What are the advantages of a bowtie vs a cloverleaf interchange and vice versa?
What are the advantages of a cloverleaf vs a diamond interchange and vice versa?
Quote from: XamotCGC on August 15, 2021, 01:07:49 AM
What are the advantages of a bowtie vs a cloverleaf interchange and vice versa?
What are the advantages of a cloverleaf vs a diamond interchange and vice versa?
For the latter:
- Cloverleaf offers a no-stoplight, theoretically free flow junction. Can be used for freeway-to-freeway system interchanges.
- Diamond uses less right of way and has no weaving issues, compared to a cloverleaf.
There are no advantages to a bowtie unless traffic has to stop, as it did with Kentucky's toll plazas. The short merge areas are a liability, which is why Kentucky is slowly converting the remaining bowties to diamonds (or variants) or parclos.
Quote from: TheStranger on August 15, 2021, 11:16:51 AM
- Cloverleaf offers a no-stoplight, theoretically free flow junction. Can be used for freeway-to-freeway system interchanges.
But when the cloverleaf ramps become overloaded then the two roads
connected by then frequently fail.
That is one reason why at least some state DOT's no longer allow
cloverleaf interchanges, especially at junctions of freeways, freeways
and expressways.
Quote from: cpzilliacus on August 16, 2021, 11:53:56 AM
Quote from: TheStranger on August 15, 2021, 11:16:51 AM
- Cloverleaf offers a no-stoplight, theoretically free flow junction. Can be used for freeway-to-freeway system interchanges.
But when the cloverleaf ramps become overloaded then the two roads
connected by then frequently fail.
That is one reason why at least some state DOT's no longer allow
cloverleaf interchanges, especially at junctions of freeways, freeways
and expressways.
This makes me curious:
With more recent cloverleafs, are the C/D lanes enough to help alleviate some of those issues?
It's telling that California's Department of Highways opted to essentially invent the stack interchange in the late 1940s/early 1950s as an alternative to cloverleaf usage for the Four-Level between 110/101 in downtown LA, though the space-saving aspects of that particular stack have rarely been implemented in many of the others that have been built since.
Bowtie vs cloverleaf
Bowtie
- takes less space than full cloverleaf
- no weaving between cloverleaf ramps and through traffic
Cloverleaf
- no pseudo-roundabouts at end of ramps so often less difficult for trucks
- can be used where two freeways meet
Quote from: TheStranger on August 16, 2021, 02:44:32 PM
Quote from: cpzilliacus on August 16, 2021, 11:53:56 AM
Quote from: TheStranger on August 15, 2021, 11:16:51 AM
- Cloverleaf offers a no-stoplight, theoretically free flow junction. Can be used for freeway-to-freeway system interchanges.
But when the cloverleaf ramps become overloaded then the two roads
connected by then frequently fail.
That is one reason why at least some state DOT's no longer allow
cloverleaf interchanges, especially at junctions of freeways, freeways
and expressways.
This makes me curious:
With more recent cloverleafs, are the C/D lanes enough to help alleviate some of those issues?
Yes. I would still prefer a semi-directional ramp (as found in a turbine or stack interchange) instead of a loop ramp, but the C/D separates the traffic so that the weaving occurs at an appropriate speed. The space for the C/D lanes also causes the weaving section to be longer, if both routes have C/D lanes.
Quote from: hbelkins on August 15, 2021, 11:36:48 PM
There are no advantages to a bowtie unless traffic has to stop, as it did with Kentucky's toll plazas. The short merge areas are a liability, which is why Kentucky is slowly converting the remaining bowties to diamonds (or variants) or parclos.
Quote from: skluth on August 16, 2021, 05:21:47 PM
Bowtie
- takes less space than full cloverleaf
- no weaving between cloverleaf ramps and through traffic
I think we're using two different definitions of "bowtie" here.
Quote from: Ned Weasel on August 18, 2021, 06:01:06 AM
I think we're using two different definitions of "bowtie" here.
I was thinking that earlier, but I wasn't certain, so I didn't post.
Definition 1: A two-roundabout interchange (or a squished roundabout interchange),
such as here (https://goo.gl/maps/SyoMrqqns5FsPMpf9)
Definition 2: An doubly-folded diamond interchange (as parclo as a parclo can get?),
such as here (https://goo.gl/maps/LZjmtpBaWrbvMAnC7)
Quote from: kphoger on August 18, 2021, 10:29:19 AM
Definition 1: A two-roundabout interchange (or a squished roundabout interchange), such as here (https://goo.gl/maps/SyoMrqqns5FsPMpf9)
Unless I'm missing something, I think you linked to the wrong location. I don't see any roundabouts there.
Quote from: webny99 on August 18, 2021, 10:35:40 AM
Quote from: kphoger on August 18, 2021, 10:29:19 AM
Definition 1: A two-roundabout interchange (or a squished roundabout interchange), such as here (https://goo.gl/maps/SyoMrqqns5FsPMpf9)
Unless I'm missing something, I think you linked to the wrong location. I don't see any roundabouts there.
It's a squished roundabout:
1 (https://goo.gl/maps/TYq9y6WNKAsFfgya8),
2 (https://goo.gl/maps/yw3oTAyHLbdEa1ND7).
If those crossovers were plumped out a bit more, it would be more apparent, but the functionality is the same.
Quote from: kphoger on August 18, 2021, 11:37:10 AM
Quote from: webny99 on August 18, 2021, 10:35:40 AM
Quote from: kphoger on August 18, 2021, 10:29:19 AM
Definition 1: A two-roundabout interchange (or a squished roundabout interchange), such as here (https://goo.gl/maps/SyoMrqqns5FsPMpf9)
Unless I'm missing something, I think you linked to the wrong location. I don't see any roundabouts there.
It's a squished roundabout: 1 (https://goo.gl/maps/TYq9y6WNKAsFfgya8), 2 (https://goo.gl/maps/yw3oTAyHLbdEa1ND7).
If those crossovers were plumped out a bit more, it would be more apparent, but the functionality is the same.
Am I correct in saying that is just a grade-separated Michigan Left? Didn't know we needed that...
Quote from: kphoger on August 18, 2021, 11:37:10 AM
Quote from: webny99 on August 18, 2021, 10:35:40 AM
Quote from: kphoger on August 18, 2021, 10:29:19 AM
Definition 1: A two-roundabout interchange (or a squished roundabout interchange), such as here (https://goo.gl/maps/SyoMrqqns5FsPMpf9)
Unless I'm missing something, I think you linked to the wrong location. I don't see any roundabouts there.
It's a squished roundabout: 1 (https://goo.gl/maps/TYq9y6WNKAsFfgya8), 2 (https://goo.gl/maps/yw3oTAyHLbdEa1ND7).
If those crossovers were plumped out a bit more, it would be more apparent, but the functionality is the same.
Oh, I was looking at the wrong road.
You are correct that functionally, it's
kind of like
half of a squished roundabout. I certainly wouldn't call it a roundabout, though. I'd just call it a U-turn, or, (as just noted) a grade-separated Michigan left.
Quote from: MCRoads on August 18, 2021, 12:47:06 PM
Quote from: kphoger on August 18, 2021, 11:37:10 AM
Quote from: webny99 on August 18, 2021, 10:35:40 AM
Quote from: kphoger on August 18, 2021, 10:29:19 AM
Definition 1: A two-roundabout interchange (or a squished roundabout interchange), such as here (https://goo.gl/maps/SyoMrqqns5FsPMpf9)
Unless I'm missing something, I think you linked to the wrong location. I don't see any roundabouts there.
It's a squished roundabout: 1 (https://goo.gl/maps/TYq9y6WNKAsFfgya8), 2 (https://goo.gl/maps/yw3oTAyHLbdEa1ND7).
If those crossovers were plumped out a bit more, it would be more apparent, but the functionality is the same.
Am I correct in saying that is just a grade-separated Michigan Left? Didn't know we needed that...
It's functionally no different
than this (https://goo.gl/maps/W7x9R2r26C4NABXe7)–just with different yield priorities.
Quote from: kphoger on August 18, 2021, 12:53:08 PM
Quote from: MCRoads on August 18, 2021, 12:47:06 PM
Quote from: kphoger on August 18, 2021, 11:37:10 AM
Quote from: webny99 on August 18, 2021, 10:35:40 AM
Quote from: kphoger on August 18, 2021, 10:29:19 AM
Definition 1: A two-roundabout interchange (or a squished roundabout interchange), such as here (https://goo.gl/maps/SyoMrqqns5FsPMpf9)
Unless I'm missing something, I think you linked to the wrong location. I don't see any roundabouts there.
It's a squished roundabout: 1 (https://goo.gl/maps/TYq9y6WNKAsFfgya8), 2 (https://goo.gl/maps/yw3oTAyHLbdEa1ND7).
If those crossovers were plumped out a bit more, it would be more apparent, but the functionality is the same.
Am I correct in saying that is just a grade-separated Michigan Left? Didn't know we needed that...
It's functionally no different than this (https://goo.gl/maps/W7x9R2r26C4NABXe7)–just with different yield priorities.
Huh. So it is other a long Dogbone, or a grade separated Michigan Left. That is a very strange overlap.
Here is a more obvious (but not quite the same) example. (https://goo.gl/maps/gKFGwNutWiGaFCds9)