Tomahna tram
From Guild of Archivists
In order to quicken access between the Cleft and Tomahna, Atrus built a tram from the Cleft (or a nearby location in the desert) to his lab. Power for the tram is directed from Atrus's lab, which is powered by the Waterwheel.
The tram does not appear to exist in the present day, so it is likely that the track was either dismantled or decayed in the almost 200 years since the events in Myst IV: Revelation.