San Diego–Coronado Bridge

The San Diego–Coronado Bridge, commonly referred to as the Coronado Bridge, is a prestressed concrete/steel girder fixed-link bridge crossing over San Diego Bay, linking San Diego with Coronado, California. It is signed as part of State Route 75.

Description

Construction

In 1926, John D. Spreckels recommended that a bridge be built between San Diego and Coronado, but voters dismissed the plan. The U.S. Navy initially did not support a bridge that would span San Diego Bay to connect San Diego to Coronado. They feared a bridge could collapse due to an attack or an earthquake and trap the ships stationed at Naval Base San Diego. In 1935, an officer at the naval air station at North Island argued that if a bridge were built to cross the bay then the Navy would leave San Diego. By 1964 the Navy supported a bridge if there was at least of clearance for ships which operate out of the nearby Naval Base San Diego to pass underneath it.

thumb|left|192px|Waterline view of bridge construction,

The principal architect was Robert Mosher. Mosher's job was to build a bridge that would provide transportation, allow ships access to the bay, and serve as an iconic landmark for San Diego. Mosher proposed a basic box and girder-style bridge for the framework, with a prestressed concrete and steel deck sitting atop steel girders and supported by towers. Mosher decided to make an orthotropic roadway, which used a stiffening technique that was new to the United States; it increased the strength and resistance of the bridge. As a result, the bridge was strong and eliminated the need for additional superstructures over the deck to disperse weight.

Construction on the San Diego–Coronado Bay Bridge started in February 1967. The bridge required 20,000 tons of steel (13,000 tons in structural steel and 7,000 in reinforcing steel) and 94,000 cubic yards of concrete. To add the concrete girders, 900,000 cubic yards of fill were dredged, and the caissons for the towers were drilled and blasted 100 feet into the bed of the bay. Following attempts from Barbara Hutchinson, the vice president of the Kearny Mesa Town Council, to ask the Coronado and San Diego city councils to intervene in the construction, San Diego city attorney Edward Butler stated that the state had the ultimate authority to decide whether or not to build the bridge, and that the City of San Diego could not interfere.

The bridge opened to traffic on August 3, 1969, during the celebration of the 200th anniversary of the founding of San Diego. The 11,179-foot-long (3,407 m or 2.1 mi) bridge ascends from Coronado at a 4.67 percent grade before curving 80 degrees toward San Diego. It is supported by 27 concrete girders, the longest ever made at construction time. The five-lane bridge featured the longest continuous box girder  in the world The bridge is the third largest orthogonal box in the countrythe box is the center part of the bridge, between piers 18 and 21 over the main shipping channel.

Tolls and tollbooths

When the bridge opened in 1969, a toll of 60 cents was charged in each direction (). In 1980, the toll became $1.20 (), charged only in the westbound direction towards Coronado. The toll then dropped to $1 in 1988 (). Drivers paid a total of $197 million throughout the years.

Traffic barriers along Third Street to block traffic from turning onto intersecting streets were removed in November 2004, following voter approval. The speed limit was then decreased to in October 2005 along Third and Fourth streets, after traffic increased by 20 percent following the removal of the tolls. The islands upon which the toll booths sat, as well as the canopy over the toll plaza area, are still intact, located at the western end of the bridge in the westbound lanes. Though tolls are no longer collected, beginning February 19, 2009, there was talk of resuming westbound toll collection to fund major traffic solutions and a tunnel. However nothing came of those discussions, as well as 2011 discussions of removing the unused toll plaza completely.

Lanes and traffic

The bridge contains five lanes: two eastbound, two westbound, and a reversible middle lane with a barrier transfer machine system installed in 1993, which can be used to create a reversible lane in either direction in response to traffic volume. Beginning in 2008, cyclists have the once-a-year opportunity to ride over the bridge in the Bike the Bay "fun ride".

Artwork

The pillars supporting the bridge on the eastern end are painted with huge murals as part of Chicano Park, the most extensive collection of Chicano art murals in the world. This neighborhood park and mural display were created in response to a community uprising in 1970, which protested the adverse effects of the bridge and Interstate 5 on the Barrio Logan community. Local artist Salvador Torres proposed using the bridge and freeway pillars as a giant canvas for Chicano art at a time when urban wall murals were rare in the United States, and he and many other artists created the murals when permission for the park was finally granted in 1973.

Suicides

The Coronado Bridge is frequently used as a suicide bridge; as of July 2017, at least 407 suicide deaths by bridge jumpers have occurred on the Coronado bridge, trailing only the Golden Gate Bridge in San Francisco as the bridge most-often used for suicide in the United States. Solar-powered phones were once installed on the Skyway to offer direct help for those contemplating suicide, but have since been removed. Signs have been placed on the bridge urging potential suicides to call a hotline. However, call boxes are not provided.

After an accident in 2016, where a drunk driver drove a pickup truck off the bridge and into Chicano Park, killing 4 and injuring 9, state senator Ben Hueso proposed a state funding bill to cover safety measures on the Coronado bridge and require reports to the state legislature on progress. In February 2017, Caltrans announced its intent to perform a feasibility study for suicide-dissuasion options for the bridge. Hueso stated, "The safety of residents and visitors traveling on the bridge, and those who gather below it in Chicano Park, is of the utmost importance." On March 26, 2018, Caltrans released its report; it outlined suicide-dissuasion options such as netting, fencing, and glass barriers.

Lighting

In April 1997, the Port of San Diego released an international call for artists seeking qualifications of artist-led teams interested in developing environmentally-friendly lighting concept proposals for the bridge. In 2010, a London-based design group led by Peter Fink was chosen. The winning concept envisages illuminating the bridge with programmable LED lighting in an energy-neutral manner using electricity generated by wind turbines. In 2012, two years after choosing Fink's project, the Port of San Diego cut a check for $75,000 to initiate fundraising in concert with the San Diego Foundation. The Port of San Diego says no taxpayer dollars will be used. Instead, they are relying on grants and private donations to fund this lighting project, which will ideally be complete by 2019 to coincide with the bridge's 50th anniversary.

Urban legend

A decades-old local urban legend claims the center span of the bridge was engineered to float in the event of collapse, allowing Naval ships to push the debris and clear the bay. The myth may have developed due to the hollow box design of the center span, combined with the low-profile barges that made it appear to float on its own during construction. However, Caltrans and the bridge's principal architect, Robert Mosher, maintain that the legend is false.

References

External links

CaltransBridge History and Facts
CaltransBridge Contracts
California Department of TransportationThe San Diego-Coronado Bridge
City of CoronadoTransportation Management Association Bridge