Recommendations on Standards for the Design of Medical Diagnostic Equipment for Adults with Disabilities, Advisory Committee Final Report

Observations:

1. Wheelbase dimensions for manual wheelchairs and rear-wheel drive power chairs were similar to each other but slightly less than the wheelbase for front wheel drive power chairs

2. Both 3- and 4- wheeled electric scooters had a larger wheelbase dimensions compared to manual and power wheelchairs. This sample had just three 4-wheeled scooters which limits detailed comparisons with 3-wheeled scooters

For platforms designed to accommodate wheeled mobility devices, additional space beyond the wheelbase should be provided. It would be very difficult for the occupant to have the powered device come to rest on a platform that is the exact length as its wheelbase or even a few inches more. Fine control (for example less than 1 in. increments) is difficult when operating powered wheelchair and scooter devices.

The wheelchair scale we used had a leveled surface of length 30 in. long with a bevel of 5 in. each at both ends (i.e., total length of 40 in.). Power wheelchair and scooter users often had trouble getting positioned exactly on the leveled portion of the platform requiring additional time and verbal assistance from an assistant/aide to get properly situated. Larger devices including power wheelchairs would often get positioned with two wheels on the bevel edge. We have observed that this causes an uneven weight distribution on the scale and could cause power wheelchairs to tip over when making short quick forward-reverse maneuvers in trying to get positioned on the platform. Including some aids to facilitate positioning would be a good idea also, for example, lines on either end with contrasting color and raised ridges at the ends of the level part of the platform.