4. A crest on a section of highway consists of a vertical curve with a 1500 m radius and a positive 1% grade followed by a negative 3% grade. The design requirements are as follows: Design speed= 80 km/h, Driver eye height 1.2 m. Object (to be avoided) height= 0.2 m, Stopping sight distance 300 m. What is the minimum required length of vertical curve needed to satisfy the design stopping sight distance?