Propose a rail bike frame design with 2-seat and 4-seat variations for Colebrookdale Rail Road Company.

Requirements:

2-seat design needs to be ADA compliant for people with disabilities; they should be able to get on/off the bike with minimal assistance
incorporate trays and mounts for electrification (assumptions: motor 6″ x 5″ x 5″ / 15 lb, controller 9″ x 5″ x 3″ / 2 lb, battery 15″ x 6″ x 3″ / 28 lb)
one axle powered by pedaling, the other by motor
bike rides on standard gauge rail (4 ft 8-1/2 in)
18 inch diameter wheel
consider using 1.5 inch or bigger tubing for frame
safe
cost-effecient
only design the frame instead of the entire bike

What YOU NEED to do: Make a frame design with 2-seat and 4-seat variations demonstrated as a 3D CAD model