Bay Bridge Rod Has Fractured

Bay Bridge San Francisco (Frank Schulenburg / Flickr / CC / Cropped)
Frank Schulenburg / Flickr / CC / Cropped

On Wednesday, Caltrans confirmed that one of the 424 25-foot-long steel rods supporting the Bay Bridge eastern span’s tower has fractured. Brian Maroney, Caltrans’ lead bridge engineer on the eastern span project, showed reporters the 3-inch-thick tower rod, asserting that Caltrans didn’t know what had caused it to break and that any reasons given for the break would be “speculative,” according to the San Francisco Chronicle.

He added that Caltrans has conducted mechanical pulling tests on the other rods, and they have not moved. A laboratory analysis will be conducted on the broken rod, which he called a “one-off,”

Other experts warn that corrosion from the water surrounding the rods since 2010 may have caused the rod to break. The rods were installed originally to guard the bridge against a massive earthquake, but the grouting and sealing job went awry.

In recent months, the water accumulated in the sleeves of the rods has shown elevated levels of chloride, possibly indicating that salt water from the bay has penetrated the rods. In May, tests showed that three rod sleeves had increased chloride levels; the levels were 50 times more than autumn of 2014.

Lisa Fulton, a metallurgical engineer and materials scientist at the Berkeley Research Company, added, “The fractured rod shows textbook features of hydrogen cracking.” Fulton had warned in May, “The thing clearly cracked. It means there’s little doubt that others are cracked–they just don’t know it. What are the odds this is the only one?”

Gareth Lacy, a spokesman for the state Transportation Agency, told Chronicle in May that a mechanical pull test had been performed on the rod, which moved. The pull test was scheduled after ultrasonic tests revealed the rod was 6 inches shorter than the others.