Skyway Viaduct Eastern span replacement of the San Francisco–Oakland Bay Bridge

new , old approach spans (may 2008)



cutaway illustration, showing battered piles support skyway



700-ton segment lift

the skyway viaduct connects sas portion of bridge oakland shore. 2007, 75 percent of skyway portion completed. since section crosses shallower portion of bay, foundations constructed within sheet-pile cofferdams. mid-2009, final connection of viaduct portion ground level @ eastern end being finished , pedestrian walkway being attached completed sections.

rather set pilings deep enough reach bedrock, pilings founded in firm archaic mud below soft mud deposited distant placer mining in late 19th century. since archaic mud weak in concentrated load application conventional vertical friction piles, large diameter tubular piles driven (inside pumped-dry cofferdams) @ angles, forming battered (splayed) footing, through archaic mud firm aggregated sand, mud, , gravel of alameda formation. long pilings needed, segments welded completed segments installed.

when pilings in place, reinforced concrete pad poured @ bottom of cofferdam form footing column, subsequently cast in place around rebar using reusable metal formwork.

a single viaduct segment located on each column cast in place using forms. pairs of precast span segments, fabricated in stockton, california, barged location , lifted place specialized cantilever lift. (cantilever lifts, counterweights , other equipment , materials lifted either barge crane or jack-up crane located between adjacent columns.) once in proper location, opposing segments joined through tendons (cables within conduits tensioned jacks), forming balanced cantilever on column. eventually, gap in spans between columns closed, forming tendon-reinforced beam.

the oakland touchdown curved elevated roadway connects skyway oakland shore (the beginning of bridge). curve required bring alignment of existing ground-level approach road. yerba buena island transition structure (ybits) west of main span, section end segment of new bridge , being constructed @ same pace ybits. construction process consists of 2 phases, first phase completed (westbound traffic side). eastbound touchdown not completed until existing roadway out of way. done constructing gentle swing south touchdown may completed. first stage of work move eastbound traffic south completed minor traffic delays during 2011 memorial day holiday (may 28–30). driving experience has been improved, without problems came infamous s-curve. second stage move westbound traffic space made available required construction of elevated approach. completed on february 19, 2012. designed procedure expected save time in total effort, speeding completion of span. oakland touchdown completed in march 2013.

on three-day weekend beginning 8:00 pm friday, february 17, 2012, westbound lanes shut down allow connection of approach roadbed new temporary structure. execution of task dependent upon weather, dry conditions being required re-striping lanes, , not determined until few days before work done on weekend. scheduled completion 5 a.m. on tuesday, february 21, work completed 34 hours ahead of schedule, , opened traffic @ approximately 7:15 p.m. on sunday, february 19.