A transportation system including a vehicle support structure (21), a vehicle (22) supported thereon, an elongated semi-rigid fin (44) attached to the vehicle (22), and a plurality of drive assemblies (45) positioned along the support structure (21) to frictionally engage and drive the fin (44). The fin (44) is sufficiently rigid for braking, acceleration, and steering, without lateral buckling. The fin (44) preferably is not a continuous or endless member, but extends several vehicle lengths in front of and behind the vehicle (22). A flexible traction belt (86) optionally can be coupled in tandem with the fin (44) to provide an endless loop propulsion system. In the preferred form, the vehicle (21) is suspended by a pair of aligned, load-supporting wheels (36, 36a). Laterally extending outrigger roll control assemblies (40) are used to control roll of vehicle (22) about the load-supporting wheels (36, 36a).
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