California State Route concurrencies with Interstates

[SoCal Kid]

MOD NOTE: This thread was split from the "I-405; the San Diego Freeway" thread on 5/19/19. –Roadfro

Is it me does it feel like the I-405 and CA 22 concurrency is the only Interstate-State Route concurrency in California?

[Max Rockatansky]

Is it me does it feel like the I-405 and CA 22 concurrency is the only Interstate-State Route concurrency in California?

Off the top my head I-5 has concurrencies with CA 33 and CA 99. 

[Techknow]

I know there's I-280 with CA 1 and I-280 with CA 35. I-215 and CA 60 might also be a concurrency

[Verlanka]

Is it me does it feel like the I-405 and CA 22 concurrency is the only Interstate-State Route concurrency in California?

Off the top my head I-5 has concurrencies with CA 33 and CA 99.

As well as CA 4.

[Max Rockatansky]

Is it me does it feel like the I-405 and CA 22 concurrency is the only Interstate-State Route concurrency in California?

Off the top my head I-5 has concurrencies with CA 33 and CA 99.

As well as CA 4.

CA 113 north of Sacramento.  CA 79 multiplexes I-15 and CA 74 with I-215...I think this ought to be its own thread. 

[roadfro]

SR 89 overlaps with I-80 in Truckee for about 2.5 miles.

...I think this ought to be its own thread. 

And now it is!

[bing101]

CA-12 and I-80 have a concurrency in Fairfield, CA

[Max Rockatansky]

CA-12 and I-80 have a concurrency in Fairfield, CA

CA 113 and CA 193 also multiplex I-80.

[oscar]

CA-12 and I-80 have a concurrency in Fairfield, CA

CA 113 and CA 193 also multiplex I-80.

Not sure about 193, since not only is that multiplex unsigned, but you have to take both I-80 and CA 49 to get from one 193 segment to the other. With no help from signage, it's hard to follow the connection.

For the Travel Mapping project, we decided to treat the two parts of CA 193 as separate routes, with no multiplex with either I-80 or CA 49. We preserved other concurrencies, that either are signed or make you travel only one other route to make the connection.

[TheStranger]

Parentheses mark former concurrencies

I-5:
(Route 75 in San Diego)
[Will Route 58 have a concurrency with I-5 in the future once the Westside Parkway is extended to near Buttonwillow?]
Route 33 near Coalinga
Route 4 in Stockton
Route 99 in Sacramento
(unclear if Route 16 ever really counted as it seems 1964-1984 there was a gap from downtown Sacramento to the College Greens district)
Route 113 in Woodland
(Route 299 in Redding)

I-405:
Route 22 near Long Beach

I-8:
(Route 67 in El Cajon)

I-15:
Route 79 in Temecula

I-215:
Route 74 in Perris
Route 60 in Moreno Valley/Riverside
(Note: there was an I-15/Route 18 concurrency in San Bernardino when 15 used the northern portion of modern 215)

I-80:
(Route 17 in Berkeley)
Route 113 between Dixon and Davis
Route 89 in Truckee

I-280:
(Route 85 in Cupertino until the early 90s)
Route 35 between San Mateo and San Bruno
Route 1 in Daly City

I-680:
Route 84 in one direction near Sunol

I-880:
Route 84 in Fremont/Newark

[US 89]

Isn't CA 99 also briely concurrent with the unsigned I-305 in Sacramento?

[Max Rockatansky]

Isn't CA 99 also briely concurrent with the unsigned I-305 in Sacramento?

Yes but the State doesn't consider I-305 to be an actual Route.  That multiplex bleeds onto I-5 also. 

[DTComposer]

Also formerly on I-680: CA-24 between Walnut Creek and Concord (although the northern section is legislatively CA-242, it wasn't signed as such until the 1980s)

Also formerly on I-5: CA-134 from the Ventura Freeway to Colorado Street

Between 1964 and 1970 or so, I-280 and I-680 were also concurrent (at least signage-wise) with CA-17 between today's CA-17/I-280/I-880 junction and today's I-880/CA-262 junction, during the time that the alignment for all three routes were in flux circling around downtown San Jose.

Wasn't there a second concurrence of CA-33 with I-5, between CA-152 and Santa Nella (after the Henry Miller/Ingomar Grade section of CA-33 got decommissioned, and before the southern part of Santa Nella Road got transferred from CA-207)?

[Exit58]

I believe CA 1 overlaps I-10 along the Santa Monica between PCH and Lincoln Blvd, about a mile but still a concurrence.

[TheStranger]

I believe CA 1 overlaps I-10 along the Santa Monica between PCH and Lincoln Blvd, about a mile but still a concurrence.

I had always been under the impression that the Santa Monica Freeway essentially starts as Route 1 through the tunnel, then I-10 begins right after Route 1 takes the offramp to Lincoln.  (Though IMO 10 really should just cover the entirety of the freeway for continuity purposes)

[ClassicHasClass]

^^^^

This seems congruent with the bridge log for D7 which credits the bridges west of Lincoln to CA 1 (R34.67 at 5th St to 35.07 at Main St). The only weird thing is that I-10 is at PM 2.16 at the CA 1 separation, implying there are 2 miles west of that position. They may be unconstructed.

[TheStranger]

The only weird thing is that I-10 is at PM 2.16 at the CA 1 separation, implying there are 2 miles west of that position.

Does 2 miles go right to the tunnel entrance?

Interestingly, a 1959 topographic map of the area on HistoricAerials shows Alternate US 101 using the tunnel and then Olympic Boulevard to Lincoln, with the 1936-1960 Route 26 then continuing east on Olympic as had been the case for years. (The map also shows 26 using Lincoln southbound for a few blocks, then Pico west to the coastline)  Between 1963 and 1968, the portion of Santa Monica Freeway to the tunnel was completed, with what had been US 101A/Olympic subsumed by ramps to Lincoln and that westernmost extent of the freeway (the 1964 aerial photo shows a temporary configuration where the tunnel led out to Olympic, with the Santa Monica Freeway right of way being cleared out in a parallel path to the south) 

What that mileposting for I-10 makes me wonder is if the entire Santa Monica Freeway project was thought of as I-10, up to the tunnel, even though the portion of freeway that replaced Olympic/US 101A has always been part of post-1964 Route 1.

[DTComposer]

The only weird thing is that I-10 is at PM 2.16 at the CA 1 separation, implying there are 2 miles west of that position.

Does 2 miles go right to the tunnel entrance?

Interestingly, a 1959 topographic map of the area on HistoricAerials shows Alternate US 101 using the tunnel and then Olympic Boulevard to Lincoln, with the 1936-1960 Route 26 then continuing east on Olympic as had been the case for years. (The map also shows 26 using Lincoln southbound for a few blocks, then Pico west to the coastline)  Between 1963 and 1968, the portion of Santa Monica Freeway to the tunnel was completed, with what had been US 101A/Olympic subsumed by ramps to Lincoln and that westernmost extent of the freeway (the 1964 aerial photo shows a temporary configuration where the tunnel led out to Olympic, with the Santa Monica Freeway right of way being cleared out in a parallel path to the south) 

What that mileposting for I-10 makes me wonder is if the entire Santa Monica Freeway project was thought of as I-10, up to the tunnel, even though the portion of freeway that replaced Olympic/US 101A has always been part of post-1964 Route 1.

If you continue to follow the freeway, through the tunnel and onto PCH, then 2.16 miles past the Lincoln Blvd. separation gets you to the Santa Monica/Los Angeles city limit (right by Will Rogers State Beach).

However, for a more fun and conspiratorial idea, continuing due SW (through the tunnel, out the pier and into the ocean) would get you onto the proposed manmade island/causeway...

http://www.surfsantamonica.com/ssm_site/the_lookout/news/News-2003/Sept-2003/09_29_03_Dreaming_Big_The_Road_in_the_Sea.htm

[mrsman]

I believe CA 1 overlaps I-10 along the Santa Monica between PCH and Lincoln Blvd, about a mile but still a concurrence.

I had always been under the impression that the Santa Monica Freeway essentially starts as Route 1 through the tunnel, then I-10 begins right after Route 1 takes the offramp to Lincoln.  (Though IMO 10 really should just cover the entirety of the freeway for continuity purposes)

As far as routing is concerned, IMO there is no need for a concurrency if one of the routes ends at the routing of the other.  If I-10 somehow continued west of CA 1, then it would make sense to have the routing continue.  But since I-10 does not exist west of route 1, there is no point to a one mile concurrency. 

Now, of course, the signing should indicate that you are going to I-10, and perhaps for funding purposes this is I-10 since it was part of the interstate highway funding, but there is no reason why this should legally be part of I-10.

[TheStranger]

I believe CA 1 overlaps I-10 along the Santa Monica between PCH and Lincoln Blvd, about a mile but still a concurrence.

I had always been under the impression that the Santa Monica Freeway essentially starts as Route 1 through the tunnel, then I-10 begins right after Route 1 takes the offramp to Lincoln.  (Though IMO 10 really should just cover the entirety of the freeway for continuity purposes)

As far as routing is concerned, IMO there is no need for a concurrency if one of the routes ends at the routing of the other.  If I-10 somehow continued west of CA 1, then it would make sense to have the routing continue.  But since I-10 does not exist west of route 1, there is no point to a one mile concurrency. 

Now, of course, the signing should indicate that you are going to I-10, and perhaps for funding purposes this is I-10 since it was part of the interstate highway funding, but there is no reason why this should legally be part of I-10.

I meant it in the sense that the I-10 mainline lanes continue directly to the west of Lincoln (into the tunnel) with Route 1 being an exit off of that, rather than a freeflowing split.  And the trajectory to the tunnel is east-west.

[bing101]

I-710 and CA-710 is supposed to be co-signed at the gap section between Pasadena to South Pasadena from the CA-134@I-210 interchange to the I-710 section near the East L.A. Interchange. But that has been debated though.

[bing101]

CA-99 is supposed to be cosigned with I-9 or I-7 if the interstate is approved.

I do remember CA-21 was cosigned with I-680 in Solano County in the past though until Caltrans decommissioned CA-21 because of I-680's completion though.

[Max Rockatansky]

CA 60 briefly multiplexes I-215. 

[roadfro]

CA-99 is supposed to be cosigned with I-9 or I-7 if the interstate is approved.

Ideas of I-9/I-7 becoming a thing along the CA 99 corridor are very speculative...

[FightingIrish]

CA-99 is supposed to be cosigned with I-9 or I-7 if the interstate is approved.

Ideas of I-9/I-7 becoming a thing along the CA 99 corridor are very speculative...

California doesn't move very fast when it comes to establishing new Interstate routes. They pretty much make upgrades whenever they have money and aren't very aggressive about assigning miles. Examples include CA 99, 58, 15, 210, 905, etc.