Jun 08, 2014 · d 2 is the temporary width of the rOkaynstruction subgrade on the side near existing subgrade, according to the half of the minimum width of subgrade, generally is about 2.2 m (according to the thickness of ballast is 0.25 m, subgrade slope is 1:1.5, top width of ballast bed is 2.8 m, shoulder width is 0.2 m); When raising embankment, in order