BG ICF Double-Decker Interiors --- A DD coach may carry about twice passengers as many as a normal car, without requiring double the weight to pull or material to build. The double-deck design usually includes lowering the bottom floor to below the top level of the wheels, closer to the rails, and then adding an upper floor above. Such a design fits under most bridges, tunnels and OH cables. For cost and safety, this design also minimizes car height and lowers the centre of gravity. ICF uses a 'split level' car design, where the doors are located on a middle level, with access into the upper or lower level with stairs or ramps going both up and down.