James M. Coughlan

Brandon Biggs, David Sloan, Brett Oppegaard et al.

Digital geographic maps remain largely inaccessible to blind and low-vision individuals (BLVIs), despite global legislation adopting the Web Content Accessibility Guidelines (WCAG). A critical gap exists in defining "equivalent purpose" for maps under WCAG Success Criterion 1.1.1, which requires that non-text content provide a text alternative that serves the "equivalent purpose". This paper proposes a systematic framework for evaluating map accessibility, called the Map Equivalent-Purpose Framework (MEP Framework), defining purpose through three items (Generalized, Spatial Information, and Spatial Relationships), and establishing 15 measurable criteria for equivalent information communication. Eight text map representations were evaluated against visual map baselines using the proposed MEP Framework. Results show that legacy methods such as tables and turn-by-turn directions fail to meet the MEP Framework criteria, while Audiom Maps, Multi User Domain (MUD) Maps, and Audio Descriptions meet the criteria. The evaluation highlights the necessity of holistic, systematic approaches to ensure non-visual maps convey all generalized spatial information and relationships present in visual maps. The MEP Framework provides a replicable methodology for comprehensively assessing digital map accessibility, clarifying WCAG's "equivalent purpose", and guiding compliant and usable map creation. Compliant maps will support BLVIs' participation in map-dependent professions and civic engagement.

Brandon Biggs, Christopher Toth, James M. Coughlan et al.

Digital maps are used to communicate generalized spatial information and relationships, yet are commonly made "accessible" using tables that lack geographic information. This study examines whether these tables and interactive text maps (ITMs) may be comparable to visual maps. Twenty sighted and 20 blind and low-vision individuals (BLVIs) performed tasks designed to compare visual maps, ITMs, and tables. Participants answered numeric, geographic, and combined numeric geographic questions using each representation, and performance, preference, and NASA-TLX were measured. Across both participant groups, map representations (visual and ITMs) significantly outperformed tables on geographic-based questions, while performance differences were minimal for numeric questions. For sighted participants, performance on geographic questions did not significantly differ between visual maps and ITMs, indicating that a larger powered study may find an "equivalent purpose" across these two conditions. Participants preferred map-based representations over tables. Perceived workload was highest for the ITM, intermediate for the visual map, and lowest for the table. Consistent with the Map Equivalent Purpose Framework, these findings indicate that Web Content Accessibility Guidelines-compliant ITMs can provide access to spatial information, unlike tables. These findings challenge prevailing accessibility practice that recommends tables lacking geographic information as map alternatives, and motivate reconsideration of accessibility legislation exempting digital thematic maps.