In November 2008, 3 Alexander-Dennis Enviro 500 double decker buses, numbered 1201-1203 by OC Transpo, were introduced for a trial project that is expected to be completed after 2 years. These double decker buses are assigned to specific assignments and routes everyday due to concerns of height clearance along the transitway. The Enviro 500 double deckers are used mostly on the busiest routes serving the transitway between Airport in the south, to Terry Fox / Kanata in the west, and Millennium Park in the east. These buses can usually be seen on route 94, 96, 97 and 98 throughout the entire day; route 35, 61 and 77 during peak hours. This experimental trial is expected to end in November 2010 at the earliest, and March 2011 at the latest. It is unlikely for OC Transpo to purchase double deckers in the near future, as 306 articulated buses have recently been ordered (in May 2010) to replace the ageing fleet of New Flyer articulated buses manufactured between 2001-2004. A new bus garage has also been recently built, and the entrance gates are too small to accomodate with double decker buses.