Timeline: History of major Bay Bridge milestones and problems

After nearly 12 years of construction and an estimated price tag of $6.4 billion, steel supporting the new eastern span of the Bay Bridge continues to be plagued with problems. May 2015 (Photo by Justin Sullivan/Getty Images)

The Bay Bridge connects San Francisco and Oakland, and carries about 280,000 vehicles a day. The latest reiteration of the span cost $6.5 billion and opened five years ago. And while many agree that the sleek architecture is pleasing to the eye, the bridge has also been beset by a host of financial and structural problems.

Here are some of those significant milestones:

November 1936: Bay Bridge opens to traffic. It costs $77.6 million to build.

September 1992: Safety repairs estimated to cost $150 to $250 million.

July 2000: Interim retrofit of old east span of Bay Bridge.

August 2007: Caltrans audit of suspension steel fabricator in China notes welders lack bridge experience.

September to November 2009: Caltrans crews discover damaged steel.

September 2013: Bay Bridge opened at a cost of $6.5 billion.

May 2015: Tests showing signs of saltwater intrusion into the bridge tower’s foundation and damage to its anchor rods.  In addition, there were reports that anchor bolts holding the Bay Bridge signature tower to the bay floor failed. 

January 2016: Big chunk of concrete fell from Bay Bridge tunnel at the Yerba Buena Island.

February 2016: Steel reinforcements on Bay Bridge tunnel show signs of corrosion.

February 2017: Lights went out on the bridge during the morning commute. 

August 2017: Questions arise regarding strength of steel supporting the bridge.

January 2018: Microbes corroding submerged Bay Bridge welds.

Sources: Baybridgeinfo.org, KTVU reporting, San Francisco Chronicle, SFPublicPress.org.