A164 to be Converted to Dual Carriageway

[Hdeng16]

On reviewing the AADT figures the design is a little less bad than I thought. The A164 is over 30k AADT, which is massive on an S2 so presumably has a lot of suppressed demand, while the A1079 is only around 18k. The fork isn't 'pointless', it addresses the main problem, which is dispersing A164 traffic, in an elegant way - high speed freeflow with lane gains and drops is as good as it gets really.

The concept is basically similar to Longbridge, but with the crucial difference of the roundabout on the A1079, which clearly the designers think can be sacrificed for the busier road. I don't agree with that and would have thought a six arm parclo would achieve much the same in terms of dispersing A164 traffic without dumping a roundabout on the A1079. But while it's far from optimal I have seen worse designs than this.

Pointless was a tad harsh - I wasn’t aware there was particularly high flows ‘across’ the 1079. I’m not against a fork GSJ - any GSJ seems unusual these days. I’m just not sure it’s the best design - it’ll be interesting to see if it really is quicker to get to Minster way on the original line. Yes you bypass the roundabout but from memory it is very urbanised (granted the slip road closures will help)

[Fluid Dynamics]

On reviewing the AADT figures the design is a little less bad than I thought. The A164 is over 30k AADT, which is massive on an S2 so presumably has a lot of suppressed demand, while the A1079 is only around 18k. The fork isn't 'pointless', it addresses the main problem, which is dispersing A164 traffic, in an elegant way - high speed freeflow with lane gains and drops is as good as it gets really.

The concept is basically similar to Longbridge, but with the crucial difference of the roundabout on the A1079, which clearly the designers think can be sacrificed for the busier road. I don't agree with that and would have thought a six arm parclo would achieve much the same in terms of dispersing A164 traffic without dumping a roundabout on the A1079. But while it's far from optimal I have seen worse designs than this.

Pointless was a tad harsh - I wasn’t aware there was particularly high flows ‘across’ the 1079. I’m not against a fork GSJ - any GSJ seems unusual these days. I’m just not sure it’s the best design - it’ll be interesting to see if it really is quicker to get to Minster way on the original line. Yes you bypass the roundabout but from memory it is very urbanised (granted the slip road closures will help)

It isn’t the best design but the original preferred option, converting the current junction into a 2 bridge GSJ roundabout junction, was ruled out by the associated utilities cost.

Interesting comparison with Longbridge which is a much more congested junction with more roads meeting. The difference of course is that one of the routes is fully separated through the junction.

[Hdeng16]

Hardwick might be a better example? Although I’m not sure this design will allow for clever signage to distribute flows

[jackal]

I'd say it's halfway between Longbridge and Hardwick. The fork is more like the former, the roundabout more like the latter. The three form a family of partial GSJs that split flows on a busy DC before crashing into roundabouts.

It seems very simple to sign though - basically at the fork the mainline will be for A164 traffic, the diverge for A1079. There won't be any signing for A1079 over the bridges as that would be very circuitous and would stress the S2 link across the A164.

[M19]

It looks to me like it was designed by two sets of separate consultant teams who followed two different options and were then told at the last minute to make it meet in the middle.

And there you have it.

[Hdeng16]

I know we were mostly primed for losing the freeflow under but I don’t understand why the ‘old’ road needs the fork? Why not just stop it up. Was the whole scheme originally to effectively switch the free flow over? Even if the west fork is there to bypass the new roundabout, you then crash into a flow cross over at the Minster way roundabouts.

You keep the old road so that traffic heading to/from Beverley (and probably Minster Way as well) can bypass the A1079 roundabout. If you didn't have that, and just blocked up the old road, you would be putting a lot more traffic through that roundabout, which would reduce capacity and cause more congestion than there is now.

going back to this.... in terms of jocks lodge itself, this scheme will completely switch over the freeflow then. There might well be roundabouts everywhere else, but in terms of the existing freeflow under the 164, that goes and instead the A164 gets a freeflow over the top.

[Stevie D]

going back to this.... in terms of jocks lodge itself, this scheme will completely switch over the freeflow then. There might well be roundabouts everywhere else, but in terms of the existing freeflow under the 164, that goes and instead the A164 gets a freeflow over the top.

The A164 is actually busier than the A1079, according to the traffic counts, so there is some sense to it. If the A1079 was still single-carriageway through the junction rather than having an odd isolated bit of dual-carriageway just 1 mile long then we might not assume it was the more major road. I guess the difference is that at the moment the A1079 is properly free-flow, with more than 2 miles in either direction to the next roundabout, whereas even with the changes the free-flow branch of the A164 will still hit a roundabout in no time at all so there doesn't seem to be as much reason to make it free-flow if it's immediately going to stop again.

[A303Chris]

Only in the UK would we remove a GSJ on a piece of dual carriageway and replace it with a roundabout.

[Stevie D]

Only in the UK would we remove a GSJ on a piece of dual carriageway and replace it with a roundabout.

As I said, it's barely a dual carriageway – it's only 1 mile long, and was only included because they were building a GSJ – I believe it was to avoid having sliproads on a single-carriageway, although it may also have been to future-proof the junction in preparation for further dualling that never went ahead.

The A1079 is then single-carriageway for nearly 15 miles until you're past Shiptonthorpe, so it isn't as though it is part of an improved route.

[Hdeng16]

going back to this.... in terms of jocks lodge itself, this scheme will completely switch over the freeflow then. There might well be roundabouts everywhere else, but in terms of the existing freeflow under the 164, that goes and instead the A164 gets a freeflow over the top.

The A164 is actually busier than the A1079, according to the traffic counts, so there is some sense to it. If the A1079 was still single-carriageway through the junction rather than having an odd isolated bit of dual-carriageway just 1 mile long then we might not assume it was the more major road. I guess the difference is that at the moment the A1079 is properly free-flow, with more than 2 miles in either direction to the next roundabout, whereas even with the changes the free-flow branch of the A164 will still hit a roundabout in no time at all so there doesn't seem to be as much reason to make it free-flow if it's immediately going to stop again.

Oh I agree it was fairly pointless anyway - I was more just musing if this was rare/a first to swap in such a way.

[wrinkly]

Oh I agree it was fairly pointless anyway - I was more just musing if this was rare/a first to swap in such a way.

The GSJ on the A1 approaching Gateshead from the south (adjacent to where the Angel of the North now is) was rebuilt to switch priority to the western bypass.

[Chris Bertram]

Oh I agree it was fairly pointless anyway - I was more just musing if this was rare/a first to swap in such a way.

The GSJ on the A1 approaching Gateshead from the south (adjacent to where the Angel of the North now is) was rebuilt to switch priority to the western bypass.

Yes, originally the A1 went through Gateshead, over the Tyne Bridge and through the centre of Newcastle, then later around the Central Motorway East, while the to-be Western Bypass was at first A69 and did not go north of the Wall. There have been a lot of changes to road numbers and layouts in that small area, including plugging A182 in as well.

[wrinkly]

while the to-be Western Bypass was at first A69

I think it was something with 3 digits before it was A69 ... yes, I have a Landranger from 1976 which shows it as A613. However, despite all the numerous changes in the area, I only know of one occasion where they went as far as demolishing a bridge and replacing it with two new ones, just to change which road was the mainline.

[jackal]

Oh I agree it was fairly pointless anyway - I was more just musing if this was rare/a first to swap in such a way.

The GSJ on the A1 approaching Gateshead from the south (adjacent to where the Angel of the North now is) was rebuilt to switch priority to the western bypass.

I find this a little hard to square with this 1976 Bartholomew map of the Gateshead Western Bypass:



The exact layout is ambiguous, but it doesn't look like the mainline turned into Gateshead at this time. Probably there is some important detail I am missing.

[Bryn666]

Oh I agree it was fairly pointless anyway - I was more just musing if this was rare/a first to swap in such a way.

The GSJ on the A1 approaching Gateshead from the south (adjacent to where the Angel of the North now is) was rebuilt to switch priority to the western bypass.

I find this a little hard to square with this 1976 Bartholomew map of the Gateshead Western Bypass:



The exact layout is ambiguous, but it doesn't look like the mainline turned into Gateshead at this time. Probably there is some important detail I am missing.

It's a Barts map showing not much detail. The A1 went straight into Gateshead and some substantial earthworks were undertaken to realign the A69 as was.

https://www.old-maps.co.uk/#/Map/426746 ... /10/101320

https://www.sabre-roads.org.uk/maps/ind ... 4&layer=36 prior to that it was a flat roundabout at the end of the original Birtley Bypass.

[jackal]

Thanks, that clears things up, and probably also accounts for the unusual current layout.

[wrinkly]

I visited the site two or three times during the works to reposition the mainline. The southernmost of the three bridges of the present interchange was pretty much unaltered. The original northern bridge was completely demolished and replaced by the present middle bridge - the sites of the two mostly overlap. The new northernmost bridge was required to fit in the new southbound off slip.

[Bryn666]

Thanks, that clears things up, and probably also accounts for the unusual current layout.

Yes, it's hard to work out why they didn't save a bridge and just bring the southbound A1 exit slip road onto the A167 to the north, similar to the double weirdness of M9 J5 and J6. If you look closely on Google's aerials the old northbound entry slip onto the A167 is now a footpath.

[wrinkly]

Another survivor of the days before DfT wanted to bypass Newcastle is the GSJ between the ex-A1 and the ex-ex-A1 just south of the north end of the Newcastle western bypass.

[SouthWest Philip]

Perhaps the most surprising thing about this map extract is the appearance of the A8061 in the Newcastle suburbs?!