The Web maps often offer links to different
additional services (such as hotels and tourist
attractions), which either have their own map interface
or no map at all. If a user wanted information on how to
use the underground rail network to get from one
tourist attraction to a hotel, at least three different maps
and services had to be opened at the same time: an
underground route map, a map with hotels on it, a map
with tourist attractions on it, and perhaps even a base map
for combining all this information. If all of these have their
own maps with different scales and visualisations, users will
find it difficult to combine the information. The best
solution would be to have all these embedded within the
same map service, or to have harmonised maps between
different services, but it is clear that this requires further
study.