Construction began Monday on a $10.7 million rehabilitation of the Route 1 Twin Bridges over the Schuylkill in Philadelphia.

The left lanes in both directions will be closed from 9 a.m. to 3 p.m., and motorists are advised to expect delays, the Pennsylvania Department of Transportation said.

The project to resurface and spruce up the bridges is expected to last about a year.

The bridges, which carry traffic between I-76 and Roosevelt Boulevard, span the river, Kelly Drive, Martin Luther King Drive, and Ridge Avenue.

They were built in 1960 and partially reconstructed in 1985.

PennDot district executive Lester Toaso said the project would improve the bridges’ “overall strength and extend their life span.”

Among the repairs, workers plan to resurface the bridges’ concrete decks and the Route 1 ramps to I-76; remove and replace fencing; remove and reset light fixtures; and clean and repair deck joints.

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The northbound bridge is 11 spans stretching 1,921 feet. The southbound bridge is 12 spans over 1,990 feet. Both are steel-plate girder bridges.

Average traffic on the bridges is 109,931 vehicles per day, PennDot said.

The project cost is entirely covered by federal American Recovery and Reinvestment Act funding.

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