World First Bus acquired the whole CMB fleet, it also replaced the Victories and the remaining Fleetlines with new super low floor buses, the last Fleetlines and Victories were withdrawn in August 2000. Bus-bus interchange became a common practice since the 1990s. In 1991 bus-bus interchange was introduced for Shing Mun Tunnel routes. Later on bus-bus interchange using transfer tickets was introduced on some overnight routes and Tai Lam Tunnel routes. With the Octopus card being accepted on some franchised bus routes since 1997, the first bus-bus interchange using Octopus card was first introduced in 1999. 2000s: On the edge, to the scrapyard In the 2000s, the franchised bus companies continued to introduce new super low floor double-deckers. In 2003, KMB introduced the first new generation super low floor double-decker (TransBus Enviro500) with wider (with the width of 2550mm instead of 2500mm) bodywork and straight staircase. In August 2002, NWFB withdrew its last non-air-conditioned buses and became the second franchised bus company to operate fully air-conditioned bus fleet. In June 2003, Citybus was acquired by Chow Tai Fook Enterprises, the parent company of its major rival operator New World First Bus. The 2000s also saw the withdrawal of second generation rear-engined double-deckers. Actually CMB had already withdrawn several in the 1990s. When NWFB took over in 1998, they withdrew the rest of these buses, with the last leaving the fleet in 2002. KMB also started to withdraw these double-deckers from 2000, including Leyland Olympians, Dennis Dominators/Dragons and MCW Metrobus. The withdrawal process of these buses was underway throughout the 2000s. The last MCW Metrobus was withdrawn by KMB in 2007, which marks the extinction of MCW buses in franchised bus companies. 2010s: Introduction of two-axle air-conditioned double deckers and extinction of non-low floor (including Hotdog) buses In 2010, franchised bus operators introduced the first two-axle air-conditioned double deckers. KMB introduced one Alexander Dennis Enviro400, Citybus introduced two Enviro400s, later in the same year both KMB and Citybus have received one two-axle Volvo B9TL. The first production two-axle air-conditioned double deckers appeared in 2011. The withdrawal of KMB's non-air-conditioned double deckers also reached the final stage in the 2010s. In late 2011, one KMB's non-air-conditioned double decker received advertisement banners, stating "Farewell KMB Non Air-Conditioned Bus (2012)". The last non-air-conditioned buses were removed from service on 9 May 2012 when the last four KMB routes were converted to fully air-conditioned bus