To identify the potential usability problems of Web mapping sites, four different sites were evaluated: Google Maps, MSN
Maps & Directions, MapQuest, and Multimap. The experiment comprised a series of expert evaluations and user tests.
During the expert evaluations, eight usability engineers and eight cartographers examined the Web mapping sites by
paying attention to their features and functionality. Additionally, eight user tests were carried out by ordinary users in a
usability laboratory. In all, 403 usability problems were identified during the trial and were grouped according to their
severity. A qualitative description is given of these usability problems, many of which were related to search operations
that the users performed at the Web mapping sites. There were also several problems relating to the user interface, map
visualisation, and map tools. We suggest some design guidelines for Web mapping sites based on the problems we
identified and close the paper with a discussion of the findings and some conclusions.