2. Premises, Test Bay and Equipment Layout. Premises, test bays and equipment will be considered suitable if they meet the requirements laid out in "Requirements for Authorisation for Vehicle Testing Station (Common to all Classes. 2.1 Premises with a) a facility to prevent the buildup of exhaust fumes, either by means of ventilation or by exhaust extraction equipment for connection to the exhaust pipes of vehicles. 2.2 A test bay with a) vehicle entrances and exits at least m high and m wide for double deck vehicles m high and m wide for single deck vehicles b) a width of at least m c) headroom of at least m for double deck vehicles and m for single deck vehicles except over a lift) d) headroom over a lift of at least m for double deck vehicles or m for single deck vehicles, measured from the platform surfaces when fully lowered, extending over an area of at least m on each side of the lift longitudinal centre and at least m fore and aft of the lift transverse centre line.