An access road to a quarry is being cut in a plane surface in the direction of strike, the full dip of 1 in 12.86 being to the left of the direction of drive. The road is to be constructed throughout on a formation grade of 1 in 50 dipping, formation width 20 m and level, side slopes 1 in 2 and a zero depth on the centre-line at chainage 0 m. At chainage 400 m the direction of the road turns abruptly through a clockwise angle of 40?; calculate the volume of excavation between chainages 400 m and 600 m.