Two buses collided onto a broken-down container truck on Wong Chu Road, a dual carriageway trunk highway in Tuen Mun on 22 March 2013. This incident resulted in 26 casualties, including three serious cases. In this chain collision, the front of the double decker bus in the middle was compressed. This is not an isolated incident as rear-front type of collisions involving buses on highways are typical of multi-casualty events in Hong Kong. Upper deck front seat passengers are particularly susceptible to severe injuries given the virtual lack of a crumple zone, even if seat belts are worn. Given the widespread deployment of double decker buses on the highways and expressways in Hong Kong, further steps for protecting bus passengers will be necessary.