Suspension of Blue Line Service between Airport and Bowdoin stations extended through May 17

MBTA employee Brian Brady used a flashlight and hand signals to the crane operator to move an old track rail that was replaced inside the Blue Line tunnel last week.David L. Ryan/Globe Staff

The suspension of Blue Line service between the Airport and Bowdoin stations will be extended through Tuesday, May 17, with service expected to resume the following day, the MBTA said Thursday.

The delay until May 18 is due to the derailment of a construction tool cart this week near Airport station, MBTA spokesperson Lisa Battiston said in a news release Thursday. There were no injuries, but the process to rerail the cart, and “make other repairs while continuing to finish scheduled work means additional time is needed to safely complete the project,” the statement said.

Battiston declined to respond to questions about exactly how many derailments happened in the area since the project began. The MBTA is required to report derailments to the Federal Transit Administration and the Massachusetts Department of Public Utilities.

A spokesperson for the FTA said the MBTA reported two derailments of rail maintenance vehicles to the federal agency in the last week, but the spokesperson declined to say where they occurred.

Danielle Burney, a spokesperson for the Executive Office of Energy and Environmental Affairs, and Elizabeth Cellucci, director of the DPU’s Transportation Oversight Division, did not respond to multiple requests for comment Thursday. The DPU is part of the EEA.

Officials said previously that shuttle buses would replace train service between the Airport and Government Center stations until May 8, and that Bowdoin Station near Beacon Hill would be closed completely, with shuttles stopping at Government Center.

The T said alternate shuttle bus and ferry service will continue to be provided during the suspension, which took effect late last month. Details on alternatives are available online at mbta.com/harbortunnel, and riders should continue to expect delays in shuttle bus service, the statement said.

“The MBTA apologizes for the need to extend this diversion, and for the inconvenience experienced by riders during this service suspension,” the statement said. “The MBTA knows how frustrating any service interruption is for riders, including unscheduled extensions in shuttle bus diversions, and work crews are actively working as quickly and safely as possible to get the work done. The MBTA continues to express its appreciation of riders’ patience as this important Blue Line work is completed correctly.”

The T has said previously that the Blue Line shutdown was meant to accelerate the work being done to repair the Harbor Tunnel, which officials estimated would have taken a year if done during nights and weekends. Workers are replacing 1,800 feet of track, sealing leaks, and inspecting tunnels and drainage systems.

One goal of the project is to make the Blue Line, a vital transit link to East Boston and Revere, less susceptible to flooding. The tunnel between Aquarium and Maverick stations already floods during storm surges, and the Blue Line is the most susceptible to flooding in the MBTA system, according to a study conducted by researchers from the Massachusetts Institute of Technology and Tulane University.

“Shuttle buses will continue to operate from Rockport Line [commuter rail] stations to Beverly station for continued train service to Boston at North Station through May 15 with normal train service between Newburyport and Boston,” said Thursday’s T statement. “Due to the extension of this Blue Line suspension, there will be some adjustments to upcoming alternate service for work taking place on the Newburyport/Rockport Line that begins next week.”