PAWTUCKET — The state Department of Transportation started emergency repairs on the Pawtucket River Bridge yesterday and is removing a non-structural part for fear it might fall on someone.

The work began following the agency’s announcement Friday that it will post a reduced weight limit and close one entrance ramp permanently because of deterioration of the structure.

Late yesterday, workers from Aetna Bridge Co. were using heavy timbers to build the base of a temporary pier that will help support part of a northbound lane of Route 95 where part of the steel supporting structure has rusted away. The work is under way on the east bank of the Seekonk River, to help support the ramp for the School Street exit from the highway

Kazem Farhoumand, the DOT’s acting chief engineer, said that while the agency plans to close an adjacent entrance ramp, from George Street, “We have to keep School Street open.” He said the School Street exit ramp carries 16,000 vehicles per day and is critical, in part, because it serves Memorial Hospital of Rhode Island.

He also said that the DOT is removing sections of a steel panel, or “skirt,” that extends about three feet below the level of the bridge deck and covers part of the bridge structure, for fear that it might come loose.

“We have to make sure they don’t fall on anybody,” he said. The skirt is aesthetic rather than structural, he said.

Although the DOT is shifting traffic away from the bridge’s edges, where the worst deterioration is, the bridge’s problems are not evident to drivers crossing it. However, some of them have been made obvious from below the bridge by the removal of a section of the skirt where the work is going on.

Much of the deterioration affects the bridge’s brackets, steel supports extending out from the sides of its main, longitudinal beams, supporting part of the deck. The skirt has been removed in the area where Aetna is working, showing where parts of the bracket ends have rusted away.

The brackets support parts of the deck that make up the highway’s right lanes on both sides of the bridge. On the northbound side, where the work is going on, that lane serves as both the acceleration lane for the George Street entrance ramp and the deceleration lane for the School Street exit.

The temporary pier will extend perhaps 30 feet from the ground, behind a car dealership on Division Street, up to the bridge.

Besides the temporary pier, Farhoumand said Aetna will also reinforce another section of brackets and install a plate to keep a light pole from falling because of deterioration of the concrete it is bolted to.

DOT Director Jerome F. Williams says the bridge is safe, and that his agency is only taking steps to make sure it stays that way. DOT spokeswoman Dana Alexander Nolfe said yesterday that the bridge will formally have its new 22-ton weight limit posted next week, although the DOT is already telling truckers to detour around it on Route 295.

Farhoumand said the DOT is analyzing the results of an inspection of the bridge done last summer, and is also planning detours around the bridge.

blandis@projo.com