A428 Black Cat - Caxton Gibbet improvement

The study of British and Irish roads - their construction, numbering, history, mapping, past and future official roads proposals and general roads musings.

There is a separate forum for Street Furniture (traffic lights, street lights, road signs etc).

Registered users get access to other forums including discussions about other forms of transport, driving, fantasy roads and wishlists, and roads quizzes.

Moderator: Site Management Team

Post Reply
User avatar
trickstat
Member
Posts: 8737
Joined: Sun Apr 06, 2014 14:06
Location: Letchworth Gdn City, Herts

Re: Black Cat - Cambourne rumour?

Post by trickstat »

Lewis1997 wrote: Fri Jun 26, 2020 12:37
KeithW wrote: Thu Jun 25, 2020 17:21
jackal wrote: Thu Jun 25, 2020 17:15 If you don't "get" what a strategic movement is, a simple version is to think about movements between major towns and cities. No major urban centres are linked by turns between the A1 and A428, whereas some are linked by turns between A1N and A421, e.g. MK or Luton to Peterborough. (Strategic movements also take into account other things like port access, but it's a similar story there.)
Turns from the A1 onto the A428 take you to Cambridge and its Science Park and via the A14/A11 to Norwich, Ispwich and Felixstowe. If you are heading in that direction from a point north of Welwyn the only alternative is the A505 which is a pretty poor west of Royston. Sounds pretty strategic to me.
Do you mean the A505 being pretty poor east of Royston? I mean the dual carriageway between Royston and Baldock is sub-standard anyway with its poor sight lines and terrible at-grade junctions.
While the A505 between Baldock and Royston is very far from the safest road, as a through route it is still reasonably fast and not lacking in capacity.
User avatar
KeithW
Member
Posts: 19205
Joined: Thu Dec 04, 2014 13:25
Location: Marton-In-Cleveland North Yorks

Re: Black Cat - Cambourne rumour?

Post by KeithW »

jackal wrote: Fri Jun 26, 2020 13:03
Having a strategic destination at one end does not a strategic route make - if so any road leading from a village to the national network would be strategic. You need strategic destinations at both ends.

From Stevenage or Letchworth A1+A428 is a vastly longer route than the A505. You might use A1+A428 from Sandy or Biggleswade, though this is not a given as it's again much longer than other roads. In any case, A1/A428 will clearly not be a practical link between major towns/cities/ports so it's not strategic.
If on the other hand you are coming along the A421 from Oxford, Milton Keynes and Bedford its very much a strategic route which is rather the reason for the project. Prior to the new A421 being built the Black Cat was a minor irritation. Its also the reason behind the East West rail link and the driving factor behind ideas for an Oxford Cambridge Expressway. There are increasing volumes of traffic both passenger and freight on an east west axis between East Anglia; Lincolnshire and the Thames Valley

Even with the lower amount of traffic at present the congestion at the Black Cat is worst on the A1 northbound and the A421 eastbound. On the A428 there is congestion eastbound at Caxton Gibbet. The S2 A428 has an AADF of 25k. This is not what you see on a road between villages. The A428/A421 is a natural route as it flows straight on to the A14 at the Cambridge northern bypass.

The main weakness of our strategic road and rail network south of Birmingham has been its London centric nature, we need to improve the east west strategic links.
User avatar
KeithW
Member
Posts: 19205
Joined: Thu Dec 04, 2014 13:25
Location: Marton-In-Cleveland North Yorks

Re: Black Cat - Cambourne rumour?

Post by KeithW »

trickstat wrote: Fri Jun 26, 2020 14:41
Lewis1997 wrote: Fri Jun 26, 2020 12:37
KeithW wrote: Thu Jun 25, 2020 17:21

Turns from the A1 onto the A428 take you to Cambridge and its Science Park and via the A14/A11 to Norwich, Ispwich and Felixstowe. If you are heading in that direction from a point north of Welwyn the only alternative is the A505 which is a pretty poor west of Royston. Sounds pretty strategic to me.
Do you mean the A505 being pretty poor east of Royston? I mean the dual carriageway between Royston and Baldock is sub-standard anyway with its poor sight lines and terrible at-grade junctions.
While the A505 between Baldock and Royston is very far from the safest road, as a through route it is still reasonably fast and not lacking in capacity.
But very much lacking in capacity between Royston and the M11 not to mention being darned dangerous and slow. If anything the A10 is worse. When commuting to Cambridge from Edgware I would and did sometimes use the A505 to Royston and the A1198 and A603 route from there. The A505 is like the curates egg - good in parts. East of Royston It was to be avoided like the plague on a weekday morning as traffic heading for the Whittlesford Parkway station and the A11 could tail back for miles

Most often I got off the A1 south of Biggleswade and took the unclassified road through Dunton to the B1042/A603.
85CF380
Member
Posts: 326
Joined: Sat Jun 29, 2013 18:51
Location: W Yorks

Re: Black Cat - Cambourne rumour?

Post by 85CF380 »

KeithW wrote: Fri Jun 26, 2020 16:00 The main weakness of our strategic road and rail network south of Birmingham has been its London centric nature, we need to improve the east west strategic links.
I think you can say not 'south of Birmingham' but the whole of the UK.

As for Black Cat, I think movements west to south & north to east & vice versa will be negligible. An all directions roundabout will cover all bases but some poorly ie North to west & that they could cut costs with a limited access junction using 3 bridges.
User avatar
trickstat
Member
Posts: 8737
Joined: Sun Apr 06, 2014 14:06
Location: Letchworth Gdn City, Herts

Re: Black Cat - Cambourne rumour?

Post by trickstat »

KeithW wrote: Fri Jun 26, 2020 16:23
trickstat wrote: Fri Jun 26, 2020 14:41
Lewis1997 wrote: Fri Jun 26, 2020 12:37

Do you mean the A505 being pretty poor east of Royston? I mean the dual carriageway between Royston and Baldock is sub-standard anyway with its poor sight lines and terrible at-grade junctions.
While the A505 between Baldock and Royston is very far from the safest road, as a through route it is still reasonably fast and not lacking in capacity.
But very much lacking in capacity between Royston and the M11 not to mention being darned dangerous and slow. If anything the A10 is worse. When commuting to Cambridge from Edgware I would and did sometimes use the A505 to Royston and the A1198 and A603 route from there. The A505 is like the curates egg - good in parts. East of Royston It was to be avoided like the plague on a weekday morning as traffic heading for the Whittlesford Parkway station and the A11 could tail back for miles

Most often I got off the A1 south of Biggleswade and took the unclassified road through Dunton to the B1042/A603.
I have never used the A505 east of Royston to get to Cambridge itself. I have used to get it to the A11/A14 on the way to places like Bury St Edmonds, Ipswich and Norwich. This has been at weekends and I would definitely not go that way if there's an air show at Duxford!
User avatar
jackal
Member
Posts: 7549
Joined: Tue Jan 08, 2008 23:33
Location: M6

Re: Black Cat - Cambourne rumour?

Post by jackal »

KeithW wrote: Fri Jun 26, 2020 16:00
jackal wrote: Fri Jun 26, 2020 13:03
Having a strategic destination at one end does not a strategic route make - if so any road leading from a village to the national network would be strategic. You need strategic destinations at both ends.

From Stevenage or Letchworth A1+A428 is a vastly longer route than the A505. You might use A1+A428 from Sandy or Biggleswade, though this is not a given as it's again much longer than other roads. In any case, A1/A428 will clearly not be a practical link between major towns/cities/ports so it's not strategic.
If on the other hand you are coming along the A421 from Oxford, Milton Keynes and Bedford its very much a strategic route which is rather the reason for the project. Prior to the new A421 being built the Black Cat was a minor irritation. Its also the reason behind the East West rail link and the driving factor behind ideas for an Oxford Cambridge Expressway. There are increasing volumes of traffic both passenger and freight on an east west axis between East Anglia; Lincolnshire and the Thames Valley

Even with the lower amount of traffic at present the congestion at the Black Cat is worst on the A1 northbound and the A421 eastbound. On the A428 there is congestion eastbound at Caxton Gibbet. The S2 A428 has an AADF of 25k. This is not what you see on a road between villages. The A428/A421 is a natural route as it flows straight on to the A14 at the Cambridge northern bypass.

The main weakness of our strategic road and rail network south of Birmingham has been its London centric nature, we need to improve the east west strategic links.
Looks like we agree A1 south to/from A428 isn't strategic.
User avatar
KeithW
Member
Posts: 19205
Joined: Thu Dec 04, 2014 13:25
Location: Marton-In-Cleveland North Yorks

Re: Black Cat - Cambourne rumour?

Post by KeithW »

jackal wrote: Sat Jun 27, 2020 08:34 Looks like we agree A1 south to/from A428 isn't strategic.
Its certainly not the main traffic path but Highways England think the road is strategic - they maintain it. I have clearly said several times that the major strategic traffic paths at the new Black Cat will be North-South and East West with most turns being A1 South to A421 West and A428 East. Dont forget the A428 is the site of rapidly growing new towns such as Cambourne and Caldecote soon to be joined by another on the Bourn Airfield site.
https://www.scambs.gov.uk/planning/loca ... field-spd/

When it comes to commuter traffic the burgeoning high tech industries in Cambridge is attracting people from Bedford to the West, Bury St Edmunds to the east, Peterborough to the north and north London. I personally spent 2 years commuting between Edgware and Cambridge, one of my colleagues came from Hertford every day.

As it happens it was a fairly easy commute as I was out of sync with the main traffic flow. I am flattered to find that Google maps recommends my route, Camrose Ave and A5109 to Barnet Way/Barnet By-Pass/A1. Of course I started using route in 1994 my navaids being the latest AA Road Atlas and London A to Z. The latter took quite a bashing over the years.

When I was doing that commute the A1/A428 was not an option. If for no other reason that the A428 (then A45) was S2 all the way from the A1 to Cambridge, that road has an AADF of 25k and is in fact saturated at peak times. At the time the A505 took you through the centre of Baldock and was horribly slow and the A1 at Tempsford was pretty sketchy, this is the old southbound carriageway.
https://www.google.co.uk/maps/@52.17144 ... 312!8i6656

As an aside at the time there was a cutoff from the A1 Northbound to the old A428, you can still see it if you know what to look for.
https://www.google.co.uk/maps/@52.18390 ... a=!3m1!1e3

Then of course there was the Black Cat, getting across the old small roundabout from the A1 northbound at 8 AM was no fun even before the A421 opened. My actual route involved B roads from the A1 north of Baldock to the A603 at Orwell.
User avatar
Burwellian
Member
Posts: 531
Joined: Thu Mar 20, 2008 02:28
Location: Cheshire
Contact:

Re: Black Cat - Cambourne rumour?

Post by Burwellian »

jackal wrote: Sat Jun 27, 2020 08:34 Looks like we agree A1 south to/from A428 isn't strategic.
Are we talking as in the M1 south of the M25 isn't strategic from the M25?

If coming off the A421/A428, you'd probably not turn south down the A1 past Black Cat; if coming from Bedford or MK, you'd take the M1 instead (or shortcut with the A603). You might come this way and turn north if heading for Peterborough though. If coming from Cambridge, you'd either use the A10/A505 combo and join the A1(M) further south at Baldock or just use the M11. Equally, you'd not turn north from Cambridge as traffic heading to Peterborough would generally take the A14. Vice versa obvs also true.

The A1 straight through N-S is strategic though, as a route from Peterborough to London. This has been the signed route for London city & west from Alconbury for example (I'd guess the same at Brampton now?). I'd suspect there's a fair bit of traffic that might come this way if the road were better standard but currently take the M1 (if further afield) or the A14/M11 instead.
User avatar
jackal
Member
Posts: 7549
Joined: Tue Jan 08, 2008 23:33
Location: M6

Re: Black Cat - Cambourne rumour?

Post by jackal »

Burwellian wrote: Sun Jun 28, 2020 00:06
jackal wrote: Sat Jun 27, 2020 08:34 Looks like we agree A1 south to/from A428 isn't strategic.
Are we talking as in the M1 south of the M25 isn't strategic from the M25?
As in the specific movements between the A1 south and A428 at Black Cat.
KeithW wrote: Sat Jun 27, 2020 09:52
jackal wrote: Sat Jun 27, 2020 08:34 Looks like we agree A1 south to/from A428 isn't strategic.
Its certainly not the main traffic path but Highways England think the road is strategic - they maintain it.
By this logic every movement between trunk roads is strategic, even U-turns with next to zero traffic. Not to mention that HE think A1nb to A428 is so unimportant they were happy to exclude it altogether (option B).
User avatar
trickstat
Member
Posts: 8737
Joined: Sun Apr 06, 2014 14:06
Location: Letchworth Gdn City, Herts

Re: Black Cat - Cambourne rumour?

Post by trickstat »

Burwellian wrote: Sun Jun 28, 2020 00:06
jackal wrote: Sat Jun 27, 2020 08:34 Looks like we agree A1 south to/from A428 isn't strategic.
Are we talking as in the M1 south of the M25 isn't strategic from the M25?

If coming off the A421/A428, you'd probably not turn south down the A1 past Black Cat; if coming from Bedford or MK, you'd take the M1 instead (or shortcut with the A603). You might come this way and turn north if heading for Peterborough though. If coming from Cambridge, you'd either use the A10/A505 combo and join the A1(M) further south at Baldock or just use the M11. Equally, you'd not turn north from Cambridge as traffic heading to Peterborough would generally take the A14. Vice versa obvs also true.

The A1 straight through N-S is strategic though, as a route from Peterborough to London. This has been the signed route for London city & west from Alconbury for example (I'd guess the same at Brampton now?). I'd suspect there's a fair bit of traffic that might come this way if the road were better standard but currently take the M1 (if further afield) or the A14/M11 instead.
I have a colleague who lives in Peterborough and occasionally drives to Heathrow to pick up family members. Her preferred route is A1 to Black Cat - A421 - M1 - M25.

Google Maps thinks I should use the A421 for Milton Keynes and the northbound M1 from here in Letchworth, but it seems a long way around to me. It would be my third choice route just for Bedford.
User avatar
KeithW
Member
Posts: 19205
Joined: Thu Dec 04, 2014 13:25
Location: Marton-In-Cleveland North Yorks

Re: Black Cat - Cambourne rumour?

Post by KeithW »

trickstat wrote: Sun Jun 28, 2020 11:16 I have a colleague who lives in Peterborough and occasionally drives to Heathrow to pick up family members. Her preferred route is A1 to Black Cat - A421 - M1 - M25.

Google Maps thinks I should use the A421 for Milton Keynes and the northbound M1 from here in Letchworth, but it seems a long way around to me. It would be my third choice route just for Bedford.
Odd indeed - unless there were problems on the roads my route would be

A1/A1(M) to Hatfield
A414 North Ortbital to M25 J21a
M25
User avatar
M4Simon
Elected Committee Member
Posts: 10121
Joined: Sun Mar 17, 2002 22:35
Location: WGC, Herts
Contact:

Re: Black Cat - Cambourne rumour?

Post by M4Simon »

KeithW wrote: Sun Jun 28, 2020 14:24
trickstat wrote: Sun Jun 28, 2020 11:16 I have a colleague who lives in Peterborough and occasionally drives to Heathrow to pick up family members. Her preferred route is A1 to Black Cat - A421 - M1 - M25.

Google Maps thinks I should use the A421 for Milton Keynes and the northbound M1 from here in Letchworth, but it seems a long way around to me. It would be my third choice route just for Bedford.
Odd indeed - unless there were problems on the roads my route would be

A1/A1(M) to Hatfield
A414 North Ortbital to M25 J21a
M25
Travelling from Peterborough to Heathrow via the A421 and M1 seems very odd to me too. The only thing I'd do differently is take the A414 then the A1081 to Junction 22 - fewer big roundabouts and the left turn at London Colney can be a little quicker than the straight(ish) ahead movement to stay on the A414. When doing the reverse trip, I'll often stay on the M25 to South Mimms then straight onto the A1(M). That is a simple left turn going in this direction. and is quicker these days now that the M25 has 4 lanes through this stretch. I would never go this way when heading from A1(M) to the M25 as it involves going three quarters of the way round the roundabout, through what feels like a million sets of traffic lights!

Simon
Did you know there's more to SABRE than just the Forums?
Add your roads knowledge to the SABRE Wiki today!
Have you browsed SABRE Maps recently? Try getting involved!

Please contact me if you want to know more
camflyer
Member
Posts: 64
Joined: Wed May 30, 2018 21:57

Re: Black Cat - Cambourne rumour?

Post by camflyer »

The A14 upgrade page has been renamed for the A428 project

https://www.facebook.com/A428BlackCat
User avatar
SouthWest Philip
Member
Posts: 3478
Joined: Sun Mar 31, 2002 19:35
Location: Evesham, Worcestershire

Re: Black Cat - Cambourne rumour?

Post by SouthWest Philip »

camflyer wrote: Tue Sep 01, 2020 19:15 The A14 upgrade page has been renamed for the A428 project

https://www.facebook.com/A428BlackCat
A good starting point would be if they rename it again to A421BlackCat! Surely they're not going to stick with another Cirencester numbering scenario?
Jon Waters
Member
Posts: 27
Joined: Sat Mar 23, 2019 14:49

Re: Black Cat - Cambourne rumour?

Post by Jon Waters »

User avatar
jackal
Member
Posts: 7549
Joined: Tue Jan 08, 2008 23:33
Location: M6

Re: Black Cat - Cambourne rumour?

Post by jackal »

The planning application documents are now online: https://infrastructure.planninginspecto ... ction=docs. PINS should decide whether to accept it for examination in the next week or so.

Digging around I found some different drawings of the options. Here's my favourite, the rejected option A:

A428 Black Cat Option A - Copy.JPG

The option being built (with minor changes) is Option C, a stackabout:

A428 Black Cat Option C - Copy.JPG

There was also an unusual stackabout variant with folded slips, option C+, which I haven't seen before:

A428 Black Cat Option C+ - Copy.JPG

This was an attempt to avoid impacts on a listed building at the northbound merge. It's quite a mess.

Costs are astonishing - £286.8 million for option C and £316.2 million for option C+. Please let's never again hear about stackabouts being cheap.

Sadly I couldn't find any further details or drawings for option 4, the cloverstack option I've mentioned previously: "Junction with slip roads and interchange links for all directions. Loop slip roads between A1 northbound and A428 eastbound as well as A1 southbound and A428 westbound".

Junction design document: https://infrastructure.planninginspecto ... ptions.pdf
User avatar
ChrisH
Elected Committee Member
Posts: 3975
Joined: Wed Nov 13, 2002 11:29

Re: Black Cat - Cambourne rumour?

Post by ChrisH »

The assumptions used in the junction design are interesting. They say that RIS2 requires the creation of a freeflowing network, but defines that as the through-routes not the slip roads. It also specifically mentions that because the A1 will dip and require pumping, that any junction option needs to offer "resilience" of getting traffic off and on again: i.e. the stackabout is the only option. Quelle surprise :roll:
User avatar
KeithW
Member
Posts: 19205
Joined: Thu Dec 04, 2014 13:25
Location: Marton-In-Cleveland North Yorks

Re: Black Cat - Cambourne rumour?

Post by KeithW »

ChrisH wrote: Tue Mar 16, 2021 10:36 The assumptions used in the junction design are interesting. They say that RIS2 requires the creation of a freeflowing network, but defines that as the through-routes not the slip roads. It also specifically mentions that because the A1 will dip and require pumping, that any junction option needs to offer "resilience" of getting traffic off and on again: i.e. the stackabout is the only option. Quelle surprise :roll:
Given that the delays at the Black Cat are mainly down to traffic queuing to make the turn and that both the A1 and A428/A421 will be free flow this does not seem an unreasonable compromise. On the plus side getting rid of the Caxton Gibbet roundabout and the horrible B1040/A428 flat junction will be be a huge improvement.

My one concern is that the dip of the A1 could produce flooding.
User avatar
c2R
SABRE Wiki admin
Posts: 11162
Joined: Fri Jul 05, 2002 11:01

Re: Black Cat - Cambourne rumour?

Post by c2R »

Yup, it's better than doing nothing, although not what I would have done, even in a limited budget constraint of, er, £287m...
Is there a road improvement project going on near you? Help us to document it on the SABRE Wiki - help is available in the Digest forum.
Have you browsed SABRE Maps recently? Get involved! - see our guide to scanning and stitching maps
Herned
Member
Posts: 1363
Joined: Thu Jul 20, 2017 09:15

Re: Black Cat - Cambourne rumour?

Post by Herned »

jackal wrote: Tue Mar 16, 2021 10:09 Costs are astonishing - £286.8 million for option C and £316.2 million for option C+. Please let's never again hear about stackabouts being cheap.
I wonder how much is down to having to build it around two existing dual carriageways? It surely wouldn't cost that in the middle of a field, would it?
Post Reply