Pardon me for creating another random trivia thread, but I was nosing around Steve's site, and the following quote caught my eye regarding unbuilt I-78 in New York City.
QuoteI-78 was intended to go east from the Holland Tunnel, across the Williamsburg Bridge and through the heart of Brooklyn between Bushwick Ave. and Broadway (the proposed Bushwick Expressway). From there it would have used what's now NY 878 (and I-878), up an unbuilt freeway to I-295 (Clearview Expressway), and ending at I-95 - after having crossed 95 in New Jersey. East-west and north-south routes aren't supposed to cross more than once.
Mainly the last sentence. I see what he's saying, but it also doesn't strike me as terribly unfeasible to have one of the routes loop around and meet the other again. (In fact, had I-78 been built this way, neither route would have to go the "wrong" direction, at least not significantly. I-95 goes north than east, while I-78 would go east then north.)
And yet I can't think of a case, at least among the interstates, where this actually happens. So how common is this?
(Let's keep this to routes of the same system. There are numerous cases like -- turning to a random page in my atlas -- I-89 and US 2, ostensibly perpendicular, but run parallel from Burlington to Montpelier, crossing many times. Also, concurrencies don't count. I-39 and I-90 meet once in Illinois and once in Wisconsin, but it's really only one crossing.)
ETA: Immediately after posting, I remembered the obvious one that I knew must exist somewhere. I-10/I-17 in Phoenix. But still, let the discussion beginulate!
prior to 1964, US-6 and US-91 intersected in Salt Lake City and ended at each other in Long Beach.
I-10 and Future I-49.
do we dare mention the clawing horror which is made of I-73 and I-74?
(Yes, I know this isn't the same system, but it's an interesting diversion.) This probably happens fairly often when a U.S. Route parallels an Interstate, and a perpendicular U.S. Route comes along for a while before splitting off. If the two parallel routes cross more than once along the overlap section, this happens.
For example, US 17-92 crosses I-4 thrice.
An obvious corollary is that at the center intersection the directions are reversed. So you exit I-4 west onto a straight ramp and turn right to go south.
(Back to the original topic, which, given the examples, is not about crossing but intersecting.)
I-69 and I-94 would count if I-69 didn't become east-west. There are probably a number among the U.S. Routes like this, where the directions change in between.
I found one pure example with no direction changes between two crossings (counting a short overlap as a crossing): US 70 and US 321. There are two crossings on the wrong-way extension, at Eaton Crossroads and Newport, as well as a third on original US 321, at Hickory.
Quote from: NE2 on October 29, 2012, 03:49:51 PM
There are probably a number among the U.S. Routes like this, where the directions change in between.
US 250 and 33 being an example of that. They meet in West Virginia, where US 250 is posted north-south, and again in Richmond.
US 69 and I-35 in Northern Missouri cross five times between Kansas City and the Iowa State Line, then at exits 4 and 136 in Iowa. They never meet again going north.
Quote from: rarnold on October 29, 2012, 08:04:21 PM
US 69 and I-35 in Northern Missouri cross five times between Kansas City and the Iowa State Line, then at exits 4 and 136 in Iowa. They never meet again going north.
Which are neither perpendicular, nor of the same system. Try again, my good sir.