Accessible Design: Best Practices

Timed Response

Using Time Out Scripts .

Web pages can be designed with scripts so that the web page disappears or "expires" if a response is not received within a specified amount of time. Sometimes, this technique is used for security reasons or to reduce the demands on the computer serving the web pages. Someone's disability can have a direct impact on the speed with which he or she can read, move around, or fill in a web form. For instance, someone with extremely low vision may be a slower-than-average reader. A page may "time out" before she is able to finish reading it. Many forms, when they "time out" automatically, also delete whatever data has been entered. The result is that someone with a disability who is slow to enter data cannot complete the form. For this reason, when a timed response is required, the user shall be alerted via a prompt and given sufficient time to indicate whether additional time is needed

Auto-Forwarding (Redirect)

Most designers violate this standard because they use an auto-forward technique to redirect users to a new page location or to a secure server. Most typical is a message like this:

Our site has recently undergone a update and the page you are looking for is now located at : http://www.new.location. Your browser will automatically take you to this page in 15 seconds.

Users may have difficulty with this method of redirect, because:

1. Screen readers may not have enough time to read the entire redirect message before the new location loads. Users may become confused or may be left unaware that the URL has changed and will continue to use the old address.
2. Redirects break the browser HISTORY and make it difficult to use the BACK button. If, for instance, a student visitor accidentally selected a link to the "Faculty" page and then was redirected to a new location, when the student tries to use the BACK button to return to the main menu, the "Faculty" page is again selected and the student is again redirected. The resulting continuous loop can only be broken if the user has the ability (and knowledge) to double-click the BACK button faster than the redirect can be engaged.

Because of the inherent usability problems with automatic redirects, the W3C recommends using a static page that requires the user to engage a link in order to go to the new page location.

If an automatic redirect technique is used, it should be as "invisible" as possible. That is, the page should automatically refresh to the new location without the delay and without displaying a redirect message like the example shown above. Of course, this method still does not resolve the issue of the broken HISTORY list and BACK button. The WAC recommends avoiding renaming/reorganizing your site if at all possible to avoid the need for redirects.

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