(https://i.imgur.com/xiuaTTk.jpg)
Some Eastern European engineers have come up with a new type of interchange (https://www.itl-interchange.com/) that's gotten a small amount of media attention (https://www.newcivilengineer.com/innovative-thinking/future-of-roads-space-saving-motorway-interchange-inside-turning-left-09-03-2020/). They call it the inside turning left interchange and involves having the main carriageways split apart creating an open square where the left turn ramps go.
They make great claims, saying that it can handle more traffic than even stack interchanges while requiring fewer grade separated bridges than any interchange design besides the cloverleaf making it less expensive. What do you guys think about it?
^ Looks somewhat similar to I-70 at I-170 (https://goo.gl/maps/4SQCvYFKyUkUT9wS7) in the St. Louis area but requiring more ROW. It would also have problems with left side exits, which a stack does not.
Maybe the eastern I-80/I-35/I-235 interchange in Des Moines prior to the last major modification (which put in the lanes going straight through between I-35 and I-235) (https://goo.gl/maps/X3mryKofxF83andY6) would be a better comparison for how wide the median would have to get
Quote from: Revive 755 on October 24, 2020, 10:51:29 PM
^ Looks somewhat similar to I-70 at I-170 (https://goo.gl/maps/4SQCvYFKyUkUT9wS7) in the St. Louis area but requiring more ROW. It would also have problems with left side exits, which a stack does not.
Maybe the eastern I-80/I-35/I-235 interchange in Des Moines prior to the last major modification (which put in the lanes going straight through between I-35 and I-235) (https://goo.gl/maps/X3mryKofxF83andY6) would be a better comparison for how wide the median would have to get
There's a similar interchange between CT 9 and I-91 (https://www.google.com/maps/@41.6253413,-72.6971854,1725m/data=!3m1!1e3?hl=en).
They have videos (https://www.youtube.com/channel/UCCWDZivagToJjigjVUu3rHA) showing how such an interchange could fit in the existing area of current conventional interchanges. They claim it uses no more space than a cloverleaf and less space than a turbine.
I-390/NY 390 and I-490 (https://www.google.com/maps/@43.1576757,-77.679631,1199m/data=!3m1!1e3) also does this.
Quote from: vdeane on October 24, 2020, 11:29:39 PM
I-390/NY 390 and I-490 (https://www.google.com/maps/@43.1576757,-77.679631,1199m/data=!3m1!1e3) also does this.
I think this may be like the Diverging Diamond Interchange. Someone in one part of the world thinks up one type of interchange without knowing that that design has already been implemented unceremoniously in another part of the world.
Numerous issues:
Left exits are generally not favored.
At least in this example, there are only two thru lanes thru the interchange on each carriageway. Reducing throughput by even one lane generally creates congestion. Here, it's reduced by 2 lanes, which greatly reduces capacity, not increase it.
Also in this example, there is a significant amount of overpasses. Overpasses are extremely costly. For the most part the overpasses can be eliminated in favor of embankment, but even then there's still a need for 8 separate overpasses.
There are S curves approaching and leaving the interchange area. Whenever possible, it's better to place interchanges and the accel/decel lanes on straightaways.
Quote from: jeffandnicole on October 25, 2020, 02:26:42 AM
Numerous issues:
Left exits are generally not favored.
At least in this example, there are only two thru lanes thru the interchange on each carriageway. Reducing throughput by even one lane generally creates congestion. Here, it's reduced by 2 lanes, which greatly reduces capacity, not increase it.
Also in this example, there is a significant amount of overpasses. Overpasses are extremely costly. For the most part the overpasses can be eliminated in favor of embankment, but even then there's still a need for 8 separate overpasses.
There are S curves approaching and leaving the interchange area. Whenever possible, it's better to place interchanges and the accel/decel lanes on straightaways.
That's supposed to be one of the great advantages. It requires fewer overpasses than a comparable stack or turbine interchange.
This is the old Zoo Interchange in Milwaukee. It's quite similar with left on and off ramps in all directions. It was named for the nearby zoo, not because it was terrible with lots of weaving and accidents causing backups on both freeways with drivers turning into animals. They rebuilt it a few years back into an interchange that worked (https://www.google.com/maps/@43.026143,-88.0367421,1253m/data=!3m1!1e3?hl=en). Let's not repeat the mistakes of the past with an alleged new idea, like politicians or fashion designers.
(https://urbanmilwaukee.com/wp-content/uploads/2013/06/8955136000_43dfbbff37.jpg)
It's not new. It's effectively a directional interchange (https://www.aaroads.com/forum/index.php?topic=23254.0)...
Quote from: froggie on October 25, 2020, 11:27:14 AM
It's not new. It's effectively a directional interchange (https://www.aaroads.com/forum/index.php?topic=23254.0)...
But it has much shorter left turn ramps.
Quote from: kernals12 on October 25, 2020, 08:22:19 AM
Quote from: jeffandnicole on October 25, 2020, 02:26:42 AM
Numerous issues:
Left exits are generally not favored.
At least in this example, there are only two thru lanes thru the interchange on each carriageway. Reducing throughput by even one lane generally creates congestion. Here, it's reduced by 2 lanes, which greatly reduces capacity, not increase it.
Also in this example, there is a significant amount of overpasses. Overpasses are extremely costly. For the most part the overpasses can be eliminated in favor of embankment, but even then there's still a need for 8 separate overpasses.
There are S curves approaching and leaving the interchange area. Whenever possible, it's better to place interchanges and the accel/decel lanes on straightaways.
That's supposed to be one of the great advantages. It requires fewer overpasses than a comparable stack or turbine interchange.
But more than a cloverleaf.
Quote from: kernals12 on October 25, 2020, 11:29:25 AM
Quote from: froggie on October 25, 2020, 11:27:14 AM
It's not new. It's effectively a directional interchange (https://www.aaroads.com/forum/index.php?topic=23254.0)...
But it has much shorter left turn ramps.
Doesn't matter. Fundamental design is still the same..."left-turning movements" have ramps on the left.
Four overpasses: M25 at A1(M), also M25 at M20 if you ignore the minor roads
Quote from: skluth on October 25, 2020, 11:23:38 AM
This is the old Zoo Interchange in Milwaukee. It's quite similar with left on and off ramps in all directions. It was named for the nearby zoo, not because it was terrible with lots of weaving and accidents causing backups on both freeways with drivers turning into animals. They rebuilt it a few years back into an interchange that worked (https://www.google.com/maps/@43.026143,-88.0367421,1253m/data=!3m1!1e3?hl=en). Let's not repeat the mistakes of the past with an alleged new idea, like politicians or fashion designers.
(https://urbanmilwaukee.com/wp-content/uploads/2013/06/8955136000_43dfbbff37.jpg)
I don't see where the weaving would occur
The junction between I-26 and I-40 outside Asheville, NC is similar, though has a couple missing movements due to proximity to other connections.
https://www.google.com/maps/@35.5544399,-82.6066082,1881m/data=!3m1!1e3!5m1!1e1?hl=en
Junction of I-95 at MD-32 (Patuxent Freeway) in Columbia, Howard County, Maryland has some similarities. Google Maps here (https://www.google.com/maps/place/39%C2%B009'29.8%22N+76%C2%B049'38.5%22W/@39.158282,-76.8295357,17z/data=!3m1!4b1!4m14!1m7!3m6!1s0x89b7e7578b21c5bb:0x94a0b5f24fc2b19f!2sSavage,+MD!3b1!8m2!3d39.1378733!4d-76.8217374!3m5!1s0x0:0x0!7e2!8m2!3d39.1582822!4d-76.8273473).
The point (https://www.google.com/maps/place/39%C2%B009'29.5%22N+76%C2%B049'26.4%22W/@39.158203,-76.8261917,17z/data=!3m1!4b1!4m14!1m7!3m6!1s0x89b7e7578b21c5bb:0x94a0b5f24fc2b19f!2sSavage,+MD!3b1!8m2!3d39.1378733!4d-76.8217374!3m5!1s0x0:0x0!7e2!8m2!3d39.1582029!4d-76.824003) at which the left-side ramp from eastbound MD-32 to northbound I-95 merges on the left is problematic (I have seen several crashes here over the years).
The cloverleaf ramp (https://www.google.com/maps/place/39%C2%B009'27.0%22N+76%C2%B049'21.1%22W/@39.157488,-76.8236273,18z/data=!3m1!4b1!4m14!1m7!3m6!1s0x89b7e7578b21c5bb:0x94a0b5f24fc2b19f!2sSavage,+MD!3b1!8m2!3d39.1378733!4d-76.8217374!3m5!1s0x0:0x0!7e2!8m2!3d39.1574875!4d-76.8225332) from northbound I-95 to westbound MD-32 is quite sharp, (signed for 30 MPH) and there have been truck mishaps on that ramp more than once.
Quote from: skluth on October 25, 2020, 11:23:38 AM
This is the old Zoo Interchange in Milwaukee. It's quite similar with left on and off ramps in all directions. It was named for the nearby zoo, not because it was terrible with lots of weaving and accidents causing backups on both freeways with drivers turning into animals. They rebuilt it a few years back into an interchange that worked (https://www.google.com/maps/@43.026143,-88.0367421,1253m/data=!3m1!1e3?hl=en). Let's not repeat the mistakes of the past with an alleged new idea, like politicians or fashion designers.
(https://urbanmilwaukee.com/wp-content/uploads/2013/06/8955136000_43dfbbff37.jpg)
The old Albuquerque Interchange of I-25 and 40 was built quite like this old Zoo interchange as well. Built in the mid sixties, it became overloaded within two decades. Lack of a Beltway meant all longer distance traffic needed to go through it, and it was under-built to begin with.
Exiting means one had to move over to the fast lane to exit, and then one enters the fast lane upon reaching their chosen route. Not good design.
Not sure why Connecticut adopted the left hand exit/entrance mode to the extent that they did.
Quote from: kernals12 on October 25, 2020, 01:19:12 PM
Quote from: skluth on October 25, 2020, 11:23:38 AM
This is the old Zoo Interchange in Milwaukee. It's quite similar with left on and off ramps in all directions. It was named for the nearby zoo, not because it was terrible with lots of weaving and accidents causing backups on both freeways with drivers turning into animals. They rebuilt it a few years back into an interchange that worked (https://www.google.com/maps/@43.026143,-88.0367421,1253m/data=!3m1!1e3?hl=en). Let's not repeat the mistakes of the past with an alleged new idea, like politicians or fashion designers.
(https://urbanmilwaukee.com/wp-content/uploads/2013/06/8955136000_43dfbbff37.jpg)
I don't see where the weaving would occur
It's the same problem as every other highway with left entrance/exit ramps compounded by the nearby interchanges within a mile in all four directions. There was a lot of traffic using the left entrance/exit ramps in combination with using those next interchanges. Others would be surprised by the left exits and rapidly cross to make their exits. Many were visitors going to the zoo, the state fairgrounds, and the nearby hospitals and unfamiliar with the area. I believe it was either the busiest or second-busiest (after the Marquette Interchange at I-43/I-94 downtown) interchange in Wisconsin. I know my relatives in Oak Creek and Waukesha hated it.
Either this interchange would need to be really expansive, or the grades on the inner ramps would need to be colossally steep.
Quote from: kernals12 on October 25, 2020, 01:53:53 AM
Quote from: vdeane on October 24, 2020, 11:29:39 PM
I-390/NY 390 and I-490 (https://www.google.com/maps/@43.1576757,-77.679631,1199m/data=!3m1!1e3) also does this.
I think this may be like the Diverging Diamond Interchange. Someone in one part of the world thinks up one type of interchange without knowing that that design has already been implemented unceremoniously in another part of the world.
Except there is one small difference: the DDI was actually a good idea. This design has already been built numerous times, and almost all of them were replaced by interchanges that actually work. It is almost funny how bad this design is!
A similar interchange at I-96 and US-23 was rebuilt. I don't recall if the old one had left exits/entrances for all 4 directions, but it had several. The median of I-96 was so wide that there were houses in it.
Quote from: froggie on October 25, 2020, 11:27:14 AM
It's not new. It's effectively a directional interchange (https://www.aaroads.com/forum/index.php?topic=23254.0)...
Quoted for emphasis.
All they did was spread the mainline lanes apart instead of keeping them together. Other than that, it's the same beast.
Another close one - I-37 / US-281 / I-35 junction in San Antonio, TX
https://www.google.com/maps/@29.4391138,-98.4786416,923m/data=!3m1!1e3!5m1!1e1
Has a few left exits and entrances, particularly due to I-37 / US-281 splitting, though has a few semi-directional ramps.
Quote from: kphoger on October 26, 2020, 10:17:38 AM
Quote from: froggie on October 25, 2020, 11:27:14 AM
It's not new. It's effectively a directional interchange (https://www.aaroads.com/forum/index.php?topic=23254.0)...
Quoted for emphasis.
All they did was spread the mainline lanes apart instead of keeping them together. Other than that, it's the same beast.
My mom hated that interchange with a passion . Going from NB I-44 to WB I-44 was especially harrowing, as the mainline traffic was going 65-70, but ramp traffic is going around 40-45.
But my mom's absolutely most hated interchange was the I-35 and I-240. I don't blame her. The loop ramps are tiny, and I-240 traffic did not give 2 craps about people merging onto the freeway. Hell, I wasn't driving, and I was always afraid we would get rear-ended by a butthole exiting SB I-35 at 65. Thank god they are redoing that interchange, I won't miss it.
The interchange that came to mind for me is I-70/77 in Ohio which also does half of this proposal. And looking at that existing interchange makes me believe that you would have to separate the carriageways by a significant amount more than that existing interchange to fit the ramps in the middle. Perhaps as much as doubling the distance between the carriageways would be necessary. The image above looks nice but I think it's deceiving about the size of such an interchange. I think it's just too big to actually make it worth while without even getting to the left exit issue.
Also take into account that the advisory speed for one of the left exit ramps in the interchange I mentioned is only 45 mph.
Meanwhile, the interchange I thought of was the original I-95/695 interchange northeast of Baltimore, where the carriageways crossed over each other to facilitate the left exit/entrance ramps. (Since replaced with a more conventional stack interchange, courtesy of the I-95 ETL construction in that area.)
Quote from: Revive 755 on October 24, 2020, 10:51:29 PM
^ Looks somewhat similar to I-70 at I-170 (https://goo.gl/maps/4SQCvYFKyUkUT9wS7) in the St. Louis area but requiring more ROW. It would also have problems with left side exits, which a stack does not.
Wow I'm surprised there's no advisory speed posted for the left exit the in the SE quadrant. They went for warning arrows instead. Ugh. The other left exits are 35 or 40 mph.
Quote from: jmacswimmer on October 26, 2020, 05:14:10 PM
Meanwhile, the interchange I thought of was the original I-95/695 interchange northeast of Baltimore, where the carriageways crossed over each other to facilitate the left exit/entrance ramps. (Since replaced with a more conventional stack interchange, courtesy of the I-95 ETL construction in that area.)
That one was much better in terms of footrpint. I wouldn't be surprised if that kind of interchange led to the diverging diamond interchange.
Quote from: BrianP on October 26, 2020, 05:27:04 PM
Quote from: jmacswimmer on October 26, 2020, 05:14:10 PM
Meanwhile, the interchange I thought of was the original I-95/695 interchange northeast of Baltimore, where the carriageways crossed over each other to facilitate the left exit/entrance ramps. (Since replaced with a more conventional stack interchange, courtesy of the I-95 ETL construction in that area.)
That one was much better in terms of footrpint. I wouldn't be surprised if that kind of interchange led to the diverging diamond interchange.
It did.
I-80 / I-57 is half of it
https://www.google.com/maps/@41.564707,-87.7420771,1244m/data=!3m1!1e3?hl=en
Quote from: skluth on October 25, 2020, 11:23:38 AM
This is the old Zoo Interchange in Milwaukee. It's quite similar with left on and off ramps in all directions. It was named for the nearby zoo, not because it was terrible with lots of weaving and accidents causing backups on both freeways with drivers turning into animals. They rebuilt it a few years back into an interchange that worked (https://www.google.com/maps/@43.026143,-88.0367421,1253m/data=!3m1!1e3?hl=en). Let's not repeat the mistakes of the past with an alleged new idea, like politicians or fashion designers.
(https://urbanmilwaukee.com/wp-content/uploads/2013/06/8955136000_43dfbbff37.jpg)
The US 75/SH 11 interchange in Tulsa (https://www.google.com/maps/@36.1993641,-95.9515759,1402m/data=!3m1!1e3) is exactly the same design. I haven't been there in a few years now, but every time I've passed through that interchange there's been a hell of a lot of weaving between the Gilcrease and 36th St. N interchanges on 75.
Quote from: vdeane on October 24, 2020, 11:29:39 PM
I-390/NY 390 and I-490 (https://www.google.com/maps/@43.1576757,-77.679631,1199m/data=!3m1!1e3) also does this.
Glad you mentioned that interchange, because that's the first thing I thought of when I saw the OP. It was basically identical before the current improvement project(s).
There's another one at I-40, I-26, and I-240 west of Asheville (https://www.google.com/maps/@35.5553279,-82.6137488,16z), too, though it's missing one movement. The interchange is to be reconstructed, and a scheme was put forth that eliminated the left-hand entrances and exits, but then they decided to build it back to the same layout, except with the missing movement added.
Quote from: BrianP on October 26, 2020, 05:23:18 PM
Quote from: Revive 755 on October 24, 2020, 10:51:29 PM
^ Looks somewhat similar to I-70 at I-170 (https://goo.gl/maps/4SQCvYFKyUkUT9wS7) in the St. Louis area but requiring more ROW. It would also have problems with left side exits, which a stack does not.
Wow I'm surprised there's no advisory speed posted for the left exit the in the SE quadrant. They went for warning arrows instead. Ugh. The other left exits are 35 or 40 mph.
There is. It's 35 MPH (https://goo.gl/maps/LVfnvoV2Spheo4JJ7).
Quote from: MCRoads on October 27, 2020, 12:42:48 AM
Quote from: BrianP on October 26, 2020, 05:23:18 PM
Quote from: Revive 755 on October 24, 2020, 10:51:29 PM
^ Looks somewhat similar to I-70 at I-170 (https://goo.gl/maps/4SQCvYFKyUkUT9wS7) in the St. Louis area but requiring more ROW. It would also have problems with left side exits, which a stack does not.
Wow I'm surprised there's no advisory speed posted for the left exit the in the SE quadrant. They went for warning arrows instead. Ugh. The other left exits are 35 or 40 mph.
There is. It's 35 MPH (https://goo.gl/maps/LVfnvoV2Spheo4JJ7).
Aahh thanks. I missed it on streetview which was hard to do. I was expecting the sign to be later so I started right under that sign gantry. Which was far enough to not see it.