The Massachusetts Department of Transportation board of directors approved a $222.2 million contract Monday that will replace a fleet of 325 MBTA buses by June 2017.

The new 40-foot, low-floor, hybrid and compressed natural gas buses will replace a current MBTA fleet approaching the end of its 12-year expected service life. New Flyer Industries Inc., the Canada-based contractor of the buses, predicts delivery will begin in July 2016, according to a statement from MassDOT. The MBTA will review and inspect a pilot bus before the full fleet is manufactured and delivered.

“This is a wise investment that meets an urgent need to retire an aging portion of our bus fleet that has presented significant maintenance challenges and deliver new, top-quality replacements that will serve thousands and thousands of our customers each day,” MBTA interim General Manager Frank DePaola said in the statement.