The Northeast Corridor mainline from New Haven to Boston was electrified in 1999, completing the thwarted ambition of the former New York, New Haven and Hartford Railroad. This electrification was part of the Acela Express high-speed project, and involved the building of overhead lines electrified at , requiring trains to handle a change of voltage on the fly at New Haven. Plans to convert the rest of the Northeast Corridor to have been shelved, although the section from New Haven to the Hell Gate Bridge has been converted to by Metro-North.