Top 25 Highway Projects

As the state prepares to fund some much-needed - and long delayed -- infrastructure projects approved by voters in November, our rankings this year nonetheless include many high-profile highway projects, such as the tricky Devil's Slide tunnel and bridge projects, a complex 2 mi widening project on the Santa Ana Freeway in Orange County, and another widening project for the perennially congested I-238 in San Leandro.

By Greg Aragon

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Our annual Top 25 Highway Projects rankings this year accounts for more than $1.5 billion in state and municipal projects. Twenty-one of those projects belong to Caltrans, which has contracted top heavy construction companies such as Kiewit, FCI Constructors, OC Jones, MCM Construction, Granite Construction, Yeager Skanska and Ghilotti Brothers.

The top ranked project is the long-awaited fixing of Devil's Slide.

The beautiful Northern California coast between Pacifica and Montara will soon be connected by twin tunnels running through San Pedro Mountain.



Measuring 4,200-ft- long and 30-ft- wide, the Devil's Slide Tunnel Project will cost $272 million to build and take until the fall of 2011 to open.



The project, which broke ground in May of 2006, is being constructed by Kiewit Construction Co., Omaha; and overseen by owner/engineer Caltrans.
Construction will bypass a notorious portion of Highway 1 known as Devil's Slide. This steep and unstable region, which hugs the coastline, has a long history of closure due to rockslides and land slippage. One of the longest road closures happened in 1995. It lasted 158 days, and cost $3 million to repair.


The tunnel boring will progress from south to north using excavation techniques that rely on inherent rock strength for support - known as the New Austrian Tunneling Method. Both tunnels will be bored at the same time, one tunnel faces approximately 60 yds ahead of the other.

Caltrans says that work will continue 24 hours a day, seven days a week resulting in a 24-month timetable to break through to the north portal. The estimated cost for the tunnels is between $180 million and $200 million.

Tunnel highlights include one vehicle lane and a shoulder in each direction; 11 cross linking passages and three underground equipment rooms; a day and night transition lighting system; and a ventilation system run by 16 jet fans.

There will also be electronic message signs displaying safety/advisory information, emergency call box telephone systems, and bicycle access.

Excavation work will move more than 600,000 cu yds of material, requiring about 30,000 truck loads.

The project will also include two bridges, connecting the north portal of each tunnel to Highway 1. Both bridges will pass over a valley at Shamrock Ranch that contains a pond and wetlands. During construction, the wetland area will be fenced off to protect an environmentally sensitive area.

Each bridge will stretch approximately 1,000 ft. Two sets of twin piers on each side of the valley produce main spans about 445 ft long. At the highest point the bridges are 125 ft above the valley floor and are curved to provide a smooth transition from each portal to the existing alignment of Highway 1.

A cast-in-place cantilever method will be used to avoid building temporary support towers in the environmentally sensitive area of the valley during construction.

San Mateo-based Disney Construction is building the bridges at a cost of $40.9 million.

A third element of the project requires the $10 million re-aligning of Highway 1 at the south portal to ensure a sufficient line of sight for vehicles traveling at 45 mph to exit and enter the tunnels safely. This job will remove approximately 85,000 cu yds of rock from the west facing rock slope to yield the required curve radius.

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