Most Number of Lanes on a Stack-Interchange

[BJ59]

Anyone know what is the most lanes on a single ramp in a stack interchange? I've seen a lot of ramps that have 2 lanes but I was wondering if there was any that have 3 or possibly more?

[Dirt Roads]

Not sure if the infamous Springfield Interchange in Virginia is technically considered a "Stack Interchange", but the ramp from I-95 northbound -to- I-495 northbound converges from four lanes to three lanes as it threads under the ramps from the Shirley Reversible -to- the Beltway eastbound (ergo, I-95 northbound).  After that, it becomes the top level of two different double stacks.

https://www.google.com/maps/place/Springfield,+VA/@38.7892506,-77.1762732,114m/data=!3m1!1e3!4m6!3m5!1s0x89b64de885e53a9d:0x67e76f2416faa504!8m2!3d38.7892801!4d-77.1872036!16zL20vMDEwbThu?entry=ttu

[kphoger]

Not sure if the infamous Springfield Interchange in Virginia is technically considered a "Stack Interchange", but the ramp from I-95 northbound -to- I-495 northbound converges from four lanes to three lanes as it threads under the ramps from the Shirley Reversible -to- the Beltway eastbound (ergo, I-95 northbound).  After that, it becomes the top level of two different double stacks.

https://www.google.com/maps/place/Springfield,+VA/@38.7892506,-77.1762732,114m/data=!3m1!1e3!4m6!3m5!1s0x89b64de885e53a9d:0x67e76f2416faa504!8m2!3d38.7892801!4d-77.1872036!16zL20vMDEwbThu?entry=ttu

And here's Street View:  https://maps.app.goo.gl/C8fwM4vwo5t1UfxC9

[jeffandnicole]

How many levels are we defining a stack interchange?

[Rothman]

How many levels are we defining a stack interchange?

One.

[kphoger]

How many levels are we defining a stack interchange?

For the purpose of this exercise, I'd personally go allow a minimum of three levels, but the ramp in question has to be directional between the two highways.  This would allow for stack hybrids that still fit the spirit of the topic, even if they're not true stacks.

[Dirt Roads]

In Dallas, there's four full lanes on the I-35E northbound where it comes into the overlap between the Stemmons and the Tom Landry.  Even though it is considered the through movement, those lanes are at the top level.

https://www.google.com/maps/place/Fort+Worth,+TX/@32.7688475,-96.8047975,58m/data=!3m1!1e3!4m6!3m5!1s0x864e6e122dc807ad:0xa4af8bf8dd69acbd!8m2!3d32.7554883!4d-97.3307658!16zL20vMGYyczY?entry=ttu

[Henry]

At the Jane Byrne Interchange (which has never really been a stack, but still qualifies for the sake of being three levels), there are four through lanes approaching from all directions, with the exception of the southern approach, which has five going away from it. Plus, the NB to WB and EB to SB ramps are two lanes each, although the latter shrinks to one just before reaching the Dan Ryan mainline.

[Dirt Roads]

Double whammy!  The are a pair of ramps crossing each other on the Atlanta Perimeter that both transition from 3 lanes to 2 lanes in roughly the same location.  One ramp is from I-85 southbound to I-285 eastbound; the other from I-285 eastbound to I-85 northbound.

https://www.google.com/maps/place/Atlanta,+GA/@33.8920663,-84.2582756,125m/data=!3m1!1e3!4m6!3m5!1s0x88f5045d6993098d:0x66fede2f990b630b!8m2!3d33.748752!4d-84.3876845!16zL20vMDEzeXE?entry=ttu