Why placement is a design decision
A screen can have excellent content and still be unusable if a seated visitor cannot reach the buttons or see the image. Wheelchair users, people of short stature, children and many others benefit when interactive media sits at a comfortable height and can be reached without strain. Because placement is fixed once an exhibit is built, it is better to get it right early, in the layout drawings, than to adjust it after installation.
A reach range is the span of heights within which a person can comfortably touch a control. It depends on whether the person approaches from the front or from the side, on their body size and mobility, and on what the furniture allows. There is no single value that suits everyone.
Published guidance and local rules
Many countries publish accessible design standards that set numeric reach ranges and clearances. In the United States, for example, commonly cited guidance puts the reach for controls at a range of roughly 15 to 48 inches (about 380 to 1,220 millimeters) above the floor for an unobstructed approach. Other countries give similar but not identical figures, and some standards also set limits when a visitor must reach over an obstruction such as a shelf. Local rules and updates vary, so check the standard that applies to your venue and use these numbers as an illustration rather than a specification. Where a project is publicly funded or sits in a regulated building, a qualified access consultant can confirm the details.
Within those ranges, the middle is usually more comfortable than the edges. Controls placed at the very top or bottom of the allowed span can still be tiring or awkward for some people.
Approach space and clearances
Reach is only one part. A seated visitor also needs room to get to the exhibit.
- Clear floor space. A wheelchair needs a level area in front of the exhibit, with enough room to arrive, stop and sometimes turn. Many standards describe a clear space of about 30 by 48 inches (roughly 760 by 1,220 millimeters) for a single stationary wheelchair; again, confirm local figures.
- Forward approach and knee space. If the visitor can roll up to the front, the exhibit needs open space underneath for knees and footrests. A solid cabinet below a touchscreen forces a side approach and a longer reach. Table-style displays often work well, as long as the underside is open.
- Side approach. If the unit has a solid base, controls should be near the front edge, because the reach across the base is longer.
- Routes. The paths to the exhibit should be wide, level and free of cables, ramps with steep slopes or stray furniture. Rugs and loose mats can catch wheels.
Screen height and viewing angle
Reaching a screen is one thing; seeing it comfortably is another. A screen mounted high on a wall may be reachable by standing visitors but awkward to read from a seat, and a very low screen can be hard for taller visitors to read.
- Tilt. Angling the screen slightly back from vertical can help seated and standing visitors. Large screens can be difficult at close range because they require the eyes to move a lot.
- Placing the key content. Put essential text and controls in the part of the screen closest to the reachable zone, rather than at the very top.
- Check from several eye heights. The eye level of a seated adult is generally lower than a standing adult’s, and that of a young child lower still. Test from each.
- Reflections. A screen angled toward a window or a spotlight can pick up glare from a seated position that is not visible from standing. See the discussion of screen glare for more.
Fixed height is often a compromise. Adjustable-height mounts, lift columns or a pair of displays at different heights can serve a wider range of visitors, though they add cost and complexity and require that people know how to use them. Explore the choices with your hardware team when choosing screen enclosures, so that cabinets do not block the approach.
Controls: size, force and form
- Large, well-spaced targets make touch accurate for people with limited hand control. The guidance on touch targets applies at all heights.
- Low operating force. Controls that need little pressure and no tight gripping, pinching or twisting suit more people. Avoid actions that require holding a position for a long time.
- Alternatives to precise gestures. A touchscreen exhibit that relies on dragging small items or multi-finger gestures should also offer a single-tap method.
- Physical controls such as large buttons or a trackball can be easier for some users than touchscreens, and they should be placed in the same reach zone.
Placing a fixed handset, headphone socket or ticket slot too high or too far back is a frequent oversight. Check every item a visitor has to touch, not only the main screen. In a self-service kiosk setting, card readers and printers need the same treatment. Remember that shared surfaces get regular wiping, so the approach to touch hygiene should not create obstacles such as removable covers that are hard to reach.
Everyone benefits
Families with children, visitors of short stature, people leaning on a stick, and people carrying bags often find a lower and more open exhibit easier to use, which is a central idea behind family visitors and group use of the same exhibit. Wide approaches also help when several people share a display. A seated-friendly design is often simply a more comfortable design.
Check before you build
- Mark the exhibit footprint and clear floor space on the plan.
- Mock up the screen and controls at cardboard scale, or use an adjustable temporary stand.
- Ask wheelchair users and people of different heights to try it, and note where they have to stretch.
- Measure the reach range and clearances against the applicable standard.
- Re-check after any change to furniture, cabling or enclosures.
Mock-ups and test sessions are inexpensive and tend to reveal practical problems that drawings hide.