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[J N Winkler]

I believe the I-235/I-44 interchange will be the first four stack in the state.

It won't be a Maltese cross stack (per rendering) because some movements will continue to be served by loop ramps.

I think 35/I-240 is planned as 4 stack as well.

If Oklahoma DOT is sticking with the plan that comes up first in a casual Google search (result), then it will be a turban/cloverleaf hybrid.

What strikes me is the extent to which various states nickel-and-dime themselves out of building true Maltese cross stacks.  In Wichita, for example, it was one of the options for the I-235/US 54 interchange, but KDOT decided to have a pair of less heavily used direct connectors cross in plan (thus creating a stack/turban hybrid) with their design speeds reduced from 45 MPH to 35 MPH.  KDOT also spent over $200 million on the Johnson County Gateway, yet left two loop ramps (making it a cloverstack) instead of upgrading them to direct connectors (which was proposed at one point).

[Plutonic Panda]

^^ Interesting. I haven't heard that term before "maltese cross." OkDOT is branding I-235/I-44 as the states first four level. I agree with you however, I am not a fan of labeling directional/cloverleaf interchanges as any types of true stacks even though there are different levels.

Here is the 44/75 interchange proposal in Tulsa although this one has no identified funding: https://www.odot.org/meetings/a2017/171102/View1.pdf

[kphoger]

I believe the I-235/I-44 interchange will be the first four stack in the state.

It won't be a Maltese cross stack (per rendering) because some movements will continue to be served by loop ramps.

That looks like a three-level stack to me, too, not a four–although I guess it is sort of four-ish.

[In_Correct]

Is the I-244/I-444 interchange at the northeast corner of the IDL considered a stack?

Only in the very loose sense that any interchange with more than two levels is a stack.  It is not a true Maltese cross stack because some of the movements are directional (involving left exits for left-turns) rather than semidirectional.

I try to keep a list of Maltese cross stacks worldwide, and my criteria include offside turning movements (left-turning in right-driving countries, right-turning in left-driving countries) served by semidirectional direct connectors such that opposite-facing movements do not cross in plan.  There are no Maltese cross stacks in Oklahoma.  Nor are there any in Kansas (though three have been proposed).  Texas has nearly as many Maltese cross stacks as the rest of the US combined.

If the name for a complete stack Interchange is Maltese Cross Stack, then what is this thing?

https://i.imgur.com/XBAJ74O.jpg

[kphoger]

Do my eyes deceive me, or is that functionally equivalent to a Maltese cross, but only three levels?

[Chris]

^^ Interesting. I haven't heard that term before "maltese cross."

I believe this has a German origin: 'Malteserkreuz' A 4-way Autobahn interchange is also called a 'kreuz' (cross) in German.

[J N Winkler]

If the name for a complete stack Interchange is Maltese Cross Stack, then what is this thing?

https://i.imgur.com/XBAJ74O.jpg

I count it as a Maltese cross stack, albeit not yet complete as shown (one of the direct connectors has what appear to be Cor-Ten girders, no deck yet).  I'm guessing this is I-10/Loop 375 (Americas interchange) southeast of El Paso.

^^ Interesting. I haven't heard that term before "maltese cross."

I believe this has a German origin: 'Malteserkreuz' A 4-way Autobahn interchange is also called a 'kreuz' (cross) in German.

Yes, I think this is correct, and originates from the ramps (at least in early layouts like the Four Level in Los Angeles) resembling a Maltese cross.  I am not aware the term was used in English at the time the first few stacks were being built.  The Four Level was called just that, and not spoken of by how the ramps lay out in plan.

Ironically, Germany's one stack that is classifiable as a Maltese cross (the A45/A480 Wetzlarer Kreuz in Hesse) is very irregular, and one of the arms is an unfinished stub, a bit like I-70/I-695 in Baltimore.

[rte66man]

I believe the I-235/I-44 interchange will be the first four stack in the state. I think 35/I-240 is planned as 4 stack as well. Also the master build out of US-75/I-44 interchange in Tulsa is supposed to be a 4 or 5 stack.

The OK74/Kilpatrick is a 4-level even if there is  only one ramp (WB to SB) on the 4th level.

[Bobby5280]

What strikes me is the extent to which various states nickel-and-dime themselves out of building true Maltese cross stacks.  In Wichita, for example, it was one of the options for the I-235/US 54 interchange, but KDOT decided to have a pair of less heavily used direct connectors cross in plan (thus creating a stack/turban hybrid) with their design speeds reduced from 45 MPH to 35 MPH.  KDOT also spent over $200 million on the Johnson County Gateway, yet left two loop ramps (making it a cloverstack) instead of upgrading them to direct connectors (which was proposed at one point).

For my own criteria, a modern freeway to freeway directional stack interchange is one which has zero cloverleaf ramps. NONE. And the four ramps that cross inside the interchange have to meet in the middle to create that Maltese Cross appearance (and the four levels). Raising the criteria higher, there should be no left exits to off ramps. That's what ruins the I-44/I-40 interchange in OKC.

The I-44/I-235/Broadway Extension interchange in Oklahoma City, an interchange project that has been going on in fits and starts for over a decade (and still not finished) will have TWO cloverleaf loop ramps. Kind of like a pair of Mickey Mouse ears worked into the design.

The I-35/I-240 "Crossroads Renewal" interchange in OKC will have cloverleaf loops at the NW and SE corners of the interchange. This project will be an improvement over the old, slow cloverleaf interchange. But it's not going to be as efficient as a true directional stack.

The I-44/US-75 interchange proposed in Tulsa is a hodge-podge concept. One of the movements is served by a cloverleaf loop, which is an immediate disqualification in my book for stack interchanges. Two of the flyovers (SB US-75 to EB I-44 and NB US-75 to WB I-44) meet in the center of the interchange in the fashion of a Maltese Cross stack. But then the WB I-44 to SB US-75 movement is a really long ramp curving well outside the center of the interchange. It's more like one of the movements from a pinwheel interchange, kind of the I-85/I-485 interchange on the NE side of Charlotte.

[J N Winkler]

For my own criteria, a modern freeway to freeway directional stack interchange is one which has zero cloverleaf ramps. NONE. And the four ramps that cross inside the interchange have to meet in the middle to create that Maltese Cross appearance (and the four levels). Raising the criteria higher, there should be no left exits to off ramps. That's what ruins the I-44/I-40 interchange in OKC.

Though they look a lot less like Maltese crosses than older interchanges like the original Four Level and I-75/US 35 in Dayton, Ohio, I count modern stacks that have opposite-facing direct connectors separated quite widely from each other, like the US 60/Loop 202 SuperRedTan interchange in Mesa, Arizona.  My observation has been that modern design tends to favor this wider separation because it allows higher horizontal curve radii for the direct connector ramps, which in turn increases the design speed.  I believe that if you spread the required movements far enough out in plan, it is conceptually possible to build a "four-level" stack that has no more than two levels at any given point.

I do agree that left exits and entrances are disqualifying, as are loop ramps unless they are additional to connectors that fill out the basic stack layout.  (I-10/Loop 375 Americas interchange, mentioned above, is an example of a stack interchange of freeway mainlines that is superimposed on a cloverleaf interchange for the frontage roads.)

[Bobby5280]

The US-60/Loop 202 interchange in the Phoenix area still fits my definition of a true directional stack interchange. The opposing flyover ramps are spread a little farther apart, but the ramps still create that symmetrical, 4-level appearance. The I-10/Loop 375 interchange on the SW side of El Paso is pretty unique in that the two freeways intersect in a true directional stack interchange yet do so above frontage roads that meet in their own separate cloverleaf interchange.

I agree if a freeway to freeway interchange is built on a large enough footprint it's possible to build a directional interchange with no more than 2 levels and no cloverleaf loops. The design would require the two carriageways of both intersecting freeways to be spread well apart so the intersecting "flyover" movements wouldn't create 3 level crossings.

4 level directional stack interchanges can easily fit within the same footprint as a cloverleaf interchange or even go a bit tighter. The stack interchange in San Antonio at Loop 1604 and US-281 fits pretty snug into its surroundings, but has ramp with 45mph speeds as a consequence.

There is one stack interchange where I'm willing to forgive the existence of loop ramps: the I-95/I-395/Capitol Beltway interchange in Springfield, VA. The primary main lane movements of that interchange are all on directional ramps, even though the ramps don't have a symmetrical Maltese Cross appearance. The mash-up of Loops and Y junctions on the NW side of the interchange are all for HOV lane access -some of which are reversible due to the HOV arrangement on I-395 and I-95 South of the interchange. Overall it's a very impressive interchange. I-95 South of there thru Springfield and Franconia is pretty amazing.

[kphoger]

I believe that if you spread the required movements far enough out in plan, it is conceptually possible to build a "four-level" stack that has no more than two levels at any given point.

I agree if a freeway to freeway interchange is built on a large enough footprint it's possible to build a directional interchange with no more than 2 levels and no cloverleaf loops. The design would require the two carriageways of both intersecting freeways to be spread well apart so the intersecting "flyover" movements wouldn't create 3 level crossings.

This is why I don't consider the planned 235/44 interchange to be a four-level stack.  At no point are there four roads on top of each other, so it's not a four-level anything.

[bugo]

Is the I-244/I-444 interchange at the northeast corner of the IDL considered a stack?

Only in the very loose sense that any interchange with more than two levels is a stack.  It is not a true Maltese cross stack because some of the movements are directional (involving left exits for left-turns) rather than semidirectional.

All the exits from I-244 to I-444 and vice versa are left exits except for one: NB I-444 to EB I-44. The other seven movements feature left exits. I-244 was designed by dimwitted monkeys on LSD.

[bugo]

Here is the 44/75 interchange proposal in Tulsa although this one has no identified funding: https://www.odot.org/meetings/a2017/171102/View1.pdf

That interchange is badly needed. I drive through this interchange every day, from WB I-44 to SB US 75 and from NB US 75 to EB I-44, and it is not safe. The loop ramps suck because they are loop ramps, and the merge from the SB US 75 ramp into the EB I-44 collector lane is terrifying because it is hard to tell at night if a car traveling EB is in the collector lane or in the mainline I-44 lanes because there is no barrier between the I-44 mainline lanes and the collector road, only a curb. There also isn't much of a merge area. Then there is the questionable ramp from the EB I-44 collector road to Skelly Drive. This ramp is signed for Elwood Avenue. This interchange is scary and needed to be rebuilt 30 years ago.

[bugo]

Ironically, Germany's one stack that is classifiable as a Maltese cross (the A45/A480 Wetzlarer Kreuz in Hesse) is very irregular, and one of the arms is an unfinished stub, a bit like I-70/I-695 in Baltimore.

The ramp from eastbound to southbound has a weird curve in it. It looks like it might be slightly dangerous.

[bugo]

Ironically, Germany's one stack that is classifiable as a Maltese cross (the A45/A480 Wetzlarer Kreuz in Hesse) is very irregular, and one of the arms is an unfinished stub, a bit like I-70/I-695 in Baltimore.

The WB-SB has a weird curve in it where it jukes to the left to avoid the EB-NB ramp. It looks like it might be slightly dangerous. Is the accident rate here any higher than the other seven ramps?

[kphoger]

designed by dimwitted monkeys on LSD.

That's in Chicago.

[rte66man]

Is the I-244/I-444 interchange at the northeast corner of the IDL considered a stack?

Only in the very loose sense that any interchange with more than two levels is a stack.  It is not a true Maltese cross stack because some of the movements are directional (involving left exits for left-turns) rather than semidirectional.

All the exits from I-244 to I-444 and vice versa are left exits except for one: NB I-444 to EB I-44. The other seven movements feature left exits. I-244 was designed by dimwitted monkeys on LSD.

Won't argue that but the railroad running through the middle of the interchange greatly complicates things.

[Plutonic Panda]

This is a small pet peeve of mine but I really wish governments in Oklahoma would do a better job of being more transparent and keeping their public information up to date. There’s still several Driving Forward projects going on and will probably be going on for another year. They haven’t updated a single thing on their website since 2018: https://www.drivingforwardok.com/

[Scott5114]

This is a small pet peeve of mine but I really wish governments in Oklahoma would do a better job

You could have just stopped there.

[Plutonic Panda]

This is a small pet peeve of mine but I really wish governments in Oklahoma would do a better job

You could have just stopped there.

I use the quote from Dumb and Dumber to justify my enthusiasm for progress in Oklahoma one day.

[Plutonic Panda]

Surplus land from these projects to be auctioned off:

https://tulsaworld.com/business/local/surplus-land-to-be-auctioned-next-month-from-oklahoma-turnpike-authority-a-grand-opportunity/article_02f88a60-dabf-11ec-a4de-4be088b903e1.html