Kursk 43 - Obstacle Movt

[Green]

I believe the calculation is done as follows;

movement cost = (terrain cost + full movement allowance/4) x environmental condition %

Basically, the cost of entering the obstacle is also affected by the environmental conditions. For your example this means;

movement cost = (6 + 26/4) x 150%
                      = 18.75

The difference is rounding.