A Break



New East Span Bay Bridge (on right)

We departed Emeryville on July 8^th and made our way back across the Bay, this time passing under the east span of the Oakland Bay Bridge.  We were able to see the construction of the new Bay Bridge which is due to open December 2013.  Temporary repairs were made to the old bridge following the fatal Loma Prieta earthquake; later, Bay Area politicians spent ten years agreeing on a design for a new east span bridge.

Old and New Oakland Bay Bridge

The new bridge was scheduled to open on Labor Day in 2012 but was postponed after 32 bolts were found to be fractured.  The fractures were discovered in March after the rods/bolts were tensioned.  These high-strength steel rods or bolts were installed in seventeen different locations on the bridge, adding to the scope of safety concerns.  A metallurgical investigation team found that the rods failed due to hydrogen embrittlement, the process by which metals become brittle and fracture following exposure to hydrogen.  

New Bay Bridge Span

The metallurgical condition of the steel rods was found to differ in hardness from the center to the edge, and at the surface.  High strength steel above 150 ksi (the force in 1,000 pounds per square inch to elongate steel beyond its yield) has an affinity for hydrogen.  Additionally, the steel rods for the new Bay Bridge were hot-dipped galvanized in order to protect the steel from corrosion; this method can also make the steel susceptible to hydrogen embrittlement due to excessive heat, releasing internal hydrogen.  Rods sitting in ducts for five years before they were tensioned may have also been a factor.  Temporary drainage and sealing had not prevented the ingress and collection of rainwater, which may have been a contributing source of hydrogen contamination in the rods.  

Looking Back - We made it past the construction

After hearing about the engineering challenges of the Bay Bridge on the local news, I decided to do some more research on the Internet – it is all very interesting and I’ll probably find myself looking for fractures as we pass under and over the many bridges on our drive home to Seattle this week to visit family and friends.  Yes, it's a short break from boating, but after our return we'll be off exploring more of the San Francisco Bay Area.


Aerial View - Oakland to San Francisco (new bridge on right)