is that instead of queuing in traffic at Bandon and Sarsfield roundabouts, the cars are now queuing at the tunnel.

There is the argument that a lot of the traffic going through Sarsfields and Bandon would exit before the tunnel, but the remaining traffic which was still heading towards the tunnel would still make the situation worse.

Schools back and this could turn into a disaster. Makes no difference for those coming from Sarsfield Roundabout and back as the queuing will be no different (just a single queue now instead of 2 or 3 queues) but for those coming on at Kinsale, Bloomfield or Mahon it's a disaster.

alaimacerc

spacetweek wrote: »

I'm just back from Norway and I spotted a narrow manned street sweeping vehicle brushing an offroad bicycle lane. We need that.

I was watching the BBC do a feature on the UK's "spend" on cycle provision, compared to the European norm, and IIRC it was something like £25 per person per year, vs 1. I doubt that an Ireland:Norway comparison would be any less depressing... (At a wild guess, I'd take a stab at even moreso.)

cork_south

Bacchus wrote: »

Do you get down to Cork often? Have you seen the tailbacks lately? Not trying to be smart here but they have gotten worse the past few weeks. Maybe there is some other reason for it but Monday and Tuesday this week were the worst tailbacks I've ever seen heading east towards the tunnel. If I was heading that way this evening, I'd rather hang back at work for another hour than face that traffic.

There was a lady broken down just before the tunnel on Tuesday.
That caused the massive tailbacks.
I know this because I saw her.

Traffic was very light at 5.15 today.
Was not even backed up as far as Mahon slip.

alaimacerc

Things are afoot once more on the N71 eastbound! Closed off entirely at BRR around 11pm this evening, with all traffic being diverted via Bishopstown. Hopefully they're getting cracking with the resurfacing.

On the westbound, they've tarmacked the final part of the footpath. It's still coned off, though -- in fact, as the adjacent slip lane still is too, it's somewhat "double-coned".

alaimacerc

Open again tonight, and indeed, 'twas resurfacing. Not the whole thing yet, though, just from the SRR west to some way short of the onramp/roundabout split. Both lanes, though they only have one open at the moment. Also a short distance on the north side of the roundabout, taking care of that really scrappy bit on the inside lane.

blindsider

From the CCC update via email:

One of the more significant outstanding items is the installation of low noise surfacing on the old eastbound
lanes between Bandon Road Roundabout and Sarsfield Road Roundabout. In order to minimise traffic
disruption it is proposed to progress this item under weekend working over the next two weekends. On this
coming weekend localised diversions (via Bishopstown and Wilton Roundabout) will be in place for traffic
wishing to head east from Bandon Road Roundabout on the old road. The diversion will be put in place at
9.00 p.m. on Friday 16th August 2013 – the road will certainly be reopened to traffic before the rush hour on
Monday morning and in fact it is anticipated that the road will be reopened to traffic sometime on Saturday
night. In order to ensure that this timescale can be met, works will continue through the night on Friday
night.

Traffic on the South Ring mainline will not be affected and no major traffic disruption is anticipated.
Similar traffic management arrangements will be put in place at 9.00 p.m. on Friday 23 rd August 2013 with a
similar timescale associated with the works over that weekend. Regular updates will be issued over both
weekends via local radio stations and media outlets as the works progress to completion.
*************************

Will I bother mentioning the utter cretin in the silver Astra who overtook me in the 60KPH zone (Eastbound) this afternoon - he was easily doing 120KPH. Of course, he had only just passed me in the outside lane, when he screeched across 3 lanes to exit at Togher Gda Station/Tramore Rd - great driving kiddo!

alaimacerc

BTW... someone should edit the subject line to remove the "(under construction)". I think the flyovers are as built as they're gonna get.

(Or else change it to "roadworks", if removing it entirely seems premature.)

mydiscworld

alaimacerc wrote: »

BTW... someone should edit the subject line to remove the "(under construction)". I think the flyovers are as built as they're gonna get.

(Or else change it to "roadworks", if removing it entirely seems premature.)

Same with Tralee Bypass, now also open

neddynasty

Drove through the JL tunnel on Tuesday heading east @ 5.40pm approx. Traffic was fine. Bit of a tailback but it moved constantly about 10-15mph and were through the tunnel in only a few minutes.

It'll be October before we see the real effect on traffic in the tunnel area. Need to have schools and colleges back and a couple of weeks settling down time before we see the final pattern.

spacetweek

alaimacerc wrote: »

BTW... someone should edit the subject line to remove the "(under construction)". I think the flyovers are as built as they're gonna get.

Technically the project includes the ancillary works on the frontage roads, roundabouts etc. so until they're finished this isn't over. (The word 'flyover' shouldn't really appear in the title).
The Tralee bypass, on the other hand, actually really is finished.

alaimacerc

spacetweek wrote: »

Technically the project includes the ancillary works on the frontage roads, roundabouts etc. so until they're finished this isn't over. (The word 'flyover' shouldn't really appear in the title).

I kinda covered that, really. It doesn't say "N40 Cork SRR Interchanges" as the NRA is calling it, it says "Flyovers (under construction)", which either way you want to look at it, is not longer correct. As I said in the first place.