Smallest and largest freeflow interchanges

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ChrisH
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Smallest and largest freeflow interchanges

Post by ChrisH »

What are the most compact, or the most sprawling, interchanges you know of?

I'll start off with one contender for each from Qatar:

This one Google Maps OSM link manages free-flow turns and straight-across movements in all directions but has built-up areas right up close to it, and is only about 150m across.

Whereas the new Orbital Highway has some absolutely gargantuan interchanges such as this stack interchange Google Maps OSM link, which is about 600m across at its minimum.
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Re: Smallest and largest freeflow interchanges

Post by Bryn666 »

Locally Croft Interchange is huge.

From the westbound exit slip road leaving, to the eastbound exit slip road leaving, the two extreme points of the interchange, is a distance of 2520m, or just over 1.5 miles.

You can fit the circle of the Coventry Ring Road between those two diverges twice.
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Re: Smallest and largest freeflow interchanges

Post by Owain »

This would probably count technically as a free-flow interchange: https://www.google.co.uk/maps/place/070 ... d8.9400383

It won't be the world's largest, but it has always struck me as being 'unnecessarily large' (and confusing in the middle of the night, too!).

Italy seems to specialise in both extremes of 'sprawling interchanges' and 'unbelievably compact' ones.
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Re: Smallest and largest freeflow interchanges

Post by Truvelo »

The most compact freeflow GSJ will obviously be a very small cloverleaf at the junction of two single carriageways. Italy may well be a contender given the rather dodgy GSJ's I've seen over there.
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Re: Smallest and largest freeflow interchanges

Post by JohnnyMo »

Owain wrote: Thu Jul 09, 2020 18:46 This would probably count technically as a free-flow interchange: https://www.google.co.uk/maps/place/070 ... d8.9400383
...
How can this count as free flowing
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Re: Smallest and largest freeflow interchanges

Post by Steven »

JohnnyMo wrote: Thu Jul 09, 2020 20:34
Owain wrote: Thu Jul 09, 2020 18:46 This would probably count technically as a free-flow interchange: https://www.google.co.uk/maps/place/070 ... d8.9400383
...
How can this count as free flowing
It's in Italy.

Driving laws are more general guidelines than rules.

:wink:
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Re: Smallest and largest freeflow interchanges

Post by Owain »

Steven wrote: Thu Jul 09, 2020 20:36
JohnnyMo wrote: Thu Jul 09, 2020 20:34
Owain wrote: Thu Jul 09, 2020 18:46 This would probably count technically as a free-flow interchange: https://www.google.co.uk/maps/place/070 ... d8.9400383
...
How can this count as free flowing
It's in Italy.

Driving laws are more general guidelines than rules.

:wink:
:laugh: It's also on Google Maps, which means it's a mistake! Should've referenced SABRE Maps instead!! :facepalm:

The thing is a massive anticlockwise gyratory which has no 'stop' or 'give way' signs/lines. In some places - possibly even all of it - the carriageway is a one-way S3. There is so little traffic that you can drive through it without meeting more than one or two other vehicles at any time of day or night. In fact the only reason for even slowing down at all is to avoid missing an exit and having to drive all the way round the thing again (I think my record was 3 laps before finding the correct turn, after discovering that the sign had fallen off its post!).
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Truvelo
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Re: Smallest and largest freeflow interchanges

Post by Truvelo »

There are roundabouts which are truly freeflowing with no stop or give way markings.

https://goo.gl/maps/zJLWKhfZrWfGPe7N7
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Re: Smallest and largest freeflow interchanges

Post by M4 Cardiff »

I remember last year there was a thread on Massive Junctions, and I compiled a list
viewtopic.php?f=1&t=40885&p=1086016#p1086016

The biggest definitive single one in the UK I could find was Croft, with an internal area of 90 hectares. The only bigger ones were the M6-M6(T)-M42 at Water Orton, which is really a set of linked junctions and the M3-M27 that may or may not be a single junction. However both of these have some ends that drop off to roundabouts, so probably don't qualify for this thread.
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Re: Smallest and largest freeflow interchanges

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Re: Smallest and largest freeflow interchanges

Post by Owain »

Truvelo wrote: Thu Jul 09, 2020 19:51The most compact freeflow GSJ will obviously be a very small cloverleaf at the junction of two single carriageways. Italy may well be a contender given the rather dodgy GSJ's I've seen over there.
For your pleasure ..... these are all in the vicinity of Cagliari:

1. A 'squashed' freeflow GSJ
SS131-SS554 squashed freeflow GSJ.jpg

2. A freeflow GSJ which appears to have been built using as many existing roads as possible!
SS131-SS131dir use-as-many-existing-roads-as-possible GSJ.png

3. An incredibly compact urban GSJ, which is freeflowing apart from where the red slips meet the yellow carriageway
SS131dir-exSS125 compact GSJ.jpg
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Owain
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Re: Smallest and largest freeflow interchanges

Post by Owain »

I guess both of these would technically count as giant freeflowing interchanges, because the carriageways on the route passing through the junction are separate for kilometres before and after the meeting point with the connecting route:


A10-A26
A10-A26 interchange.jpg

A7-A12
A7-A12 interchange.jpg
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Re: Smallest and largest freeflow interchanges

Post by c2R »

Owain wrote: Fri Jul 10, 2020 17:03 3. An incredibly compact urban GSJ, which is freeflowing apart from where the red slips meet the yellow carriageway
SS131dir-exSS125 compact GSJ.jpg
That reminds me very much of the Ilford junction on the North Circular, which is of a similar design, although the slip roads cross one another at grade. Ilford_Bridge_Interchange
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From the SABRE Wiki: Ilford Bridge Interchange :

Ilford Bridge Interchange is a uniquely shaped junction serving Ilford in East London.

The junction was originally planned as part of the Ringways during the 1960s and early 1970s. The layout at the time would have been a roundabout with the M15 passing below. The southbound exit slip would have avoided the roundabout completely.

The M15 along with the rest of the

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