Only one stack interchange in NM?

[Truvelo]

I'm currently spending the weekend in Albuquerque and looking at maps of the area there appears to be just one four way stack in the entire state. Unless someone knows of another one tucked away on a smaller road is this the lowest in any state?

I took some pictures of it today which was much better than Friday afternoon when it was crawling from the airport.

[agentsteel53]

does Massachusetts have any stacks?  they seem to rather like their cloverleafs even for major freeway-to-freeway interchanges.

[agentsteel53]

also, I'd have to guess Alaska.  because, hey, it's Alaska.

[Truvelo]

Perhaps I should loosen the definition of a stack slightly. What about any four way interchange where all movements are freeflowing with no traffic lights or at-grade conflicts? Massachusetts has plenty although they are all cloverleafs. Alaska would still have non. Even the UK has more than New Mexico.

[agentsteel53]

so basically just an "interchange" in general?  Or specifically, between two freeways where both cross as opposed to one ending at the other?

Alaska's only freeway-to-freeway connection is, I believe, the 1/3 junction, but 3 and 1 merge together.  3 stops being signed, but it is mileposted starting from downtown Anchorage so the freeway from the 1/3 junction into downtown Anchorage is, technically, the 1/3 multiplex, even though it is signed only as 1.

[Truvelo]

What I mean is an interchange where all eight turning movements have direct ramps that permit uninterrupted travel. They must not have things like traffic lights, roundabouts, stop signs or movements that use a gap in the median. In NM I can find only one interchange that meets that requirement - I-25/I-40 in Albuquerque. Parclos don't count because some of the left turns cut across the median.

[agentsteel53]

What I mean is an interchange where all eight turning movements have direct ramps that permit uninterrupted travel. They must not have things like traffic lights, roundabouts, stop signs or movements that use a gap in the median. In NM I can find only one interchange that meets that requirement - I-25/I-40 in Albuquerque. Parclos don't count because some of the left turns cut across the median.

you are right on that, because 10/25 in New Mexico is not fully realized, as 25 ends there.  so 40/25 is indeed the only full interchange that permits eight uninterrupted movements.

does Maine have any full interchanges?  I seem to remember all the freeways end at interchanges, as opposed to pushing through.

Hawaii has the H-1/H-3/H-201 complex, which does not precisely meet our definition of a clean eight uninterrupted movements, and otherwise I do not think that state has any full interchanges.

[J N Winkler]

The "Big I" in Albuquerque does not meet the strict definition of a stack (i.e., Maltese cross configuration) because it has two left-turning semidirectional direct connectors which cross in plan.  It is, in fact, a hybrid of a turban interchange and a true Maltese cross stack.

As a generalization, freeway-to-freeway interchanges are rare in NM and there are in fact some lengths of freeway which intersect at interchanges which are not free-flowing.  At the I-25/US 70 interchange in Las Cruces, for example, all of the freeway-to-freeway movements are free-flowing but the interchange as a whole is not fully free-flowing.

In regard to NM/GB comparisons, keep in mind that the UK has 26 million licensed drivers while NM has a total population of about 1.5 million and probably no more than 1 million licensed drivers.

[froggie]

does Maine have any full interchanges?  I seem to remember all the freeways end at interchanges, as opposed to pushing through.

I-95/I-395 in Bangor technically meets the "looser" definition, though the road to the west becomes a surface road right away where it meets US 2/ME 100.

[english si]

In regard to NM/GB comparisons, keep in mind that the UK has 26 million licensed drivers while NM has a total population of about 1.5 million and probably no more than 1 million licensed drivers.

Northern Ireland population if you want to make a comparison - NI doesn't have a single one (but that's more to do with geography than lack of trying - there was only ever one 4-way interchange planned in the 60s motorway plans - then again, there aren't any three-way full access free-flowing interchanges either).

As far as I can see, Scotland has 3 (the Octopus, the A739/A814 crazy interchange and the cloverleaf in Livingston) and Wales has none, England (more populous than Texas) has just 11.

[Alps]

Try finding a stack in NJ.  NJ 4/17 was retrofit into a half stack, and that's about it.  Our interchanges are spaghetti bowls.

[agentsteel53]

Try finding a stack in NJ.  NJ 4/17 was retrofit into a half stack, and that's about it.  Our interchanges are spaghetti bowls.

I think there may be two reasons for that:

1 - a lot of the old expressways were built at the time when cloverleafs were the most advanced thing around in terms of limited access structures, and a lot of routes instead had no-left-turn expressways controlled by infrequent traffic lights (the classic "Jersey Expressway" setup, complete with jughandles).

2 - two of the major freeways in the state are toll roads, and one cannot put a toll collection/ticket issue point into a stack.

[J N Winkler]

2 - two of the major freeways in the state are toll roads, and one cannot put a toll collection/ticket issue point into a stack.

Actually, yes, you can.  The Greeks have done it.

http://maps.google.com/maps?q=Athens,+Greece&ie=UTF8&hq=&hnear=Athens,+Greece&ll=38.061684,23.750221&spn=0.004359,0.009645&t=h&z=17

It is certainly true, though, that the main justification for stack construction is to allow transitions from one freeway to the other to be made safely at high speed, and this does not occur when tollbooths are situated on the direct connectors.

[Truvelo]

Interesting to see with the Greek example there is congestion on the ramps that are not tolled

[agentsteel53]

well, in the 1950s when the NJ Turnpike and the Garden State Parkway were built, it would not have been doable!  If you can hand a human being a dime or whatever the toll was back then while doing 75mph, you're a better man than I! 

[mightyace]

With the movement to AET (All Electronic Tolling), interchanges can be built in any configuration as you just need to put the toll gantries up.

[yakra]

does Maine have any full interchanges?  I seem to remember all the freeways end at interchanges, as opposed to pushing through.

I-95/I-395 in Bangor technically meets the "looser" definition, though the road to the west becomes a surface road right away where it meets US 2/ME 100.

The other full cloverleaf here is I-295 & US302 in Portland. 302's a surface street, traffic lights lurking nearby on both sides.

[yakra]

I'll consider weaving a form of "at-grade conflict", but heck, that's only really a problem in the freeway route. Heh. The yields at the bottom of the off-ramps are de facto stops.

[sandiaman]

We  are  quite proud of the Big I,  or  as you call it a stack interchange.  It replaced a hideous  outdated  interchange  a few years ago.  It has  a nice turquoise  color  stripe on  the  walls, that  often  match  the turquoise  skies  here  in NM.  Last year, the state managed to aquire  some dinero  to landscape , and it even has  flood lights that change  color at night  as drive  through  it.   I  can't recall  seeing any other  interchange  that does that.  The lanes are designed   for high speeds, you hardly need  to slow down  to  negocaite a turn!  There are  sets of frontage roads underneath  it  that carry local traffic,  that are totally  hidden  from  the interstates.  And, it was finished  AHEAD  of  schedule.     I  have  never heard  any  negative  reaction  of our   beloved  BIG EYE  from anybody here  in Albuquerque.