There will be construction on Route 28 northbound and southbound between Third Street in Cambridge and Broadway in Somerville through Aug. 25, the state Department of Transportation said Friday.

The work of sidewalk, wheelchair ramp and driveway reconstruction began Monday. Work hours will be 7 a.m. to 3:30 p.m., Monday through Friday, causing the contractor to make varying around-the-clock single-lane closings and pedestrian detours.

The work is part of a $15.6 million project to perform bridge repairs, paving and other related work on 1.5 miles of Monsignor O’Brien/McGrath Highway, Route 28, between Cambridge and Somerville.