A428 Black Cat - Caxton Gibbet improvement

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trickstat
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Re: Black Cat - Cambourne rumour?

Post by trickstat »

Truvelo wrote: Sat Jan 01, 2022 23:00
Gav wrote: Sat Jan 01, 2022 22:12 https://www.youtube.com/watch?v=BTY5G_4-Wns

in the original opening sequence of auf wiedershien pet series the black cat roundabout featured.....
All the times I've watched it I never even noticed that. I have seen signs for Birmingham on the A428 but they are all west of Bedford. That's the first time I've seen one that far out.
I do vaguely remember Birmingham appearing on at least one sign on the A1 when I was younger. Probably on our regular journeys from Stevenage to my grandparents who lived at Little Paxton just north of St Neots from about 1974 to 1980. The Black Cat seems the most likely location.
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Re: Black Cat - Cambourne rumour?

Post by KeithW »

trickstat wrote: Sun Jan 02, 2022 09:18 I do vaguely remember Birmingham appearing on at least one sign on the A1 when I was younger. Probably on our regular journeys from Stevenage to my grandparents who lived at Little Paxton just north of St Neots from about 1974 to 1980. The Black Cat seems the most likely location.
That is a road I used many time and back in the day it was the least worst option which tells you how bad all the others were. The traditional route was the A45 which by the 1970's it was a bad joke. Car transporters from the north had a tendency to take the shortest route which was the B661/B645 from the roundabout at Buckden through Kimbolton to pick up the A45 at Staughton, note the signs warning car transporters to take extra care.
https://www.google.co.uk/maps/@52.29633 ... 8192?hl=en

Later they were banned as they kept damaging buildings so car transporters were banned and there was and still is a sign on the A1 at at Buckden to that effect. I do wonder ho long it is since and transporters took that route ?
https://www.google.co.uk/maps/@52.29580 ... 8192?hl=en

The A428 ran from the Black Cat through Great Barford and Bedford from where you either took the A428 to the M1 at Northampton or my favourite route the A421 to the M1 at Brogborough
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Re: Black Cat - Cambourne rumour?

Post by roadphotos »

Birmingham used to be signed on what was the A45 (now the A14) Newmarket By-Pass (miles east of the A1). The sign at the A45/A11 junction used to read Cambridge and Birmingham A45 and Harlow and London A11. The Birmingham sign was replaced and now reads The Midlands
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Re: Black Cat - Cambourne rumour?

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fridayy
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Re: Black Cat - Cambourne rumour?

Post by fridayy »

Opinions on a possible A421 upgrade near bedford? The 2040 AADT prediction on the D2 A6-A600 section is 103,200 if this gets built (higher than part of the new D3 A14)

I assume the AADT between marsh leys and the A6 is higher than 103,200 as it's already D3.

Also, the existing a428 between Girton-Caxton is also going to be numbered A421 according to this document.
aadt.JPG
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Re: Black Cat - Cambourne rumour?

Post by A320Driver »

fridayy wrote: Sun Apr 03, 2022 11:48 Opinions on a possible A421 upgrade near bedford? The 2040 AADT prediction on the D2 A6-A600 section is 103,200 if this gets built (higher than part of the new D3 A14)

I assume the AADT between marsh leys and the A6 is higher than 103,200 as it's already D3.
I think it will need to be looked at, for sure. Significant amount of local traffic uses the A421 between Marsh Leys and Great Barford. An upgrade to D3 won’t come cheap though as a new viaduct across the Great Ouse will be needed.
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Re: Black Cat - Cambourne rumour?

Post by jackal »

fridayy wrote: Sun Apr 03, 2022 11:48 Opinions on a possible A421 upgrade near bedford? The 2040 AADT prediction on the D2 A6-A600 section is 103,200 if this gets built (higher than part of the new D3 A14)

I assume the AADT between marsh leys and the A6 is higher than 103,200 as it's already D3.
Not necessarily. The extra lane could well be due to the tight junction spacing.

I also find these forecasts a bit dubious (though thanks for providing them!). A D2 above about 70k AADT is likely to be so heavily congested that there would be significant suppression effects and I doubt these are fully accounted for. 103,200 is absurdly high - the only D2 above 100k that I'm aware of is the A406 around the M11 junction.

But even if you shave off a few k the numbers are still obviously too high for a D2, so widening between the M1 and A1 would be required. The M1 junction would also need a rethink...
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Re: Black Cat - Cambourne rumour?

Post by KeithW »

jackal wrote: Sun Apr 03, 2022 15:38
Not necessarily. The extra lane could well be due to the tight junction spacing.

I also find these forecasts a bit dubious (though thanks for providing them!). A D2 above about 70k AADT is likely to be so heavily congested that there would be significant suppression effects and I doubt these are fully accounted for. 103,200 is absurdly high - the only D2 above 100k that I'm aware of is the A406 around the M11 junction.

But even if you shave off a few k the numbers are still obviously too high for a D2, so widening between the M1 and A1 would be required. The M1 junction would also need a rethink...
The Bedford Southern Bypass between the A6 and A600 is a particular problem as it has become part of a de facto Bedford Southern Ring road and there has been massive housing and retail development along it . The results is it has an AADF of around 80k while that to the east and west its closer to 50k. Between those junctions most of the road is D2 but it mostly copes. If worst comes to worse there is room to widen it as was recently done on the A19 between Portrack and Wolviston where there is a similar pattern

There are large industrial/retail parks at the A600 and A6 junction with a large housing development to the North. All of this depends on the A421 to provide access.
https://www.google.co.uk/maps/@52.11458 ... !1e3?hl=en

I dont see the new A428 adding that much traffic to be honest, at Brogborough on the M1 approach AADF is around 25-30k while at the A1 its around the same, the main delay there is simply the Black Cat.
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Re: Black Cat - Cambourne rumour?

Post by Alderpoint »

is this still a "rumour"?

Could a mod possibly update the thread title....
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Re: Black Cat - Cambourne rumour?

Post by Tinpusher »

In an ideal world, the solution to the Bedford ADT problem, is a parallel local distributor road to keep the through traffic away. Would still be expensive and require a new bridge. A US style road with only one junction giving access to Bedford and the other movements catered for on the local lanes could also work.
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Re: Black Cat - Cambourne rumour?

Post by KeithW »

Tinpusher wrote: Mon Apr 04, 2022 08:26 In an ideal world, the solution to the Bedford ADT problem, is a parallel local distributor road to keep the through traffic away. Would still be expensive and require a new bridge. A US style road with only one junction giving access to Bedford and the other movements catered for on the local lanes could also work.
Only one junction for the strategic route would be good idea for a greenfield design but there are problems, there are 2 junctions for the A6 north and south alone for example as well as the A600. The problem with a distributor road is that there is no space north of the A421 as the council allowed development up to the edge of the road after the bypass opened. Realistically if it become necessary the best option would be widening I think but if you had D3 it might be possible to use US style express lanes for lanes 2 and 3.
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Re: Black Cat - Cambourne rumour?

Post by fridayy »

KeithW wrote: Mon Apr 04, 2022 12:49
Tinpusher wrote: Mon Apr 04, 2022 08:26 In an ideal world, the solution to the Bedford ADT problem, is a parallel local distributor road to keep the through traffic away. Would still be expensive and require a new bridge. A US style road with only one junction giving access to Bedford and the other movements catered for on the local lanes could also work.
Only one junction for the strategic route would be good idea for a greenfield design but there are problems, there are 2 junctions for the A6 north and south alone for example as well as the A600. The problem with a distributor road is that there is no space north of the A421 as the council allowed development up to the edge of the road after the bypass opened. Realistically if it become necessary the best option would be widening I think but if you had D3 it might be possible to use US style express lanes for lanes 2 and 3.
The A600 doesn't need a junction, it's not much further to the A603. Anybody going eastbound already goes to the A603 junction.
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Re: Black Cat - Cambourne rumour?

Post by jackal »

The Planning Inspectorate has sent the recommendation report to the SoS, who has 3 months to decide, supposedly.
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Re: Black Cat - Cambourne rumour?

Post by fridayy »

New HQDCs like this deserve junction numbers.

J1: M1J13
J2: Marston
J3: A428/Marsh Leys
J4: A6/Ampthill rd
J5: A600
J6: A603
J7: A4280
J8: A1/Black cat
J9: St-neots
J10: A1198/Caxton gibbet
J11: Camborne
J12: Dry drayton
J13: A1303/Madingley mulch
J14: A14/Girton
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Re: Black Cat - Cambourne rumour?

Post by KeithW »

fridayy wrote: Mon May 30, 2022 23:30 New HQDCs like this deserve junction numbers.

J1: M1J13
J2: Marston
J3: A428/Marsh Leys
J4: A6/Ampthill rd
J5: A600
J6: A603
J7: A4280
J8: A1/Black cat
J9: St-neots
J10: A1198/Caxton gibbet
J11: Camborne
J12: Dry drayton
J13: A1303/Madingley mulch
J14: A14/Girton

There is nothing even remotely new about that route apart from the fact that it doesnt exist yet :)

Cambridge to the A1 at Wyboston is the A428
A1 to the M1 from the Black Cat is the A421

There is a bit of A1 in between :)
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Re: Black Cat - Cambourne rumour?

Post by fridayy »

KeithW wrote: Mon May 30, 2022 23:52
fridayy wrote: Mon May 30, 2022 23:30 New HQDCs like this deserve junction numbers.

J1: M1J13
J2: Marston
J3: A428/Marsh Leys
J4: A6/Ampthill rd
J5: A600
J6: A603
J7: A4280
J8: A1/Black cat
J9: St-neots
J10: A1198/Caxton gibbet
J11: Camborne
J12: Dry drayton
J13: A1303/Madingley mulch
J14: A14/Girton

There is nothing even remotely new about that route apart from the fact that it doesnt exist yet :)

Cambridge to the A1 at Wyboston is the A428
A1 to the M1 from the Black Cat is the A421

There is a bit of A1 in between :)
I must’ve worded it badly, I meant when they finish the new road, as it’ll all be the A421 then.
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Re: Black Cat - Cambourne rumour?

Post by Chris5156 »

fridayy wrote: Mon May 30, 2022 23:30 New HQDCs like this deserve junction numbers.

J1: M1J13
J2: Marston
J3: A428/Marsh Leys
J4: A6/Ampthill rd
J5: A600
J6: A603
J7: A4280
J8: A1/Black cat
J9: St-neots
J10: A1198/Caxton gibbet
J11: Camborne
J12: Dry drayton
J13: A1303/Madingley mulch
J14: A14/Girton
No reason why not, and it’s pleasing that the A14 is J14!

One point to consider is a possible westward extension towards Oxford. This road will never go further east but it might go further west, so what if numbering starts at Girton? It may even be possible to contrive that M1 J13 is also A421 J13 with a bit of fiddling.
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Re: Black Cat - Cambourne rumour?

Post by KeithW »

Chris5156 wrote: Wed May 04, 2016 16:29
I think it's generally understood, further up the thread, that the A421 will be taking the mainline through the junction, and the A1 will stop for a roundabout or two underneath it until such time as it's upgraded off line.
Its a 3 tier junction with both the A1 and A421 being free flow and a roundabout for turning traffic.
https://nationalhighways.co.uk/our-work/a428-black-cat-to-caxton-gibbet/about-the-scheme/ wrote:New roads, junctions and bridges
a new three tier junction at Black Cat roundabout which will allow traffic to flow freely on the A1 by travelling under the junction and on the new dual carriageway over the junction

new junctions at Caxton Gibbet and Cambridge Road, connecting the new dual carriageway to the existing A428 and increasing the local road network’s ability to cope with unforeseen incidents

new Roxton Road link to connect Wyboston and Chawston
new bridges crossing over the new dual carriageway at Roxton Road, Barford Road and Toseland Road
new bridges over the River Great Ouse and East Coast Main Line railway
Note they are also sorting out the mess at the Kelpie Marine boatyard.

As for numbering I suspect the entire road from Girton to the M1 will become the A421, A428 has only been used for that stretch since the 1990's, prior to that it was the A45. The A421 would then run from Cambridge to the A43 at Juniper Hill and down to the M40 at J10, a good start for a proper route to Oxford if only we can get rid of the roundabouts in Milton Keynes.
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Re: Black Cat - Cambourne rumour?

Post by Chris5156 »

KeithW wrote: Tue May 31, 2022 10:58
Chris5156 wrote: Wed May 04, 2016 16:29
I think it's generally understood, further up the thread, that the A421 will be taking the mainline through the junction, and the A1 will stop for a roundabout or two underneath it until such time as it's upgraded off line.
Its a 3 tier junction with both the A1 and A421 being free flow and a roundabout for turning traffic.
In fairness, I wrote that in 2016 when the design did have the A1 passing through some roundabouts. The three tier junction was a later revision.
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Re: Black Cat - Cambourne rumour?

Post by fridayy »

KeithW wrote: Tue May 31, 2022 10:58 As for numbering I suspect the entire road from Girton to the M1 will become the A421, A428 has only been used for that stretch since the 1990's, prior to that it was the A45. The A421 would then run from Cambridge to the A43 at Juniper Hill and down to the M40 at J10, a good start for a proper route to Oxford if only we can get rid of the roundabouts in Milton Keynes.
It is going to become the A421 up to girton. A428 will end at Bedford I assume.
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