Construction incidents Eastern span replacement of the San Francisco–Oakland Bay Bridge

1 construction incidents

1.1 weld controversy
1.2 potential foundation problems
1.3 bolt failure
1.4 water leaks in superstructure attachments
1.5 hold down rod grouting failure
1.6 substandard component fabrication , related project management issues

construction incidents
weld controversy

on april 6, 2005, fbi announced investigation allegations fifteen former welders , inspectors on new span welders rushed extent affecting performance on one-third of welds, , workers ordered cover defective welds re-welding in superficial manner. many of these welds embedded in concrete, deep underwater.

a california department of transportation (caltrans) spokesperson responded public assertion not possible defective welds hidden caltrans inspectors. subsequently tested radiological, ultrasonic , microscopic inspection of of welds accessible , alleged deficient. on april 21, 2005, news reports indicated federal highway administration hired private inspectors remove 300-pound (136 kg) sections detailed laboratory analysis.

on may 4, 2005, federal highway administration said tests 3 independent contractors showed welds pulled 3 500-pound steel chunks of bridge either met or exceeded required specifications. since of material removed inspection identified welders complaints worthy of inspection, finding received news.

potential foundation problems

in november 2011, sacramento bee newspaper reported , analyzed various reports (including whistle-blower statements) concerning potential falsified inspection reports associated deep pile foundations, including supporting sas main tower. article, , later sacramento bee article published on may 26, 2012, provided details construction , testing concerns , quoted experts in relevant engineering fields raised questions adequacy of caltrans’ testing , oversight, , construction , testing practices of bridge builder. on june 12, 2012, shortly after publicly supporting further study of concerns raised in may bee article, caltrans issued press release attached letter bee s executive editor caltrans director malcolm dogherty. letter included request full retraction of article, after asserting number of specific technical refutations , criticisms of language , tone of article. on june 24, 2012, joyce terhaar, executive editor of bee, responded in defense of article , mission of paper. caltrans has responded one-hour video presentation.

on august 4, 2012, bee reported on study in progress caltrans engineers, examining foundation testing agency. team of engineers, called gamdat team caltrans, found new evidence of questionable data associated tests of tower foundation. following bee article, california senate transportation committee asked state legislative analyst’s office convene panel of independent experts examine concerns sas tower foundation, , report on findings. report expected released in spring of 2013.

the sacramento bee published further article on june 7, 2014.

bolt failure

three inch (7.5 cm) diameter bolts connect portions of bridge deck mounting bosses several concrete columns. there 288 such bolts of various lengths. bolts tested in place overtightening retaining nuts. in 2 weeks subsequent tightening, 30 of first 96 bolts loaded failed. these bolts vary in length 9 17 feet , failure attributed hydrogen embrittlement, hydrogen introduced during either manufacturing or electroplating. of bolts can replaced while others cannot removed , load transfer require more complex remediation methods. repairs not expected delay opening, later believed delay opening until december. fix cost 5 million dollars. temporary fix announced on august 15, 2013, opening revised original date. solution selected add tendon-secured saddle @ each deck boss location. suggested internally issues tensioning main cable may have led bolt failures.

the retrofit repair bolt failures put service on december 19, 2013. fix ended costing 25 million dollars, higher original estimates , cost projections.

water leaks in superstructure attachments

some bridge components mounted on upper surface of primary structure. many of these require sealing against water intrusion interior of deck box sections. improper application of sealants beneath barriers contain traffic on bridge has been found allow water entry interior. interior moisture has led damaging corrosion, must fixed.

hold down rod grouting failure

the steel support structures attached concrete foundations partially threaded steel rods in conduits. these conduits supposed filled concrete grout after installation. of these voids temporarily closed @ top concrete seal. later workers incorrectly interpreted of these locations having been grouted when sealed @ top. incomplete grouting can lead salt-water intrusion accelerate corrosion of these critical rods. planned bore small holes grouting determine locations require additional grouting or alternative, injection of oil or similar material, displace water.

substandard component fabrication , related project management issues

the automated welding procedures used deck boxes fabricator (shanghai zhenhua port machinery co. ltd.) performed in rain. such welding has been long recognized leading cracking of imperfect welds. such welds considered caltrans management of low criticality in bridge owing compressive forces imposed on deck structure particular design. there reports of vendor being uncooperative concerns of caltrans inspectors , engineers. owing fragility of old cantilever structure , possibility of destructive earthquake, caltrans felt motivated avoid further delays in new span s completion.

in late january 2014, contra costa times article reported results of california state senate transportation panel investigation. panel s report titled san francisco-oakland bay bridge: basic reforms future . preliminary report, written contractor committee, states

it finding of investigation there appears have been chronic attempts keep many of serious safety allegations quiet, put aside , not dealt in open, businesslike manner in public s interest .

another leading california newspaper, sacramento bee, reported on july 31, 2014:

a california senate report released thursday said department of transportation managers gagged , banished @ least 9 top experts new $6.5 billion san francisco-oakland bay bridge after complained substandard work shanghai, china, firm built of span.

the full report preliminary report released in january 2014 may found @ site:

caltrans initial response may viewed here.

a state senate investigation continued in august, threats of criminal prosecution directed caltrans.