Although it's all well and good to pillage roads most terrain squares need roads or railroads
grassland, plains, dessert for trade
hills (if mined), mountains (if mined), and forests for the extra shield
admittedly tundra, glacier, jungle, and swamp don't need roads but if that square has a river or a special resource that square will produce trade (roads on squares that already produce trade increase it further) or enough production that railroads will increase it further (the notable exception to this rule of building roads on specials in the musk ox)
Keep the roads, unless you are desperate
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This has been Karl Marx the Penguin.
-- "Workers [penguins] of the World Unite"