The crossword solution for the term 'NO TOP ON RUINED BRIDGE' is 'PONTOON'. A PONTOON is a type of boat that is flat-bottomed and often used for leisure activities such as fishing or pleasure cruising. It is also commonly used as a form of transport, particularly in shallow waters. PONTOON bridges are also used to span rivers or other bodies of water, and are typically constructed from a series of pontoons connected together.