Asection of a two-lane highway (12-ft lanes) is designed for 75 mi/h. at one point a vertical curve connects a -2.5% and +1.5% grade. the pvt of this curve is at station 36+50. it is known that a horizontal curve starts (has pc) 294 ft before the vertical curve’s pvc. if the superelevation of the horizontal curve is 0.08, the side friction is 0.09 and the central angle is 38 degrees. what is the radius of the horizontal curve?