I've never had a problem with my son's umbrella stroller because it's small. Even on crowded trains, an umbrella stroller fits between your legs. However, I have a big problem with people who bring their full-sized strollers on the train when it's crowded. I couldn't get off the train because one family brought theirs on and couldn't figure out how to move it out of the aisle so I could get through. The entire row of people had to move so we could get out.