The passenger hit the female inspector as the service pulled into Edinburgh Waverley.
The 24-year-old was assaulted in the early hours of Wednesday near Waverley Mall in Edinburgh.
The incident happened between Falkirk High and Glasgow Queen Street railway stations on Monday afternoon.
The major engineering works at Haymarket East Junction were completed over the festive period.
ScotRail has warned rail users there will be no trains running to or from Edinburgh until Sunday.
Shops, street lights and Haymarket station have been impacted by the blackout.
The incident was reported to have occurred on a service between Greenfaulds and Edinburgh Waverley.