WASHINGTON — U.S. transportation officials proposed spending more than $120 billion over the next 30 years to revamp and overhaul railroad tracks in the Northeast Corridor, shaving 80 minutes off the trip between Washington and Boston, and expanding rail service throughout New Jersey. The report by the Federal Railroad Administration said a mixture of funding sources would need to be tapped to fulfill the plan of improved service along the 457-mile corridor, including some new tracks, new stations and new trains.