Police are driving this undercover bus to catch yobs causing anti-social behaviour (ASB) and dodgy drivers.
The 'Trojan Horse' bus patrols have been carried out so far in Wakefield and Ossett at key times to try to catch crooks in the act.
Wakefield District Police have teamed up with Arriva Yorkshire to target areas known for ASB problems.
In November last year, officers from Batley and Spen used a bus to stop traffic offences, including using mobile phones, failing to stop for red lights and dangerous driving.
West Yorkshire Police said: "So far officers on the special patrols have spotted and foiled potential anti-social behaviour by youths, identified and confiscated illegal motor cycles spotted while on Trojan patrols, and taken action against drivers seen using mobile phones while behind the wheel."
Police also foiled a potential serious assault after finding a man who was carrying a hammer on a bus heading towards Wakefield Bus Station.
Arriva Yorkshire have also supported one of their drivers to become a policing special constable through the ESP (Employer Supported Policing) scheme.
Once trained he will carry out policing in Wakefield in paid time.
Inspector Helen Brear of Wakefield Central NPT, said: “Trojan bus patrols are highly effective for us in being able to provide reassurance to passengers.
“They also allow us catch those committing criminal offences unawares by deploying officers in places where residents would not ordinarily expect to find them.
“We have had some excellent results in the last four patrols and area already planning more operations for the near future.”
Paul Flanagan, General Wakefield Manager for Wakefield Arriva Yorkshire, said: “These operations are something we, as a local bus operator are keen to continue as we see ourselves as an important part of the local Wakefield Community and will do all we can to support a better and safer city region through partnership working with West Yorkshire Police.”