A47 Corridor improvement programme

[jackal]

This has apparently been split into six schemes for the purposes of public consultation, which is due in March:

https://www.gov.uk/government/news/11-b ... st-economy

(Thanks to wrinkly for link.)

[Ruperts Trooper]

Yes, perhaps one of the pros can explain what the thinking is with this sort of layout and how it relieves pressure on the main roundabout - there's obviously a bit of a fashion for it and presumably it must work.

It does work... so, one bridge is required (or two, depdendent on location).

At King's Lynn, traffic heading s/b on the A149 from Hunstanton can exit at the first exit from the roundabout junction and head either towards Norwich or towards Wisbech/the North on the A47/A17. It does this without impacting upon the A10 n/b carriageway, which can head into King's Lynn without being interrupted.

Depends on your definition of "works" - Hunstanton A149 > Wisbech A47 is quicker going further round the roundabout to the forth exit and joining the A47 on the original slip road - much quicker at peak periods because the nearside queue backs up on the A149.

[doebag]

Depends on your definition of "works" - Hunstanton A149 > Wisbech A47 is quicker going further round the roundabout to the forth exit and joining the A47 on the original slip road - much quicker at peak periods because the nearside queue backs up on the A149.

Agreed, and also if the A47 eastbound is busy, traffic in the n/s lane has to give way at the small roundabout for long enough to make the old roundabout worth using.

[Derek]

As for the flyover at the Pullover roundabout A47/A17 I wonder if that will ever happen. It must been over thirty years after the by-pass had been built and the earthworks made that the one at the Hardwick roundabout was completed.

1973 - that's 44 years.

Derek

[jackal]

Any thoughts on the A47 North Tuddenham to Easton dualling scheme? It's pretty substantial (5 miles) but I've heard nothing about it.

[jackal]

Consultations for six A47 schemes are now live. The Thickthorn improvement is actually good!

https://highwaysengland.citizenspace.co ... -container

[roadtester]

Consultations for six A47 schemes are now live. The Thickthorn improvement is actually good!

https://highwaysengland.citizenspace.co ... -container

Yes - interesting, that one. On the other hand, Guyhirn seems to be a bit disappointing - looks like just a bigger roundabout...

[Berk]

The Wansford-Sutton consultation... is just absolute crap, basically. It's so thin in detail as to be meaningless. Although there are three specific corridors (I won't call them options, because there's so little detail about them) to choose from, there are no specifics, such as how the local roads will tie in to the new road.

I've been waiting for this for some time, and am very disappointed. Does this mean waiting another 9 months or so until the 'Preferred Route' is announced, and then finding that Sutton Heath Road will be permanently closed??

What does that matter, you may ask?? Well, surprisingly enough there are no motorways in the area, and the only parkway roads are much closer to the city centre. So the country roads are still a good way to access the A1 from further north. Cut them off, and you will force everyone on to the parkways to get to the A1.

[ais523]

Lack of detail is quite a common issue with this set of consultations. Consultations normally have a breakdown of the various options and how they compare, but these "pick from some very similar routes for dualling" consultations don't have anything like that, and don't give much of an idea of which routes would be better than which other routes.

I went and sent some feedback on the Guyhirn junction improvement. In particular, the lane markings they suggest for their roundabout don't make any sense, with three concentric circulating lanes connecting to S2 roundabout arms; once you reach the middle of the roundabout, where are you meant to go from there? In general, roundabout lane markings and lane assignments are something that we often badly screw up in the UK, and it looks highly likely that the same issue would happen here. (Besides, how are you meant to make use of three lanes on the entrance to a roundabout, when there's only two useful exits and you can't safely exit the roundabout side-by-side with another vehicle?)

However, the sort of roundabout width they're suggesting here would easily give space for freeflow lefts (well, "first exit" movements) on the roundabout itself; you don't even need any tarmac changes to the current plans, just some paint with which to draw ghost islands (having a segregated lane would likely be overkill, but separating the outermost lane off with hatching is simple and commonly used). I said as much in my response; if congestion is an issue at the roundabout, having filter lanes to bypass it is going to halve the number of journeys that encounter it, and thus seems like the best possible use for a space that wide.

[jackal]

The Wansford-Sutton consultation... is just absolute crap, basically. It's so thin in detail as to be meaningless. Although there are three specific corridors (I won't call them options, because there's so little detail about them) to choose from, there are no specifics, such as how the local roads will tie in to the new road.

I've been waiting for this for some time, and am very disappointed. Does this mean waiting another 9 months or so until the 'Preferred Route' is announced, and then finding that Sutton Heath Road will be permanently closed??

What does that matter, you may ask?? Well, surprisingly enough there are no motorways in the area, and the only parkway roads are much closer to the city centre. So the country roads are still a good way to access the A1 from further north. Cut them off, and you will force everyone on to the parkways to get to the A1.

This way of presenting the plans, without junctions details, is standard for an initial consultation. There will be a further consultation after the preferred route announcement, and changes are often incorporated at that stage.

In any case, I imagine Sutton Heath Rd will be closed or LILOed. It is only a short diversion to the roundabout to the east, so noone would be forced onto the A1. Surely a much better solution than putting in another roundabout on that short stretch of A47.

[jackal]

Local press report here, including the proposed option for Thickthorn:

[autismuk]

Yes, perhaps one of the pros can explain what the thinking is with this sort of layout and how it relieves pressure on the main roundabout - there's obviously a bit of a fashion for it and presumably it must work.

Given the err design of the Postwick Hub and the new threat to put traffic lights on the A11 at Mildenhall, I don't think there's any sort of thinking.

[roadphotos]

Guyhirn junction improvement is very disappointing. I would have liked to have seen some grade separation here but the A47/A11 junction improvement looks better, also when the Blofield to Acle section is dualled are they going to grade separate the existing roundabout on the A47 at Blofield as there are only fields on the north side of the roundabout so no shortage of space.

[c2R]

Guyhirn junction improvement is very disappointing. I would have liked to have seen some grade separation here.

That would cost mega-money. You've got a bridge at a higher level than the roundabout immediately off of the roundabout, with local accesses on the other side. The A47 to the north here is higher than ground level as it is half way up the river dyke, and ground level itself is below sea level. The land is very soft and fertile, so is prone to allowing carriageways to sink.

If there was money, it would probably be idealresolve this by grade separating the roundabout at the southern end of the Wisbech bypass and driving a new two lane dual carriageway across the river at this point, taking a direct line to the eastern end of the Thorney bypass and cutting off the corner in the process.

[Berk]

I feel that's the only way the Thorney-Wisbech stretch will ever be dualled. The current road would become the LAR.

[skiddaw05]

Local press report here, including the proposed option for Thickthorn:

I can foresee problems where the new freeflow slip joins the main E/B carriageway. If there isn't a lane gain here (not clear from the plan but I suspect not) it'll lead to queues developing on the approach.

I had a look at the main report and one thing I found rather interesting is that they plan to 'widen the Breydon bridge'. Seeing as this is a lifting bridge I'd like to see how!

[jackal]

I don't see any reason why there'd be queuing on the eastbound carriageway. It's a pretty standard merge between a semi-direct connector and mainline with pretty standard flows (45k).

[skiddaw05]

Even now it can get a bit sluggish where the slip road from the roundabout joins the eastbound carriageway, but as the roundabout is signalised it controls the flow onto the slip road to an extent. With an unrestricted flow (and presumably two lanes' worth of it) pushing its way in I would expect this having an adverse effect on mainline traffic. But I'd like to be proved wrong as separating this movement from the roundabout would in theory reduce the sometimes horrendous northbound queues you get on the A11 towards the roundabout.

[c2R]

Even now it can get a bit sluggish where the slip road from the roundabout joins the eastbound carriageway, but as the roundabout is signalised it controls the flow onto the slip road to an extent. With an unrestricted flow (and presumably two lanes' worth of it) pushing its way in I would expect this having an adverse effect on mainline traffic. But I'd like to be proved wrong as separating this movement from the roundabout would in theory reduce the sometimes horrendous northbound queues you get on the A11 towards the roundabout.

I think part of the existing problem is the quality of some of the drivers in the area. I followed someone on Monday to join the A47 eastbound from the junction who managed to achieve a whole 35mph by the merge point, and of course there was a platoon of vehicles behind. The addition of these free flowing links should at least separate A11-A47 traffic (much of which will be longer distance) from local traffic just using the bypass to junction hop. It is likely that if two lanes of traffic is put through on the sliproad it would tiger tail and have a longer merge length as well rather than the existing set-up.

[jackal]

Exactly, the merge length will be significantly extended and tigertailed (hence the widening of the railway bridge), plus the merging traffic will be moving faster as it will be coming from a 50mph freeflow link rather than from a standing start. A lot of the time it is the mismatch between merge and mainline speeds that causes problems.