In C-evo, as generally in games of this type, the time a settler or engineer takes to perform terrain improvement tasks depends on the task and may also depend on the terrain. The in-game manual refers readers to a "terrain enhancement box". That box seemed to be missing from the version available in 2011. Version 1.2.0 has a "Terrain Enhancement" chart showing required movement points for various terrains, including some of the following:

(under construction)
Table of
movement points
EASY country without riverEasy country WITH riverROUGH country without river Rough country WITH riverHillMountain
Road 3 (includes desert) 12 6 15 6 9
Railroad 6 12 21 12 18
Canal (not
in Arctic)
18 18 18 18 18 N/A
Irrigation 6 6 (desert) 18 N/A
Clear N/A N/A 6 N/A N/A
Drain swamp N/A N/A 24 N/A N/A
Farmland 18 N/A N/A N/A
Mine 18 (Arctic) 12 12
Afforest 18 24 - -
Fortress (manual says "6" but that is clearly wrong for some terrains) 6 6 12 12 12 18
Military base (manual says "6" but that is clearly wrong for some terrains) 6 6 12 12 12 18
Clean up pollution 18

Engineer actions table


If you want to build a mine quickly on Arctic terrain, before you have engineers, you can build a military base (requiring Medicine) first, because it neutralizes terrain hostility letting you replace it with a mine without having to move off for recovery every few turns.