Double-decker bus
With the exception of coaches, double-decker buses are uncommon in the United States. Many private operators, such as Megabus, run by Coach USA, employs double-decker buses on its busier intercity routes.
OC Transpo Route 61
In the summer of 2006 and the winter of 2007, OC Transpo tested a double decker bus, the Alexander Dennis Enviro500 on this route as well as some express routes. The testing was made in order to determine whether double decker buses will be possible to operate within the Ottawa system as it contains a higher seating capacity than the articulated buses although with lower total capacity (including standing room only) than the latter due to the height restriction of the upper floor of the bus. . Double decker buses were re-used on the route during the summer of 2009.