Designing Accessible Web Pages and Web Applications
Lila Laux, llaux@uswest.com
U S WEST
The goal of Human Factors in Web design is to design Web sites to make them accessible to the largest number of potential users, including those with disabilities. This article provides the rationale for developing accessible Web pages and Web sites and resources to help you design and evaluate those sites for accessibility.
Why worry about accessible Web sites?
There are over 30 million people in the US and many millions worldwide who have physical, sensory, or cognitive limitations that may make interacting with computers and computer applications difficult. Assistive and adaptive computer technology can enable most people with disabilities to use a computer efficiently and effectively, but this does not guarantee that the Web sites you develop will be accessible to them. Excellent sites providing "how-to" information for designing accessible Web sites are supported by the Trace Research & Development Center at the University of Wisconsin (http://trace.wisc.edu/docs/html_guidelines/version7.htm) and the Web Accessibility Initiative of the World Wide Web Consortium (W3C) (http://www.w3.org/WAI/)
Basic accessibility issues for Web sites
The largest groups of users with handicapping conditions who want to use the WWW are users who 1) are blind / visually impaired, 2) are deaf / hard-of-hearing, or, 3) have motor problems relating to input/output devices. Some general guidelines to make pages accessible to the broadest range of users with disabling conditions include:
- ensure that your pages are compatible with screen-reading software and other adaptive technology like screen magnification.
- use a consistent, simple layout across all pages of the site.
- ensure that contrast between the background and foreground (especially text or other symbols) is high.
- provide a text alternative to all graphics/image maps (alt-text or D-tag.)
- provide descriptive captions for all pictures.
- use tables and frames sparingly or offer alternative pages for screen readers.
- use large, clearly identifiable buttons/controls.
- caption video and transcribe audio displays.
- do not require that users be able to use a mouse to navigate through your pages/site.
If you want your site to be accessible to people who use screen readers, keep the following problems often associated with Web pages and screen readers in mind:
- Screen-readers read an entire line of text. If there are many links on the same line, it is difficult to tell which link a cursor is pointing to. Links embedded in paragraphs are hard to navigate because it is not apparent to the user where the link is.
If there are frames, the screen reader doesn't always recognize them and skips across the boundaries in reading. But, frames can be made more accessible to screen readers. Consider the following basic guidelines:
- Use the noframes option for users employing text readers like Lynx.
- If your homepage has frames, consider creating an introductory page, before the home page, offering access to the frames or noframes version of the site.
- Create individual pages for each frame on a page and place links to the individual frame pages on the page that will link between frames. Those who use a graphical browser have the option to use the frames or go to the individual pages.
- Be sure that scrollbar controls on each frame are labeled so that screen readers render them intelligibly.
- Graphical images and icons that are not text (alt) tagged are indecipherable to screen readers. The screen reader will only see (and say) [LINK], [INLINE], or [IMAGE]. Pages created by Web page authoring software, do not necessarily include alt tags.
- ISMAPs and BISMAPs are features that are entirely graphical and entirely inaccessible to the screen reader. If you have a totally graphic page, provide comprehensive alt tags or an alternate text only page for screen readers.
- Forms are difficult for screen readers to translate and visually impaired users may need an alternative such as an email alternative.
Verify your accessibility
The ultimate usability test is to "view" your site with a text only browser - if your site can't be understood when displayed by a text only browser, it is largely inaccessible to vision-impaired Web users using screen readers. Many blind users find that the entry page on a site is the barrier for them - other pages are accessible, but it is impossible for them to "get to" those other pages. Assess the accessibility of your web page for all disabilities by using Bobby.
Much of this information appeared in a chapter I wrote entitled "Designing Web Pages and Web Applications for People with Disabilities" which was published in Human Factors and Web Development, Chris Forsythe, Eric Grose, and Julie Ratner, Eds., Lawrence Earlbaum Associates, 1998.
© Internet Technical Group
Last update: Mar 6, 1999
URL: http://www.sandia.gov/itg/newsletter/mar99/accessibility_lila.html
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