Brattleboro police Sgt. Mark Carignan said the woman, whose name was not released, suffered "significant" injuries and was found near the abutment of a railroad bridge spanning the West River where it meets the Connecticut River.
"Whether the train hit her - the circumstances under which she fell - all of that is being investigated," Carignan said at the scene.
It is a 25-foot drop from the tracks to the ground where medics treated the woman before she was transported via a waiting Rescue Inc. ambulance.
The victim was conscious and speaking to emergency responders, Carignan said.
The accident was reported at 12:34 p.m.
The southbound train stopped nearby and was held for less than an hour while police investigated. Putney Road remained open.