Some buses operating across Nottingham have been filled with undercover police officers in a bid to prevent attacks on services.
Nottingham City Transport (NCT) services have been the subject of vandalism and anti-social behaviour, with some taken out of operation on occasion, tweets have suggested.
As a result a partnership with Nottinghamshire Police has led to the creation of a "Trojan Bus".
The name is derived from the Greek 'Trojan Horse', whereby warriors were said to hide inside a giant structure in a bid to gain access to a city without its defenders noticing.
It is now also used to describe computer malware which at first sight does not appear to be dangerous.
In the case of the 'Trojan Bus', officers from the force hide on board ready to pounce on any offenders.
NCT says: "Our thanks to Nottinghamshire Police for their continued support in addressing recent cases of objects being thrown at our buses.
"Police are travelling on buses in the affected areas, including on our 'Trojan Bus', a bus full of officers ready to respond to issues and apprehend offenders."
