|PROJECT MANAGER:||Ramon Ruelas||(619) 688-6803|
|PUBLIC AFFAIRS OFFICE:||Jim Larson||(619) 688-6678|
FACTS AT A GLANCE
|LOCATION:||San Diego - Coronado|
|LENGTH:||11288 ft ( including approaches )|
|CHANNEL SPAN:||1880 ft|
|STRUCTURE:||channel span - 3 span continuous orthotropic box girders|
|VERTICAL CLEARANCE:||200 ft|
|OPENED:||August 3, 1969|
|COST:||$ 47.6 million|
|AUTO TOLL:||$ 1.00|
|COLLECTION:||$ 8,000,000.00 per year|
|TRAFFIC LANES:||5 lanes (2 in each direction, the middle lane is reversible)|
|AVG. DAILY TRAFFIC:||68,000 vehicles/day|
The orthotropic design used in the 2.12-mile long bridge originated in Germany during World War II in the construction of battleships. The structure uses the world's longest continuous box girder to conceal the braces, joints, and stiffeners normally visible in other bridges providing a vertical clearance of 200 feet over the shipping channels, and giving the exterior a sleek, smooth appearance. The 90-degree turn mid-span serves to make the bridge long enough to achieve a 4.67 percent grade, allowing the bridge enough height to clear an empty aircraft carrier.
The 30 mission-arch shaped concrete towers, designed to reflect regional historical architecture, rest on 487 prestressed reinforced concrete piles, 54 inches in diameter. Some piles were jetted to depths of 100 feet into the sand and clay beneath the bay.
Under the roadway is a steel-mesh catwalk built to facilitate bridge maintenance. Caltrans conducts routine inspections to detect concrete flaking and exposed bare metal surfaces. Painting the bridge is a never-ending job. A four-person crew works year-round to keep it protected from corrosive ocean breezes. The blue color was chosen to blend with sky and sea.
In the 1976 the bridge was retrofitted with special rods to protect against earthquake damage.
The roadway consist of five lanes. The center lane doubles as a safety median, and with the help of a new moveable barrier system as a switch lane to provide three lanes in one direction during peak traffic periods. The 34 inch high barrier railings are low enough to allow an unobstructed view while crossing the bridge. The design of the railings, wide at the bottom and narrow at the top, redirects the wheels of a vehicle back to the roadway with little or no damage.
A toll has been charged to cross since the bridge first opened. In 1969 the cost was $0.60 each direction. In 1980 it was changed to $1.20, only collected entering Coronado. Proceeds from the toll retired the revenue bonds seventeen years early. Today the round trip toll is one dollar. Carpools of two or more people cross free. The proceeds pay for bridge maintenance and transportation improvements along the bridge corridor.
SAN DIEGO - CORONADO BRIDGE
The San Diego-Coronado Bay Bridge, built with an eye to appearance as well as transportation service, is rapidly becoming a symbol of the San Diego area-just as the Golden Gate and San Francisco-Oakland Bay Bridges symbolize that area around the world.
Its distinctive towers and graceful curve add a striking new landmark to the harbor area. In 1970, it received the Most Beautiful Bridge Award of Merit of the American Institute of Steel Construction.
The bridge was financed by a California Toll Bridge Authority $47.6 million bond issue which is being repaid from tolls. It is one of nine State-owned toll bridges operated by the Division of Bay Toll Crossings, which is also responsible for their planning, design and construction.
Construction started in February 1967, and the bridge was opened to traffic on August 3, 1969 during the celebration of the 200th anniversary of the founding of San Diego, oldest city on the West Coast.
It is notable among the world's great bridges for the number and size of its concrete towers. There are 30 towers and over the channel they reach a height of 200 feet. They were designed with a curved cap to echo the mission arch shape,associated historically with regional architecture.
The towers rest on 487 prestressed reinforced concrete piles. The piles, 54 inches in diameter and with walls 5 inches thick, were driven and jetted into the sand and clay of the bay bottom up to lengths of 100 feet. The mud was removed from inside the piles which were then filled with concrete. Clusters of up to 44 piles were used under some towers.
Girders of the steel superstructure are painted blue to harmonize with the predominant color of the sky, bay and sea.
Beginning at the toll plaza in Coronado, traffic ascends on a 4.67% grade, curving gracefully 90 degrees toward San Diego. This 2,850-foot section is the longest in the U.S. using curved steel plate girders.
The shipping channels are spanned by the world's longest continuous three-span box girder, 1,880 feet.
The roadway is of orthotropic steel plate design and serves as the top flange of the box girder. Its spans are third longest of their kind in use in the country. This design saves steel and provides a slender superstructure with a smooth exterior, all braces arid stiffeners being inside the box girder.
The steel superstructure was fabricated and partially erected in the San Francisco Bay Area. Girders were barged down the Pacific Coast and lifted into place by the largest barge crane in the West, the "Marine Boss."
Precast prestressed concrete girders of up to 165-feet in length were manufactured in Long Beach. These are among the longest of their kind in use in the country.
The roadway has five lanes. The center line, now reserved as a safety median, will be available as a switch lane in the future to provide three lanes for peakhour traffic when demand warrants.
The 34-inch-high concrete barrier railings are low enough to permit an unobstructed view from vehicles on the roadway. Wide at the bottom and narrow at the top, the railings are safety-designed to redirect the wheels of a vehicle back to the roadway with little or no damage.
The 12-lane toll plaza, with an architecturally designed canopy on sculptured pedestals, received special landscape attention, including extensive lighting to enhance the appearance.
Traffic volume on the bridge has grown at a healthy rate, permitting several toll reductions. The basic auto toll is currently $1.00. Toll is only collected in the westbound direction. Commute books at the San Diego-Coronado Bridge are unique to the California toll bridge system in that they have no validity period. Books are $24.00, representing a reduced toll of 60 cents and are on sale 24 hours a day at the toll plaza.
Caltrans now employs 54 persons to operate and maintain the bridge. Among the first toll collectors on the bridge were employees from the ferry boat that was supplanted by the construction of the bridge. The total westbound traffic volume for the bridge in 1997 was 12,217,468. This figure was up the 1996 figure of 11,926,027.
Caltrans Toll Bridge Seismic Retrofit Construction Program always welcome any
comments or suggestions.
Author: Yader A. Bermudez