Germany's Deutsche Bahn announced its plans to test small drones, trying to reduce the amount of graffiti being sprayed on its property.
The plan involves the use of airborne infra-red cameras to collect evidence, which could then be used to prosecute vandals who deface property at night.
A company spokesman said drones would be tested at rail depots soon.
Graffiti is reported to cost Deutsche Bahn about 7.6m euros ($10 million) a year.
German media report that each drone will cost about 60,000 euros ($77,496) and fly almost silently, up to 150m (495ft) above ground.