All posts by Michael F Ballard

Michael F Ballard is the author and administrator of the Southern California Regional Rocks and Roads website, https://socalregion.com, since 1995. I have been studying the geology and highway history throughout southern California for most of my life. I am also the President of the Ridge Route Preservation Organization. Founder of the Historic Highway 99 Association of California, https://historic99.org .
Corona, District 8, History, Old Alignment, Old Bridge, Riverside County, US 91

Following old US 91 near Corona

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I took a trip recently to the Corona area to check out some of the old alignments of US 91. I had been there before, but it has been a long time. Starting from the Green River exit off of the 91 Freeway, I headed east along the south side of the freeway. Here, the roadways named Green River Road and Palisades Drive cover the pre-freeway alignment of US 91. This section is also a portion of the 1939 Prado Dam Relocation. This realignment took the highway out of the riverbed to the north and pushed it closer to the hills. A significant portion remains today relatively intact.

Near the Green River Road interchange, an abandoned portion of the roadbed is revealed by a 1939 culvert. The pavement has long since been removed. A portion of the old median, complete with curb divots, remains to the east. The best portion, however, is on Palisades Drive. This section has a fairly continuous old median, old bridges, wooden railing, and even a mile marker from Route 91. This whole section was bypassed in the early 1970’s along with a change to the 91 / 71 interchange.

Abandoned section of US 91 near Green River Road.
Abandoned section of US 91 near Green River Road.
1939 culvert on the abandoned section.
1939 culvert on the abandoned section.
Old raised median on Green River Road.
Old raised median on Green River Road.
Section of Palisades Drive, restriped to two lanes from four. Old raised median and wooden railing are visible here.
Section of Palisades Drive, restriped to two lanes from four. Old raised median and wooden railing are visible here.
Nice section of intact wooden railing.
Nice section of intact wooden railing.
Old Route 91 milemarker.
Old Route 91 milemarker. Reads “091, RIV, mileage illegible”
Former onramp from SB State 71 to WB US 91.
Former onramp from SB State 71 to WB US 91.
1939 bridge and railing near the eastern end.
1939 bridge and railing near the eastern end.
Toll Lanes

91 Express Lanes

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I found out recently that the 91 Express Lanes, the toll lanes in the median of the 91 Freeway from the 55 to the Riverside County Line are free for motorcyclists. Now, as I love to travel all roads that are available to me, I ended up signing up for a transponder. It has offered me an interesting look at what goes into getting one and how they work. I shall be posting photos and videos about how these devices work in the near future.

In addition to the transponder, I also obtained a special bag to put the device in when I travel toll lanes that are free and don’t need a transponder. Eventually, I hope that all lanes are the same and won’t need such devices.

91 Express Lanes Welcome Kit and Transponder.
91 Express Lanes Welcome Kit and Transponder.

Geology, Los Angeles

M5.1 Earthquake hits La Habra

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From the USGS – Updated:

http://earthquake.usgs.gov/earthquakes/eventpage/ci15481673#summary

intensity

lahabraci15481673_ciim

Event Time

  1. 2014-03-29 04:09:42 UTC
  2. 2014-03-28 21:09:42 UTC-07:00 at epicenter
  3. 2014-03-28 21:09:42 UTC-07:00 system time

Location

33.919°N 117.944°W depth=7.5km (4.6mi)

Nearby Cities

  1. 1km (1mi) S of La Habra, California
  2. 4km (2mi) W of Brea, California
  3. 5km (3mi) NNW of Fullerton, California
  4. 6km (4mi) E of La Mirada, California
  5. 546km (339mi) W of Phoenix, Arizona

Tectonic Summary

A M5.1 earthquake occurred at 9:09PM on March 28, 2014, located 1 mile easy of La Habra, CA, or 4 miles north of Fullerton, CA. The event was felt widely throughout Orange, Los Angeles, Ventura, Riverside, and San Bernardino counties.  It was preceded by two foreshocks, the larger of M3.6 at 8:03pm.  The demonstration earthquake early warning system provided 4 second warning in Pasadena.

There have been 23 aftershocks as of 10:00PM on March 28, the largest of which was a M3.6 at 9:30PM, and was felt locally near the epicenter. The aftershock sequence may continue for several days to weeks, but will likely decay in frequency and magnitude as time goes by.

The maximum observed instrumental intensity was VII, recorded in the LA Habra and Brea areas, although the ShakeMap shows a wide area of maximum intensity of VI. The maximum reported intensity for the Did You Feel It? map was reported at VI in the epicentral area.

This sequence could be associated with the Puente Hills thrust (PHT).  The PHT is a blind thrust fault that extends from this region to the north and west towards the City of Los Angeles.  It caused the M5.9 1987 Oct. 1 Whittier Narrows earthquake.

Previously, the M5.4 2008 Chino Hills earthquake occurred in this region.  It caused somewhat stronger shaking in Orange County and across the Los Angeles Basin.

The moment tensor shows oblique faulting, with a north dipping plane that approximately aligns with the Puente Hills thrust.

The demonstration earthquake early warning system provided 4 second warning in Pasadena.

Related Links

Angels Flight, Los Angeles

Angels Flight in Los Angeles

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Angels Flight is a short funicular railway in downtown Los Angeles. It has been around since 1901, though not continuously. It used to run from Hill St and 3rd St west up Bunker Hill. It was moved about 1/2 block south about 15 years ago. I took this video of it in 2010.

San Diego

Old signs in Downtown San Diego

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Some buildings were demolished a few years ago on Kettner Blvd between Ash St and A St revealing some really cool old signs. I’m not sure how old they are but I’m guessing 1940’s.

Closeup of the Hires Root Beer sign.
Closeup of the Hires Root Beer sign.

Southern end of the sign.
Southern end of the sign.

Dr Pepper and Hires sign at an old bottling plant
Dr Pepper and Hires sign at an old bottling plant