1.1 Ensure that all operable parts are reachable by people of all heights and people sitting in a wheelchair or buggy

The operable parts include such things as buttons and keypads, input slots for cards or money and dispensers for tickets, receipts or returned money. Users should be able to access all of these from whatever position and orientation they find themselves in naturally when using the terminal. Preferably, this should be a single position which does not require the person to reorientate themself during operation.


Users who are extremely short or who sit in a wheelchair have substantially less reach than average sized users who are standing up. If they have to overstretch to reach things, they may risk injury or, in extreme cases, may not be able to operate the terminal or collect their outputs. Whilst tall users can extend their reach by stooping, this could be embarrassing for extremely tall users who may find themselves having to bend or crouch a long way.

Access to operable parts

Access to operable parts
Ensure that all operable parts are within reach.

Wheelchair users may find it awkward to reorientate themselves during use if this involves swivelling in a confined or crowded space. The following anecdotes describe some typical problems that this can cause in the case of card door entry systems.

" The biggest problem with card readers for opening doors is that they are positioned at a height I can't reach, or somewhere I can't manoeuvre into easily, like a corner.
" - wheelchair user

"The card reader was installed next to the hinge so that it was difficult to open the door after swiping the card. And if I was using it when someone came through the door from the other side they would trap me against the wall.
" - wheelchair user

Directions and Techniques

Refer to anthropometrical data

Refer to appropriate physical design guidelines or building accessibility guidelines which give minimum and maximum heights and reach distances. The United Nations have a useful set of anthropometrical data covering ranges of height and reach when standing or sitting in a wheelchair, plus required path and turning space dimensions for wheelchairs.

  Common reach zones

Common reach zones
Ensure that users of all heights can reach all operable parts. The comfortable range is between 1200 and 900mm. The maximum acceptable reach height for wheelchair users is 1400mm.

Careful positioning

Be careful with the positioning of things like advice slip bins, which may make it difficult to get close to the terminal.

Provide a clear access path

Provide a clear access path
Ensure easy access to the device for people using wheelchairs, buggies or mobility aids.

How you could check for this:

Self-test early prototypes

Designers can run simple reach tests themselves at the initial design or prototype stage. Using a mock-up with the controls placed in their intended positions based on appropriate physical design guidelines, you can simulate short and tall people and wheelchair users by sitting in a chair, standing on a raised area or kneeling down. Whilst this will not be a replacement for proper testing with real users, it will give some insight into what it is like to be reaching for controls from the user's perspective and will help reveal any serious problems in the layout before further work is carried out. If standing on something, you should make sure it is sufficiently strong and stable and take care to avoid the possibility of injuries caused by falling off it.

Include user data in the design

If you are designing using a CAD package, it may be possible to include various simulated users as elements in the design, based on human anthropometrical data.

Test with real users

During development, you should test the prototype in a realistic situation with real people, particularly people who routinely use wheelchairs or motorised buggies.
About user testing

Knee clearance for wheelchair users

Knee clearance for wheelchair users
This image shows a terminal with knee clearance for wheelchair users.