The subway bus. Pictured is one of the Boston area’s silver line buses. I can’t think of much better way to describe it than a subway bus. This is because while it functions above ground much as a regular bus, while below ground it acts a lot like a subway. And that goes right up to including having subterranean bus stations such as the one pictured. To further the similarity to the subway train the bus is also quite a bit longer than your typical bus with an accordion junction in the middle of it. This allows the bus to negotiate around turns in the city where it otherwise wouldn’t be able to do to its great length. We rode this bus from Boston South Station to the Boston Logan international airport.