he sold his company. Triple-decker buses There have been attempts to build a triple-decker bus. However such vehicles are problematic in that the high centre of gravity leads to instability and there is the risk of hitting trees or bridges. In almost all models the third level was a small compartment in the rear part of the bus, such as a triple-decker capable of carrying eighty-eight people from Rome to Tivoli in 1932 or the General American Aerocoach 3 Decker Bus of 1952. The only three-decker with a full-length third level ever built is the Knight Bus that John Richardson created for Harry Potter and the Prisoner of Azkaban by combining two AEC Regent III RTs. Although the AEC was merely a film prop, a British built ECW bodied Bristol VR double-decker bus imitation of the Knight bus was a functioning bus, which even went on tour. Comparison with articulated buses Operators worldwide must often decide between articulated and double-decker buses on popular routes. Articulated buses, entirely on one level, offer more room for disabled passengers, luggage and pushchairs; they may also be needed on routes going under low bridges or weak bridges that cannot take high axle loads. Double-decker buses, however, have a smaller road footprint and as such disrupt traffic, or block turning lanes less than articulated buses. Double-decker buses may be more popular with passengers because of the better view, and with cyclists, who may be at less risk than they are with the unpredictable swing of an articulated bus's tail. Articulated buses normally offer more standing room while double-decker buses may sometimes (not always) offer more seats. Articulated buses have less dwell time because of the extra doors, and double-decker buses offer fewer chances for fare dodgers since there are fewer or no unmanned doors. Collisions with bridges There have been a significant number of incidents in which a double-decker bus has collided with a low bridge, often a railway bridge. This is often caused by the driver making a wrong turn, driving a route they are unfamiliar with, or being used to driving single-decker buses and forgetting to allow for their vehicle's extra height when driving a double-decker. A collision with a railroad bridge by a Megabus in September 2010 at Syracuse, New York killed four passengers and injured 17. In recent years in the United Kingdom, six people had minor injuries after their bus