Montesson is a commune in the Yvelines department in the Île-de-France region in north-central France. It is located in the western suburbs of Paris. Transport in Montesson is served by buses with T-tickets as well as by several Paris-suburban lines: Line 01, Line 04, Line 07, Line 19, Line 22. The bus tickets have a category called "Bus T" which is for occasional users and replaces the old tickets in the notebooks of the previous bus network.