By WENDY STEWART
Beat Staff Writer

The Bay Bridge — the reason for many commuters’ angst and extended travel times for the past 6 days — reopened Monday morning.

A marathon construction and inspection effort by engineers and bridge safety officials to ensure that the replacement to a failed repair for a cracked eyebar would withstand vibrations that brought down the initial fix that went into place during the Labor Day weekend passed muster Monday morning, allowing Caltrans to give the go ahead to allow vehicles back onto the 73-year old span around 9:00 a.m.

State and federal bridge inspectors spent extra time scrutinizing the installation of the replacement steel tierods and modifications to the fix for a cracked eyebar that was installed during the bridge closure on Labor Day weekend.

A setback in repair work left the bridge closed through over the weekend as repair crews furiously worked to perform inspections and stress tests.

Caltrans and contractor officials said that the failure was caused by the metal tierods in the original repair vibrating in place, causing metal fatigue — damage similar to repeatedly bending a paper clip back and forth.

• BAY BRIDGE CLOSURE TWITTER UPDATES: Follow @californiabeat for up-to-the-minute updates on the repair.
• RELATED: Caltrans’s diagram of modifications to the eyebar repair (PDF, 660 KB)
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• RELATED: Day One: The Bay Area without the Bay Bridge
• RELATED: PHOTOS: Crack in structure may delay Bay Bridge reopening

High winds on the span, which create additional vibrations in the structure, may have contributed to the break.

That repair failed during Tuesday afternoon’s commute when a massive brace for the tierods along with the cabling fell onto the roadway below striking three vehicles. No one was injured in the incident, but a CHP spokesperson said someone could have been seriously injured or killed if the metal had fallen directly onto the roof of passing vehicles.

The failure of the eyebeam fixed prompted state transportation officials to shut down the bridge within hours of the parts falling onto the upper deck of the span.

The 6-day emergency closure of the bridge was unprecedented.

It stretched the Bay Area’s transportation infrastructure to its seams. Commuters crowded transbay BART trains in record droves and shattered the transit agency’s single-day ridership record after more than 442,000 trips were logged on Thursday.

Those who chose to drive endured heavy traffic that stretched for miles along alternate bridges. The Golden Gate and Hayward-San Mateo Bridges became the workhorses during the bridge closure as motorists sought a way to navigate the region without a critical main east-west transbay traffic artery.

Commute times on Bay Area roadways tripled and in some cases, quadrupled.

Another point of frustration was the elusive reopening date for the bridge.

Late Thursday, Caltrans announced that the bridge could reopen in time for the Friday morning commute only to announce during a Friday afternoon press conference that the bridge may not even be reopened for the Monday morning commute.

That didn’t sit very well with commuters who braced for the continuation of the closure. On a normal weekday, the Bay Bridge carries more than 266,000 cars.

The good news came down during an 8:30 a.m. Caltrans press conference when it was announced that the bridge passed inspections and would reopen by 9:00 a.m.

The first cars were escorted by CHP cruisers across the upper deck of the span in a procession-like parade of motorists traveling 25 MPH across the bridge.

Eastbound cars began crossing the bridge at around 9:10 a.m.

Many motorists were seen giving thumbs up as they crossed the bridge, signaling a respite from the emergency repair work that severed access to the span.

Beat Staff Writer Steven Luo contributed to this report. E-mail Wendy Stewart at californiabeat@gmail.com. Join the California Beat on Facebook, and get breaking news headlines, story alerts and previews when you follow us on Twitter.