A train in motion is a train carrying out its purpose. So why bother stopping at stations?!
That's the idea behind this concept train from China. Check out the video below which demonstrates how it works: Passengers step onto a compartment platform above an incoming train, which is then snagged by the train as it moves through the platform. At the next station, anyone wanting to get off moves up into the compartment, which is then snagged by the station. The train itself never stops, it simply trades embarkation capsules as its moves through a station, giving passengers a window of time to board without the train needing to stop.