California SR 142 (Carbon Canyon Road)

[M3100]

This route connects California SR 90 in Brea (Orange County) with California SR 71 in Chino Hills (San Bernardino County).  The end points are separate city streets (Valencia in Brea; Chino Hills Parkway in its namesake city).  Carbon Canyon is a semi-rural highway connecting the two, with some hairpin curves. There are advisory signs for trucks posted at each end. Here are some pics from Sunday afternoon (7/19/20):

Heading north on Valencia, this first confirmation sign (with an arrow).


Across the street, there is a similar sign for southbound traffic approaching Imperial Highway, where CA 142 ends.  This sign also has an arrow (??)  How close can a confirmation sign be, without actually being an "end" sign?


Many of the postmiles in Orange County are completely faded, though this one is visible (and a bit banged up). 


Here is the sign for eastbound traffic at the San Bernardino County line.  The three point corner of Los Angeles, Orange, and San Bernardino counties is nearby, on Private Property.  San Bernardino County restarts the mileage at 0.0.


Here is the confirmation sign for westbound traffic, inside the Sleepy Hollow area just before the county line.


Here is the furthest east confirmation sign in Chino Hills.


There is an "End" sign right before the SR 71 underpass (not pictured).

[RZF]

Driving this road beats going north on the 57 when it multiplexes with the 60 getting into the Inland Empire. You shed a few minutes of stop-and-go traffic that plagues Diamond Bar during rush hour.

[sparker]

It used to be one of the great "back roads" to get out of OC to the Inland Empire until around 2003-04, when folks seemed to discover it; likely because with the 1998 advent of the CA 241 toll road emptying out onto EB CA 91, the always nasty peak commute traffic on the latter became even worse.  The canyon approach from old Brea-Olinda Road east of Valencia was brought out to 6 lanes (3+3), eventually dropping to 2+2 before narrowing down to the single lane through most of the canyon.  During peak hours it took as much as 20 minutes to get from the 6-lane section east of Valencia to the canyon itself because of the lane merges; once in single-file the flow picked up all the way over the top into Chino Hills.  In any case, the signage from Imperial Highway was always dicey; at the end any CA 142 trailblazing was confined to a reference on smallish green signs.  But once through the canyon WB on 142 there is presently no indication that CA 90 exists along Imperial Highway; signage to that effect was gone by about 2001.   

[M3100]

But once through the canyon WB on 142 there is presently no indication that CA 90 exists along Imperial Highway; signage to that effect was gone by about 2001. 

Actually...there is a California SR 90 sign right at the Imperial Highway intersection (no 'advance warning').  It is just a speck in picture #2, but it is there (with a bi-directional arrow below it), right above whatever made that bright reflection.  I've cropped and maxxed a segment of the picture here:

[mrsman]

But once through the canyon WB on 142 there is presently no indication that CA 90 exists along Imperial Highway; signage to that effect was gone by about 2001. 

Actually...there is a California SR 90 sign right at the Imperial Highway intersection (no 'advance warning').  It is just a speck in picture #2, but it is there (with a bi-directional arrow below it), right above whatever made that bright reflection.  I've cropped and maxxed a segment of the picture here:

While I do like mileage signs, I wold not advice Fullerton traffic to turn right on Imperial Hwy.  Most of Fullerton is to the south an there aren't enough guidance signs to guide people from Imperial Highway to there.  Instead, Fullerton traffic (especially heading to Downtown or CSUF) should stay on Valenica and turn on Yorba Linda Blvd instead.  A better city for mileage on Imperial Hwy would be Norwalk.

Or maybe just guide people to the 57 freeway instead.

[sparker]

^^^^^^^^^^^
Don't remember the CA 90 trailblazer at Valencia & Imperial from the last time I was down in the area (2012).  If D12 posted it in the meantime, more power to them!  And I certainly agree that Fullerton isn't the optimal choice for a control city on WB Imperial/CA 90; a better choice would be La Habra -- the last city that section of CA 90 encounters before terminating (unremarkably!) at CA 39/Beach Blvd.