Major British interchanges

jackal · Post by **jackal** » Thu Apr 24, 2008 23:46

Since sabristi are often citing examples of particular interchange types I thought there might be some interest in the list of major British interchanges I've put together.

To qualify an interchange must (i) have full access (so no M1/M25), and (ii) have no break* in the central reservation of two mainlines that are at least dual carriageway (so no A303/A36 or A889/A705). 47 junctions have been identified - around three quarters of them some kind of stacked roundabout! - that meet these criteria, all in England, Scotland and, thanks to Craggs, Wales. Let me know if any are missing, but bear in mind that I've deliberately excluded junctions that are just planned or under construction.

I've ordered the interchanges by type, expanding on this useful classification. The bullet pointed examples are from CBRD, though in some cases I've used my own classification; the numbered examples have been added. Thanks to Chris for the help, though he didn't know he was providing it!

*The 'no break' requirement applies for the section of central reservation between the PHYSICAL (i.e. not road marking) merge and demerge points at each end. Hence Spaghetti junction is admitted but M53/A552 is not.

A. STACK (FOUR LEVEL INTERCHANGE)
• M25/M4
• M25/M23
• M4/M5

B. WHIRLPOOL (TURBINE)
• M25/M3

C. OCTOPUS
• M25/M11
• M74/A723
• M60/M62/M602

D. STACK/PARTIALLY UNROLLED CLOVERLEAF HYBRID (STACKLEAF)
• A19/A66

E. PARTIALLY UNROLLED CLOVERLEAF (CLOVERSTACK)
• M6/M62
• M4/A329(M)
• M25/M40

F. CLOVERLEAF
• A441/A448/A4189

G. STACKED ROUNDABOUT (STACKABOUT)
• M1/A52
• M60/M62/M66
• A1(M)/M18
• M25/A3
• M6/M65
• M61/M65
7. M5/A40
8. A38/A386
9. A50/A38
10. M25/A12
11. M25/A127
12. M25/A13
13. M25/A1(M)
14. A406/A41
15. A12/A11
16. M62/A162
17. A45/A46/A444
18. M42/A45
19. A470/A48
20. A38/B4114
21. M74/A725
22. A19/A1058

H. STACKED ROUNDABOUT WITH FREEFLOW RIGHT TURN (IMPROVED STACKABOUT)
• M1/M62
• M25/A2
3. M8/M73
4. M25/M20
5. M57/M62

I. INVERTED STACKED ROUNDABOUT (INVERTED STACKABOUT)
• M6/A34

J. ROUNDABOUT INTERCHANGE WITH BYPASS
1. A406/A5
2. M4/A34
3. M6/M69

K. STACKED DUMBELL (STACKBELL)
1. M20/A229
2. A34/A303

L. OCTOPUS/DUMBELL HYBRID (OCTOBELL)
1. M6/M56

M. SPAGHETTI
1. M5/A38(M)

N. DOUBLE ROUNDABOUT INTERCHANGE
1. M1/A41/A4008

EDIT 1 included addition of A470 junctions and M42/A45, and removal of two duplicates.
EDIT 2 included rationalization of qualifying criteria, addition of M6/A38(M) and M56/M6, and new stacked roundabout categories.
EDIT 3 included addition of A386/B3413, M6/M69 and M1/A41/A4008, as well as new name for improved stackabout.
EDIT 2014 (six years later!) - criteria modified to include continuous DC as a minimum; A889/A705, M53/A552 and A386/B3413 removed, A38/B4114 added.
EDIT 2017 - M74/A725 added, M4/A470 removed.
EDIT 2024 - A19/A1058 added belatedly (opened early 2019).

Jeni · Post by **Jeni** » Fri Apr 25, 2008 00:10

Wales has the M4/A470 under G

nirs · Post by **nirs** » Fri Apr 25, 2008 00:15

jackal wrote:Let me know if I've missed any - especially in Wales, NI or indeed ROI

Nothing to add from here, I'm afraid, though I wish there was.

jackal · Post by **jackal** » Fri Apr 25, 2008 00:20

Craggs wrote:Wales has the M4/A470 under G

Good spot. Any more for any more?

Jeni · Post by **Jeni** » Fri Apr 25, 2008 00:26

Thinking about it, A48/A470 too for G

I think thats just about it for Wales, theres nothing on the A55, and no more on the M4

mackerski · Post by **mackerski** » Fri Apr 25, 2008 01:27

jackal wrote:major British interchanges I've put together.

jackal wrote:or indeed ROI

Make up your mind... But we do have a non-British interchange between M50 and N4, only just complete.

odlum · Post by **odlum** » Fri Apr 25, 2008 02:51

Well, interchanges in ROI wont be British but given the NRA's determination to have 'Europes best motorways' - we can, presumably, expect the best interchanges............or at least thats the plan. :/

Derek · Post by **Derek** » Fri Apr 25, 2008 07:43

B. WHIRLPOOL (TURBINE)
• M25/M3

C. OCTOPUS (WINDMILL)
• M25/M11

I thought the M25 / M11 was a whirlpool?

What's a turbine?

CBRD help!

Derek

wrinkly · Post by **wrinkly** » Fri Apr 25, 2008 10:31

Derek is right that M25/M11 is the same type as M25/M3 (a type I've heard called turbAN rather than turbINE, though both are highly appropriate) and different from M74/A723 and M60/M62/M602.

You've got M61/M65 twice.

Edit: have you got M6/M56(/A50)? All movements are possible, though M6(S)<->M56(E) requires going via the roundabout.

Halstead · Post by **Halstead** » Fri Apr 25, 2008 10:59

Presumably the M3/M25 and M211/M25 are the same type but different varients. One difference being that the right turn slip roads on the M3 merge into the left turn sliproads while the M11 doesn't.

Take a look here

Also I think why Chris has called the M74 junction an octopus is because of the way the slip roads merge in so early to save bridge use.

Nic · Post by **Nic** » Fri Apr 25, 2008 11:13

The M42/A45?

jackal · Post by **jackal** » Fri Apr 25, 2008 11:23

Halstead wrote:Presumably the M3/M25 and M211/M25 are the same type but different varients. One difference being that the right turn slip roads on the M3 merge into the left turn sliproads while the M11 doesn't.

Take a look here

Also I think why Chris has called the M74 junction an octopus is because of the way the slip roads merge in so early to save bridge use.

Yes, on the M11/M25 you have one diverge and two merges on each carriageway, just like the M74 junction and M60/M62/M602, while M3/M25 is I think the only genuine whirlpool in that there is one merge and one diverge on each carriageway. That seems to be the most logical way of distinguishing between the two junction variants.

Thanks for the second A470 spot Craggs, seems I need to improve my knowledge of that area! Also thanks to Nic for M42/A45 and to wrinkly for spotting the M65/M61 duplication. I've made corrections to the list.

On the 'British' question, I said 'or indeed ROI' to indicate that, while I'd like to hear if any of the Irish major junctions are ready, it would be something of a departure from the question. Sorry for any confusion - I've removed all reference to ROI now.

Zoney · Post by **Zoney** » Fri Apr 25, 2008 11:39

I know under construction isn't included, but as well as the M50/N4 (partially unrolled cloverleaf) we have:

M50/N7, will be finished soon, a hybrid partially unrolled cloverleaf (there's a tie-in GSJ on the south side of it for a local road, and there's the Luas tram passing through).

N7/N20, a partial junction under construction on the Limerick Southern Ring Road. It's in the style of partially unrolled cloverleaf, but with two movements omitted, it's simplified by one of the "unrolled loops" being absent, and the other not having to cross the mainline of the N20. (link to junction layout). This might eventually be M7/M20, and the cityside N20 may be reclassified as R once the new freeflow junction and N7 SRR phase 2 is built.

As regards planned junctions, there's the planned N6/N17/N18 (possibly to be M6/M17/M18) three level stack

Also crazy mad hybrid junction for N3/M50, and a less crazy but still non-standard junction for M50/M1/N32(M). Also in the longer planning pipeline is something for the N8/N25 junction in Cork; it's currently a GSJ roundabout (rbout at grade on the end of the N25 Southern Ring) but needs freeflow movements (e.g for traffic currently going "straight through" the roundabout). It'll likely be some kind of hybrid stackabout.

I think any of the other planned or built motorway junctions in Ireland are restricted or low capacity designs.

wrinkly · Post by **wrinkly** » Fri Apr 25, 2008 11:46

Don't forget M6/M56, which I added in an edit to my previous post.

jackal · Post by **jackal** » Fri Apr 25, 2008 11:49

Thanks for the info Zoney, just what I was looking for (though I removed the call for Irish info as you were typing!). Sounds like there'll be a few 'major junctions' around in a few years. There seems to be much more of a willingness to remodel junctions in innovative ways in Ireland, rather than just add a flyover to make a stacked roundabout. Strange in some ways then that N6/N17/N18 will be a stackabout. I guess they don't expect there to be a lot of traffic moving between the mainlines?

EDIT:

wrinkly wrote:have you got M6/M56(/A50)? All movements are possible, though M6(S)<->M56(E) requires going via the roundabout.

The reply I was going to give was that it's more than four-way, because of the A50, but I've just realized that many of the stacked roundabouts are also more than four way. So I'll probably have to say 'four way or more', and include Gravelly Hill after all (it is full access, I think) and maybe others. Does M6/M56/A50 still maybe not count because it has two numbers (20/20A), or is that too pedantic?

woodlea1 · Post by **woodlea1** » Fri Apr 25, 2008 12:15

Just north of the cloverleaf in Livingston ( A889/A705) there appears to have been another Cloverleaf which was being dismantled when this arial photo was taken http://tinyurl.com/5vse4u

woodlea1 · Post by **woodlea1** » Fri Apr 25, 2008 12:30

Oops! try this link http://tinyurl.com/6bhvfx

DavidBrown · Post by **DavidBrown** » Fri Apr 25, 2008 12:45

jackal wrote:To qualify an interchange must be (i) four way (so no Gravelly)

I'd take another look at a lot of G and H junctions as a lot of them are more than 4 way.

jackal · Post by **jackal** » Fri Apr 25, 2008 12:49

True, see the edit to my last post.

ForestChav · Post by **ForestChav** » Fri Apr 25, 2008 15:19

M1/A52 is 6 way.

A1M/A638 is an unfolded cloverleaf, as well.

SABRE

Major British interchanges

Major British interchanges

Re: Major British interchanges

Re: Major British interchanges

Re: Major British interchanges

Re: Major British interchanges

Re: Major British interchanges