calculate the length and radius of roadway curves.

Hi, I am looking for an expert, i have 6 aerial images were taken for some roadway ramps, the roads contain of a set of curves connected together (circular and spiral curve), firstly, i want to detect the start and ends of each sub-curves using the radius of curvature at 1 m or 2 m, then after the start and ends are determined i want to calculate the length and radius of each sub-curves.
please find the attached i uploaded screen-shut for one of the test image