Above links to schedule documents don't work, because once more the schedule is changing. Effective April 11, 2016, the 476/479 pair of Shuttles will once more be suspended.
Amtrak Announces Changes to Springfield Shuttle Service
On Select Dates Effective April 11 through July 29, 2016
To accommodate track work as part of the New Haven-Hartford-Springfield (NHHS) Rail Program, Amtrak has released a service change for the Springfield, Massachusetts shuttle service. Please reference the attached PDF.
The schedule will be effective through July 29, 2016.
Future updates on the status and location of construction activities will be provided on the NHHS Rail Program website at www.nhhsrail.com, Facebook, Twitter and by email. To receive email updates, please register on the NHHS Rail Program website.