The new replacement bridge that will carry the Red Line trains over Clayton Street in Dorchester was moved into its final position around 3 a.m. today, and officials said they expect to have trains running across it again first thing Monday morning.
The 56-hour replacement, the first Accelerated Bridge Construction project of a Massachusetts subway line, was running on schedule today, MBTA spokeswoman Kelly Smith said.
Workers built the new 60-by-40-foot bridge about 200 feet up the road, then tore down the old bridge Friday and began moving the new one into its place late Saturday afternoon.
Shuttle buses replaced Red Line trains between JFK/UMass and Ashmont stations starting Friday evening.
The old bridge, between the Fields Corner and Savin Hill stations on the Ashmont branch of the Red Line, had been damaged and worn over 102 years of use.
Tearing it down and rebuilding the traditional way would have taken about 30 months, according to MBTA estimates. Globe Correspondent Zachary T. Sampson contributed to this report. Gal Tziperman Lotan can be reached at firstname.lastname@example.org.