Officers from the British Transport police are appealing for witnesses to an incident which caused damage to a train in Doncaster.
The incident happened on May 6 between 4.30 and 6.30pm near to St Peters Road in Doncaster.
A spokesman for British Transport Police said: "Concrete lids used to protect railway signal cables and planks of wood were placed on the middle of the track – which later caused the underside of a passing train to be damaged.
"Placing items on the tracks is incredibly dangerous and officers are working hard to identify who is responsible."
Officers are asking for help from anyone in the area at the time, who saw anybody acting suspiciously or gaining access to the railway.
If you did or you have any other information about this incident, text British Transport Police on 61016 quoting 422 of May 10.
Alternatively you can contact Crimestoppers anonymously on 0800 555 11