What is the approximate optimal length for a transitional spiral curve when using a 2,400 feet (ft) circular curve and a design speed of 70 miles per hour (mph)?

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The approximate optimal length for a transitional spiral curve when using a 2,400 ft circular curve and a design speed of 70 mph is 225 ft. Solution: Use the transitional spiral curve formula L = 1.6 (design speed)³ / radius of the circular curve Given, Design speed = 70 mph Radius of circular curve = 2,400 ft L = 1.6 (70 mph)³ / 2400 ft = 228.66 ft (use 225 ft)

What Is the Approximate Optimal Length for a Transitional Spiral