Nonetheless, the first completed segments were based on the HAFRABA plans and thus consisted of straightaways long joined by curves that were arcs of circles, as in railroads; the minimum radius of the curves was defined in planning documents (, less in mountainous terrain, down to ).
12.
Arcs of circles of latitude are sometimes used as boundaries between countries or regions where distinctive natural borders are lacking ( such as in deserts ), or when an artificial border is drawn as a " line on a map ", which was made in massive scale during the 1884 Berlin Conference, regarding huge parts of the African continent.
