Oakland – Caltrans has reached another historic milestone in the removal of the original east span of the San Francisco-Oakland Bay Bridge. Starting as soon as tomorrow, crews will begin lowering the first 504-foot truss span. This is scheduled to take place over a 2-day period, beginning as soon as Thursday, February 4th, weather permitting.
In 1935, the building of the “504s”, as they’re called, was relatively straightforward and used disruptive piles to hold the steel frame high above the bay. The lowering and dismantling process later this week is more complex, but also more environmentally friendly.
The five 504s stretch from Pier E4 to Pier E9, extending approximately half a mile. The weight in steel of each 504 truss to be lowered is equivalent to 2,500 tons.
“The deconstruction of the cantilever was a bold and outstanding engineering achievement and the implosion of the Pier E3 foundation was an environmental success. Now, the lowering of the first 504-foot truss, without using a single pile, is our next environmental challenge,” explained Chief Bridge Engineer, Brian Maroney.
Day one of the project will focus on severing the truss from its towers and its slow decent toward the bay below. The second day will concentrate on setting the truss down on barges and transporting it to the Port of Oakland for disassembly. Each day is expected to take anywhere from 12 to 14 hours. The lowering operation is highly weather dependent. Heavy rains and/or high winds could cause changes.
This is the second part in a three part process to dismantle the Old Bay Bridge. Phase I was completed the end of 2015, with the complete demolition of the cantilever section and S-curve to Yerba Buena Island. Now, Phase II continues with removal of the first five 504s and then removal of fourteen 288-foot truss span sections that extend to the Oakland shore. Phase III will focus on the demolition of the remaining marine foundations.
The lowering of the 504s is a slow and methodical operation compared to the 6-second implosion of Pier E3 that was performed in mid November. Although these are very different operations, environmental measures have been priorities for both. In addition to no piles being needed for this process, contractors are working closely with a bird deterrence contractor and engineers to coordinate activities to avoid other impacts.
A live stream will allow for public viewing during the operation. We encourage the public to use this method for observing the operation. You can see the stream here: http://www.youtube.com/channel/UCm-wXGyG0tHq4NAco-TzKRg/live
Day 1 – Truss Lowering
Work hour 6:00 am to 8:00 pm
(Best visuals for media will likely occur at mid to late morning, when strands are hanging down. The truss is scheduled to be lowered at a rate of 25 feet per hour.)
Day 2 – Truss Set-Down and Transport
(Throughout the day, the truss will be closer the barges.)
You can see an animation of the lowering at this link: