Abstract: A ramp unit for heavy duty vehicles includes multiple ramp segments and wall segments coupled with each other in a perimeter. Each of the ramp segments and wall segments are provided as modular units configured to be assembled with each other. The ramp unit also includes a deck extending between the multiple ramp segments and wall segments. An inner volume defined by the plurality of ramp segments and wall segments and the deck is configured to receive and fully enclose a bulk material such that an underside of the deck provides a barrier from an exterior of the ramp unit.