BrightBus

MASS Engineering (also known as MAS Special Enginering, MASS Transit, MASS Reliance, MASS Leon and Brightbus) is a bus operator currently based at North Anston between Sheffield and Worksop. MASS's Doncaster Depot closed in early September 2007.

They operate mainly school contract work from both depots, and whilst some public service routes are run in Doncaster (inherited from Leon Motors who were taken over in 2004) these have drastically decreased recently to just three and the remaining routes MASS inherited are now operated by First South Yorkshire until late October 2007 because these services are being withdrawn. However MASS are looking into new routes to compete with other companies including a number of minibus these include one that'll operate between Conisborough and Mexborough known as the 348 but it's rummored that it wont last long because of the fact that no one uses it. The company runs a large fleet of ex-London Leyland Titans and ex-Hong Kong tri-axle buses, MASS has been the subject of criticism due to the vehicle quality, service cuts and the attitude of staff.