Miriam Yarimi, 32, pled guilty to manslaughter last month for the crash that happened last March.
John Sampson said the heart-stopping moment was over as quickly as it began. "I just went into rescue mode," he said.
Crowds could be seen gathered below the tracks trying to guide the boy to safety as he was in danger of falling off the rail.
Officials at West Point applauded 10-year-old Maya Ozuna for her strength, resilience and courage.
Thanks to the officers' quick-thinking and teamwork, the 1-year-old child is expected to make a full recovery.