Forth Replacement Crossing

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Rain
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Re: Forth Replacement Crossing

Post by Rain »

6637 wrote:Can someone expain why the non-motorway A90-A904 traffic can't use this route?
It would send extra traffic through South Queensferry. With the current plans, traffic for the A904 will just have to turn left at the roundabout before the new bridge.
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si404
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Re: Forth Replacement Crossing

Post by si404 »

6637 wrote:Can someone expain why the non-motorway A90-A904 traffic can't use this route? :?
Because what they are building actually looks like this (or thereabouts), and sending one direction of class IV traffic through Queensferry is apparently a big no no.
qferry.PNG
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Rain
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Re: Forth Replacement Crossing

Post by Rain »

If the non-motorway section is still going to be a special road then there may well be the interesting situation of 70 signs at the end of the M9 spur followed by NSL signs just a mile later. Traffic from the A90 to the bridge would also go NSL - 70 - NSL.
S Parkinson
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Re: Forth Replacement Crossing

Post by S Parkinson »

si404 wrote:Because what they are building actually looks like this (or thereabouts), and sending one direction of class IV traffic through Queensferry is apparently a big no no.
Even that could be avoided by building a ramp from the B800 bridge to the w/b A90 as shown.

Ok, the ramp would require serious retaining walls either side but surely not that difficult to have included.

Edit: Or even just raise the A90 to be a flat junction with the B800 (as per 6637's post btm of previous pg)?
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Last edited by S Parkinson on Thu Nov 10, 2011 12:49, edited 1 time in total.
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FurryBoots
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Re: Forth Replacement Crossing

Post by FurryBoots »

Rain wrote:If the non-motorway section is still going to be a special road then there may well be the interesting situation of 70 signs at the end of the M9 spur followed by NSL signs just a mile later. Traffic from the A90 to the bridge would also go NSL - 70 - NSL.
Why would there be? Motorways in Scotland typically have 70 signs anyway, including the current M9 spur here. In fact, the current speed limit from the Forth Road Bridge to a point about half a mile down the M9 spur is currently limited to 50. I wonder whether this would this be retained once the new route is built?
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FurryBoots
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Re: Forth Replacement Crossing

Post by FurryBoots »

S Parkinson wrote:
si404 wrote:Because what they are building actually looks like this (or thereabouts), and sending one direction of class IV traffic through Queensferry is apparently a big no no.
Even that could be avoided by building a ramp from the B800 bridge to the w/b A90 as shown.

Ok, the ramp would require serious retaining walls either side but surely not that difficult to have included.

Edit: Or even just raise the A90 to be a flat junction with the B800?
They wish to be able to have the ability to divert all traffic onto the existing A90 and over the existing bridge in case there is an emergency or other problem on the new bridge. This is a very sensible contingency and makes perfect sense. If they rerouted the existing A90 as suggested in your edit, that would remove the ability to switch to the other bridge (without diverting heavy traffic over that proposed B900 junction, causing gridlock).

I'm sure that there are ways that they could have created a non-motorway route but they haven't.
si404 wrote:That said, I don't know why the bus-only slips to the B800 can't be open to all and be for non-motorway traffic.
That is an obvious solution but the decision to open up what was going to be a public transport only route in order to allow a motorway link to be completed would likely have the green camp up in arms as usual!
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Gav
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Re: Forth Replacement Crossing

Post by Gav »

This would be simple to solve - the bridge has to be kept as an emergency crossing from what I gather so the road layout would need to accomodate this - A simple integration of the slips to the M90 would suffice this action. Much the same as the M9 spur to the M9 mainline at present. but with some extra slips for the classes barred from the Motorway. These slips being integrated with the old B900 route. Remember this road did carry a significant amount of traffic before as it was the main link from the M9 to the bridge. It well able to cope with the traffic demands of the old bridge.
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S Parkinson
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Re: Forth Replacement Crossing

Post by S Parkinson »

FurryBoots wrote:
si404 wrote:That said, I don't know why the bus-only slips to the B800 can't be open to all and be for non-motorway traffic.
That is an obvious solution but the decision to open up what was going to be a public transport only route in order to allow a motorway link to be completed would likely have the green camp up in arms as usual!
But we are only talking about the slips between South Queensferrry and the A90. The old bridge itself would remain public transport only. Doesn't sound like much of a concession.
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PishedPaul
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Re: Forth Replacement Crossing

Post by PishedPaul »

I could be wrong but I can't see more than 60 busses crossing the old bridge in an hour - 1 bus a minute through isn't going to make much difference to the traffic on the B8000 - especially when it was originally the main road between the M9 and the bridge.
S Parkinson
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Re: Forth Replacement Crossing

Post by S Parkinson »

I've been thinking about, on the occasions of the new bridge being closed for maintenance, what a poor job the alternative route is n/b, ie. slip up to a small roundabout then the S2 B900 toward the old bridge.
Then it dawned on me, looking at the layout as shown here (with the A90 'disappearing' into the new carriageway), I wonder if the plan is to actually tie the old and new carriageways together (with an adjacent gap in the central reservation of the new carriageways) ready to 'traffic manage' traffic onto the old carriageways on the rare occasion it is required to close the new bridge. At all other times the existing underpass at South Queensferry would be coned off to traffic with cones also used at the tie in point to prevent any erronous double-back manouvers e/b and to close off the central reserve gap.

ps. I still think class IV traffic should be allowed to permanently use the bus slip roads (and B800 n/b) between the existing South Queensferry junction and the A90 to the east.
m80
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Re: Forth Replacement Crossing

Post by m80 »

Here are the start / finish dates for each element of the works:-

http://www.transportscotland.gov.uk/fil ... ntract.pdf
m80
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Re: Forth Replacement Crossing

Post by m80 »

Construction drawing of South network:-

http://www.transportscotland.gov.uk/fil ... A1__2_.pdf
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Truvelo
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Re: Forth Replacement Crossing

Post by Truvelo »

Was there already an intention to build a new Forth Bridge when the M9 spur was completed a few years ago?

It seems to me like the spur was extended to the A90 simply because it was the most convenient and less destructive alignment to link to the existing bridge. However for the new bridge it looks like a very roundabout route of getting there from the M9. With hindsight would it have been better to leave the M9 spur terminating on the A8000 and build a direct link to the M9 via a new junction 1b as some plans show?

The whole road network in that part of the country appears very disjointed. To get from the A720 to the M90 involves so many turns. Had the A720 north of Gogar been completed then it would have been a very simple route to either the existing or new Forth Bridges with no TOTSOs.
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novaecosse
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Re: Forth Replacement Crossing

Post by novaecosse »

Truvelo wrote:It seems to me like the spur was extended to the A90 simply because it was the most convenient and less destructive alignment to link to the existing bridge. However for the new bridge it looks like a very roundabout route of getting there from the M9. With hindsight would it have been better to leave the M9 spur terminating on the A8000 and build a direct link to the M9 via a new junction 1b as some plans show?
It would, but John "Slasher" Swinney took out his red pen in order to reduce costs.
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Gav
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Re: Forth Replacement Crossing

Post by Gav »

There were indeed some grand plans for this bridge on the south side to link in with the existing road network - Infact id go as far to say that there were some sabre members involved with the scale of these plans.......

The road network proposed had some interesting designs and some reworks of the M9 spur and A90 junction - It would have been more distance as to use the new bridge you would have had to go back down the M9 spur to the M9 and then go west to pick up the bridge link.

Some layouts being proposed and Im sure there were many more Ill have a look and see if I can find them and post them. The one they settled with seems to be the best option - make the M9 spur fully free flowing with the M9. Still think it could be motorway all the way and they could have put in some interesting slips to allow this however the current plan of having the old bridge diversion tie in with the new road may have some implication with the motorway status - it may be this that stops them from having the motorway all the way to the bridge.
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Gav
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Re: Forth Replacement Crossing

Post by Gav »

interesting take on the M9 spur M9 junction
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Gav
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Re: Forth Replacement Crossing

Post by Gav »

Some more obtained from the web of previous ideas....
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Gav
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Re: Forth Replacement Crossing

Post by Gav »

This is a pretty amazing junction - Also probably the most complicated to build and it would have involved the reroute of the M9 mainline to the bridge. Whos to say they would not have renamed that section the M90 and be done with it. It would have fitted in with the M9 juntions and would have simplified traffic flows. But it would have been geek heaven indeed !
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S Parkinson
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Re: Forth Replacement Crossing

Post by S Parkinson »

si404 wrote:Because what they are building actually looks like this (or thereabouts), and sending one direction of class IV traffic through Queensferry is apparently a big no no.
The only argument I can think of against opening up these bus slip roads to all non-motorway traffic is that it wouldn't just be a few learner drivers and scooters that would use them but potentially anyone travelling between Edinburgh and South Queensferry and as such buses might be held up for a few seconds at the roundabout on the B800 at the top of the n/b (w/b) slip road.

So, here's the solution:
Simply build an extra lane on the n/b carriageway as shown below in sky blue, seperated from the main motorway lanes/hard shoulder by a concrete barrier.
Auxilary lane to be not under motorway restrictions.
Benefit - No tractors and scooters chancing their arm on the A90-non-quite-a-motorway main carriageway
Cost - Extremely minimal given the overall cost of the bridge and connecting roads

Transport Scotland - Don't worry, I'll waiver a Consulting fee on this occasion
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