It is important to consider that wheelchair user might not only have limited physical mobility, but may also have one or more additional impairments. These could include visual, hearing, cognitive or language impairments, or any combination of these.
Therefore accessibility issues for people in wheelchairs can be placed under the following categories:
- Those relating to the disability that has confined them to a wheelchair (e.g. is there a necessity to reach buttons/controls at a certain height?).
- Those relating to additional disabilities.
- Those specifically arising from the fact that they are in a wheelchair (e.g. what are the minimum space requirements for manoeuvrability?).
All of these factors should be considered when designing a system for
In general, a major problem experienced by wheelchair users is that of limited space caused by both fixed (e.g. a door, a street lamp or a bus stop) and temporary (e.g. a sign on the footpath outside a shop or a bicycle locked to a street lamp) obstacles. Although facilities are gradually improving to cater for persons in wheelchairs, many areas are still virtually inaccessible.
Relevant Measurements (as provided in the Department for Transport's Inclusive Mobility Report)
Measurements taken of wheelchair visitors to the 1999 Mobility Roadshow Survey showed considerable variation in overall length of 'wheelchair plus user', the greatest lengths being those of occupant-propelled wheelchair users with leg supports (maximum 1500mm-1545mm) and electric scooters (maximum 1500mm). The combined length of an occupant-propelled wheelchair user and a personal assistant was approximately 1750mm. A maximum width of approximately 700mm (for powered chairs) was reported, but this does not allow for the wheelchair user's elbows and hands.
The overall mean height of 'wheelchair plus user' (The 1999 Mobility Roadshow Survey) for all types of wheelchair users was 1243mm, with a 5th percentile of 1076mm, 95th percentile of 1374mm and a maximum of just over 1450mm. As with overall length, scooter users gave slightly greater figures, with a mean height of 1340mm, 5th and 95th percentiles of 1202mm and 1438mm respectively and a maximum of 1502mm.
A wheelchair user and an ambulant person side-by-side need 1500mm width, a width of 2000mm allows two wheelchairs to pass one another comfortably.
According to the ISO standard for wheelchairs (ISO 7193), to propel a wheelchair manually needs a clearance of not less than 50mm, preferably 100mm, on both sides.
Skilled users of manual wheelchairs can turn through 360° in a space no more than 1500mm x 1500mm. This is insufficient for larger chairs, particularly outdoor electric wheelchairs (turning circle 4200mm), electric pavement vehicles (turning circle 4350mm) and for wheelchair users with extended leg rests.
Within transport related buildings, the following dimensions should be taken as the minimum acceptable (Inclusive Mobility Report):
- Right angle turn (along corridor) 1200mm x 1200mm
- 180° turn (within corridor) 1600mm (width) x 2000mm (length)
It should be noted, however, that users of electric scooters and large electric chairs might need greater space than this for 180° turns.
Other Manoeuvrability Considerations
Where there is a change of level, lifts/elevators and ramps should be provided. Lifts/elevators need to be of adequate size. The slope of ramps should be appropriate in order to be safe and usable by persons using powered scooters, walking aids and wheelchairs. Not only is the physical effort of getting up a steeper gradient beyond many wheelchair users, but there is also a risk of the wheelchair toppling over. In general guidelines from many countries recommend that a slope of 8% (1 in 12) is the maximum that may be used, though most guidelines agree that 5% (1 in 20) is preferred.
It is essential that emergency evacuation routes are obvious, intuitive and accessible to wheelchair users.
Where queuing is likely, consideration should be given to some non-obstructive method of queue control such as variation in colour of flooring or pavement. The system should maintain privacy and security for the user.
Access to a Terminal: Reaching the Terminal
As regards the accessibility of information and communication technology systems, the major problems for wheelchair users are viewing and reaching the various parts of the user interface on a public terminal.
It is not possible to specify exact dimensions for what can be reached or viewed from a wheelchair, but specifications can be made that a certain percentage of wheelchair users could operate controls at a specified height. The potential users will vary depending on the application.
The variation stems from two main sources:
(a) Variation in the abilities of individual users. For instance some users can grip a card when their arm is horizontal, but have limited grip when their arm is raised 45°. Users of electric wheelchairs are more likely to have limited hand/arm movement and weak grip.
(b) Variation in height of wheelchairs (see Manoeuvrability above). Dimensional variations are much greater for electric wheelchairs than for occupant-propelled models. The variations for scooters are greater still, but their occupants are more likely to be able to walk very short distances in order to approach the ICT terminal.
In order to ensure access to the terminal area, the floor surface should be level in the direction parallel to the facia of the terminal. The gradient of any crossfall should not exceed 5% (1 in 20).
To allow wheelchair users to manoeuvre in front of the machine, there should be a clear space of 1850mm x 2100mm.
A space beneath the facia of the terminal will allow for the footrest of a wheelchair. This will also make it easier for a person in a wheelchair to get as close as possible to a screen. This is important for visually impaired wheelchair users and also in general for maximising privacy (i.e. blocking the screen from the view of passers by).
To use a touchscreen from a user-propelled wheelchair, the height of the active areas should be between 1000mm and 1300mm above ground. Also, the screen should be perpendicular to the line of sight. If the terminal is also to be used comfortably by standing users, this may involve using two screens or a variable height screen. The Department for Transport's Inclusive Mobility Report states that eye height typically ranges from 960mm (5th percentile) to 1250mm (95th percentile) for wheelchair users and from 1080mm (5th percentile) to 1315mm (95th percentile) for scooter users.
If only a forward approach in a wheelchair is possible, then the maximum height of any interactive element on the terminal should not exceed 1200mm. The lowest height of any operable part of the user interface should not be less than 750mm. Ideally the terminal, or user controls, should be adjustable in height, as is done on some drive-in cash dispensers.
For a parallel approach in a wheelchair, the maximum height of any interactive element on a terminal should not exceed the following distances:
|Reach of 300mm||Maximum height of interactive element 1300mm|
|Reach of 400mm||Maximum height of interactive element 1200mm|
|Reach of 600mm||Maximum height of interactive element 1100mm|
The conflicting requirements of tall pedestrian users and short wheelchair users can lead to a significant group of users having parallax problems when lining up the function keys with the displayed option. Lines on the user-interface leading from the key to the surface of the display can alleviate this problem.
Information that is of particular relevance to wheelchair users should be put at the bottom of the display and any important information should not be more than 1700mm above ground.
For terminals that provide a headset for audio interface or a telephone handset, the cord should be at least 735mm long to bring it within comfortable reach of a wheelchair user.
to a Terminal: Using Cards
For many wheelchair users, such as those with arthritis, it is not just a problem of reaching the card reader, but still having any useful grip as the arm is raised above the horizontal. This is particularly acute for swipe card readers.
A contactless card, working at a distance of up to 10cm, will help those who have problems placing a card in a slot. This is of particular importance to wheelchair users, those with Parkinson's disease or arthritis, and people with a visual disability.
A vicinity card is one that operates in the range of 10cm to 2 metres. The main applications are in public transport where a passenger could be logged both entering and leaving a vehicle. Vicinity cards offer the possibility of incorporating a number of facilities useful for disabled passengers; these vary from automatically requesting a wheelchair ramp to triggering audible announcements of the destination of a bus.
- AS 3769 Automatic Teller Machines: User Access
- B651.1-01 Barrier-Free Design for Automated Banking Machines
- ISO 7165-5 Wheelchairs - Part 5 Determination of overall dimensions, mass and turning space
- UN Anthropometric Data
- Automatic Service Machines - In Our Way
- ITM accessibility checklist from US Department of Justice
- US voting system standards
- Section 508 guidelines on self-contained closed products
- Accessibility for the disabled (part 1), (part 2)
- Irish Accessibility Guidelines for Public Access Terminals