 Since boarding must be allowed directly from flat ground, long and steep staircases are needed.Transit buses also use high floors to provide mechanical clearances for solid axles, but the use of dropped axles has enabled the creation of low-floor buses and by 2008 in the United States, the majority of new transit bus orders were for low-floor types.Today, in Germany, all rapid transit railways, most commuter trains, and many light rail vehicles operate as high-floor networks.