It is not often that the guardrail is at the top of the engineering–and political– challenges in a $45 million bridge project.
However, not every bridge offers views as spectacular as that over the Ten Mile River on Highway 1 in Mendocino County, a bucolic river with a thunderous beach and towering bluffs.
The retrofitting and/or replacement of more than 2,200 bridges in California at a cost of some $8 billion may be the most expensive public works project in history.
While controversy was expected over projects like the more than $5 billion retrofit/replacement of the San Francisco/Oakland Bay Bridge, the force of the controversy over scenic railings on the remote and sparsely-populated Mendocino Coast twice took California Department of Transportation (Caltrans) by surprise.
When Caltrans proposed a Ten Mile River Bridge with standard guardrails and no pedestrian walkway two years ago, the entire bridge was rejected by the California Coastal Commission. One Coastal Commissioner called Caltrans bridge rail “dog ugly.”
Two years before, many of the same activists had forced Caltrans to redesign the guardrail for the bridge that spans the scenic Noyo Harbor entrance to the city of Fort Bragg. Beauty, ecological issues and public access twice topped utility, safety and even cost.
“Most of the agencies we deal with are not really that concerned with aesthetics,” said Alan Escarda, Caltrans’ project manager for the Ten Mile River Bridge. “But it ranks pretty high with the Coastal Commissioners.”
Commissioners overruled their own staff by voting against the measure. Caltrans had to redo the entire design. The politically sensitive rail remains the item still incomplete in the bid package.
“We still don’t have the final design on the rail. We will do a contract change order during construction, which will be an added cost,” said Escarda. Escarda was working on bid packages for a project expected to commence in January. The contract calls for a cast in place prestress box girder bridge.
“We didn’t want to delay the entire bridge until we could reach agreement on the rails. We won’t be putting the rails on the bridge for two and a half years,” Escarda said. He said uncertainty over the rails may compel contractors to pump up their bids to account for the political, rather than the engineering challenges.
Switching plans involved testing the new rails at the Caltrans crash testing facility near Sacramento. All new guardrails are tested by being slammed by cars and even heavy trucks at a facility better known for its use by the auto industry.
“It is about six months to a year to crash test. It must stand over 50 mph impacts. You can’t just draw a new rail on a piece of paper,” Escarda said.
This was the second time in just 10 mi. of oceanfront Highway 1 that Caltrans was forced by community pressure to use a scenic bridge rail. In the replacement of the Noyo River Bridge that spans the entrance to the city of Fort Bragg, community activists led by Vince Taylor pressured the City Council to insist on an ST-10 see through scenic railing, and the activists got the state agency to change its design.
In California, the pressure for the special scenic railings is most intense on the Mendocino Coast, said Escarda. Fights over scenic rails aren’t really happening in the rest of the state.
“There are a group of people on the Mendocino Coast who have taken it upon themselves to get involved with the process and see their wishes through. I have a lot of respect for that kind of civic involvement,” he said.
An effort led by the Sierra Club’s Mark Massara and the non-profit Friends of the Ten Mile helped convince the Coastal Commission to thwart construction of what Taylor deemed “an urban expressway bridge.” The rejected bridge, which was proposed in literally the last hours of the availability of Proposition 192 funds, came with 8-ft.-wide shoulders. Friends of the Ten Mile criticized that measure because it encourages high speed traffic, unsafe stops to take photos and not help with rare breakdowns in sparse traffic. Instead, the group wanted a smaller bridge, or at least one with pedestrian walkways and scenic railings, which is what is now on the drawing board following a hectic season of rejection and reauthorization.
There also were 889 letters sent opposing Caltrans plans.
Escarda said the total redesign of the bridge was done in record time following the rejection, with many public servants putting in very late nights.
“This one darn near killed half the people here,” he said.
Caltrans has revived its railing committee to deal with the situation but the panel has yet to come up with a design that has been accepted.
“We will get something that is a little bit more compatible, a bit softer,” Escarda said. “The situation is that the commissioners want an invisible rail and our people wanted something that people won’t get hurt on. We have to find a middle ground.”
Ten Mile River Bridge, built in 1954 with reinforced concrete, is still susceptible to collapse during a magnitude 8.0 earthquake due to wooden footings placed on concrete pilings.
The famed San Andreas Fault is 11 mi. west of the bridge, running along the bottom of the ocean. The proposed concrete bridge is 1479 ft. long (450 m) and 44.9-ft.-wide (13.7 m) with two 12-ft. (3.65 m) lanes and 6-ft. (1.8 m) shoulders. A 5-ft.-wide (1.5 m) ADA compliant sidewalk will be constructed on the west side of the bridge to accommodate users of the California Coastal Trail. The new bridge will offer a net gain in habitat for bats, birds, wetland and eel grass. Much of the costs also are to protect a myriad of endangered species in the river estuary, ranging from coho salmon to the Menzies Wallflower and the Western Snowy Plover. The building season is restricted to a matter of weeks each year because of identified environmental issues. Work is restricted to between June 15 and Oct. 30, with most work in the river itself to be done between Sept. 15 and Oct. 30 of each year.
The replacement bridge will be constructed on a parallel alignment approximately 60 ft. (18. 2 m) east of the existing structure, which will be demolished in the last two years of the project, expected to end in 2011.
California’s massive earthquake safety program has been a boon – and a challenge – for contractors. The new Ten Mile bids are set to be opened on Dec. 5, but bid opening has been delayed twice already.
The delays have been caused by unexpected difficulty Caltrans has had in getting permits from fellow state agencies, Escarda said. The Department of Fish and Game changed permitting requirements to require quieter pile driving both on land and in the river. He said for the first time, DFG required pile driving noise to be below 190 decibels to prevent fish kills. Escarda said the convoluted process and conditions involved so far have already made the Ten Mile Bridge the biggest and most environmentally complex now underway in the state – outside of the Bay Bridge replacement project.
Research sponsored by Caltrans at the University of California, San Diego, led to a retrofit procedure that involved the installation of steel jackets to increase the strength of columns. Following the Loma Prieta earthquake, Caltrans sponsored accelerated retrofit research primarily conducted at the University of California at Berkeley and the University of California at San Diego.
Caltrans appointed a Seismic Advisory Board of external engineering and scientific experts to advise the department on seismic safety policies, standards and technical practices. Peer-review panels of independent seismic and structural experts also are used to review earthquake-strengthening strategies on major, complex retrofit projects. More than $40 million has been spent on seismic research since 1989.
Where possible, California’s Seismic Safety Retrofit Program strengthens columns of bridges by encircling them with a steel casing or an advanced woven fiber casing, according to Caltrans documents. In addition to the column casing, some of the bridge footings are made bigger and given more support by placing additional pilings in the ground or by using steel tie-down rods to better anchor the footings to the ground, according to bid documents. In a few projects, bridge abutments had to be made larger and the existing restrainer units stronger because encasing the columns makes them stiffer and can change the way forces are transmitted within the bridge. Many seismic retrofits involve “hinge seat extensions” which enlarge the size of the hinges that connect sections of bridge decks and helps prevent them from separating during severe ground movement.
There are more than 12,000 bridges in the California State Highway system, plus an additional 11,500 city and county bridges. Each bridge is inspected at least once every two years, according to Caltrans documents.
California has a history of furious construction activity following earthquakes. Modern earthquake standards for bridges were adopted following a 1971 earthquake.
Caltrans retrofitted 1,036 state bridges, mostly single-column bridges between 1986 and 1994, most following the 1989 Loma Prieta earthquake in the San Francisco Bay Area. After the 1994 Northridge earthquake, Caltrans identified 1,155 more state-owned bridges in need of retrofit, including the Ten Mile River Bridge, which needed complete replacement.
The “Phase 2 Program” consisted of mostly multi-column bridges. Funding for this $1.35 billion program has flowed from the $2-billion Proposition 192 bonds, which voters approved in 1996. Work is now complete on 1,136 of these bridges, and the others are now nearing completion. Other earthquake-unsafe bridges which Caltrans failed to get replaced or retrofitted following the 1989 earthquake include three in Alameda County, one in Santa Barbara County and one near the port of Long Beach, said a Caltrans spokeswoman.
Caltrans gained reauthorization of the CEQA-exempt program for the six bridges that weren’t replaced during the 15-year Phase 2 program. Completion of the last three replacement bridges of Phase 2, including the Ten Mile River Bridge, will occur after 2008.
More expensive than this huge undertaking is the $6 billion seismic retrofitting of the state’s handful of toll bridges – including the most expensive bridge replacement/retrofit project in history– the $5 billion replacement of the eastern span of the San Francisco-Oakland Bay Bridge, with retrofit work also being performed.
Other toll bridges that require seismic retrofitting include the Richmond-San Rafael, Benicia-Martinez, San Mateo-Hayward, and the Carquinez bridges all in the San Francisco Bay Area; the Vincent Thomas Bridge from San Pedro to Terminal Island in Los Angeles County and the San Diego-Coronado Bridge. These are among the state’s largest bridges
“The toll bridges are the largest and most complicated bridges in the state, consequently, the most complex seismic retrofit schemes ever undertaken,” the state Web site said.
There also are local bridges being replaced or retrofitted.
About 560 projects out of a total of 1,234 planned for retrofit have had seismic safety retrofit work completed or do not require retrofit work.
While minimalist design carries the day in the 21st century, Vince Taylor’s Dharma Cloud Institute Web site documents the decline in bridge railings after World War II. From 1926-28, chief California Highways Commission (Caltrans) Bridge Engineer Harlan Miller set the precedent of aesthetics being a primary concern in California, according to the Web site California Highways.
His successor, Charles Andrew, is credited with setting architecture standards that led to famous concrete bridges along the coast like the Big Sur Bixby Arch Bridge, completed in 1932.
Iron railings using narrow vertical rods connecting top and bottom horizontals were the order of the day on projects like the Golden Gate Bridge – the world’s most popular tourist attraction.
Concrete railings in those days were made of arches that complimented the arches of the bridge itself, the Cloud Forest Web site reports. Scenic bridge construction went into decline in the hustle-bustle of construction after World War II and the advent of the box girder bridge, Taylor reports. Bridges with solid, vision-blocking concrete bottoms topped by iron rails could be laid quickly along the many freeways sprouting all over the state in the 1960s. As safety and cost became more and more important, solid concrete walls became the order of the day, Taylor noted.
“We want to encourage the adoption of this newly-approved railing, the California ST-10, wherever scenic vistas are threatened by new bridges with visually opaque railings,” reads the Web site www.bridgerailings.org, which is sponsored by Taylor and his Dharma Cloud institute.
“We also hope those in other states will lobby for use of the predecessor railing, the Wyoming Rail, fully approved for use on federal highways.”
Taylor said Caltrans has put more emphasis on designing alternatives to the New Jersey barrier since the Noyo Bridge and Ten Mile Bridge issues arose. CEG
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