But because Walsh Construction Co. will have to redesign steel girders for the project, those closures and the project’s completion will be pushed back a year, state transportation officials said. Officials said Walsh notified the state of the problems last month.

Under the original timeline, significant portions of the bridge would have been closed at times between July 21 and Aug. 29 this summer, and for several weeks during the summer of 2017.

The $81.8 million project to rebuild portions of the Commonwealth Avenue Bridge will be delayed a year because of design errors by a construction company, officials from the Massachusetts Department of Transportation announced on Monday.


The project is now scheduled to be done by fall 2019, according to Jacquelyn Goddard, a MassDOT spokeswoman.

The state is replacing the concrete deck and steel beams of the bridge, which was constructed around 1965, because of deterioration and corrosion, according to MassDOT.

The bridge carries the MBTA’s Green Line over Interstate 90, also known as the Massachusetts Turnpike, and the MBTA’s commuter rail. The closures would have affected the Green Line, traffic on Commonwealth Avenue, I-90, and the commuter rail.

Walsh Construction Co. won the project with a bid of $81.8 million and was given the notice to proceed in June 2015, according to officials.

In a statement, representatives from the construction company said they have resolved the issues with the steel girders “and look forward to successfully completing the first phase of the project in the summer of 2017.”

The company will not receive the $7.2 million incentive that it could have received for successfully completing the 2016 closure phase, according to MassDOT.

The project had required the state transportation department to close one of four lanes of Interstate 90, but the delay will allow the state to open the roadway back up to four lanes on June 30. Traffic will be reduced from four lanes to two during the 2017 closures.


The project’s delay comes about half a year after MassDOT announced that its attempt to rebuild the Longfellow Bridge would be delayed two years. In that case, officials blamed complications associated with preserving the historic nature of the bridge.

Nicole Dungca can be reached at nicole.dungca@globe.com. Follow her on Twitter @ndungca.