The so-called "Knowledge Corridor" high speed passenger train service from Connecticut to Vermont through Northampton is on schedule, according to state transportation officials.  They told Monday night's inaugural meeting of Northampton's Rail Advisory Committee that physical work on the project starts this Summer.  It will include the upgrading of about 47 miles of track between Holyoke and the Vermont border.  Railroad ties are also being placed alongside tracks in Northfield, Greenfield and Northampton.  The return of rail service for Northampton is expected next year.