Use MetroNorth Railroad's Hudson Line with service to & from Grand Central terminal, in New York City. The Aqueduct trail is within a half-mile walk uphill & eastward from most of the stations from Greystone to Ossining. Check online schedules.
Parking is available in municipal parking lots, MetroNorth parking lots (some have free parking) and along many streets. Motorists should obey local parking regulations. (Again, our Map will help you with this.)
The trail is accessible from several bus routes of the Westchester County Beeline bus service - along Route 9/Broadway and other major roads serving village centers. Check Beeline Bus Line for schedules.