Alternate Interstate Highways

[peterj920]

Here is one of many Alternate Interstate Highway signs that are popping up all over the place in Wisconsin.  Part of the reason why it is taking so long to sign Interstate 41 is because WISDOT is posting Alternate Interstate 41 signs all over the place.  WISDOT is also using pretty large signs to post these alternate routes.  They're supposed to guide motorists in case of an accident or if the mainline is congested.  I have traveled to other states and I have not seen any other states post as many alternate interstate routes as Wisconsin is.  Are any other states starting to do the same thing?  Just to show how prolific these signs are I have a few other examples below:

Alt I-94 in the Eau Claire Area:
https://www.google.com/maps/@44.8943134,-91.499254,3a,37.5y,278.56h,89.88t/data=!3m6!1e1!3m4!1sbd_cJglVYdQWHjInlf4tqA!2e0!7i13312!8i6656?hl=en
https://www.google.com/maps/@44.8120447,-91.4550371,3a,15y,179.6h,87.53t/data=!3m6!1e1!3m4!1swnHFCV1kJWVRFfXCk1E4SQ!2e0!7i13312!8i6656?hl=en

Alt I-90 This example is very interesting.  One sign says Alt 90 to go left or right, yet there is an Alt 90 reassurance sign in the background.  From Wis 16 west, there is an Alt 90 sign that guides traffic to go south on Wis 27.  This is in Sparta
https://www.google.com/maps/@43.9391459,-90.82077,3a,37.5y,191.8h,85.28t/data=!3m6!1e1!3m4!1sJfJGpvxodBxq0gsxsa17xg!2e0!7i13312!8i6656?hl=en

Alt I-43 in Plymouth:
https://www.google.com/maps/@43.7553899,-87.9411384,3a,37.5y,30.04h,88.66t/data=!3m6!1e1!3m4!1sqXBzrfu5cJkaKqfQLSBFaw!2e0!7i13312!8i6656?hl=en

[english si]

On Tuesday I saw a signs for ALT I-405 on I-10 quite some way inland of I-405 (La Brea or La Cienega sort of area)

[thenetwork]

Akron, OH has had a signed "Alternative" corridor for Interstates I-77 and I-76 for construction zone bypasses for years using SR-21 and, of course I-77 and I-76/US-224.

That's odd seeing ALTERNATIVE spelled out in full instead of just ALT.

Meanwhile, in PA, Interstate alternative routes are simply color-coded DETOUR route signs.

[roadman65]

Kansas City:  I-670 is (or was) signed ALT I-70.   In fact in 00 and 01 the I-70 shields were removed from its mainline, and it was made to look like the defacto I-70 when I visited there two years in a row.

[bassoon1986]

Louisiana signs an alternate route for I-10 between Lafayette and Baton Rouge for accidents that occur on the elevated Atchafalaya Swamp bridge. The route follows I-49 from Lafayette, and US 190 between Opelousas and Baton Rouge where it connects to I-110.

Here's the first mention on I-49 northbound just past exit 1C:
https://www.google.com/maps/@30.2725781,-92.0185125,3a,75y,17.15h,80.49t/data=!3m6!1e1!3m4!1spzqKKHYdC7cllZ0A80kWgA!2e0!7i13312!8i6656

Along US 190, it is signed with a shield and a distance:
https://www.google.com/maps/@30.4910326,-91.2615939,3a,37.5y,253.68h,82.73t/data=!3m6!1e1!3m4!1smFWWqSWCiUzlPMPLSdI5XQ!2e0!7i13312!8i6656



Recently I also found an alternate route for I-10 in SE Texas. It follows TX 73, TX 87, and TX 62 as a bypass of Beaumont:
https://www.google.com/maps/@29.8269546,-94.3867404,3a,37.5y,102.88h,90.7t/data=!3m6!1e1!3m4!1sc3-frwdrdtyM0Ltm2T55hg!2e0!7i13312!8i6656

[txstateends]

Someone posted a while back a pic of ALT I-35E and ALT I-35W signs in Hillsboro, TX along TX 81 at the point where the historic alignments of US 77 and US 81 split.  A quick check of Street View doesn't show them.

[roadman]

I-95 (MA 128) between Woburn and Canton was signed as 'ALT 93' during the Medford Fast 14 bridge reconstruction project in 2011.

[corco]

Nebraska pretty religiously signs the US highways paralleling both I-80 and I-76, even just a few feet from the state line


I-80 typically gets a unisign like this

[Brandon]

Illinois signs ALT I-80 along US-6 and US-52 during periods of construction.  Michigan has EMERGENCY I-94 along Old US-12.

[SD Mapman]

Nebraska and Wisconsin are the only states I've seen that apply them religiously everywhere. I haven't seen any others, though.

[Anthony_JK]

Louisiana signs an alternate route for I-10 between Lafayette and Baton Rouge for accidents that occur on the elevated Atchafalaya Swamp bridge. The route follows I-49 from Lafayette, and US 190 between Opelousas and Baton Rouge where it connects to I-110.

Here's the first mention on I-49 northbound just past exit 1C:
https://www.google.com/maps/@30.2725781,-92.0185125,3a,75y,17.15h,80.49t/data=!3m6!1e1!3m4!1spzqKKHYdC7cllZ0A80kWgA!2e0!7i13312!8i6656

Along US 190, it is signed with a shield and a distance:
https://www.google.com/maps/@30.4910326,-91.2615939,3a,37.5y,253.68h,82.73t/data=!3m6!1e1!3m4!1smFWWqSWCiUzlPMPLSdI5XQ!2e0!7i13312!8i6656



Recently I also found an alternate route for I-10 in SE Texas. It follows TX 73, TX 87, and TX 62 as a bypass of Beaumont:
https://www.google.com/maps/@29.8269546,-94.3867404,3a,37.5y,102.88h,90.7t/data=!3m6!1e1!3m4!1sc3-frwdrdtyM0Ltm2T55hg!2e0!7i13312!8i6656

Ummm....that's not so much an official alternate signing of I-10 as it is a detour route for the Atchafalaya Basin segment of I-10 when accidents or weather closes that section down.

[bassoon1986]

WISDOT is also using pretty large signs to post these alternate routes.  They're supposed to guide motorists in case of an accident or if the mainline is congested.

The Louisiana example is signed permanently in the field, and it has an alt route banner. What more do you need?

[ET21]

I've seen small sections of ALT I-39 across northern Illinois, however it seems like each section is broken. The most common one I always see is ALT I-39 on IL-251 around Rochelle

[roadman65]

Louisiana signs an alternate route for I-10 between Lafayette and Baton Rouge for accidents that occur on the elevated Atchafalaya Swamp bridge. The route follows I-49 from Lafayette, and US 190 between Opelousas and Baton Rouge where it connects to I-110.

Here's the first mention on I-49 northbound just past exit 1C:
https://www.google.com/maps/@30.2725781,-92.0185125,3a,75y,17.15h,80.49t/data=!3m6!1e1!3m4!1spzqKKHYdC7cllZ0A80kWgA!2e0!7i13312!8i6656

Along US 190, it is signed with a shield and a distance:
https://www.google.com/maps/@30.4910326,-91.2615939,3a,37.5y,253.68h,82.73t/data=!3m6!1e1!3m4!1smFWWqSWCiUzlPMPLSdI5XQ!2e0!7i13312!8i6656



Recently I also found an alternate route for I-10 in SE Texas. It follows TX 73, TX 87, and TX 62 as a bypass of Beaumont:
https://www.google.com/maps/@29.8269546,-94.3867404,3a,37.5y,102.88h,90.7t/data=!3m6!1e1!3m4!1sc3-frwdrdtyM0Ltm2T55hg!2e0!7i13312!8i6656

Here is one of the I-10 Alternate signs I photographed 3 years ago.

[CNGL-Leudimin]

Someone posted a while back a pic of ALT I-35E and ALT I-35W signs in Hillsboro, TX along TX 81 at the point where the historic alignments of US 77 and US 81 split.  A quick check of Street View doesn't show them.

IMO that Alt I-35E at that split should be Alt I-35, as it goes to intersect I-35 just South of where the later splits. Only when the road becomes US 77 should Alt I-35 change to Alt I-35E. This would be funny, as Alt I-35 would split into Alt I-35 and Alt I-35W and then the former suddenly becomes Alt I-35E .

[hbelkins]

When there were issues on I-75 between Knoxville and the Kentucky state line a few years ago, TennDOT posted "Alt I-75" signs along US 25E between Morristown and the state line. I presume such were also posted on I-40 and I-81 east of Knoxville. There were a couple of those signs still on 25E northbound last October, the last time I was on that route. AFAIK, Kentucky never signed 25E as an alternate to I-75.

[GaryV]

Michigan has EMERGENCY I-94 along Old US-12.

With orange EMERGENCY banners.

There are also Emergency I-75 signs in strange locations through Troy - why go all the way over to Dequindre Road?  What's wrong with John R or Rochester Rd?

[mariethefoxy]

there is a poorly signed Alternate I-495 (in some spots it has a State Route 495 sign) in Jericho and Syosset (Long Island)

[mrsman]

On Tuesday I saw a signs for ALT I-405 on I-10 quite some way inland of I-405 (La Brea or La Cienega sort of area)

This was mentioned in the Pac SW forum, but essentially La Cienega Blvd between I-405 in Inglewood and I-10 in Culver City adjacent is a signed alternate to connect westbound I-10 to southbound I-405 and northbound I-405 to eastbound I-10.  The 3 roads form a triangle and it is much shorter to take La Cienega, than to make the transition from I-405 to I-10 at the interchange in West L.A.  Also, about 3 miles of La Cienega are designed as a mini-freeway without traffic lights or at-grade intersections between Fairview and Rodeo Rd (the exception being the annoying light at Stocker northbound).

LC is known to be a great shortcut to LAX.

[ibagli]

In Ohio, a flood-prone stretch of I-70 in Licking County has two alternate routes (to the south on OH 37 and OH 79, to the north on OH 37, US 40, and either OH 79 or OH 13 depending on how busy it is). If only one direction is closed, cars use one route and trucks use the other. There are also permanent detour signs that can be unfolded (when folded, the ones on the freeway are emergency stopping only signs and the ones on the ramps are guide signs).

[TEG24601]

This is actually something sorely needed in Washington.  There are several places where the alternative routes are so convoluted, that some form of signs would be helpful.

[Katavia]

Over in Concord on Poplar Tent Road, there is a sign that says:

ALT
  TO
  I-85
   /|\
    |

(did the best I could do with text) (I-85 not signed using text)

[jp the roadgeek]

I've seen several LGS alternate I-91 and I-84 signs south and west of Hartford that suggest using routes like I-691, CT 72, and CT 9.

https://goo.gl/maps/i1KTnSNHPUH2

[catch22]

Michigan has EMERGENCY I-94 along Old US-12.

With orange EMERGENCY banners.

Here's an example, on Michigan Avenue (Old US-12) near Francisco Road in Grass Lake Township.

https://www.google.com/maps/@42.2665847,-84.1423295,3a,75y,99.05h,76.55t/data=!3m6!1e1!3m4!1sboDrHMwBnevZE7d83jiOcw!2e0!7i3328!8i1664?hl=en

[wxfree]

Someone posted a while back a pic of ALT I-35E and ALT I-35W signs in Hillsboro, TX along TX 81 at the point where the historic alignments of US 77 and US 81 split.  A quick check of Street View doesn't show them.

The Alt signage appears to be gone.  I haven't checked every location where a sign existed, but I've seen that some of them are no longer there.  The old Street View imagery in 2009 and 2013 shows where they were.  For reference, I wrote some time back about how it was signed differently in different directions.  It was signed as Alt I-35 going south, where it was headed toward I-35, and was signed W/E northbound north of the split.  It was signed Alt I-35 north along SH 81 in town, where it was headed toward the split.  In that post I suggested the signage was haphazard, but looking at it again it seems quite orderly, being signed based on where the route was headed.  Northbound in town it was signed without directional reference because it could be used as an alternate for either branch.
https://www.aaroads.com/forum/index.php?topic=13483.msg2007210#msg2007210