Freeways of Los Angeles

Everything you always wanted to know about Los Angeles freeway history and engineering but were afraid to ask. We cover local state highways too.

[Freeways of Los Angeles @FreewaysLA]

1963 - Interchange designer Marilyn Reece and colleague Carol Schumacher during construction.

While not as widely known as Reece, Schumacher was a respected engineer, having designed parts of I-405. Schumacher also taught civil engineering classes at Cal State Long Beach.

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1964-Aug-18 - Looking NW over newly constructed San Diego Fwy (I-405)/Santa Monica Fwy (I-10) interchange, built as part of the new Santa Monica Fwy, which remains under construction west of the interchange (DOH D7 Archives photo). Sawtelle Blvd at left;

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[Freeways of Los Angeles @FreewaysLA]

Sepulveda Blvd at right; Olympic Blvd along top. Many questions have arisen why the north leg of I-405 has reversing curves at this interchange, as if to avoid an obstacle. There a large post office facility on Exposition Blvd seemingly in the path of I-405.

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[Freeways of Los Angeles @FreewaysLA]

Courtesy of Gary Smith of Camp Cajon:

1964-11-18 - Great image of Route 66 in the Blue Cut area of Cajon Pass. This is the first triple highway sign from the area we've seen that includes the upcoming I-15 freeway. The vehicle is traveling northbound. (San Bernardino Sun photo).

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Note background signs where US-101 is still shown on Santa Ana target (control) city sign, and US-99 is still shown on San Bernardino target city sign.

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[Freeways of Los Angeles @FreewaysLA]

1963 - Roadside guide sign on SB Golden State Fwy (I-5) approaching interchange with San Bernardino Fwy (I-10/US-70). At that time US-60 had already been decommissioned as Pomona Fwy (CA-60) planning was underway (CH&PW photo).

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[Freeways of Los Angeles @FreewaysLA]

1954-Feb - Looking NW over Hollywood Fwy (US-101) from Hill St OC. Grand Ave OC in upper background. Broadway off-ramp at left (DOH D7 Archives photo).

Although it was not signed as such, the Hollywood Fwy between the four level and Ramona Fwy carried US-99 to Arroyo Seco Pkwy.

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Hollywood Fwy (US-101) passing through its namesake city. Photo by Carlos G. Lucero.

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@dilanesper Yes, you are correct. 👍

[Freeways of Los Angeles @FreewaysLA]

On Memorial Day, we recognize this LA landmark along the Harbor Freeway (I-110).

The Los Angeles Memorial Coliseum was commissioned in 1921 as a memorial to Los Angeles veterans of World War I, and was rededicated to all United States veterans in 1968. Pictured here in 1967.

[Freeways of Los Angeles @FreewaysLA]

US-99 continued on to Ramona Fwy via Santa Ana Fwy. Famed US-66 continued on to Hollywood Fwy (US-101) then to Santa Monica Blvd. US-6 continued on to Harbor Fwy where it was co-signed with CA-11.

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[Freeways of Los Angeles @FreewaysLA]

1953-Nov-10 - Looking southerly at newly opened Arroyo Seco Pkwy (then US-6-66-99/CA-11, now CA-110) at Alpine St OC. Sunset Blvd OC and four level interchange in background.

Note 1948 year of construction stamped on Alpine St OC [Bureau of Public Roads (BPR) photo].

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[Freeways of Los Angeles @FreewaysLA]

c. 1989 - Harbor Fwy (I-110) Transitway "double deck" construction (CT Archives photo). Rebar column frame being lowered into piling opening.

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c. 1989 - Harbor Fwy (I-110) Transitway "double deck" construction (CT Archives photo). Column supports appear ready for superstructure formwork.

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Apparently, early highway planners of that era thought a four-lane freeway (two lanes in each direction) would suffice. An extra wide median provided room for future expansion as well as sufficient recovery space for errant vehicles.

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[Freeways of Los Angeles @FreewaysLA]

1953-July-07 - Looking SE over newly constructed Santa Ana Fwy (then US-101, now I-5) at Grand Ave/Lincoln St exit in Santa Ana (Santa Ana Public Library).

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c. 1935 - Roosevelt Hwy, later Coast Hwy (US-101 Alt), now Pacific Coast Hwy (CA-1), near Castellammare in Pacific Palisades.

Castellammare POC at center has since been reconstructed. View SE at Castle Rock Beach -- Ernest Marquez Collection.

[Freeways of Los Angeles @FreewaysLA]

ADDED NOTE: This plan lays out the interchange geometric alignment, or horizontal control map. More detailed layout construction plans are drawn at a larger scale (i.e. 1"=50' or 1"=20') that include roadway details such as curbs, dikes, guard rail, pavement type, etc.

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Freeway Engineering 101

1948 - Geometric plan showing horizontal alignment for the four level interchange, where the Hollywood Fwy (US-101) meets the Harbor Fwy (then US-6/CA-11, now CA-110) & Arroyo Seco Pkwy (then US-6-66-99/CA-11, now CA-110).

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Tangents are listed showing a length and bearing. Each curve has its own data listed, including angle of curvature, radius, tangent and length. Calculated coordinates are shown at each node point (e.g. beginning and end of curvature, angle points, radius points, etc.).

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