What is the most unexpected concurrency?

[pderocco]

I grew up in New England with lots of alternates (mostly with A suffixes, not banners) that were old alignments. Keeping the same number made sense because it indicated their historic relationship.

I don't see how their historic relationship has much to do with navigation, so it doesn't necessarily "make sense" to me to keep the same number.

Route numbers aren't purely about navigation, as they sometimes come to function as names. ("128" around Boston, "the 405" in L.A., "route 66" across half the country.) But if you see route 1A split off from 1, it's a safe bet that they're going to come back together in a while, so you learn to assume that 1 is the new way and 1A is the old way to the same place.

[DandyDan]

One that surprises me by its mere existence, which I have traveled, is WI 54 with WI 35, WI 93 and US 53. It should end (or begin) at its eastern intersection with US 53. The bridge to Winona, MN can be its own number.

[kurumi]

I grew up in New England with lots of alternates (mostly with A suffixes, not banners) that were old alignments. Keeping the same number made sense because it indicated their historic relationship.

I don't see how their historic relationship has much to do with navigation, so it doesn't necessarily "make sense" to me to keep the same number.

Route numbers aren't purely about navigation, as they sometimes come to function as names. ("128" around Boston, "the 405" in L.A., "route 66" across half the country.) But if you see route 1A split off from 1, it's a safe bet that they're going to come back together in a while, so you learn to assume that 1 is the new way and 1A is the old way to the same place.

In the 1930s, Connecticut built several bypasses along US 1, marking them US 1A. Surveys found out that motorists were reluctant to take the newer, better bypasses, preferring to stay on the US 1 mainline, even through downtown congestion. For that reason, the state flipped all the "US 1" and "US 1A" designations in 1939.

[-- US 175 --]

My guess for an unexpected overlap would be the I-271/I-480 one in Cleveland, as it's so rare.

Closer to home would be any FMs or RMs overlapping in TX, as those are rare also.

[DandyDan]

I struggled to come up with one for Iowa, but historically, IA 12 shared pavement with I-29 through Sioux City. One that currently exists is the north end of US 67 being concurrent with IA 64 by Sabula.

[Bickendan]

The wrong-way concurrency of OR 19 and 207 in the John Day area.

[Molandfreak]

One that surprises me by its mere existence, which I have traveled, is WI 54 with WI 35, WI 93 and US 53. It should end (or begin) at its eastern intersection with US 53. The bridge to Winona, MN can be its own number.

And Google can stop spamming "Wisconsin Firefighters and Emergency Medical Technicians Highway" for at least a few miles.

There used to be a bit more of those pointless overlaps just to get to a bridge at a state line, though at least STH-54 is independent over the bridge. STH-13 used to be signed along US 53 just so that it could reach the border.

[flan]

Someone on this forum (can't remember off the top of my head unfortunately) has a signature that pokes fun at the absurd amount of concurrencies in Wisconsin. I didn't realize how abundant they were in WI until this summer when I had a couple fairly lengthy trips around the state and that signature kept popping up in my head.

[Great Lakes Roads]

IN SRs 16/119 east of Buffalo. Why does this concurrency exist just for SR 119 to end at SR 39?

[paulthemapguy]

US360 follows US58 west to Danville, VA instead of just ending in South Boston. I never understood why US360 does that.

[wxfree]

TX-130 overlapping I-10 between San Antonio and Seguin, rather than just starting at Seguin.

For anyone who doesn't know this, TxDOT did that as a giveaway to the toll road company (the southern part of the road is run for profit by a private company).  In San Antonio, they put up signs for the concurrency advertising the toll road with destinations Austin and Waco.  Those signs use the toll state highway shield in addition to the white shield.  Since the concurrency is not a toll road, they could have gotten sneaky and just signed SH 130 with destinations Austin and Waco, and not told drivers it becomes a toll road.  Then they'd have to decide whether to follow the toll road or go some round-about way.  They have some hint of ethics, not tricking people to head that way while not mentioning that it becomes a toll road.

To clarify, the concurrency runs along I-10 to I-410 and along I-410 to I-35.  That way the first sign can be all the way back on I-35 in far south San Antonio.
https://maps.app.goo.gl/J8ehFPTkoGrACseW9

[hbelkins]

US360 follows US58 west to Danville, VA instead of just ending in South Boston. I never understood why US360 does that.

Wasn't the original route of US 360 what is now VA 360, which does end in Danville?

[epzik8]

First one I can think of that I've personally seen is I-80/PA 66 in western PA.

[Flint1979]

Another Michigan one that is jarring is M-54 and M-83 running together on Birch Run Road. If you are headed eastbound on Birch Run Road you are going north on M-83 and south on M-54. M-54 comes up from the Flint area mostly being in Genesee County and while still in Genesee County makes a turn onto Clio Road which turns into Gera Road in Saginaw County to meet head on with M-83 at Birch Run Road then both roads head west. Honestly it's about 1.5 miles less to stay on Saginaw Road/Dixie Highway than to follow M-54 to get to Birch Run but M-83 and M-54 running together doesn't make much sense and I'm sure the only reason that M-54 is on Birch Run Road at all is just to hit I-75 again

[Flint1979]

IN SRs 16/119 east of Buffalo. Why does this concurrency exist just for SR 119 to end at SR 39?

I know that IN-119 used to extend further south to Monticello and IN-39 was extended to the Michigan state line. It's probably so it can connect to Buffalo and IN-39.

[Quillz]

CA-168 has a signed concurrency with US-395, even though concurrencies don't officially exist. It's odd because CA-168 is basically three distinct segments that have little thematic connection to one another, and no physical connections between them. (The western segment goes up the western Sierra, the central segment goes down the escarpment, the eastern segment provides alternate access into Nevada/Death Valley.) US-395 travels in a perpendicular direction, and it's an expresssway for long-haul travel. So a regional state route suddenly being signed with a major US highway for about 15 miles always felt odd to me.

[pderocco]

CA-168 has a signed concurrency with US-395, even though concurrencies don't officially exist. It's odd because CA-168 is basically three distinct segments that have little thematic connection to one another, and no physical connections between them. (The western segment goes up the western Sierra, the central segment goes down the escarpment, the eastern segment provides alternate access into Nevada/Death Valley.) US-395 travels in a perpendicular direction, and it's an expresssway for long-haul travel. So a regional state route suddenly being signed with a major US highway for about 15 miles always felt odd to me.

That seems normal to me. It also has a concurrency with 120, and another with 299 way up north. And it used to have one with 190, when the latter found its way up Horseshoe Meadow Rd.

[Quillz]

CA-168 has a signed concurrency with US-395, even though concurrencies don't officially exist. It's odd because CA-168 is basically three distinct segments that have little thematic connection to one another, and no physical connections between them. (The western segment goes up the western Sierra, the central segment goes down the escarpment, the eastern segment provides alternate access into Nevada/Death Valley.) US-395 travels in a perpendicular direction, and it's an expresssway for long-haul travel. So a regional state route suddenly being signed with a major US highway for about 15 miles always felt odd to me.

That seems normal to me. It also has a concurrency with 120, and another with 299 way up north. And it used to have one with 190, when the latter found its way up Horseshoe Meadow Rd.

I'm specifically referring to 168. 299 is a major west-east thruway, and 120 serves Yosemite and the Central Valley. 

[ClassicHasClass]

Actually, I think a case could be made for US 395-CA 299 being an unexpected concurrency. US 299 didn't extend past US 395, and current CA 299 through Cedarville to the Nevada border is a minor road that terminates at the relatively poorly maintained WashoeCo 8A. (Despite the "NV 8A" shield, it is immediately followed by a marker for the county route.)

[LilianaUwU]

QC 219 and 221 cross each other in Napierville, causing a wrong-way concurrency while crossing over A-15. This means that at the A-15 interchange and at the QC 217 intersection, each one gives three options to continue NB and three to continue SB.