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The Devil’s Slide Trail - How a State Highway Became a Scenic Paradise

Posted on Tue, Mar 17, 2015

By Jonathan Berlin, MESM

This article was originally published in the APA California Northern News Newsletter (April 2015 edition). The original article can be read here.

1953 slideCalifornia has several trails to hell: the Devil’s Backbone Trail in the San Gabriel Mountains (precipitous falls to either side), the Devils Kitchen Trail in  Lassen Volcanic National Park (boiling and hissing mud pots), and the Devil’s Slide Trail (treacherous landslides). The last trail, which hugs a spectacular rocky coastline south of Pacifica in San Mateo County, is a recent addition to this list. Since its grand opening on an abandoned stretch of State Route (Highway) 1 in March 2014, the 1.3-mile Devil’s Slide Trail has already become the most popular destination managed by the San Mateo County Parks Department. Visitor counts show that an average of 1,100 people come to the trail per day, which amounts to more than 400,000 people per year. This level of interest greatly exceeds the County’s early expectations of more than 60,000 people per year. Sam Herzberg, a senior planner at the Parks Department, believes that as awareness of the Devil’s Slide Trail grows, it “might become a national or international attraction.” This success story in-the making did not, however, come easily. It depended on a controversial re-routing of Highway 1 that involved decades of political strife among planners, engineers, and activists.

Bedeviling the engineers

Since the late 19th century, engineers have waged war against the Devil’s Slide formation. The first County road was abandoned in 1914, due to rock falls, and replaced with a winding bypass route to the east over San Pedro Mountain. In 1906, the Ocean Shore Railroad between San Francisco and Santa Cruz was under construction when the Great San Francisco Earthquake caused the Devil’s Slide section to plunge into the ocean. Following in the shadow of these doomed routes, Highway 1 opened between Pacifica and Half Moon Bay in 1937. Landslides at the Devil’s Slide have resulted in road closures every decade since, some lasting months at a time. In the worst instance, a landslide during heavy winter rains in January 1995, the roadbed dropped about 30 feet, says Herzberg, and Highway 1 remained closed for 159 days. To stabilize the roadway, engineers installed “a 50-foot-long metal girder holding up the road” and bolted a steel net to the slope above to catch detached rocks. Despite these repairs, the highway remained vulnerable to shifting rocks. The landslide-prone area extends from an elevation of about 900 feet down to at least sea level at the coastline, with a width of about 4,000 feet, according to a guidebook published by the National Association of Geoscience Teachers in 2001. Given the long-term instability of this area, Caltrans considered its repairs to be stop-gap measures until a bypass route for Highway 1 was selected and built.

Political struggle over bypass routes

As early as 1958, the California Division of Highways determined that the Devil’s Slide should be abandoned and began studying alternate routes. The California Highway Commission approved a six-lane overland bypass route in 1960 that would have required extensive grading on Montara Mountain. Between 1969 and 1972, Caltrans acquired 55 percent of the right-of-way needed to build the adopted bypass. However, a coalition of environmental advocacy groups sued Caltrans in 1972 for not preparing an Environmental Impact Statement, as required by the recently enacted National Environmental Policy Act for federally led or funded projects. This lawsuit halted the construction contract for the bypass and directed Caltrans to study environmental impacts. An overland bypass remained the preferred alignment until the catastrophic landslide of 1995 motivated the County Board of Supervisors to set up an independent panel of technical experts to identify the best alignment. Although the panel recommended building a pair of tunnels through San Pedro Mountain, the Board decided in favor of an overland route. But San Mateo County citizens took matters into their own hands and approved Measure T in November 1996 to amend the County’s Local Coastal Program to select the tunnels as the preferred bypass. The initiative also required that a separate trail for pedestrians and bicyclists be provided outside the tunnels.

Birth of the trail

K RailsThrough the tunnels’ permitting process under the California Coastal Act, the County agreed to assume responsibility for the Devil’s Slide Trail. As a condition of approval of the Coastal Development Permit to build the tunnels, approved in May 2004, the County would accept the deed to the old roadway and improve it for non-motorized transportation. The permit also required that Caltrans build parking lots at the future northern and southern trailheads, says Herzberg. The County’s commitment to building the Devil’s Slide Trail was effectively an unfunded mandate. By the time that the Board of Supervisors approved $2 million for this purpose in the County’s 2012–2013 budget, almost a decade later, Herzberg notes that a whole new set of Supervisors had been elected and the expense had to be justified. Once the tunnels opened in March 2013, the Parks Department used this funding to coat the abandoned roadbed with a polymer to smooth out the surface for bicyclists, to re-stripe it for two six-foot-wide bike lanes and an eight-to-12-foot pedestrian path, and to erect signs and fencing. Two scenic overlooks also were constructed, with benches and coin-operated telescopes. “I think they did a fantastic job with the benches and lookout points,” says Anthony Ricarte, a resident of Pacifica, who walked the trail on February 15 with Monika Hanson and his two-year-old daughter, Sophia.To improve the aesthetics of the trail, the Parks Department painted three-foot-high concrete barriers known as K-rail in a tan earth tone that approximates exposed bedrock. The inner K-rail serves as a barrier to protect the trail from small falling rocks, says Carla Schoof, a community programs specialist with the Parks Department. Structural improvements dating to the 1995 landslide remain visible. To Monika Hanson, a first-time visitor from Walnut Creek, old elements such as the series of giant bolts supporting the rock face at Devil’s Slide, serve as points of historic interest.

Scenic views

PowBut visitors most appreciate the opportunity to enjoy scenic views of the coastline and exposed bedrock. Jeffrey Chang, a South Bay resident and founder of a high-tech start-up, remembers when the Devil’s Slide was open for motorists. “Sometimes we’d stop on the side of the road illegally, just to enjoy the view,” he laughs. After taking his 13-year-old son Andrew to a soccer tournament in Pacifica this February, Chang was excited to find the route open as a trail. Chang brought his entire family to walk the trail, including Andrew, still wearing soccer cleats, and his parents visiting from Taiwan. An avid hiker who has explored Yosemite, Mount Diablo, and other parks, Chang says that the view here is “one of the best” and reminds him of the rocky northeastern coast of Taiwan. “It’s the pow of the view,” agrees Wendy Antipa, from San Francisco. On a clear day, her husband Greg notes, it is possible to see the Farallon Islands, about 25 miles off the coast, and Point Reyes to the north. The Antipas were visiting the Devil’s Slide Trail “to size up the site for a geology walk” for the Retirement Association at San Francisco State University. The southern end of the trail features exposed granite from Montara Mountain, while road cuts at the northern end reveal rough sedimentary layers of shale and sandstone.

Trail ambassadors

Chang FamilyAs a consequence of its popularity, parking at the Devil’s Slide Trail can get competitive. About 40 parking spaces exist at the northern and southern trailheads combined. Immediately after the trail opened, the parking lots filled and visitors resorted to parking on Highway 1, where California Highway Patrol officers ticketed them, says Herzberg. Anthony Ricarte adds that “the parking is kind of a nightmare” on weekends. To improve parking capacity, the Parks Department is working with the Golden Gate National Recreation Area and the California Department of Parks and Recreation. This partnership may lead to shared parking nearby, with a shuttle running to the Devil’s Slide Trail, says Herzberg. Currently, a free weekend shuttle runs from Pacifica to the trail, and SamTrans Route 17 stops at the trailhead, but Herzberg says that there is a lack of awareness about these transit options. The trail’s lifespan also depends on the stability of the Devil’s Slide. Heavy equipment operated by the Parks Department can clear minor rockslides from the trail. But in the event of a catastrophic landslide, if the trail “goes off into the ocean, it’s just gone,” says Schoof. The Parks Department does not foresee restoring the trail in that case. Herzberg hopes that the trail will last longer than it would have as a motorized route because of the lighter impact of non-motorized users. In the meantime, the project has underscored the popularity of trails as a means to provide access to valued landscapes and open spaces. And the Devil’s Slide Trail has become an active interpretive site informing Californians about coastal geology and our storied state highway system.Because the Parks Department anticipated high use of the Devil’s Slide Trail – if not 400,000 people per year – and lacked staffing to fully serve the completed trail, it created a Trail Ambassadors program. To date, 50 members of the public have registered as Ambassadors, receiving training in radio use, the history of the trail, and environmental features. In the field, they report trail conditions, answer visitor questions, and communicate with park rangers, says Schoof. Ambassadors are present on the trail on all weekends, some weekday mornings, and “when there’s a really good sunset,” says Schoof. One benefit of this program is the skills and knowledge base that local citizens bring, including expertise on native plants and birds. 


JonAuthor Jonathan Berlin is an Associate Environmental Planner at Rincon Consultants, where he serves as a lead analyst and project manager for trails and open space planning projects. Jon also specializes in CEQA/NEPA review and noise impact studies. He holds a Master in Environmental Science and Management (MESM) from UC Santa Barbara and a BA in Journalism from the University of Maryland. You can reach him at

Topics: Caltrans, American Planning Association, Devil’s Backbone Trail, Lassen Volcanic National Park, San Mateo County, State Route 1, Highway 1, Pacifica, APA, Transportation, active transportation, San Gabriel Mountains