What is the rate of superelevation required for a horizontal curve on a 45 mile per hour (mph) two-lane rural highway with a minimum safe radius of 710.5 feet? Assume the coefficient of side friction is 0.15.

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the rate of superelevation required for a horizontal curve on a 45 mile per hour (mph) two-lane rural highway with a minimum safe radius of 710.5 feet is 4%. Solution: Use the Minimum Radius equation using emax and fmax Rmin = V² / 15(0.01e_max + f_max) Where V = 45 mph R_min = 710.5 feet f_max = 0.15 710.5 = (45)² / 15(0.01e_max + 0.15) 710.5 = 2025 / (0.15e_max + 2.25) e_max = 4%

What Is the Rate of Superelevation Required for a Horizontal