Abstract: In one embodiment, a vehicle for transporting passengers can include a chassis, a support member, and a labyrinthine girder. The support member can be rigidly engaged to and project from the chassis. The labyrinthine girder can include a coupling platform that is coupled to the support member. The labyrinthine girder can form a partial enclosure that surrounds a portion of the frame rail. An offset distance can be disposed between the labyrinthine girder and the frame rail.

Abstract: In one embodiment, a vehicle for transporting passengers can include a passenger section, an elevated passenger section, a subfloor discontinuity, and a retractable step. The subfloor discontinuity can be located between the passenger section and the elevated passenger section. The subfloor discontinuity can span the elevation change. The retractable step can be located at the subfloor discontinuity. The retractable step can include a housing, a riser door, and an articulating tread. The housing can at least partially surrounds a volume. The riser door can be in rotatable engagement with the housing such that the riser door rotates into and out of the volume of the housing. The articulating tread can be in rotatable engagement with the housing such that the riser door rotates into and out of the volume of the housing. The retractable step can articulate between a step position and a ramp position.

Abstract: In one embodiment, a vehicle for transporting passengers can include a passenger section, an elevated passenger section, a subfloor discontinuity, and a retractable step. The subfloor discontinuity can be located between the passenger section and the elevated passenger section. The subfloor discontinuity can span the elevation change. The retractable step can be located at the subfloor discontinuity. The retractable step can include a housing, a riser door, and an articulating tread. The housing can at least partially surrounds a volume. The riser door can be in rotatable engagement with the housing such that the riser door rotates into and out of the volume of the housing. The articulating tread can be in rotatable engagement with the housing such that the riser door rotates into and out of the volume of the housing. The retractable step can articulate between a step position and a ramp position.

Abstract: In one embodiment, a vehicle for transporting passengers can include a chassis, a support member, and a labyrinthine girder. The support member can be rigidly engaged to and project from the chassis. The labyrinthine girder can include a coupling platform that is coupled to the support member. The labyrinthine girder can form a partial enclosure that surrounds a portion of the frame rail. An offset distance can be disposed between the labyrinthine girder and the frame rail.