Smallest and largest freeflow interchanges

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ChrisH
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Re: Smallest and largest freeflow interchanges

Post by ChrisH » Wed Jul 15, 2020 17:17

Owain wrote:
Wed Jul 15, 2020 13:39
This one in Basel seems to squeeze as many movements as possible! The A2/A3 multiplex runs east-west, while the A18 runs through it north-south.


Switz.png
To be honest the whole A2 through Basel feels like one gigantic underground free flow interchange! But that is a particular hotspot as you say.

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Vierwielen
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Re: Smallest and largest freeflow interchanges

Post by Vierwielen » Wed Sep 02, 2020 14:29

Within the UK, the M60/M61/M62 junction has some claim to being a large freeflow incterchange (or is it a series of interchanges?)

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Re: Smallest and largest freeflow interchanges

Post by M19 » Fri Sep 04, 2020 23:28

The A167(M) exit for the A1058 is freeflow and very compact.
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danfw194
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Re: Smallest and largest freeflow interchanges

Post by danfw194 » Mon Sep 14, 2020 16:06

Probably a case of my own perception superseding the actual reality of the size, but the trumpet at J2 A50 always feels nice and big, certainly by UK standards.

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Re: Smallest and largest freeflow interchanges

Post by jackal » Sat Sep 19, 2020 14:01

ChrisH wrote:
Thu Jul 09, 2020 16:01
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.
I'm late here, but those are both full stacks, just with a few extra bits and pieces in the first case.

The original four-level interchange in LA is actually not much bigger than the first example. Both at 17 zoom:

https://www.google.co.uk/maps/@25.35206 ... 205056,17z
https://www.google.co.uk/maps/@34.06247 ... 488829,17z

The second example is pretty big for a stack, though still smaller than Colnbrook and Merstham, which are also bigger than most if not all American stacks.

With obvious exceptions like Scotstoun, UK freeflow interchanges are generally on the larger side. I don't recall any four-way interchange bigger than Croft, and I've seen a lot of interchanges [/1000 yard stare]
Last edited by jackal on Sat Sep 19, 2020 21:55, edited 1 time in total.

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Re: Smallest and largest freeflow interchanges

Post by booshank » Sat Sep 19, 2020 20:13

jackal wrote:
Sat Sep 19, 2020 14:01
ChrisH wrote:
Thu Jul 09, 2020 16:01
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.
I'm late here, but those are both full stacks, just with a few extra bits and pieces in the first case.

The original four-level interchange in LA is actually not much bigger than the first example. Both at 17 zoom:

https://www.google.co.uk/maps/@25.35206 ... 205056,17z
https://www.google.co.uk/maps/@34.06247 ... 488829,17z

The second example is pretty big for a stack, though still smaller than Almondsbury and Merstham, which are also bigger than most if not all American stacks.

With obvious exceptions like Scotstoun, UK freeflow interchanges are generally on the larger side. I don't recall any four-way interchange bigger than Croft, and I've seen a lot of interchanges [/1000 yard stare]
Are you sure? Google maps seem to use different scales for different parts of the world. I measured the second Qatari example as 2.21 km from diverge to merge on the westbound carriageway, while Almondsbury is only 1.15 km on the M4 eastbound. It's a little difficult to decide exactly where to measure from, but the Qatari interchange is about twice the maximum dimension of Almondsbury.

Perhaps a more easily standardisable measurement is the distance between opposite left turn movements (right turn in right hand traffic countries). This probably gives a better idea of the tightness of the turns as merges and diverges are rather variable in how elongated they are. Measuring from (outer) hard shoulder rumble strip to rumble strip the Qatari interchange is 600 m across NE to SW and Almondsbury is 480 m across NW to SE.

Colnebrook is larger than Almondsbury, 590 m NW to SE. Merstham is quite squashed, 685 m NW to SE, but only 415 m NE to SW

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Re: Smallest and largest freeflow interchanges

Post by booshank » Sat Sep 19, 2020 20:36

The largest interchange I have personal experience is probably this one in Calgary, Canada. It's about 870 m across between the right turn movements NW to SE.

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Re: Smallest and largest freeflow interchanges

Post by jackal » Sat Sep 19, 2020 21:54

booshank wrote:
Sat Sep 19, 2020 20:13
jackal wrote:
Sat Sep 19, 2020 14:01
ChrisH wrote:
Thu Jul 09, 2020 16:01
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.
I'm late here, but those are both full stacks, just with a few extra bits and pieces in the first case.

The original four-level interchange in LA is actually not much bigger than the first example. Both at 17 zoom:

https://www.google.co.uk/maps/@25.35206 ... 205056,17z
https://www.google.co.uk/maps/@34.06247 ... 488829,17z

The second example is pretty big for a stack, though still smaller than Almondsbury and Merstham, which are also bigger than most if not all American stacks.

With obvious exceptions like Scotstoun, UK freeflow interchanges are generally on the larger side. I don't recall any four-way interchange bigger than Croft, and I've seen a lot of interchanges [/1000 yard stare]
Are you sure? Google maps seem to use different scales for different parts of the world. I measured the second Qatari example as 2.21 km from diverge to merge on the westbound carriageway, while Almondsbury is only 1.15 km on the M4 eastbound. It's a little difficult to decide exactly where to measure from, but the Qatari interchange is about twice the maximum dimension of Almondsbury.

Perhaps a more easily standardisable measurement is the distance between opposite left turn movements (right turn in right hand traffic countries). This probably gives a better idea of the tightness of the turns as merges and diverges are rather variable in how elongated they are. Measuring from (outer) hard shoulder rumble strip to rumble strip the Qatari interchange is 600 m across NE to SW and Almondsbury is 480 m across NW to SE.

Colnebrook is larger than Almondsbury, 590 m NW to SE. Merstham is quite squashed, 685 m NW to SE, but only 415 m NE to SW
Sorry I meant Colnbrook rather than Almondsbury.

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Re: Smallest and largest freeflow interchanges

Post by jackal » Sat Sep 19, 2020 22:02

booshank wrote:
Sat Sep 19, 2020 20:36
The largest interchange I have personal experience is probably this one in Calgary, Canada. It's about 870 m across between the right turn movements NW to SE.
Seems about as big as Croft.

https://www.google.com/maps/@51.1751755 ... 031653,15z
https://www.google.co.uk/maps/@53.42543 ... 576912,15z

So too this outside Edmonton:

https://www.google.co.uk/maps/@53.56644 ... 398541,15z

Really surface area needs to be measured to arbitrate between such cases, though that doesn't help with the issue that in some cases (such as Edmonton) it's unclear where one interchange starts and another ends.

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Re: Smallest and largest freeflow interchanges

Post by booshank » Sat Sep 19, 2020 22:42

jackal wrote:
Sat Sep 19, 2020 22:02
booshank wrote:
Sat Sep 19, 2020 20:36
The largest interchange I have personal experience is probably this one in Calgary, Canada. It's about 870 m across between the right turn movements NW to SE.
Seems about as big as Croft.

https://www.google.com/maps/@51.1751755 ... 031653,15z
https://www.google.co.uk/maps/@53.42543 ... 576912,15z

So too this outside Edmonton:

https://www.google.co.uk/maps/@53.56644 ... 398541,15z

Really surface area needs to be measured to arbitrate between such cases, though that doesn't help with the issue that in some cases (such as Edmonton) it's unclear where one interchange starts and another ends.
Yeah I'm really thinking of 4-way interchanges that are relatively symmetrical in perimeter in both planes, so it works to compare stacks, cloverleaves and hybrids of the two.

This is what I meant by measuring from left turn to left turn (right turn to right turn in RH traffic countries):-

Image

Image

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Re: Smallest and largest freeflow interchanges

Post by booshank » Tue Sep 22, 2020 23:33

Abu Dhabi must be in the running for largest trumpet interchange. The loop has a diameter of over 950 m! It's not even clear why it needed to be large as it leads into what looks like a relatively minor road.

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Re: Smallest and largest freeflow interchanges

Post by Chris5156 » Wed Sep 23, 2020 10:58

booshank wrote:
Tue Sep 22, 2020 23:33
Abu Dhabi must be in the running for largest trumpet interchange. The loop has a diameter of over 950 m! It's not even clear why it needed to be large as it leads into what looks like a relatively minor road.
Especially when the left turns at the same junction are so much tighter. Bizarre!

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Re: Smallest and largest freeflow interchanges

Post by Truvelo » Wed Sep 23, 2020 11:29

Chris5156 wrote:
Wed Sep 23, 2020 10:58
booshank wrote:
Tue Sep 22, 2020 23:33
Abu Dhabi must be in the running for largest trumpet interchange. The loop has a diameter of over 950 m! It's not even clear why it needed to be large as it leads into what looks like a relatively minor road.
Especially when the left turns at the same junction are so much tighter. Bizarre!
Such a huge junction is also wasted when one of the roads ploughs into a roundabout.
How would you like your grade separations, Sir?
Big and complex.

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Re: Smallest and largest freeflow interchanges

Post by Bryn666 » Wed Sep 23, 2020 20:40

Truvelo wrote:
Wed Sep 23, 2020 11:29
Chris5156 wrote:
Wed Sep 23, 2020 10:58
booshank wrote:
Tue Sep 22, 2020 23:33
Abu Dhabi must be in the running for largest trumpet interchange. The loop has a diameter of over 950 m! It's not even clear why it needed to be large as it leads into what looks like a relatively minor road.
Especially when the left turns at the same junction are so much tighter. Bizarre!
Such a huge junction is also wasted when one of the roads ploughs into a roundabout.
It's in the middle of the desert so land is probably not a concern, and it gives the local supercar owners chance to slow down from 130 to 90...
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Re: Smallest and largest freeflow interchanges

Post by booshank » Wed Sep 23, 2020 23:23

Bryn666 wrote:
Wed Sep 23, 2020 20:40
Truvelo wrote:
Wed Sep 23, 2020 11:29
Chris5156 wrote:
Wed Sep 23, 2020 10:58

Especially when the left turns at the same junction are so much tighter. Bizarre!
Such a huge junction is also wasted when one of the roads ploughs into a roundabout.
It's in the middle of the desert so land is probably not a concern, and it gives the local supercar owners chance to slow down from 130 to 90...
It's still a bit weird as it's much larger than any of the motorway-motorway interchanges, which are themselves on the large side but within the bounds of what might be considered "normal" sized. Eg the cloverleaf immediately to the south is bigger than Colnebrook, but could fit inside that loop.

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