The 5-foot-10 white male was last seen at Hawkins 66 Gas Station, across the street from the railroad tracks.
He was wearing camouflage pants, a black jacket, plaid shirt and white tennis shoes.
Investigators believe he weighed between 150 to 175 pounds.
The St. Joseph Police Department received the call about the accident 6:30 Saturday morning.
Investigators ruled the death a suicide.
Traffic at Highway 59 and Alabama Street is no longer blocked East and West Bound, but expect delays as the train moves through the area.
If you have any information, contact Detective Richard Shelton at (816) 271-4777.