Passengers’ lives were put at risk after metal road signs and concrete slabs were placed on train tracks, police have warned.
The objects were left on the tracks in Feniton, Devon, between 3.25pm and 3.55pm on Tuesday.
The line is served by South Western Railway trains to destinations such as London Waterloo and Exeter St David’s.
A spokesman for British Transport Police said: “Putting anything on the railway is extremely dangerous and risks both the lives of those on the tracks and passengers on board trains.”
Anyone with information is urged to contact the force on 0800 405040 or texting 61016 and quoting 578 of July 3.