Why US 138 and I-238, but no US 38 or I-38?

[Henry]

I don't know if this question has been asked before, but here goes...

US 138 is a spur off the short-lived US 38 that not too many people knew about, and then there's the more infamous I-238 that exists in a place where its implied parent, I-38, would never go to. Why are those designations allowed to exist, even though neither parent route does?

[froggie]

US 138 is an original U.S. route from 1926, and was a spur off of US 38 which was also part of the original system.  Just happened to be that US 38 was eliminated (replaced in part by US 34) while US 138 wasn't.

No different of a situation than the x66 routes that remain today, even though US 66 was decommissioned.


I-238 was numbered due to it originally being CA 238, and AASHTO allowed an exception to the normal numbering rules so as to avoid renumbering confusion.

[Evan_Th]

I-238 was numbered due to it originally being CA 238, and AASHTO allowed an exception to the normal numbering rules so as to avoid renumbering confusion.

Also because there weren't any x80's available at the time.

[vdeane]

I-238 was numbered due to it originally being CA 238, and AASHTO allowed an exception to the normal numbering rules so as to avoid renumbering confusion.

Also because there weren't any x80's available at the time.

I-180 was available, but would have required renumbering CA 180 for CA to maintain their "no duplication" mandate.

[sturmde]

I-180 was available, but would have required renumbering CA 180 for CA to maintain their "no duplication" mandate.

Actually, no.  It was not available.  I-180 was the original set-aside designation for what is now the northern extension above I-80 of I-580 that ends at US 101.
180 (see above) Richmond spur to US 101
280 West side of Bay
380 Connector on west side of Bay
480 Embarcadero to 101 cancelled freeway
580 The former southern half of I-5W
680 East side of Bay
780 Spur of 680
880 Originally, Sacramento Bypass
980 Oakland spur
.
Theoretically, if 4di's exist, one could consider I-238 to actually be I-2380, the 23rd daughter route of I-80.   That's my "head canon" that it's a 4di with the last digit truncated!

[sparker]

I-180 was available, but would have required renumbering CA 180 for CA to maintain their "no duplication" mandate.

Actually, no.  It was not available.  I-180 was the original set-aside designation for what is now the northern extension above I-80 of I-580 that ends at US 101.
180 (see above) Richmond spur to US 101
280 West side of Bay
380 Connector on west side of Bay
480 Embarcadero to 101 cancelled freeway
580 The former southern half of I-5W
680 East side of Bay
780 Spur of 680
880 Originally, Sacramento Bypass
980 Oakland spur
.
Theoretically, if 4di's exist, one could consider I-238 to actually be I-2380, the 23rd daughter route of I-80.   That's my "head canon" that it's a 4di with the last digit truncated!

I-238 is an ironic and unfortunate product of very bad but unforeseeable timing:  both the I-880 (2nd iteration over former CA 17) and I-238 (subsuming part of CA 238) designations were approved in 1984, with field posting commencing in late 1986.  The number "480" was still in use as a state highway (Embarcadero Freeway) in S.F., although the Interstate designation had been revoked in 1965 in concert with the S.F. "freeway revolt", so it was still on the state books.  Of course, CA 480 was rendered unusable a couple of years later (1989) with the Loma Prieta earthquake, and formally relinquished several years after that.  If they wanted, Caltrans could simply renumber I-238 as I-480 -- but given their current disinterest in route continuity, numbering, or much of anything else dealing with the system, asking them to draft the requisite legislation, cobble up new BGS's, and send a crew out to install that as well as reassurance/trailblazer signage -- PLUS the P.R. effort required to smooth out the designation change (after 33 years of field deployment) with the driving public -- would likely be met with a "you're kidding, of course!" response from the agency.  Let's put it this way -- we roadgeeks don't much care for I-238, but the general public couldn't care less.  Unless down the line I-580 somehow gets "upgraded" to a 2di, there's little or no chance that anything will be officially done regarding I-238.   

[vdeane]

Actually, no.  It was not available.  I-180 was the original set-aside designation for what is now the northern extension above I-80 of I-580 that ends at US 101.

That I-180 was canned in 1983 for the same reasons it wasn't assigned to I-238.

http://www.kurumi.com/roads/3di/i180.html#180ca

[roadman65]

I-238 was numbered due to it originally being CA 238, and AASHTO allowed an exception to the normal numbering rules so as to avoid renumbering confusion.

Also because there weren't any x80's available at the time.

Where is I-180?  Where is I-380? 

I-238 sort of set the precident for I-41 from US 41.  Though not a direct continuation of keeping a route number alive as different designation in WI, but they did use I-41 to keep Route 41 used for the interstate designation of the US 41 freeways north to Green Bay, and cause it fits into the grid as a coincidence. 

Then again AASHTO has been known to break rules like keeping I-278 and I-678 in NY when I-78 got truncated to the Holland Tunnel.  Those should be x95s and I-278 could be I-87 continued further south and into NJ.

[sturmde]

Where is I-180?  Where is I-380? 

I-238 sort of set the precident for I-41 from US 41.  Though not a direct continuation of keeping a route number alive as different designation in WI, but they did use I-41 to keep Route 41 used for the interstate designation of the US 41 freeways north to Green Bay, and cause it fits into the grid as a coincidence. 

Then again AASHTO has been known to break rules like keeping I-278 and I-678 in NY when I-78 got truncated to the Holland Tunnel.  Those should be x95s and I-278 could be I-87 continued further south and into NJ.
[/quote]

I-380 runs E/W on the West side of the San Fran Bay as a short spur off I-280.  I-180 was replaced by I-580, and wouldn't be reused as it duplicates CA 180.
.
Totally agree with you about New York's x78's.  There's I-478 in the Battery Tunnel, too.  The Extend 87 concept is a great one for helping sort out I-87 in New York having THREE different runs of Exit numbers:  (i) South of the end of the Thruway, (ii) the Thruway, and (iii) the Northway.  By extending I-87 southward along I-278 and switching to mileage based exits, none of the current exit numbers would be similar to new mileage based ones extending north from the crossing from Staten Island northward.  My Extend 87 even more concept... when it meets the NJTP, continue south duplexing I-95 to the new "Philadelphia Cutoff", and then become the number for the rest of the NJTP.  Jump over the Del Mem Bridge, and then run down DEL 1?  It can sort of make the Southern I-87's Norfolk - Raleigh route somehow seem like a distant extension.

[sparker]

I-238 was numbered due to it originally being CA 238, and AASHTO allowed an exception to the normal numbering rules so as to avoid renumbering confusion.

Also because there weren't any x80's available at the time.

I-180 was available, but would have required renumbering CA 180 for CA to maintain their "no duplication" mandate.

CA 180, being one of the original state highways -- and one that has never been renumbered -- is all but iconic in the Fresno area; Caltrans was reluctant to engage in any designation shifting that would have required renumbering that route.