Laurencekirk GSJ
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Re: Laurencekirk GSJ
All of the options look fine. I think that option 2 would get my vote in this case.
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- novaecosse
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Re: Laurencekirk GSJ
I'm surprised the Forties Pipeline System isn't shown as a Design Constraint, it's quite close to the A90 at Laurencekirk.
Re: Laurencekirk GSJ
By the time it is built the pipe will be emptynovaecosse wrote:I'm surprised the Forties Pipeline System isn't shown as a Design Constraint, it's quite close to the A90 at Laurencekirk.
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Re: Laurencekirk GSJ
Option 2, with both sub-option A's. However, the bridge should be perpendicular not skewed, and the cloverleaf loops should be in the other two quadrants so that the link road can be nicely connected to the south roundabout (as it is in Option 1).
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Re: Laurencekirk GSJ
I'm not in a position to give a detailed opinion of the options - but we sometimes stay with our caravan just north of Laurencekirk at Pitrennie Mill - the left turn from the south is easy but the right turn through the gap to go back south is difficult due to the amount of traffic with a caravan, even with a high-powered car - even worse for tractors.
With a GSJ south of Laurencekirk and the central gaps closed it'll be much safer to go south through the village itself - no point doing that now as it's still an at-grade turn through the gap.
With a GSJ south of Laurencekirk and the central gaps closed it'll be much safer to go south through the village itself - no point doing that now as it's still an at-grade turn through the gap.
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Re: Laurencekirk GSJ
I'm not keen on Option 2 because of the extremely sharp turns the design provides. This seems needlessly substandard and landtake wise it doesn't appear to offer much, if any, saving over Option 1.Peter Freeman wrote:Option 2, with both sub-option A's. However, the bridge should be perpendicular not skewed, and the cloverleaf loops should be in the other two quadrants so that the link road can be nicely connected to the south roundabout (as it is in Option 1).
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Terminally cynical, unimpressed, and nearly Middle Age already.
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Re: Laurencekirk GSJ
Ideally you'd want to see Option 1 and the north junction from Option 3 built.
I suspect Option 3 wouldn't really work because the initial design work identified that a fair amount of the existing Laurencekirk bound traffic from Montrose already uses the B974 from Marykirk or the minor road to Drumnagair.
If you put a long diversion in at Laurencekirk you'll just encourage traffic to divert to those A90 gaps further south.
Shows the problem of just developing a strategy for individual junctions when really you need an overall Dundee - Stonehaven gap closure programme looking at the whole route.
I suspect Option 3 wouldn't really work because the initial design work identified that a fair amount of the existing Laurencekirk bound traffic from Montrose already uses the B974 from Marykirk or the minor road to Drumnagair.
If you put a long diversion in at Laurencekirk you'll just encourage traffic to divert to those A90 gaps further south.
Shows the problem of just developing a strategy for individual junctions when really you need an overall Dundee - Stonehaven gap closure programme looking at the whole route.
Last edited by Altnabreac on Tue Oct 31, 2017 15:00, edited 1 time in total.
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Re: Laurencekirk GSJ
Yes, the cloverleaf loops are fairly tight, but not, of course, as tight as the roundabout circulatory carriageways. Therefore traffic approaching the roundabout only needs to slow down a little earlier, and traffic leaving the roundabout must simply defer full acceleration.Bryn666 wrote:I'm not keen on Option 2 because of the extremely sharp turns the design provides. This seems needlessly substandard and landtake wise it doesn't appear to offer much, if any, saving over Option 1.Peter Freeman wrote:Option 2, with both sub-option A's. However, the bridge should be perpendicular not skewed, and the cloverleaf loops should be in the other two quadrants so that the link road can be nicely connected to the south roundabout (as it is in Option 1).
I am very favourable to dumbbell roundabout junctions for limited access roads. Apart from their economy in structures (one bridge, versus two for a classic UK GSJ), they provide a useful way to service extra arms without traffic needlessly crossing and re-crossing the bridge(s). Either the diamond or partial cloverleaf shapes are OK for a dumbbell, but I marginally prefer the parclo as I believe it makes the roundabout work better. Its sequence of junctions as you circulate goes enter-exit-enter-exit-enter-exit, whereas the diamond form's sequence is enter-enter-exit-enter-exit-exit. It is easier to join the roundabout circulation if an exit lies immediately to your right, since exiting traffic creates a gap for you. Having no such gap-former can result in long streams of uninterrupted traffic coming off the bridge, making entry difficult or hazardous.
Re: Laurencekirk GSJ
How do the curves on the cloverleaf options compare to the curves and short acceleration lanes found elsewhere on the A90?
The Kirrie junction springs to mind as one where no sooner are you out the sharp corner than you're on the main line
The Kirrie junction springs to mind as one where no sooner are you out the sharp corner than you're on the main line
Re: Laurencekirk GSJ
Kirrie Junction is similar to the GSJ'S on the A92 between Monifieth and Arbroath all with very tight radii - one of the Laurencekirk options is similar to Muirdrum on the A92
Motorways travelled 2019 - M90 - M9 - M80 - M8 -M77 - M73 -A74(M) -M6-M42-M40 -A404(M) - M4 - M5 -M50 -M56 much better so far than last year
Re: Laurencekirk GSJ
Hm, that's one of the nicer junctions to use on that bit of the A92B9127 wrote:Kirrie Junction is similar to the GSJ'S on the A92 between Monifieth and Arbroath all with very tight radii - one of the Laurencekirk options is similar to Muirdrum on the A92
Re: Laurencekirk GSJ
Preferred option to be published on the 20th July, with public exhibitions to be held in Laurencekirk.
https://www.transport.gov.scot/news/a90 ... c-display/
https://www.transport.gov.scot/news/a90 ... c-display/
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- novaecosse
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Re: Laurencekirk GSJ
If they don’t close the centre gaps at the North and middle junctions, then the designers are idiots.wrinkly wrote: ↑Fri Jul 20, 2018 18:44 Exhibition panels and leaflet now up
https://www.transport.gov.scot/projects ... t-details/
Re: Laurencekirk GSJ
As they're proposing to retain the reservation gaps at the B9120 and A937 I have doubts about whether the scheme is really worth doing. Its quite a lot of money to get the job only a third done.
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Re: Laurencekirk GSJ
It seems they are planning to leave the other two junctions open for the sake of not building an extra 1km of local access road to the B9120.
Re: Laurencekirk GSJ
A UK junction improvement scheme that's got a massive, glaring problem with it that any sane person can spot? That doesn't sound like the kind of thing that happens very often in this country... oh, wait.
Re: Laurencekirk GSJ
No doubt the (invariably rigged in favour of the client's cost cutting measures) traffic model says no one will use the gaps because of the safety benefits the GSJ provides.
Yeah I'm not convinced some highway design engineers actually understand human behaviour.
Bryn
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She said life was like a motorway; dull, grey, and long.
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Terminally cynical, unimpressed, and nearly Middle Age already.
She said life was like a motorway; dull, grey, and long.
Blog - https://showmeasign.online/
X - https://twitter.com/ShowMeASignBryn
YouTube - https://www.youtube.com/@BrynBuck
Re: Laurencekirk GSJ
It has the feel of the right angle triangle pathway problem. Designers put in a path around the edge of small, grassy area but no-one uses the path, instead, the third side of the triangle is completed by a muddy route along said grass.Bryn666 wrote: ↑Sat Jul 21, 2018 21:40No doubt the (invariably rigged in favour of the client's cost cutting measures) traffic model says no one will use the gaps because of the safety benefits the GSJ provides.
Yeah I'm not convinced some highway design engineers actually understand human behaviour.
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Re: Laurencekirk GSJ
From my experience, the problems on the A90 on the Laurencekirk by-pass are very much concentrated at the southern junction, and the limited improvements just published are no great surprise. Even before the 50 mph speed limit was imposed, I used to regularly slow below 60 mph through this junction, just as I used to at the similar flat junctions for Glamis and Kirriemuir down on the Forfar by-pass. The middle junction and northern junction at Laurencekirk simply aren't in the same league, are too important for local traffic to be closed off, and not enough of a problem to justify building two more expensive bridges.
On the Forfar by-pass, with its junctions originally built to the same standards as at Laurencekirk, only two of the four major junctions have been grade separated: The southern Forfar junction at Lochlands is effectively unchanged, just as the corresponding northern junction at Laurencekirk will be. The northern Forfar junction at Quilkoe has had its gap closed, with northbound traffic diverted via the nearby Kirriemuir junction.
There are still plenty of other flat crossings on the A90 between Dundee and Aberdeen. It's not a motorway.
On the Forfar by-pass, with its junctions originally built to the same standards as at Laurencekirk, only two of the four major junctions have been grade separated: The southern Forfar junction at Lochlands is effectively unchanged, just as the corresponding northern junction at Laurencekirk will be. The northern Forfar junction at Quilkoe has had its gap closed, with northbound traffic diverted via the nearby Kirriemuir junction.
There are still plenty of other flat crossings on the A90 between Dundee and Aberdeen. It's not a motorway.