The failure was at the transition between the easternmost through-truss and the westernmost double-deck causeway segment, a location where the inertial response character of the structure makes an abrupt change.

Analysis of the event completed by internal staff has shown that the bridge was close to a far more catastrophic failure in which either the through-truss or the causeway segment would have dropped from their common support structure.

[18] Engineering and economic analysis in 1996 suggested that a replacement bridge would cost a few hundred million dollars more than a retrofit of the existing eastern span, would have a far longer expected useful life (perhaps 75 to 100 years rather than 30), and would require far less maintenance.

Even the U.S. Navy (at the time the controlling authority of the island) was involved at the behest of San Francisco in restricting Caltrans soil engineers' access to the proposed site [citation needed].

This was partially because of a rise in the cost of steel and concrete, particularly as a result of the concurrent building boom in China,[33] but also due to construction uncertainties owing to the innovative design.

On September 30, 2004, the office of Governor Arnold Schwarzenegger announced that, without sufficient funds authorized by the California Legislature, the bid must be allowed to expire.

Since the objective of the replacement of the eastern span is to prevent the necessity of complete rebuilding after a large earthquake, Bay Area residents felt justified in their call for state support.

The governor said that he and State Senate President Pro Tempore Don Perata had reached agreement to resurrect plans for the signature span.

At the time of the signing, the skyway portion of the bridge was 75 percent complete and the state was beginning to prepare to put the suspension span out for new bids.

By mid-2009, the final connection of the viaduct portion with ground level at the eastern end was being finished and the pedestrian walkway was being attached to the completed sections.

Once in the proper location, the opposing segments could then be joined with through tendons (cables within conduits that are tensioned with jacks), forming a balanced cantilever over the column.

On the three-day weekend beginning 8:00 PM Friday, February 17, 2012, the westbound lanes were shut down to allow the connection of the approach roadbed with the new temporary structure.

For ship channel clearance, the bridge would require at least one long span, while ready access to bedrock was found only close to Yerba Buena Island.

The curved nature of the approach and seismic safety criteria place additional constraints upon the design, which set many firsts for a SAS bridge.

Upon completion of the bridge, the entire falsework structure and all exposed underwater supports will be removed to make a safe channel for deep draft ships transiting to and from the Port of Oakland.

[60] The design employs extensive energy absorbing techniques to enable survivability and immediate access for emergency vehicles following a Maximum Credible Earthquake (MCE), estimated at 8.5 moment magnitude in a 1500-year time span.

Each roughly pentagonal column consists of four tapering and/or straight sections, joined end-to-end by external plates and internal stringer finger joints secured with fasteners.

[67] Working the entire day of May 19, 2011, operating engineers and ironworkers lifted and placed the 900,000-pound (410,000 kg) double cable saddle atop the SAS tower.

Each fixture has been adjusted independently and with the LED masking will illuminate the roadways only in the direction of travel, similar to the vehicles' headlights and therefore greatly reducing glare presented to drivers.

A concurrent effort removed the temporary S-curve allowing completion of the new span's bicycle and pedestrian path and improvement of the east-bound vehicular approaches.

As of May 2015, only a third of the rightmost span remained and by June 12, 2015 the task was completed[79] On November 14, 2015 the concrete cellular foundation of pier E3 (which supported the eastern cantilever tower) was explosively demolished with the debris falling into the steel caisson below the mud bay bottom.

[80] Numerous sequentially detonated charges and an all-around air bubble curtain were used to reduce underwater shock waves in order to protect marine life.

On April 21, 2005, news reports indicated that the Federal Highway Administration hired private inspectors to remove 300-pound (136 kg) sections for detailed laboratory analysis.

[90] On May 4, 2005, the Federal Highway Administration said the tests by three independent contractors showed that welds pulled from three 500-pound (230 kg) steel chunks of the bridge "either met or exceeded required specifications.

That letter included a request for a full retraction of the article, this after asserting a number of specific technical refutations and criticisms of the language and tone of the story.

[100] Following that Bee article, the California Senate Transportation Committee asked the state Legislative Analyst's Office to convene a panel of independent experts to examine concerns about the SAS tower foundation and to report on its findings.

[102][clarification needed] Three-inch-diameter (7.6 cm) bolts connect portions of the bridge deck mounting bosses to several concrete columns.

Such welds were considered by Caltrans management to be of low criticality in this bridge owing to the compressive forces imposed on the deck structure by this particular design.

Owing to the fragility of the old cantilever structure and the possibility of a destructive earthquake, Caltrans felt motivated to avoid further delays in the new span's completion.

This preliminary report, written by a contractor to the committee, states It is the finding of this investigation that there appears to have been chronic attempts to keep many of the serious safety allegations quiet, put aside and not dealt with in an open, businesslike manner in the public's interest .