The directors of the Massachusetts Bay Transportation Authority (MBTA) Wednesday passed a $346.2 million expansion program, which includes a 2.5 mile expansion of the Harvard Sq. line.

According to plans now favored by the MBTA, the Harvard extension would pass a tunnel under Radcliffe Yard and near a Loeb Drama Center. University officials have expressed concern over the ate, and have asked that the extension designed to eliminate any noise and vibration effects that the new tunnel might have on Harvard and Radcliffe buildings.

The entire expansion program must will be approved by the MBTA's Advise Board -- representatives from all the communities that are served by the bus and rail facilities of the MBTA.

The Harvard Square extension, as now planned, would run down Brattle St. past the Bennett St. repair yards and then continue for a short while down Mt. Auburn St. It would then make a wide loop that would bring it close to the Loeb and directly under Radcliffe Yard

The tunnel would then cross the Cambridge Common, continue up Massachusetts Ave, until Porter Square, where there would be a stop.

Despite the closeness of the new extension to Harvard and Radcliffe buildings, the University has put up no overt opposition to the plan. It has privately asked, however, that the University buildings be protected. The Harvard Planning office contemplates a study of the area to determine the type of construction necessary to shield the buildings; apparently, little work on the study has been done this summer. The start of construction is net planned before 1968.