A major section of the old eastern span of the Bay Bridge began coming down Thursday morning.
In the second part of the three-phase process of dismantling the old eastern span, crews began lowering a 504-foot truss that weighs about 2,500 tons.
There are five such trusses that were built in 1935 and they combine to stretch for about a half-mile, from Pier E4 to Pier E9.
Caltrans spokeswoman Leah Robinson-Leach said the work today will focus on severing the truss from the bridge's towers and beginning its slow descent to the Bay below.
Robinson said work on Friday will concentrate on setting the truss down on barges and transporting it to the Port of Oakland for disassembly. Eventually it will be broken apart and its scrap metal will be recycled.
Robinson said the truss will only be lowered several feet today and most of the lowering will take place on Friday. Each day of work is expected to last from 12 to 14 hours. She said it will be difficult for the public to see the lowering work so Caltrans encourages people to watch the process online. The other four trusses will be lowered at a later date.
The first phase in taking down the old eastern span was completed at the end of last year with the complete demolition of the cantilever section and the S-curve to Yerba Buena Island.
The second phase is removing the five 504-foot trusses and then removing 14 288-foot truss span sections that extend to the Oakland shore.
The third phase will focus on demolishing the span's remaining marine foundations.