A reward is being offered for information leading to the vandals of a stretch of Nottinghamshire railway.
Concrete blocks have been placed on the tracks
The line between Stoneyford and Langley Mill is being repeatedly targeted, with stones thrown at a Liverpool to Norwich service on Tuesday afternoon.
Concrete blocks were also placed on the line three times in January and on two occasions trains struck them.
Network Rail is now offering a £1,000 reward for information, which should be given to British Transport Police.
Managers say as well as risking lives such vandalism can cause serious damage to the vehicles and severe disruption for passengers.