It's about 20-25' fall over 120 yds. Was thinking 8" as it takes lorrys so probably 12/13 loadsUnless it's proper steep you wont be anywhere near the slump angle of the concrete, and unless you have a death wish you WON'T be polishing it, it'll be tamped. Laid ramps here at 15 degrees plus, it doesn't run away if it's slightly stiff.
10ft = 3m
x.15m depth (ie 6")
= 0.45 cube/ M length
So, 1 load / 6 cube will cover 13.3m length of track; 9 loads in total.
It's about 20-25' fall over 120 yds. Was thinking 8" as it takes lorrys so probably 12/13 loads
Remember that steep concrete roads can be very slippery with frost on them, heard a story years ago about a farmer digging up a steep bit of concrete on the farm road so the feeding lorries/ milk tanker could get in and out safely in a bad winter