Why no official "Alternate" Interstate highway designation?

[TheStranger]

*IIRC this was one of the earliest plans for 3dis and even the Interstate system (think I-A, I-B, etc.), correct?

IIRC, I-459 in Alabama was originally submitted as I-59B.

[roadman]

During the Medford (MA) Fast 14 bridge replacement project on I-93 in the summer of 2012, the section of I-95 (OK - 128 for those of you stuck in 1972) between Canton and Woburn was signed as "ALT 93"  At most major junctions along I-95, they had large white on green signs indicating "ALT 93 SOUTH (NORTH) with appropriate directional arrows.  At other locations between interchanges, they had confirmatory markers.

[Brian556]

ALT I-35/35E/35W signage exists around Hillsboro, Texas, due to the presence of the split.

[dfwmapper]

ALT I-35/35E/35W signage exists around Hillsboro, Texas, due to the presence of the split.

Are those still posted? Thought those were temporary while 35 was widened. No real point to them anymore with the 3 segments around Hillsboro having been finished by mid-2012.

[wxfree]

ALT I-35/35E/35W signage exists around Hillsboro, Texas, due to the presence of the split.

Are those still posted? Thought those were temporary while 35 was widened. No real point to them anymore with the 3 segments around Hillsboro having been finished by mid-2012.

They're still signed, but the signage is strange.  Alt I-35E and Alt I-35W are signed going northbound from SH 81 and SS 579, while the same routes are signed Alt I-35 going southbound.  SH 81 southbound is signed as Alt I-35 to some point, presumably the northern intersection with SH 22/171, where To South I-35 signage begins.  There is what appears to be a separate Alt I-35 going north along SH 81 from the I-35 split.  This route is signed north along SH 81 until it splits into Alt I-35E and Alt I-35W at SS 579.  The signage seems haphazard, which is uncharacteristic for TxDOT, which is usually pretty meticulous about signage (much to my appreciation).

[bing101]

You know, I've always thought of suffixed Interstates as "Alternate Interstates," in a sense. The best example I can think of is I-15E (now I-215) in California, as it returns to I-15. Of course, I-80N [now I-84 (W)] and I-15W [now I-86 (W)] may have qualified, but I can understand why they may not.

The thing is that 3dis and the occasional business loop freeway connecting to their associated 2di are what I would consider alternate Interstates. I wouldn't have minded if there were more suffixed Interstates (like I-15E)  or even lettered spurs/loops (I-95A, I-95B, etc.)* around today IMO.

*IIRC this was one of the earliest plans for 3dis and even the Interstate system (think I-A, I-B, etc.), correct?

What about I-5w in Oakland on US-50 now I-580 does this count.

[Rover_0]

You know, I've always thought of suffixed Interstates as "Alternate Interstates," in a sense. The best example I can think of is I-15E (now I-215) in California, as it returns to I-15. Of course, I-80N [now I-84 (W)] and I-15W [now I-86 (W)] may have qualified, but I can understand why they may not.

The thing is that 3dis and the occasional business loop freeway connecting to their associated 2di are what I would consider alternate Interstates nowadays. I wouldn't have minded if there were more suffixed Interstates (like I-15E)  or even lettered spurs/loops (I-95A, I-95B, etc.)* around today IMO.

*IIRC this was one of the earliest plans for 3dis and even the Interstate system (think I-A, I-B, etc.), correct?

What about I-5w in Oakland on US-50 now I-580 does this count.

Yes.

Added the bolded word for clarification.

[corco]

To me, the Nebraska method is the best for permanently signed detours- it's a one piece sign that clearly indicates the purpose, far better than an ALT banner over a full sized shield

[DaBigE]

To me, the Nebraska method is the best for permanently signed detours- it's a one piece sign that clearly indicates the purpose, far better than an ALT banner over a full sized shield

I must be missing something...Nebraska adds the word "Route" and a cardinal direction to what otherwise looks like a regulatory sign. What makes that better than a regular route marker with an Alternate banner?

[corco]

It's more clearly differentiated from a route a person might want to travel on purpose. As a route that functionally is used only as a detour, it shouldn't be signed like a normal alternate route.

[SteveG1988]

To me an alt would be a 3di..i with an even first number, since to me that means bypass, or alt route around a place.

[NE2]

It's more clearly differentiated from a route a person might want to travel on purpose. As a route that functionally is used only as a detour, it shouldn't be signed like a normal alternate route.

It should be signed instead like normal alternate routes used to be? (I think - I know I've seen BUSINESS / ROUTE plates)

[yankee.peddler]

I like PennDOT's practice the most.  The use of a colored arrow as opposed to a bannered alternate route number mitigates confusion about what the best route would normally be.  However, when there's a specific event that demands usage of an alternate route (e.g., construction, accident, inclement weather), the arrows are in place to guide traffic onward.