In 1908, the Oceanshore Railroad opened to connect San Francisco and Santa Cruz. Between Montara and Pacifica at the tip of Pedro Point, Oceanshore engineers blasted out a 354' tunnel and created a "man-made ledge" at Devil's Slide for the railroad. Later blasted shut during prohibition to prevent rum-runners from hiding their contraband liquor there, the Pedro Point tunnel illustrates that tunneling in the area of Devil's Slide is a feasible and time-honored concept.
In 1915, Coastside Boulevard opened to permit cars and trucks to travel between Pacifica and Montara. However, the grades and turns over Montara Mountain were nearly impossible to navigate, especially in the fog. Coastsiders, unhappy with the Saddle Pass Crossing, argued their need for a "Sea-Level Boulevard" on the old Oceanshore Railroad bed.
Road construction for "Sea-Level Boulevard" (Highway 1) began in 1935 and in 1940 the first catastrophic slide occurred at Devil's Slide, dumping much of the road into the surf below.
In 1960, plans for a Devil's Slide freeway bypass were developed. The freeway bypass was to be part of a 4-lane, ultimately 8-lane freeway down the coast of San Mateo County. This road supported plans by Westinghouse for a new coastside city of 150,000 people.
In 1971, Governor Ronald Reagan announced a new coastal highway planning policy to permit only minimal freeway construction along the full length of the California's Coast.
In 1972, a federal court stopped Caltrans from constructing the freeway on Highway 1.
In 1973, the Sierra Club proposed a tunnel for Devil's Slide as a less environmentally damaging damaging alternative to the freeway bypass. Caltrans proceeded to evaluate a tunnel. R.W. Reynolds of the Caltrans Bridge Geologic Studies Section wrote that, "Geologically, this alignment appears to be in an excellent location and away from the effects of the Devil's Slide and oriented favorably with the geologic structure of the site. The development of a tunnel along the proposed line should not present any serious construction problems."
Caltrans released the tunnel APS (*Advanced Planning Study) in 1974, which estimated the cost of a tunnel at $28 million for a 46' single-bore design and $45 million for a 35' twin-bore.
In 1975 with the freeway project dead, the state legislature appropriated $1 million for acquisition of the area as McNee Ranch State Park.
In 1976 the State Coastal Act increased environmental protections by requiring that Highway 1 remain a scenic 2-lane highway in rural areas.
In the late 70's Caltrans abandoned further consideration of a tunnel.
In 1983, a failure of the road at Devil's Slide and a change in political administrations led to another change in direction, with Caltrans choosing to resurrect the freeway bypass.
In 1985, Caltrans repackaged freeway bypass and described the project as a 2-lane road with continuous uphill passing lanes, runaway truck recovery areas, and wide shoulders to accommodate landslide debris. Despite the rhetoric, with a roadbed of 79' to 101' the freeway bypass would be the widest 2-lane road in the state of California.
The Sierra Club, along with other environmental and community groups, sued demanding evaluation of less environmentally damaging alternatives, and stopped the freeway construction. Documents now show that Caltrans inappropriately rejected the tunnel alternative in the 1985 Environmental Impact Statement (EIS) by claiming it would impact parkland and be too expensive. The $120 million price tag was artificially high, as Caltrans only reported costs for a tunnel much larger than required. Internal Caltrans documents show they knew there was a more appropriate and less expensive tunnel alternative.
In January 1995, the roadbed at Devil's Slide failed again this time necessitating a 5 month road closure.
In March 1995, an independent study group of geologists and engineers was convened by San Mateo County Supervisors Ted Lempert and Rubin Barrales. Their final report estimated the cost for a tunnel to be between $50 and $70 million, with design and construction estimated at two to three years. At the same time Mike Shank, representing Shank-Balfour-Beatty, the tunneling consortium building the 2-mile sewage outfall tunnel under San Francisco for the Richmond Transport Project, prepared a bid for the Devil's Slide tunnel. The bid was submitted to the San Mateo County Board of Supervisors. Shank quotes a total cost of $60.3 million for a 46' single-bore tunnel, and estimates 6 months for design and 30 months for construction.
In April 1995 , working with the California Public Records Act, citizen's groups obtained a 1993 Caltrans internal memorandum from Mr. James E. Roberts, Chief of Caltrans Division of Structures, recommending construction of a 2-lane, 46' wide tunnel at a cost of $54.3 to $77.5 million, on an alignment proposed by the Sierra Club 20 years earlier. Mr. Roberts concluded that "If the purpose of this project is to bypass the Slide and not to increase the current highway capacity, then Alternative No. 1 should be selected (2-lane single bore)." That cost estimate was confirmed by two other sources.
In June 1995, responding to the new information and the outcry from citizens and elected officials, the Federal Highway Administration (FHWA) determined that Caltrans had not adequately considered the tunnel alternative, and ordered an objective study. Caltrans spokesperson Greg Bayol responded by saying that "we'll reevaluate it and say a tunnel is too expensive."
In May 1996, Caltrans and FHWA signed a $2.6 million tunnel study contract with Woodward-Clyde, a world-class tunnel consulting firm.
In May 1996, 34,924 signatures were submitted to put Measure T, the Devil's Slide Tunnel Initiative on the November 1996 ballot in San Mateo County.
In July 1996, Caltrans broke their contractual agreement with Woodward-Clyde and San Mateo County by failing to attend a public meeting designed to inform the public about the status of the tunnel study.
In August 1996, results from the technical feasibility phase of the tunnel study confirmed that a tunnel is a feasible permanent repair solution for Highway 1 at Devil's Slide.