By CBSBoston.com Staff

MELROSE (CBS) – The MBTA announced Thursday that shuttle buses will replace Orange Line service between Oak Grove and Sullivan Square stations for an extra week. The buses will now run between those two stations through Sunday, April 11.

The Orange Line has been shut down in both directions since a slow-speed train derailment in Medford on March 16 near Wellington Station. There were about 100 passengers who were quickly taken off the train, and none were injured.

The cause of the derailment has still not been determined yet. The T said originally that it would take three weeks to make the necessary fixes. The extra week will allow workers to do track replacement on both sides at Wellington Station.

Workers will also be replacing a decades-old track switch that was damaged during the derailment. On top of that, extra improvements will be made at the Malden, Sullivan, Wellington and Oak Grove stops.

CBSBoston.com Staff