Granted, major engineering projects will have unexpected problems, challenges and even disasters. It is just the nature of the beast.

We get it. Really, we do.

But the latest ... um ... challenge involved in the reconstruction of the eastern span of the Bay Bridge again has us recoiling and wondering about both safety and overall competence.

Just a few months before the new bridge is scheduled to open, officials have discovered a significant number of giant bolts, which are integral to the seismic safety mechanism, cracked once they were tightened.

Caltrans photograph shown at the Metropolitan Transportation Committee meeting Wednesday morning March 27, 2013 in Oakland, Calif., shows how a nut lost
Caltrans photograph shown at the Metropolitan Transportation Committee meeting Wednesday morning March 27, 2013 in Oakland, Calif., shows how a nut lost tension after the failure of a threaded steel rod on pier E2 of the new Bay Bridge eastern span construction project. (Caltrans)

The discovery calls into question whether the taxpayer-financed, multi-million-dollar party scheduled for Labor Day must be postponed. We, and many of our readers, have made it clear we believe the party for such a delayed and grossly over budget project is a disgraceful waste of public funds.

Be that as it may, that issue is trumped by this latest discovery, which is more than a little disquieting.

The suspect 288 bolts are on the new bridge's single-tower suspension span. As of Wednesday, 30 of the 96 that had been tightened had failed. We are not metallurgical engineers, but a failure rate of more than 31 percent on crucial elements to the design structure cannot be acceptable.

Neither is at least one of the explanations offered so far. That theory postulated that the bolts have been exposed to hydrogen, which caused them to weaken. Well, gee, you mean these bolts holding up a bridge over water would come into contact with hydrogen? Who knew?

The bolts are part of a mechanism designed to control the bridge's movements during an earthquake. But that mechanism would essentially be useless if the bolts do not stay in place under stress. Of course, bridge safety during an earthquake was the rationale for replacing the span in the first place, so if that were to fail ... well, let's just say things would get ugly.

Some of the bolts are easily accessible while others are not. Unfortunately, it is the inaccessible ones that have failed so far.

Of course, this is far from the first issue for this project. First, there were battles over design, then the cost estimates soared from the original $1.1 billion to the current $6.4 billion, which does not account for the financing costs that nearly doubles that cost.

Then there was the discovery of microscopic cracking in steel deck sections fabricated in China as well as concerns about the welds inside the concrete columns on the bridge's skyway section. On Thursday, the Bureau of State Audits sharply rebuked Caltrans for its handling of the latter case.

At each turn we have been assured that everything is OK. No real issue here. Calm down, just move along.

But the bolt fiasco even has officials such as Steve Heminger, executive director of the Metropolitan Transportation Commission, saying there is cause for concern about the bolt failure rate.

We agree. It makes us wonder if the new bridge will be safer than the old bridge. Who knows? But hey, at least it will have cool lights on it.