2/3 movement.

[triangular_cube]

This is very easy, btw: at 2/3 MP/hex, every three hexes cost 2 MP.  If you go off the road after going one or two hexes on the road, round up; all fractions in the game are rounded up.  It's so simple even an infantryman can do it. 

Foot units are very simple. Where the "issue" arises is mechanized units moving partial down a road and then down clear. Then you are adding halves and thirds and its a headache. (at least in 4th).