The history of the new Bay Bridge has been a troubled one from the time the state decided to replace the old eastern span after the 1989 Loma Prieta earthquake.

The original price tag of a little more than $1 billion has exploded into more than $6 billion along with numerous delays.

Now Channel 2 News has learned that next Wednesday, state and local transportation officials are set to announce a new round of potentially big delays and cost overruns.

Instead of opening all the westbound lanes to San Francisco on the new bridge by December 2012, engineers now say the opening will be delayed by at least six months. What's more, the delay will cost $50 to $100 million.

Officials involved with the bridge project told us the root of the problem lies on the docks of Shanghai, China.

Caltrans is relying on a Chinese manufacturer to fabricate the steel for the new bridge.

The first major shipment of that steel was scheduled to arrive last year. But now at best it will leave Shanghai before the end of this month, more than a year late.

The problem? The welds. Caltrans, which normally inspects about 20 per cent of a project's welds has found so many problems it now is inspecting 80 per cent before accepting the finished product.

Andrew Fremier of the Metropolitan Transportation Commission said, "Those welding corrections - and they will be corrected before the steel shows up - have added some time in getting the steel here on the schedule that we originally thought."

Four years ago Caltrans asked the state legislature to allocate additional money for the troubled bridge to cover possible cost overruns, what Caltrans calls "contingencies".

That meant on top of the $5.4 billion Caltrans said it knew it needed, almost five times the original estimate, the legislature also put aside almost $1 billion more. That is considered an extraordinary amount for any project.

The bridge is not expected to be finished for at least another four years but Caltrans already has spent well over half of that contingency fund.

Bart Ney Caltrans spokesman said, "Fabrication for this bridge was always going to be challenging. It's something that our risk management process identified. That's why the contingency exists."

As for actually meeting the most recent published deadline for completing the bridge and opening both directions by December 2013, Andrew Fremier of the Metropolitan Transportation Commission said, "We have some risk - significant risk - in terms of delivering the project on the time we've anticipated. But we're still continuing to work on trying to mitigate that time."

But worries about the steel welds threaten to undermine any mitigation. In fact one authoritative Bay Bridge source told us on condition that KTVU not name him that: "Unless they make up a ton of time, they're not going to make that date."