BOSTON (AP) – The left lane in the westbound Ted Williams Tunnel was reopened Saturday afternoon after being closed Friday night when pull tests resulted in the movement of one bolt that helps hold up ceiling panels, state officials said.

One of three bolts tested Friday night slipped by three-sixteenths of an inch, said Jon Carlisle, spokesman for the Executive Office of Transportation.

The lane was closed during the tests and was at first scheduled to reopen early Saturday. However, it remained closed until about 4 p.m. while engineers performed remedial work on the bolt that slipped.

“It doesn’t represent any kind of imminent hazard,” he said. “So far, it’s not indicative of the systemic problems that have been associated with the I-90 connector.”

Carlisle said workers replaced the bolt that had shifted with a different type of bolt.

A connector tunnel system leading to the eastbound side of the Ted Williams Tunnel, as well as ramps leading from the Boston end of the westbound section, were closed after several three-ton concrete ceiling panels in the Interstate 90 connector tunnel crushed a car on July 10, killing 39-year-old Milena Del Valle.

A month later an eastbound ramp leading into the Ted Williams Tunnel toward Logan International Airport reopened to the public.

Investigators have focused on the bolt-and-epoxy system holding up the ceiling panels in those tunnels. Engineers have been conducting pull tests on the ceiling of the Interstate 90 connector tunnel and both sides of the Ted Williams Tunnel for the past four weeks, Carlisle said.

Earlier this month, Big Dig project manager Bechtel/Parsons Brinckerhoff criticized the tests, which put 8,400 pounds of pressure on brackets, each secured by two bolts, that hold up ceiling panels in the tunnel. The company has said the tests may cause damage to the epoxy adhesive and impact the tunnel’s long-term integrity.

But Gov. Mitt Romney said the pull tests were calculated for a specific load and would not yield failure.

“These tests are safe and necessary,” Carlisle reiterated Saturday.

The $14.6 billion Big Dig highway project buried a highway network that used to slice through the city, creating a series of tunnels to take traffic underground.

AP-ES-08-19-06 1753EDT