Traversing step obstacles with manual wheelchairs

In the public transport system, there are sometimes step obstacles, such as curbs, steps, entrance steps of vehicles, edges of lifting platforms, internal steps in vehicles, etc. This paper describes research work carried out in Sweden to specify the heights of step obstacles possible to traverse with a manual wheelchair manoeuvred by an attendant. The work included trials with the subjects manoeuvring two different kinds of wheelchairs, with dummies as occupants, over a step obstacle with adjustable height. It also included trials with a person in the wheelchair. The subjects were 20 healthy persons in the age range of 23-60 years, with no or only little experience of manoeuvring wheelchairs, chosen to represent bus drivers or other helpers. They rated their perceived feeling of effort on a 10-level rating scale with ratio properties. The occupant rated the feeling of comfort and safety in three grades. All trials were recorded using a video-camera. From the video-film, the situations and series of actions of the subjects were analysed and the length of time for each task was measured. The forces needed when traversing step obstacles with a wheelchair were calculated according to the principles of mechanics and processed by a computer for the different principal traversing situations. The results show that for the planning of systems for public transportation, where the passenger can get assistance, a step height of 50 mm is acceptable, and a step height of 100 mm can be acceptable if there is enough room to manoeuvre the wheelchair, so that it is possible to choose the most convenient way to traverse the step. Higher heights should be avoided.