Construction of the new eastern span of the Bay Bridge reached another milestone Friday when a ship from China delivered the first pieces of the 525-foot-tall tower for the suspension span — the sleek and showy part of the new bridge.

The first four lower leg sections — each 150-foot-tall and weighing 1,400 tons — arrived late Friday afternoon at a Caltrans dock in Oakland. They will be inspected there and then barged to the construction site for installation later this month.

"This is the first section of the tower, the signature part of the bridge, and the thing that the community wanted," Caltrans spokesman Bart Ney said.

The 525-foot-tall tower for the self-anchored suspension span will be 125-foot taller than the 400-foot towers of the existing east span, which is being replaced because of its vulnerability to earthquakes.

To build the new tower, contractors will assemble four giant legs connected by sheer beams — a big version of a four-legged stool.

The beams will act like electrical circuit breakers, absorbing earthquake shaking and protecting the tower legs.

Later this month, a big gantry crane will lift the tower's legs into place on a 200-foot foundation anchored in bedrock below the Bay.

Bay Bridge motorists won't readily see them because the lower leg sections will be installed first and they will be lower than the traffic lanes of the existing Bay Bridge. But the installation of more leg sections this fall will raise the structure above the height of the traffic lanes, Ney said.

"You're really starting to see the bridge come together," he said.

Caltrans officials said they anticipate finishing the $6.3 billion new east span in late 2013 as contractors hope to make up time lost through delays in manufacturing bridge parts in China.

Contractors this month finished "Oakland touchdown" portion of the new east span. It is where an elevated skyway touches down on land in Oakland.

Contact Denis Cuff at 925-943-8267. Read the Capricious Commuter at www.ibabuzz.com/transportation/.