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Redundant Interchanges

Started by Georgia Guardrail, June 06, 2023, 12:15:55 AM

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TheHighwayMan3561

In Bloomington, MN when the I-494/TH 77 interchange was upgraded in the 90s as part of the construction of the Mall of America, a new flyover with additional feeder ramps from the streets serving the mall was built from northbound 77 to westbound 494. However, the existing NB/WB loop of the cloverleaf was kept as the HOV/carpool ramp and recently served as the "detour" when the flyover ramp was closed for construction.
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wanderer2575

When I drove to Naperville IL a couple weeks ago, my GPS routed me off I-294 to sbd I-55 and then right back onto I-294.  I'm sure this isn't intended to be redundant, but the location of the ramps does it for this movement.



CtrlAltDel

Quote from: wanderer2575 on June 07, 2023, 09:57:01 AM
When I drove to Naperville IL a couple weeks ago, my GPS routed me off I-294 to sbd I-55 and then right back onto I-294.  I'm sure this isn't intended to be redundant, but the location of the ramps does it for this movement.

Similarly, you can get off northbound I-355 to get on eastbound I-88 and then back on to northbound I-355:



Also, this used to be exit 218 on I-40 in New Mexico at Clines Corners, with direct and indirect access to that gas station at the upper left, but the direct access was removed in about 2016.




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hbelkins

Quote from: CtrlAltDel on June 06, 2023, 12:03:22 PM
Does this count?


Exits 361 and 363 on I-70 in Colorado at Limon.

What was the logic for building this as two full diamonds instead of half diamonds? Seems wasteful and redundant to me.


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CoreySamson

A similar thread I did last year, for reference.

https://www.aaroads.com/forum/index.php?topic=30920.msg2701247#msg2701247

The one in Taylor in the OP of that thread and the stack overlaid on a cloverleaf in El Paso are probably my favorite redundant interchanges.
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1995hoo

CoreySamson, thanks for posting that link. I was getting ready to post the same two locations I had mentioned in that thread (not remembering that thread existed), but since you linked it, I'll just quote what I posted there. Regarding the method of going from I-95 to the Beltway that involves circling around past the park-and-ride, I remember we went that way once when I was a kid back before the flyover ramp existed–the only options were the loop ramp or going past what is now the park-and-ride. Normally we went the other way around the Beltway, but for that particular trip we were going around the eastern side. My mother got confused by the signs, so I gave my father directions to go the longer way around what is now the park-and-ride and when we followed it, his reaction was along the lines of, "What kind of screwy route is this?!" To which I replied, "We've never gone this way before and I wanted to see where it went." (This was probably in the late 1970s or very early 1980s.) I don't think he was all that amused, though it didn't really matter.

Quote from: 1995hoo on January 25, 2022, 03:19:12 PM
In Maryland, southbound I-95 has three different ways to access the Inner Loop of the Capital Beltway–a two-lane flyover (the newest of the three ramps), a cloverleaf-style loop ramp that was the original primary route and is now used primarily for traffic wishing to access the Beltway's exit to US-1 (which is inaccessible via the flyover), and a ramp that's accessed by circling past the park-and-ride lot at the stub end of where the road was never completed. That third ramp would have been the northbound I-95 ramp to the Inner Loop had I-95 been constructed as planned.

In Virginia, the Inner Loop of the Beltway used to have two separate ramps to westbound I-66: Exit 9A (later 49A) was a left-side exit and Exit 9C (later 49C) was a right-side loop-around. The reason for the duplicate ramps was primarily to eliminate the danger caused by requiring traffic entering from US-50 just to the south to cut across four lanes of traffic to the left-side exit in a short distance, but in practice it didn't help because people cut across anyway. The duplication no longer exists because HO/T lane construction restricted the left-side exit to HO/T traffic and the general-purpose lanes now have only one ramp available.

Then there is this oddity from southbound 416 to westbound 401 in Ontario. My sat-nav wanted me to take the longer way where you exit 416 to 16, then exit that to the right onto 401. I followed it just to see if there was any particular reason to go that way. There wasn't. Maybe whoever programmed the sat-nav knew the BGS for the longer route says "TO/VERS U.S.A." and got confused when programming it.
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zzcarp

Quote from: hbelkins on June 07, 2023, 12:37:41 PM
Quote from: CtrlAltDel on June 06, 2023, 12:03:22 PM
Does this count?


Exits 361 and 363 on I-70 in Colorado at Limon.

What was the logic for building this as two full diamonds instead of half diamonds? Seems wasteful and redundant to me.

There was an entire thread on that subject: https://www.aaroads.com/forum/index.php?topic=24830.0
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jmacswimmer

Similar to the US 29/I-70 & US 460/I-81 examples upthread, Shawan Rd WB has both a loop ramp as well as a left-turn to access I-83 SB at exit 20 in the northern Baltimore suburbs.

Quote from: 1995hoo on June 07, 2023, 01:35:14 PM
Regarding the method of going from I-95 to the Beltway that involves circling around past the park-and-ride, I remember we went that way once when I was a kid back before the flyover ramp existed–the only options were the loop ramp or going past what is now the park-and-ride. Normally we went the other way around the Beltway, but for that particular trip we were going around the eastern side. My mother got confused by the signs, so I gave my father directions to go the longer way around what is now the park-and-ride and when we followed it, his reaction was along the lines of, "What kind of screwy route is this?!" To which I replied, "We've never gone this way before and I wanted to see where it went." (This was probably in the late 1970s or very early 1980s.) I don't think he was all that amused, though it didn't really matter.

That park-and-ride trick you describe comes in handy during rush hour when traffic tends to crawl across much of the length of the flyover leading into the merge with I-495.
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michravera

Quote from: paulthemapguy on June 06, 2023, 11:53:15 AM
Every second interchange in the state of California.  They don't seem to understand the meaning of "limited-access freeway".

That's "Every second URBAN interchange on OLDER freeways in California". On newer and rural freeways, take I-280 (or even CASR-87), for instance, interchanges are all a couple miles apart.

Bruce

#34
Quote from: Amaury on June 07, 2023, 01:41:21 AM
I don't think Washington has any.

Disclaimer: While I have driven all interstates and US highways in Washington, I haven't driven all state routes in Washington. So, this is just what I think.

There are a few that might count. SR 512 around the South Hill Mall has a redundant set of ramps due to the 90-degree turn. The Eastgate interchange on I-90 has an extra set of ramps to 161st Avenue SE that are utterly pointless because of the existing entrance/exit at 166th.

A few dogbone interchanges have redundant slip ramps to bypass a very simple in-roundabout move (such as I-5 at Cowlitz Way, I-82 at Valley Mall, or I-90 at SR 902). Another one, I-90 at Grove Road, has cloverleaf ramps that bypass a roundabout with a valid entrance (see here).

Arguably the three interchanges at Snoqualmie Summit are redundant to each other as well.

SilverMustang2011

The Arlington Expressway in Jacksonville has an exit onto University Blvd with separate ramps to go south or north, but then a few hundred feet down the road there's a pair of off-ramps to the frontage road, one of which lets you turn around and head north on University Blvd: https://goo.gl/maps/GZzaMchWjnptYx7A6

Long-term the plan is to remove the ramp. People have also discussed just removing The Arlington Expressway altogether. On one hand, it's quite outdated and doesn't save that much time since it's only a couple miles long and dumps traffic onto a surface road (Atlantic Blvd). But on the other hand it's quite....quirky so I'd be sad to see it go.

jp the roadgeek

A couple in CT:

I-84 West to I-384 East.  Conventional method: Exit 59.  Unconventional: Access via Exit 62/60 c/d road.

US 5/CT 15 South to I-91 South.  Conventional method: Exit 86.  Unconventional: Access via Exit 87 and stay on ramp rather than exiting onto Airport Rd.
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SeriesE

I-5 south to Laval Road has two ramps for each direction, but the westbound ramp is redundant since it's possible to turn left to westbound Laval Road using the eastbound ramp too.

JustDrive

#38
SB 405 at the Century/Imperial exits. The east-west designations are for show, as you can access either road in any direction from any ramp.

NB 15 and 215 both access Murrieta Hot Springs Road with complete freedom of movement.

roadman65



https://www.google.com/maps/@30.3552199,-81.5548173,16.13z?entry=ttu

Merril Road EB has two exits from I-295 SB. One from the previous exit via FL 113 and the second (actual) ramp to Merrill Road that has a signalized intersection to allow left turns.

https://goo.gl/maps/7nUrdWjvw1nvhnLC8
Funny thing is the second ramp is signed for WB while EB gets signed on the previous ramp wit FL 113.
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Thing 342

I-295 SB to I-64 EB has two ramps: a loop ramp from the original cloverleaf interchange plus a flyover that was added in a later project. I'm not really sure why they decided to keep the loop ramp open after the flyover opened.

dantheman

Quote from: roadman65 on July 02, 2023, 03:03:13 PM


https://www.google.com/maps/@30.3552199,-81.5548173,16.13z?entry=ttu

Merril Road EB has two exits from I-295 SB. One from the previous exit via FL 113 and the second (actual) ramp to Merrill Road that has a signalized intersection to allow left turns.

https://goo.gl/maps/7nUrdWjvw1nvhnLC8
Funny thing is the second ramp is signed for WB while EB gets signed on the previous ramp wit FL 113.

Bonus points for this one, because if the USGS topos on Acme Mapper can be trusted, this interchange had the same redundancy in its previous design, before FL 113 was turned into a freeway. The SPUI that's now at FL 113 and Merrill Road was a four-way intersection, but the Exit 46 ramp (Merrill Road West) from I-295 SB still had a left-turn available to Merrill Road EB.

In both of these configurations, I can't see any reason why the Exit 46-to-Merrill EB left turn is needed. Why not make the end of that ramp right-turn-only, potentially allowing Merrill Road WB to be free-flowing through that intersection rather than needing a stoplight for the left turn out of the exit ramp? Unlike some examples in this thread, there is not even a single business or driveway between the two ramps, so there is not a single thing that can be accessed uniquely from a left turn from the Exit 46 ramp.

kurumi

I-880 NB at Dixon Landing Road, Milpitas: https://goo.gl/maps/i4ZEMkQVMr2Duf287

The "Dixon Landing Road West" loop ramp offers a superfluous left turn onto DLR East; and with two left turns you could use the "East" exit to access DLR west.

The NE quadrant ramp pair could be a RIRO on Dixon Landing Road; but instead it's part of a full 4-way intersection (except no left turn from DLR east onto I-880 north).
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SilverMustang2011

Quote from: roadman65 on July 02, 2023, 03:03:13 PM


https://www.google.com/maps/@30.3552199,-81.5548173,16.13z?entry=ttu

Merril Road EB has two exits from I-295 SB. One from the previous exit via FL 113 and the second (actual) ramp to Merrill Road that has a signalized intersection to allow left turns.

https://goo.gl/maps/7nUrdWjvw1nvhnLC8
Funny thing is the second ramp is signed for WB while EB gets signed on the previous ramp wit FL 113.

The direction-specific signage is due to WB Merrill Road not being accessible from the SB FL 113 ramp. They designed it in such a way that I-295 NB can make left or right turns off the connecting loop ramp but FL 113 SB can only turn right: https://goo.gl/maps/pxKJYMfrAW5PU3LW9

SilverMustang2011

Quote from: dantheman on July 02, 2023, 04:09:21 PM
Quote from: roadman65 on July 02, 2023, 03:03:13 PM


https://www.google.com/maps/@30.3552199,-81.5548173,16.13z?entry=ttu

Merril Road EB has two exits from I-295 SB. One from the previous exit via FL 113 and the second (actual) ramp to Merrill Road that has a signalized intersection to allow left turns.

https://goo.gl/maps/7nUrdWjvw1nvhnLC8
Funny thing is the second ramp is signed for WB while EB gets signed on the previous ramp wit FL 113.

Bonus points for this one, because if the USGS topos on Acme Mapper can be trusted, this interchange had the same redundancy in its previous design, before FL 113 was turned into a freeway. The SPUI that's now at FL 113 and Merrill Road was a four-way intersection, but the Exit 46 ramp (Merrill Road West) from I-295 SB still had a left-turn available to Merrill Road EB.

In both of these configurations, I can't see any reason why the Exit 46-to-Merrill EB left turn is needed. Why not make the end of that ramp right-turn-only, potentially allowing Merrill Road WB to be free-flowing through that intersection rather than needing a stoplight for the left turn out of the exit ramp? Unlike some examples in this thread, there is not even a single business or driveway between the two ramps, so there is not a single thing that can be accessed uniquely from a left turn from the Exit 46 ramp.

Posted my above comment before I read yours, good points. The best part is they just replaced the traffic light off Exit 46 with a mast arm between 2021 - 2022 per GSV so they likely intend to keep this redundancy for a while.

sprjus4

Quote from: Thing 342 on July 02, 2023, 03:29:12 PM
I-295 SB to I-64 EB has two ramps: a loop ramp from the original cloverleaf interchange plus a flyover that was added in a later project. I'm not really sure why they decided to keep the loop ramp open after the flyover opened.
Redundancy, I suppose, if any accident blocks the flyover ramp, traffic can simply be diverted to the original loop ramp.

TheStranger

I think I have mentioned this one before, but it is a Bay Area example that I've known about for years:

At Santa Teresa Boulevard, Route 85 south has a ramp that allows you to make a left and go to Route 87 north.

https://www.google.com/maps/@37.2549406,-121.8593391,3a,75y,96.88h,91.2t/data=!3m7!1e1!3m5!1sLB1GpxH2RTWQW0DEGXGB3Q!2e0!6shttps:%2F%2Fstreetviewpixels-pa.googleapis.com%2Fv1%2Fthumbnail%3Fpanoid%3DLB1GpxH2RTWQW0DEGXGB3Q%26cb_client%3Dmaps_sv.tactile.gps%26w%3D203%26h%3D100%26yaw%3D29.970085%26pitch%3D0%26thumbfov%3D100!7i16384!8i8192?entry=ttu

...Route 85 already has a flyover ramp just before it to reach northbound 87.

The one extra site that this diamond interchange left turn offers any access to is a light rail station (Ohlone/Chynoweth)
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sprjus4

^ And that light rail station is likely the reason the left turn lane on the ramp still exists.

roadman65

Also in Florida the EB Beachline (aka FL 528) has two exits for I-95 NB. One exit at FL 407 (Exit 37) and again Exit 42 B.  Originally there was only one as Exit 42 was a parclo with missing movements and had no EB to NB with FL 407 acting as the connection, but later made it into a full Cloverleaf despite the EB to NB ramp was redundant.

However now that the exit on I-95 to Port St. John Parkway was opened it makes sense to have the direct ramp, but before it was just FDOT burning federal funds offered to the when they added two other missing movements it was decided to go the hundred yards and complete it all according to a phone call with a PE at FDOT.
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mrsman

Quote from: JustDrive on July 02, 2023, 02:02:17 PM
SB 405 at the Century/Imperial exits. The east-west designations are for show, as you can access either road in any direction from any ramp.

NB 15 and 215 both access Murrieta Hot Springs Road with complete freedom of movement.

Correct.  SB 405 exits place you onto La Cienega.  You can reach either direction of Century or Imperial from LC, but the signs lead you to where you do not need to make a left from LC to Century (or Imperial).  [That's better for throughput to use right turns over left turns.]

The El Segundo exits used to be that way too, prior to the I-105 construction.

The onramp to US 101 south from Lankershim in Universal City doesn't even hide it anymore:

https://www.google.com/maps/@34.1389449,-118.3621476,3a,39.3y,230.95h,89.89t/data=!3m7!1e1!3m5!1swPW0Ggt7zJy0YQxA_Ts-tA!2e0!6shttps:%2F%2Fstreetviewpixels-pa.googleapis.com%2Fv1%2Fthumbnail%3Fpanoid%3DwPW0Ggt7zJy0YQxA_Ts-tA%26cb_client%3Dmaps_sv.tactile.gps%26w%3D203%26h%3D100%26yaw%3D257.35425%26pitch%3D0%26thumbfov%3D100!7i16384!8i8192?entry=ttu

Basically, you drive to Ventura/Cauhenga Bl W and if you make a right turn there is an onramp about a block away and if you make a left turn there is an onramp a block away.  Which one is better?  It's totally up to you.



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