Shortest Concurrency by Highway Type(s)

[Avalanchez71]

So what are some of the shortest concurrencies out there?  Looking mainly for actually signed concurrencies or if they are logged on file as one and not sign posted in the field.

Interstate/Interstate
Interstate/Other signed route.

US Highway/US Highway
State Highway/State Highway

Other posted routes such as posted county routes, Indian routes, etc.

[OCGuy81]

As far as interstates go, 5/10 in east LA is pretty short. It's an interesting one too, as it's the only section of pavement I-5 shares with another interstate.

[jp the roadgeek]

CT 71A and CT 372 are 0.07 mi (although most eastbound traffic on CT 372 uses SR 918 to avoid it altogether)

I-87 and I-90 have an 0.1 mile concurrency within Thruway Exit 24 up to the Northway exit.

[NWI_Irish96]

In Indiana:

US 24/35 have a 0.3 mi concurrency with IN 25 near Logansport
US 6 has a 0.1 mi concurrency with IN 23 in Walkerton
IN 37 has a 0.1 mi concurrency with US 150/IN 56 in Paoli

Probably a few others of the same nature.

[OCGuy81]

Interstate 41 and US 41 have about 0.9 miles concurrent in Illinois. 

[Dirt Roads]

The overlap of I-85 and I-73 on the Greensboro Outer Loop is negligible.  The overlap from I-85 Exit 120B to I-85 Exit 122 is about 1.3 miles; the overlap from I-73 Exit 95A to I-73 Exit 97B is about 1.9 miles.  However, both I-85 and I-73 are running on completely separate carriageways (never thought I'd ever use that word) in this overlap.  The mainline connection from the Outer Loop is signed for both I-85 southbound and I-73 northbound in the overlapping section, and the Outer Loop eastbound is signed for both I-73 southbound and I-85 northbound in the overlapping section.  But never the two shall meet.

Unofficially, the overlap section appears to be about 2,800 feet (just a hair over a half-mile).  I don't have a good tool for measuring maps anymore.  Somebody using Google maps might want to check.

[Avalanchez71]

US 41 and US 41A in TN actually run concurrent in Nashville for a short distance.

[Mapmikey]

VA 178 and VA 180 have a concurrence of 133 ft.

US 49/63 and US 64 have a concurrence of 163 ft

[Evan_Th]

I think @jp the roadgeek has the shortest mainline interstate concurrency, with I-90 and I-87 in Albany.  I measure it at 1470 ft NE-bound, and 1260 ft SW-bound, gore-to-gore.

That compares to 1.2 miles for the I-5 and I-10 concurrency.  The I-85 and I-73 concurrency is a close runner-up, though, with 1700 ft of southbound I-73 concurrent with the C-D lane of northbound I-85.

[plain]

I think @jp the roadgeek has the shortest mainline interstate concurrency, with I-90 and I-87 in Albany.  I measure it at 1470 ft NE-bound, and 1260 ft SW-bound, gore-to-gore.

That compares to 1.2 miles for the I-5 and I-10 concurrency.  The I-85 and I-73 concurrency is a close runner-up, though, with 1700 ft of southbound I-73 concurrent with the C-D lane of northbound I-85.

What about the I-76/I-80 interchange in Ohio?

[sprjus4]

I suppose the ramps could count as being "concurrent"  but I wouldn't consider the two highways to be the same.

In the case of I-87 / I-90, I-87 uses a very small portion of the actual mainline of I-90.

[Scott5114]

OK-39 and OK-102 have a concurrency of 882 feet, or 0.17 miles.

[Evan_Th]

I think @jp the roadgeek has the shortest mainline interstate concurrency, with I-90 and I-87 in Albany.  I measure it at 1470 ft NE-bound, and 1260 ft SW-bound, gore-to-gore.

That compares to 1.2 miles for the I-5 and I-10 concurrency.  The I-85 and I-73 concurrency is a close runner-up, though, with 1700 ft of southbound I-73 concurrent with the C-D lane of northbound I-85.

What about the I-76/I-80 interchange in Ohio?

If you do count that - and there's a really good argument to count it - it's 1000 ft along EB 80 / WB 76, and 800 ft along WB 80 / EB 76, gore-to-gore.

Good catch!

[TheHighwayMan3561]

I-35E and I-94 have a 0.2 mile concurrency in downtown St. Paul.

[index]

SR 437/438 in Florida is 0.106 miles, and also the entire length of SR 437.

[Hwy 61 Revisited]

PA 611/715 is only 365 feet.


PA 611/940 is 3 feet shorter than that, at 362.


But nothing compares to PA 196/423, a concurrency that only lasts about 50 feet.

[index]

This concurrency between NC 11 and NC 903 is only 358 feet, measuring from the end of one intersection to end of the other.

https://www.google.com/maps/@35.9885334,-77.2439304,3a,60y,44.46h,88.25t/data=!3m6!1e1!3m4!1sQ-MleW3w2mgsbD3sf7q6Uw!2e0!7i13312!8i6656

Midpoint to midpoint, it is 496 feet. I think there are shorter ones than this on NC state routes but I can't remember what they are at the moment.

I was thinking of the junction between US 220/250 in Monterey, VA, but it's not offset enough to the point where you need to actually drive on one or the other to stay on your route. So that one is almost a super short concurrency between US routes, but not quite.



Edit: This one is *not* signed, but, here is one that is really short - SC 217/US 21 - https://www.google.com/maps/place/33%C2%B005'21.3%22N+80%C2%B048'48.5%22W/@33.08926,-80.8140152,341m/data=!3m2!1e3!4b1!4m6!3m5!1s0x0:0x0!7e2!8m2!3d33.0892603!4d-80.813468

Midpoint to midpoint between the T intersections, it's 87ish feet, inner edge to inner edge of the intersections, it's only 23.5 feet.

Google maps also has this in their database as a concurrency: https://www.google.com/search?client=firefox-b-1-d&q=SC+217%2FUS+21

And it's listed as one on Wikipedia, too: https://en.wikipedia.org/wiki/South_Carolina_Highway_217 , for 0.010 miles or 52.8 feet. Unless there's one shorter than that, this is probably the shortest concurrency between an SC route and a US route.

[DandyDan]

In Iowa, the shortest is about 400 feet, for IA 17 and IA 210 in Madrid.

[thspfc]

WI-19 and WI-73 are concurrent in Marshall for less than a quarter of a mile.

[ctkatz]

there is a(n unsigned) concurrency for ky 1747/864 on fern valley road for .4 miles.  only 1747 is signed.  back before the hurstborne parkway expansion/connection fern valley was 1631 and 864 was signed on that small stretch to fegenbush as poplar level was the road that terminated at fegenbush, not fern valley/hurstborne today.

[fillup420]

This concurrency between NC 11 and NC 903 is only 358 feet, measuring from the end of one intersection to end of the other.

https://www.google.com/maps/@35.9885334,-77.2439304,3a,60y,44.46h,88.25t/data=!3m6!1e1!3m4!1sQ-MleW3w2mgsbD3sf7q6Uw!2e0!7i13312!8i6656

Thats an interesting one, because it appears that they rerouted the southern leg of 903 away from making a full 4-way intersection with 11/42 in order to make two 3-way intersections. I wonder why that is?

[index]

This concurrency between NC 11 and NC 903 is only 358 feet, measuring from the end of one intersection to end of the other.

https://www.google.com/maps/@35.9885334,-77.2439304,3a,60y,44.46h,88.25t/data=!3m6!1e1!3m4!1sQ-MleW3w2mgsbD3sf7q6Uw!2e0!7i13312!8i6656

Thats an interesting one, because it appears that they rerouted the southern leg of 903 away from making a full 4-way intersection with 11/42 in order to make two 3-way intersections. I wonder why that is?

I've heard of intersections being offset like that to reduce collisions, less conflict points. I'd imagine that's probably the case.

[FrCorySticha]

This concurrency between NC 11 and NC 903 is only 358 feet, measuring from the end of one intersection to end of the other.

https://www.google.com/maps/@35.9885334,-77.2439304,3a,60y,44.46h,88.25t/data=!3m6!1e1!3m4!1sQ-MleW3w2mgsbD3sf7q6Uw!2e0!7i13312!8i6656

Thats an interesting one, because it appears that they rerouted the southern leg of 903 away from making a full 4-way intersection with 11/42 in order to make two 3-way intersections. I wonder why that is?

Just a guess, but to remove the risk of someone on 903 blowing through the intersection at highway speeds? That's a fairly common source of serious accidents in these rural areas.

Edit: index beat me by a few seconds.

[index]

This concurrency between NC 11 and NC 903 is only 358 feet, measuring from the end of one intersection to end of the other.

https://www.google.com/maps/@35.9885334,-77.2439304,3a,60y,44.46h,88.25t/data=!3m6!1e1!3m4!1sQ-MleW3w2mgsbD3sf7q6Uw!2e0!7i13312!8i6656

Thats an interesting one, because it appears that they rerouted the southern leg of 903 away from making a full 4-way intersection with 11/42 in order to make two 3-way intersections. I wonder why that is?

Just a guess, but to remove the risk of someone on 903 blowing through the intersection at highway speeds? That's a fairly common source of serious accidents in these rural areas.

That too. Accident reduction in general seems to be the goal, it looks like they also hatched off part of the widethroat for 903 southbound to force people to pull up all the way to the stop line so they can see traffic properly before continuing. The red object markers also probably serve to identify the need to stop.

https://www.google.com/maps/@35.9885982,-77.2441903,3a,80.6y,153.54h,87.98t/data=!3m6!1e1!3m4!1sgFEQauMd1PbZ6gcDb2fLHA!2e0!7i13312!8i6656
The previous setup also had beacons that would activate when a vehicle was approaching.

[sparker]

Two extremely short concurrencies for CA state highways:  84 & 238 in the Niles District of Fremont, CA; just the Alameda Creek bridge and the UP undercrossing, about 1/3 mile.  Also, CA 46 & 43 in Wasco -- coincidentally including an underpass below the BNSF main line -- also about a third of a mile.  Actually, the 84/238 coincidence is the only instance of any CA 238 signage along the entire stretch from Hayward to Mission San Jose.