I-10 west end

[Alps]

I am having trouble tracking anything official on I-10. Does 10 end at Lincoln Boulevard overpass (centerline of 1), does it end where the ramps merge from 1 (Exit 1A), or does it end at the west side of the McClure Tunnel? Please provide backup with your answer, thanks!

[Max Rockatansky]

The Caltrans Postmile Tool has it end at the Lincoln Overpass. 

[Alps]

I tried the postmile tool but it wasn't working in Chrome in any usable way. I had heard years ago that it went through the tunnel. Is there any way to check historically if that's changed?

[Max Rockatansky]

There might be something to the tunnel as I-10 has an odd Postmile ending in the 2.1 range.  That would certainly imply it was at least once planned to go up the coast a little bit towards Malibu.  I haven't been there in years so I don't recall what signage might be in the tunnel, Daniel does have some commentary on his page that it might be signed as I-10:

https://www.cahighways.org/ROUTE010.html

[Occidental Tourist]

I am having trouble tracking anything official on I-10. Does 10 end at Lincoln Boulevard overpass (centerline of 1), does it end where the ramps merge from 1 (Exit 1A), or does it end at the west side of the McClure Tunnel? Please provide backup with your answer, thanks!

I think this question can't be answered definitively.

In the Caltrans bridge log for the Santa Monica Freeway, the Lincoln Avenue bridge over the Santa Monica Freeway is identified as being a State Route 1 bridge with a (revised) postmile listing corresponding to SR 1 instead of SR 10.  The bridge log also names calls the bridge the Route 1/10 Separation. 

All of the bridges west of the Lincoln Avenue bridge are listed in the bridge log as being State Route 1 bridges.

The next bridge in the log east of the Lincoln Avenue bridge is the 11th Street bridge.  The 11th Street bridge is a little over 2/10ths of a mile east of the Lincoln Avenue bridge.  The 11th Street bridge is listed as a State Route 10 bridge.

Thus, theoretically, the 10 freeway ends somewhere between the 11th Street bridge and the Lincoln Avenue bridge, EXCEPT the postmile listing for the 11th Street bridge is a (revised) 2.38 miles, meaning that there's another 2 plus miles of State Route 10 west of the 11th Street bridge.  Not sure how you reconcile that postmile listing when less than a quarter mile further west, all the bridges are listed as State Route 1 bridges.

The only guess I have as to why there's a 2.38 postmile listing that close to the putative end of State Route 10 is that the postmile for State Route 10 was calculated based on the planned ending at the offshore Pacific Coast Causeway that was never built.

BTW, going 2.38 miles west of the 11th Street bridge (assuming you follow the existing roadway and don't go straight into the ocean) puts you well on PCH past the interchange for the California Incline and somewhere between the Beach Club and the old Marion Davies beach estate guest house.

https://gisdata-caltrans.opendata.arcgis.com/datasets/f0f31a540f17414ba384127182f4e088_0?geometry=-118.500%2C34.011%2C-118.476%2C34.018

[Max Rockatansky]

I am having trouble tracking anything official on I-10. Does 10 end at Lincoln Boulevard overpass (centerline of 1), does it end where the ramps merge from 1 (Exit 1A), or does it end at the west side of the McClure Tunnel? Please provide backup with your answer, thanks!

I think this question can't be answered definitively.

In the Caltrans bridge log for the Santa Monica Freeway, the Lincoln Avenue bridge over the Santa Monica Freeway is identified as being a State Route 1 bridge with a (revised) postmile listing corresponding to SR instead of SR 10.  The bridge log also names calls the bridge the Route 1/10 Separation. 

All of the bridges west of the Lincoln Avenue bridge are listed in the bridge log as being State Route 1 bridges.

The next bridge in the log east of the Lincoln Avenue bridge is the 11th Street bridge.  The 11th Street bridge is a little over 2/10ths of a mile east of the Lincoln Avenue bridge.  The 11th Street bridge is listed as a State Route 10 bridge.

Thus, theoretically, the 10 freeway ends somewhere between the 11th Street bridge and the Lincoln Avenue bridge, EXCEPT the postmile listing for the 11th Street bridge is a (revised) 2.38 miles, meaning that there's another 2 plus miles of State Route 10 west of the 11th Street bridge.  Not sure how you reconcile that postmile listing when less than a quarter mile further west, all the bridges are listed as State Route 1 bridges.

The only guess I have as to why there's a 2.38 postmile listing that close to the putative end of State Route 10 is that the postmile for State Route 10 was calculated based on the planned ending at the offshore Pacific Coast Causeway that was never built.

BTW, going 2.38 miles west of the 11th Street bridge (assuming you follow the existing roadway and don't go straight into the ocean) puts you well on PCH past the interchange for the California Incline and somewhere between the Beach Club and the old Marion Davies beach estate guest house.

https://gisdata-caltrans.opendata.arcgis.com/datasets/f0f31a540f17414ba384127182f4e088_0?geometry=-118.500%2C34.011%2C-118.476%2C34.018

Regarding the Postmiles, they actually don't drop to 0 in the Postmile Tool.  The lowest Route 10 Postmile I get is R2.155. 

[Occidental Tourist]

I am having trouble tracking anything official on I-10. Does 10 end at Lincoln Boulevard overpass (centerline of 1), does it end where the ramps merge from 1 (Exit 1A), or does it end at the west side of the McClure Tunnel? Please provide backup with your answer, thanks!

I think this question can't be answered definitively.

In the Caltrans bridge log for the Santa Monica Freeway, the Lincoln Avenue bridge over the Santa Monica Freeway is identified as being a State Route 1 bridge with a (revised) postmile listing corresponding to SR instead of SR 10.  The bridge log also names calls the bridge the Route 1/10 Separation. 

All of the bridges west of the Lincoln Avenue bridge are listed in the bridge log as being State Route 1 bridges.

The next bridge in the log east of the Lincoln Avenue bridge is the 11th Street bridge.  The 11th Street bridge is a little over 2/10ths of a mile east of the Lincoln Avenue bridge.  The 11th Street bridge is listed as a State Route 10 bridge.

Thus, theoretically, the 10 freeway ends somewhere between the 11th Street bridge and the Lincoln Avenue bridge, EXCEPT the postmile listing for the 11th Street bridge is a (revised) 2.38 miles, meaning that there's another 2 plus miles of State Route 10 west of the 11th Street bridge.  Not sure how you reconcile that postmile listing when less than a quarter mile further west, all the bridges are listed as State Route 1 bridges.

The only guess I have as to why there's a 2.38 postmile listing that close to the putative end of State Route 10 is that the postmile for State Route 10 was calculated based on the planned ending at the offshore Pacific Coast Causeway that was never built.

BTW, going 2.38 miles west of the 11th Street bridge (assuming you follow the existing roadway and don't go straight into the ocean) puts you well on PCH past the interchange for the California Incline and somewhere between the Beach Club and the old Marion Davies beach estate guest house.

https://gisdata-caltrans.opendata.arcgis.com/datasets/f0f31a540f17414ba384127182f4e088_0?geometry=-118.500%2C34.011%2C-118.476%2C34.018

Regarding the Postmiles, they actually don't drop to 0 in the Postmile Tool.  The lowest Route 10 Postmile I get is R2.155. 

If 2.155 is considered the official west end of 10, then the end would be the centerline of the Lincoln Avenue bridge based on the postmile listing for the 11th Street bridge. 

I'd love to know the backstory about the machinations that led to a postmile calculation for the 10 (and a revised one at that) starting at 2.155.

[Occidental Tourist]

By the way this article states (without citation) that the causeway proposal was first made in 1961 and finally cancelled in 1965 by Pat Brown.  1965 was the year the Santa Monica Freeway was completed.  Might explain the postmile number.

https://www.toposmagazine.com/ambitious-santa-monica-causeway/

[US 89]

Regarding the revised postmiles: they switch from revised to regular right around 14.09, which is roughly at Hoover Street. After a little bit of discussion in chat and some sleuthing by NE2, we determined that this point was the west end of the Santa Monica Freeway in 1964 - so anything completed since then would be a revision from the original postmiles.

[Max Rockatansky]

The Postmiles were reset in 1964 during the State Highway Renumbering.  The "R"  suffix denotes a second alignment of a highway, I believe off the top of my that "L"  would be the third.  If one looks at the 1964 Division of Highways Map it can be observed that Legislative Route 10 was assigned to CA 26 which was on Olympic:

http://www.davidrumsey.com/ll/thumbnailView.html?startUrl=%2F%2Fwww.davidrumsey.com%2Fluna%2Fservlet%2Fas%2Fsearch%3Fos%3D0%26lc%3DRUMSEY~8~1%26q%3DCALTRANs%201964%26sort%3DPub_List_No_InitialSort%2CPub_Date%2CPub_List_No%2CSeries_No%26bs%3D10#?c=0&m=0&s=0&cv=0&r=0&xywh=560%2C9773%2C782%2C1282

That accounts for why there is R suffixed Postmiles but the mileage is still odd.  Even earlier maps show the planned Santa Monica Freeway/Legislative Route 173 ending at Lincoln:

http://www.davidrumsey.com/ll/thumbnailView.html?startUrl=%2F%2Fwww.davidrumsey.com%2Fluna%2Fservlet%2Fas%2Fsearch%3Fos%3D0%26bs%3D10%26lc%3DRUMSEY~8~1%26q%3DCALTRANs%25201960%26sort%3DPub_List_No_InitialSort%2CPub_Date%2CPub_List_No%2CSeries_No#?c=0&m=0&s=0&cv=0&r=0&xywh=756%2C10007%2C563%2C923

[US 89]

The "R"  suffix denotes a second alignment of a highway, I believe off the top of my that "L"  would be the third.

Per wikipedia, a third alignment is prefixed with M, and a fourth with N. L is an "overlap due to correction or change".

[Max Rockatansky]

The "R"  suffix denotes a second alignment of a highway, I believe off the top of my that "L"  would be the third.

Per wikipedia, a third alignment is prefixed with M, and a fourth with N. L is an "overlap due to correction or change".

That's right.  There are some other interesting suffixes like "T"  for temporary and "U"  for unrelinquished:

https://postmile.dot.ca.gov/PMQT/PostmileQueryTool.html#

[The Ghostbuster]

I find the western end of Interstate 10 to be kind of strange. It is a four-lane roadway that doesn't seem to be completely Interstate Standard, and it just feeds into Pacific Coast Highway. There are End Freeway signs, but no End Interstate 10 signs. Except for the sign at the 11th Street overpass, there is no indication that Interstate 10 is now CA 1 until the merge from the on-ramp from Ocean Avenue, past the McClure Tunnel. It would be nice if there was an End Interstate 10, Begin CA 1 sign along the route; perhaps at the 4th Street overpass, with a CA 1 North reassurance marker around the Main Street overpass. More signage on the western end of Interstate 10 would really be nice.

[Alps]

Doesn't help that 1 south is signed as 10 entering the (Troy) McClure Tunnel, which is where my confusion started.

[Occidental Tourist]

I find the western end of Interstate 10 to be kind of strange. It is a four-lane roadway that doesn't seem to be completely Interstate Standard, and it just feeds into Pacific Coast Highway. There are End Freeway signs, but no End Interstate 10 signs. Except for the sign at the 11th Street overpass, there is no indication that Interstate 10 is now CA 1 until the merge from the on-ramp from Ocean Avenue, past the McClure Tunnel. It would be nice if there was an End Interstate 10, Begin CA 1 sign along the route; perhaps at the 4th Street overpass, with a CA 1 North reassurance marker around the Main Street overpass. More signage on the western end of Interstate 10 would really be nice.

Caltrans is scandalously bad at signing the ends of routes, particularly freeway routes.  The only end route signs I am aware of on LA-area freeways are at the east end of the 105, the west end of the 134, the north end of the 405, the south end of the 261, and the west end of the 210.

Edited

[ClassicHasClass]

North end of I-605 has one too.

[JustDrive]

As does EB 118

[sparker]

I find the western end of Interstate 10 to be kind of strange. It is a four-lane roadway that doesn't seem to be completely Interstate Standard, and it just feeds into Pacific Coast Highway. There are End Freeway signs, but no End Interstate 10 signs. Except for the sign at the 11th Street overpass, there is no indication that Interstate 10 is now CA 1 until the merge from the on-ramp from Ocean Avenue, past the McClure Tunnel. It would be nice if there was an End Interstate 10, Begin CA 1 sign along the route; perhaps at the 4th Street overpass, with a CA 1 North reassurance marker around the Main Street overpass. More signage on the western end of Interstate 10 would really be nice.

Caltrans is scandalously bad at signing the ends of routes, particularly freeway routes.  The only end route signs I am aware of on LA-area freeways are at the east end of the 105, the west end of the 134, the north end of the 405, the south end of the 261, and the west end of the 210.

Edited

D7 hasn't posted new "END" signs (either roadside BGS' or stand-alone assemblies) for years; the ones cited above, with a couple of exceptions, predate the present policy (or, more appropriately, the lack thereof!).  I-105's eastern end -- and the field "notation" that it is indeed the route's terminus, was prominently posted when the facililty opened in 1992 to reassure Downey and Norwalk that there were no plans to extend it east to I-5, which had been originally projected when I-105 was commissioned in 1968, but truncated upon objections from local cities through which it would have passed.  The end shield assembly for the CA 261 toll road delineates the end of OCTA toll authority maintenance and the beginning of county maintenance on Jamboree Road -- essentially a formalization of facility ownership change, which has always been the criteria for state signage.  Here, D12 is in partnership with OCTA but the latter is the actual owner of record for 261 as well as the the other toll roads in OC; state signage is provided for navigational purposes. 

[pderocco]

Doesn't help that 1 south is signed as 10 entering the (Troy) McClure Tunnel, which is where my confusion started.

The signs entering the tunnel seem intended to tell you which lane you should be in. Everything makes sense if 10 ends at the Lincoln Blvd ramps, because then 1 is continuous (except that it has been recently relinquished along Lincoln in Santa Monica), and 10 connects to 1 with no overlap.

[Alps]

Doesn't help that 1 south is signed as 10 entering the (Troy) McClure Tunnel, which is where my confusion started.

The signs entering the tunnel seem intended to tell you which lane you should be in. Everything makes sense if 10 ends at the Lincoln Blvd ramps, because then 1 is continuous (except that it has been recently relinquished along Lincoln in Santa Monica), and 10 connects to 1 with no overlap.

It sounds like they trade off at the overpass itself, which is pretty typical of centerlines. It means there's a small stretch of freeway that's technically 1 but only accessible from 10. For example, there's a small piece of CA 51 that practically isn't overlapped with Business US 50 because of all the ramps at CA 99, but legislatively there isn't.

[TheStranger]

Doesn't help that 1 south is signed as 10 entering the (Troy) McClure Tunnel, which is where my confusion started.

The signs entering the tunnel seem intended to tell you which lane you should be in. Everything makes sense if 10 ends at the Lincoln Blvd ramps, because then 1 is continuous (except that it has been recently relinquished along Lincoln in Santa Monica), and 10 connects to 1 with no overlap.

It sounds like they trade off at the overpass itself, which is pretty typical of centerlines. It means there's a small stretch of freeway that's technically 1 but only accessible from 10. For example, there's a small piece of CA 51 that practically isn't overlapped with Business US 50 because of all the ramps at CA 99, but legislatively there isn't.

IIRC that piece of 51 between 99 and when the ramps from US 50 (former Business 80) connect has one exit (T Street) that is numbered based on the distance of Business 80, IMO the mainline for the freeway from 99 to 51 should be signed as an exit off of 99, as well as that T Street ramp.