For a portion of a national highway where a descending gradient of 1 in 25 meets with an ascending gradient of 1 in 20, a valley curve needs to be designed for a vehicle traveling at 90 kmph based on the following conditions. (i) headlight sight distance equal to the stopping sight distance (SSD) of a level terrain considering the length of the valley curve > SSD. (ii) comfort condition with allowable rate of change of centrifugal acceleration = 0.5 m/sec³. Assume total reaction time = 2.5 seconds; coefficient of longitudinal friction of the pavement = 0.35; height of the headlight of the vehicle = 0.75 m; and beam angle = 1°. What is the length of the valley curve (in m) based on the headlight sight distance condition?