Steve Heminger told MTC commissioners at their meeting today that the delay "is pretty disturbing news" for the project to build the new eastern span, which has been set with delays and cost increases over the years.
The construction project is aimed at increasing the seismic safety of the eastern span, part of which collapsed in the 1989 Loma Prieta earthquake.
"We're very concerned because we're trying to beat the next earthquake," Heminger said.
The ZPMC steel-fabrication plant in Shanghai is putting together segments for the single-tower suspension span's deck and tower.
Shipments of the first steel segments were originally expected to arrive in the Bay Area this month, but Heminger said, "Now we're hearing September at the earliest."
He said, "We need premium steel out of China to start showing up so we can finish the bridge."
Heminger said he and several other transportation officials will soon travel to Shanghai to discuss the situation with ZPMC officials in person.
ZPMC is short for Zhenhua Port Machinery Co.
Heminger said the steel delay won't affect the scheduled closure of the Bay Bridge over Labor Day weekend, when workers will remove a 300-foot stretch of the existing eastern span and roll in a new piece.
The delays at the ZPMC plant are the result of a welding problem that was first discovered last year.
Discussing the welding problem at an MTC meeting on Jan. 28, Heminger said, "We're managing it and mitigating it" and said it "is largely behind us now."
The new eastern span is currently scheduled to open in 2013.
Caltrans spokesman Bart Ney couldn't immediately be reached for comment on whether the delay in delivering the deck segments will push back the construction schedule.