And because they can have multiple carriages you have more entry/exit points. Having more entrances/exists is important if you have a lot of people who wish to

And because they can have multiple carriages you have more entry/exit points. Having more entrances/exists is important if you have a lot of people who wish to travel in wheelchairs, or while pushing buggies with babies. This reduces the time it takes people to board/leave, and helps iron out delays caused by multiple busy stops on a route.