Dividing a curve for ramps and landings

Hi,

I have a curve following the centre line of a long pathway. I want to turn this curve into a path that abides by accessibility standards with landings at appropriate intervals.

Essentially I am trying to create a sequence that does this:

A) 15m length with gradient @ 1:20

B) 1.5m length with gradient @ 1:40

C) Repeat sequence for the length of the curve

It would be great if there was a patch that could do the whole process including the gradient changes but even if someone knows how to divide the curve into the appropriate lengths that'd be fantastic. With my beginner skills I only know how to divide the curve into even increments. I can't work out how to divide it into a sequence of lengths.

The approach I thought would be the starting point is to initially divide the curve according to the centre point of the landings (15.75m) then offset these points along the curve by +0.75 and -0.75 to get the landings. I can't figure out how to do this offset maneuver though. .

Any help would be greatly appreciated.