California Highways (www.cahighways.org): Route 27

In 1963, Route 27 was defined as the route from “Route 1 near Topanga Beach north of the intersection of Sunset Boulevard and Route 1 to Route 118 at or near Chatsworth.”

In 1965, Chapter 2007 simplified the wording of the origin: "Route 1 near Topanga Beach ~~north of the intersection of Sunset Boulevard and Route 1~~...". In 1981, Chapter 292 simplified the wording of the terminus: "Route 118 ~~at or near Chatsworth~~".

Topanga Canyon originally terminated at Santa Susana Pass Road (in fact, it was known as Santa Susana Road N of Devonshire). The extension N of Devonshire St. from just S of the SP Railroad "S" curve to the new freeway was completed in 1966; this extension climbs an 8% grade to an elevation of 1,232'.

In the Chatsworth area, when Sign Route 27 (Topanga Canyon Blvd) originally met LRN 9 (Sign Route 118) at Devonshire Blvd, it changed names to Santa Susanna Pass Road, and continued as Sign Route 118. In 1964 during the great renumbering, Route 27 was extended to end at the Route 118 freeway. The original Santa Susana Pass Road remained, with a right turn onto the older routing just before the incline up the hill started. In the mid-1990s, a new intersection was created for Santa Susana Pass Road and Topanga Canyon Blvd, and the bypassed older segment (original LRN 9) became Old Santa Susana Pass Road.

Topanga Canyon Blvd was rerouted sometime in the 1960s between Plummer and Marilla Street. The original routing was along what is now Topanga Canyon Place, and went first W of the current route, crossed the current route, and then looped E and back to the current route shortly N of Marilla Street. This was to avoid a hill that was later taken down. However, the Plummer to Topanga intersection was constructed in the 1980s or 1990s.

There also appears to be rerouting between Roscoe and Nordhoff, as well as slightly around Oxnard. The original terminus was Devonshire Street, where it met Route 118 and continued N and then W as Santa Susana Ave.

Topanga Expressway

Topanga Expressway in 1958 MTEB Master Plan The 1958 Metropolitan Transportation Engineering Board (MTEB) Master Plan of Freeways and Expressways (PDF) shows that, at the regional level at least, there were plans to reconstruct Topanga Canyon Blvd as an expressway between Pacific Coast Highway (Route 1) and Newhall Road/Railroad Avenue (Route 126) in Saugus, going over the mountains N of Chatsworth. The portion between Route 1 and Route 118 was acknowledged as state highway, but the portion N of Route 118 was not. Instead, it seemed to part of a plan that the MTEB planned to submit to the state. The MTEB remained as a committee within the larger SCAG (Southern California Association of Governments) until at least the late 1990s, although their ambitious plans in 1958 never came to fruition.

Elements of this plan lasted at least through 1971, as the Topanga Expressway was still shown as planned in the map "Circulation System - Santa Monica Mountains Area" produced as part of Mulholland Drive Scenic Development Plan in 1971.
(Image source: Circulation System - Santa Monica Mountains Area, Part of Mulholland Drive Scenic Development Plan, Dated: 1971 Source: CSUN Archives, via email from Will Poundstone, 11/29/2024)

Pre 1964 Signage History

Status

March 2024 Topanga Closure

In March 2024, it was reported that Topanga Canyon Boulevard between Pacific Coast Highway and Grand View Drive has been shut indefinitely in both directions due to an ongoing active landslide, according to Caltrans. Topanga Canyon Boulevard was first shut down on March 9, 2024 due to the slide. In April 2024, it was reported that Caltrans estimates that 9.2 million pounds of earth, or 4,600 tons, gave way just south of the town of Topanga, sending a wall of dirt, rocks and debris onto the road. As of mid-April, water continued to seep out from underneath the dirt, mud and rocks, indicating the mass may move at a given moment. Because of the instability, crews need to remove material from the top down since clearing the “toe” – as it’s known – will only bring down more earth and boulders. The estimate was that the road would remain closed until Fall 2024. The landslide is twice as large as another major slide that occurred in the 1940s.
(Source: Malibu Patch, 3/13/2024; Fox 11 News, 4/14/2024)

In May 2024, Gov. Newsom proclaimed a state of emergency to help fund badly needed repairs of roads battered during this year’s storms, including scenic Topanga Canyon Boulevard that was blocked by millions of pounds of debris. The proclamation enables Caltrans to request funding from the Federal Highway Administration’s Emergency Relief Program, which could cover up to 100% of the repairs, according to the governor’s office. Declarations such as this are useful as California's emergency restoration fund is running low. On the May 2024 CTC Agenda was Agenda Item 4.17, Request for an additional $155,000,000, from $845,000,000 to $1,000,000,000, for the Fiscal Year 2023-24 Major Damage (Emergency Restoration) Reservation.
(Source: Los Angeles Times, 5/3/2024; May 2024 CTC Agenda, Agenda Item 4.17)

In May 2024, it was reported that Topanga Canyon would reopen the first weekend in June 2024, months ahead of officials’ initial estimate. Officials initially projected the closure of Topanga Canyon Boulevard between Grand View Drive and Route 1 (Pacific Coast Highway) would last until the fall. It turned out, however, that there was less dirt, rocks and other material to remove than anticipated and the landslide wasn’t as deep as originally thought. Caltrans personnel couldn’t get to the slide area to make a more accurate estimate until the earth stopped moving. The area remained unsafe for weeks. Crews ultimately removed about 15,000 cubic yards of material — much less than the 50,000 to 90,000 they thought they would have to contend with. The type of slide that occurred is what’s known as translational, which is “kind of like a tablecloth sliding off the table.” In other words, just the top layer of soil came down. Once the slide came to a halt and visual assessments were made, an access road was built adjacent to the area. This allowed crews to get heavy equipment to the site and begin digging from the top down. It was still a sizable landslide, believed to be larger than another major one that occurred there in the 1940s. According to the governor’s office, crews worked around the clock seven days a week to stabilize the area and clear the roadway. The 15,000 cubic yards of material that was removed was repurposed for Ventura County farmers, the Los Angeles County Department of Public Works and an art installation in downtown Los Angeles near the State Historic Park, officials said. To remove materials, crews built an access road adjacent to the slide to push down materials from the top using a Spider Excavator and loading the materials into Super-10 trucks with a long-reach excavator. Now that Caltrans has stabilized the slope and removed material, geotechnical engineers and geologists will monitor the site for any movement. Officials recommended a cable-mesh drapery system to prevent any sloughing of remaining loose materials and planting native seeds to further stabilize the slope.
(Source: Los Angeles Times, 5/31/2024; Real 92.3 iHeart Radio, 6/3/2024)

In June 2024, the CTC amended the following project into the SHOPP: 07-LA-27 0.0/5.0. PPNO 07-6267; ProjID 0724000257; EA 2XN90. Route 27 Near Topanga, from Route 1 to 0.1 mile north of Circle Trail. Remove debris from roadway, repair slopes, and clean culverts. Note: Winter storms from February 4 - 6, 2024 brought heavy rains, causing slides and damaged slopes. This project will remove debris and mud from the roadway, repair slopes, reconstruct damaged guardrail and fencing, and clean culverts. Allocation ($ × $1000): PA&ED $0; PS&E $0; R/W Sup $100; Con Sup $735; R/W Cap $100; Const Cap: $2,815; TOTAL $3,750.
(Source: June 2024 CTC Minutes, Agenda Item 2.1a.(1a) #34)

In June 2024, the CTC approved the following Emergency G-11 Allocation: $3,550,000. 07-LA-27 0.0/5.0. PPNO 07-6267; ProjID 0724000257; EA 2XN90. Route 27 Near Topanga, from Route 1 to 0.1 mile north of Circle Trail. Winter storms from February 4 - 6, 2024 brought heavy rains, causing slides and damaged slopes. This project will remove debris and mud from the roadway, repair slopes, reconstruct damaged guardrail and fencing, and clean culverts. Allocation: CON ENG $735,000 CONST $2,815,000.
(Source: June 2024 CTC Agenda, Agenda Item 2.5f.(1) #19)

In August 2024, the CTC approved the following Emergency G-11 Allocation: $16,745,000. 07-LA-27 0.0/5.0. PPNO 07-6267; ProjID 0724000257; EA 2XN90. Route 27 Near Topanga, from Route 1 to 0.1 mile north of Circle Trail. Winter storms from February 4 - 6, 2024 brought heavy rains, causing slides and damaged slopes. This project will remove debris and mud from the roadway, repair slopes, reconstruct damaged guardrail and fencing, and clean culverts. This supplemental is needed because drone surveys showed three additional scarps within the slide extent along with seepage, which is likely to impact the slope's stability. Additional loose debris between 5 and 10 feet deep will be removed and the slopes will be benched. Additional drains will be installed to better control drainage at the slide location. Allocation: CON ENG $265,000; CONST $16,480,000.
(Source: August 2024 CTC Agenda, Agenda Item 2.5f.(1) #16)

In May 2026, the CTC was informed about the following emergency G-11 allocation under delegated authority: $2,750,000. 07-LA-27 2.5. PPNO 07-6304; ProjID 0726000211; EA 3XA30. Route 27 Near city of Los Angeles, at 1.1 miles south of Grand View Drive. In January 2025, the Palisades fire caused significant damage to Route 27 within Topanga Canyon. Following the fire, heavy rainfall events resulted in slope failures, erosion, debris flows, and clogging of drainage systems. Emergency Director's Order 07-2XR30 was approved to address the emergency damage. However, the work to install new 84 in. and 72 in diameter culverts as part of the original scope was unsuccessful due to the contractor's inability to get through the existing bedrock. This project will bring in a new contractor to install the drainage culverts and remove that scope from the original DO under a new supplemental. Breakdown: CON ENG $250,000; CONST $2,500,000.
(Source: May 2026 CTC Agenda, Agenda Item 2.5f.(1) #37)

In May 2026, the CTC amended the following project into the 2026 SHOPP: 07-LA-27 2.5. PPNO 07-6304; ProjID 0726000211; EA 3XA30. Route 27 Near city of Los Angeles, at 1.1 miles south of Grand View Drive. Install drainage culverts. Note: In January 2025, the Palisades fire caused significant damage to Route 27 within Topanga Canyon. Following the fire, heavy rainfall events resulted in slope failures, erosion, debris flows, and clogging of drainage systems. Emergency Director's Order 07-2XR30 was approved to address the emergency damage. However, the work to install new culverts as part of the original scope was unsuccessful due to the contractor's inability to get through the existing bedrock. This project will bring in a new contractor to install the drainage culverts and remove that scope from the original DO under a new supplemental. Allocation ($ × $1000): PA&ED $0; PS&E $0; R/W Sup $0; Con Sup $250; R/W Cap $0; Const Cap $2,500; TOTAL $2,750.
(Source: May 2026 CTC Agenda, Agenda Item 2.1a.(1a) #38)

In January 2025, the CTC amended the following project into the 2024 SHOPP: 07-LA-1 38.8/40.4. PPNO 07-6290; ProjID 0724000292; EA 2XP70. Route 27 in and near the City of Los Angeles (Pacific Palisades), from 0.1 mile north of Bel Air Bay Club to 0.4 mile south of Route 27. Remove existing curb and pave the southbound shoulder, realign pavement delineation around the slide area, and adjust the loop detectors and signal heads. Note: The Tramonto Slide is located in the hills above Pacific Coast Highway in LA and has been moving intermittently from 1936 to present. The heavy rains of February and March 2024 saturated the slopes that resulted in new movement. The slide encroached into the northbound #2 lane that has resulted in significant delays. The permanent solution needs to start at the top of the slide and is City of LA's responsibility. This project will provide an interim measure. This project will remove the existing curb and pave the southbound shoulder, realign the pavement delineation around the slide area, and adjust the loop detectors and signal heads. Abatement will be sought from the City of LA. Allocation ($ × $1000) PA&ED $0; PS&E $400; R/W Sup $100; Con Sup $250; R/W Cap $100; Const Cap $2,500; TOTAL $3,350.
(Source: January 2025 CTC Agenda, Agenda Item 2.1a.(1a) #15)

In August 2016, the CTC approved $31,477,000 for Los Angeles 07-LA-118 R0.0/R14.4 Route 118 in the city and county of Los Angeles, from Ventura County line to Route 210; also on Route 27 (Topanga Canyon Boulevard) from Devonshire Street to Route 118. Outcome/Output: Rehabilitate 65.0 lane miles of roadway to extend pavement surface life and improve ride quality. Replace approach slabs and upgrade curb ramps to meet current ADA standards.

Scenic Route

[SHC 263.3] From Route 1 to Mulholland Drive.

Eligible for Scenic Highway status per [SHC 263.2]. The following portions have been officially designated as Scenic Highway and are signed:

TOPANGA CANYON STATE SCENIC HIGHWAY. LA 1.0/3.5. 2.5 mi in Los Angeles County. Designation #61, March 22, 2017

In April 2013, it was reported that the Los Angeles County Board of Supervisors has asked the state to designate the portion from Route 1 to the Ventura County line as a state scenic highway (essentially, the entire route).

27 Scenic Designation In June 2017, it was reported that Topanga Canyon Blvd had received a state scenic highway designation: "Topanga Canyon State Scenic Highway, a 2.5 mile (although another article says 3.5 mi) segment of Route 27, runs through the county and city of Los Angeles in the Santa Monica Mountains National Recreation Area near the Pacific coast." The LA Times clarified that the designation is from Mile 1 to Mile 3.5 (near Old Topanga Blvd), putting it within the SHC 263.3 designation. The new scenic highway runs parallel to Topanga Creek, with views of massive rock formations, valleys, mountains, and a diversity of plants and animals. California’s scenic state highway program was implemented in 1963 in order to “add to the pleasure of state residents,” and “encourage the growth of recreation and tourist industries.” Designated scenic highways, along with adjacent scenic corridors, require special conservation treatment. Scenic corridors consist of land that can be seen from the scenic highway and is next to the highway, even if it is outside the highway right-of-way. The legislation lets the state assign responsibility for the regulation of land use and development along scenic highways to the appropriate state, local and county agencies. “The city or county must also adopt ordinances, zoning and/or planning policies to preserve the scenic quality of the corridor or document such regulations that already exist in various portions of local codes,” Caltrans specifies. According to Westways magazine, this was the first LA County road to receive the state scenic highway designation in 45 years. It was reported as the culmination of a five-year effort by Topanga Chamber of Commerce members Joseph Rosendo and Roger Pugliese, along with the Topanga Association for a Scenic Community working with county and city officials to develop a scenic corridor protection program. The new Topanga Canyon State Scenic Highway travels through a portion of Topanga State Park, which features 36 miles of trails through open grassland and live oaks, and spectacular views of the Pacific Ocean,” it said. “The park is one of the world’s largest wildlands within the boundaries of a major city.”
(Source: OneTopanga, 6/17/2017; LATimes, June 2017; Caltrans; Malibu Times, 10/20/2017)