Accessible digital map experiences: a mountain climb or a walk in the park?

The topic of accessible maps recently came up during a conversation with an organisation we’ve been helping. They were worried about the accessibility of digital maps, and they were considering removing them from their websites. Since the maps were provided by a third party, the organisation had no idea what sort of accessibility issues might be present and no clear sense of what they could or should do to fix them.

Given that a map is a complex visual presentation of information, you might feel that the task of making it accessible is very challenging—if not impossible—and your natural reaction might be that if it can’t be made accessible, it has to be removed. But as a cartographer turned inclusive-design advocate, I’m distressed at the thought of accessibility as a reason for pulling down maps from a web site—especially given the benefits that a digital map can bring people with disabilities.

So how can we apply a sensible strategy to deal with map inaccessibility in a way that benefits everyone? Let’s consider maps from an accessible user-experience perspective.

The purpose of maps

The power of a map is in the way it uses spatial relationships to present and give meaning to data.

Interactive digital maps have brought some capabilities that paper can’t provide, including the ability to turn on and off different layers of a map, show different levels of detail when zooming in or out, and show changes over time. GPS-enabled mobile devices enable rich opportunities for location-based interaction with digital maps. And of course, compared to paper, a digital map can be quickly updated to reflect changes, such as a new road being built or a city being renamed. (Or shrinking mountains—one of my first jobs as a digital cartographer was to correct the height of Aoraki/Mount Cook, New Zealand’s highest mountain, which lost ten metres in a landslide in 1991.)

Think about these examples of maps that you might find online:

• A street map that identifies the location of a company’s office and key local landmarks, like the nearest parking area or subway station
• A map that shows the legal boundaries of a property
• A map that presents the results of a general election

In each case, a map is adding geographical meaning to some underlying data.

What makes an accessible digital map?

In a nutshell, a digital map is accessible to people with disabilities when it meets these core requirements:

1. The map’s controls are meaningfully labelled, and they can be operated without a mouse.
2. The map’s information is presented without relying on colour perception.
3. The map’s information is available in a nongraphical form.

(There are many additional, subtler requirements that depend on the specific nature of the map, but if a map can satisfy these core requirements, it’s likely to be accessible.)

The first requirement, from an accessible-coding perspective, is fairly straightforward when developers use standard controls and give them labels that convey their meaning to assistive technologies. The second requirement might initially seem to be more challenging, but there are many cartographic techniques available to convey information in ways other than colour, such as variations in shading patterns, line thicknesses, and typefaces.

For both requirements, a review against accessibility standards such as the Web Content Accessibility Guidelines will help you understand how well the map meets these requirements and what changes may need to be made to optimise the map’s accessibility.

The third requirement, “the information it conveys is available in a nongraphical form,” is the one that’s likely to seem most daunting, especially for visually complex and dynamic maps.

For all but the simplest of static maps, there is no HTML alt attribute value that can convey the same information. This is when thinking about comparable experiences becomes crucial.

Comparable map experiences

The Inclusive Design Principle of Comparable Experience encourages us to:

Ensure (y)our interface provides a comparable experience for all so people can accomplish tasks in a way that suits their needs without undermining the quality of the content.

The words comparable and quality convey that removing a visually complex map is not the answer to our problem.

So instead, let’s go back to considering the map’s purpose. Who is it provided for, and what tasks is it intended to support? What other ways could someone access the map’s underlying data in a nonvisual but meaningful way?

Answer those questions as accurately and as carefully as possible. These answers will help you identify a strategy to ensure that as many people as possible can use the map through an additional means that’s comparable and equivalent.

Let’s return to the map examples from earlier:

• The street map is there to help visitors find their way to an office. A comparable nonvisual experience might be a list of directions from the map’s key landmarks, such as the nearest parking area and nearest subway station.
• The map showing the property boundaries may be there to complement a legal definition of the boundaries that’s already described in text. Providing a link to this text definition could be a comparable nonvisual means of access.
• The map showing an election’s geographical results is using data that could be presented in many different ways. A comparable nonvisual experience might be a table of the same data along with a search form that lets users filter the data to find the results by geographical area or by political party.

These examples may leave you with additional purposes to consider. For some digital maps, solutions like sonification of graphics or tactile diagrams might be the most comparable nonvisual alternative.

An effective map-accessibility strategy starts with understanding the digital map’s purpose and the tasks that it’s intended to support.

It recognizes that a single universally accessible map might be impossible to create, and an equivalent means of access is an acceptable way to provide an accessible map.

It involves examining the map’s purpose and identifying comparable ways to provide access to the map’s information.

And with that done, you’ll have made the map experience accessible.

More reading

If you’d like to dive into more detailed discussions of map accessibility, these resources may be helpful.

General principles for accessible map design:

• Accessible map guidelines (Carnegie Museums of Pittsburgh):
• Accessible maps on the web (Thomas Logan)
• Design Accessible maps (Phase Magazine):
• Guidance on accessible maps (Penn State University)
• Map Accessibility (State of Minnesota)

Vendor advice:

• Adding keyboard accessibility to ArcGIS (ESRI)
• Accessibility in Google Maps (Google)

Opening image: Aoraki/Mount Cook in Winter with the Hooker Glacier in the foreground. Photograph by C.M.Lynch distributed under a CC-BY 3.0 license.