Silver Line tunnel closed after concrete falls on platform

A Silver Line bus headed into a tunnel in South Boston in 2015. –Jonathan Wiggs/Globe Staff/File

The MBTA shut the Silver Line tunnel through the Seaport Wednesday after construction on Congress Street caused concrete to fall onto the platform at the World Trade Center Station.

The T will run buses on city streets along that portion of the Silver Line while it conducts an engineering assessment of the tunnel.

“Out of an abundance of caution for T customers and employees, the MBTA has closed the Silver Line tunnel from South Station to Silver Line Way until that assessment is complete,’’ the agency said in a statement. “There were no known injuries as a result of this incident.’’