Bay Bridge eyebar woes date to 1930s 

The unexpected closures on the Bay Bridge last year were caused by a crack in a key support beam that was caused by the span design more than 70 years ago, Caltrans officials told The Examiner this week.

A 1.5-inch-deep crack was detected on the bridge during a Labor Day weekend inspection, when the bridge was closed for construction work. A fix for the crack was hastily installed, but metal repair pieces crashed onto rush-hour traffic in October. The bridge was closed for nearly a week while the repair was reinstalled, and the damaged section of the eyebar was later replaced.

Since the shutdown, the state agency that oversees the bridge, Caltrans, has scrutinized other vulnerable supports — called eyebars — along the eastern span, discovering and repairing tiny cracks that could have led to similar failures.

Caltrans officials told The Examiner this week that a forensic analysis of the metal piece concluded that a small crack formed along its outer edge and then spread inward.

“That first crack takes a while to get going,” said Tony Anziano, Caltrans’ manager of its toll bridges. “But once it starts tearing and cracking, it goes pretty quickly.”

The large crack may have been dangling in its gaping state above traffic for several months before it was discovered during Labor Day weekend during a routine inspection that occurs every two years.

The rough estimate of the crack’s age was based on the thin layer of rust that coated the crack, according to Anziano.

The problem that led the metal to crack dates back to the 1930s, when the bridge’s eyebars were formed by pressing molten steel into shape. The die-pressed fabrication process left sharp edges around both sides of the flat circles at the ends of the beams.

Stress caused by vibrations from wind and rumbling traffic became concentrated in the eyebar’s sharp edges, according to Anziano. After decades of accumulated stress, it’s believed that a crack formed along an edge that spread inward rapidly last year.

To prevent a repeat of the bridge closure, similar eyebars along the eastern span were identified and their sharp edges were ground down, according to Anziano.

Some tiny cracks that were discovered in recent months in the eyebars’ edges were ground out, preventing them from spreading, he said.

For safety reasons, eyebars are not used in new bridges. Eyebars in existing bridges must be inspected every two years under federal rules introduced after a bridge linking Ohio and West Virginia collapsed in 1967, killing 46 people.

But after last year’s Bay Bridge closure, Caltrans committed to inspecting the eastern span’s eyebars every three months. Other state bridges are not affected.

The first quarterly inspection finished last week, with all eyebars found to be in safe condition.

“I’m very pleased to get the most-recent bill of clean heath,” said state Sen. Mark Leno, who held hearings in the capital in the wake of last year’s closure. “Increased oversight is exactly what was needed.”

A replacement eastern span may open within four years to replace the dangerously old span, which was damaged by the 1989 earthquake, leading to a motorist’s death.

jupton@sfexaminer.com


Bridge work

$35 million Cost to repair last year’s eyebar crack*

4 Caltrans-operated spans that contain eyebars

8 Eyebar inspections planned every two years on Bay Bridge’s eastern span

1,680 Eyebars on Bay Bridge’s eastern span

480 Hours of work needed quarterly to inspect eastern span eyebars

1 Eyebar inspection planned every two years on Bay Bridge’s western span

1 Eyebar inspection planned every two years on Caltrans’ Shasta River Bridge

1 Eyebar inspection planned every two years on Caltrans’ Richmond-San Rafael Bridge

48 Non-Caltrans-operated bridges in California that contain eyebars

* Minimum

Sources: Caltrans, California Legislature

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