What is the recommended formula for the nose radius R2 for a median opening?

• A. R2 = Median/2
• B. R2 = Median/3
• C. R2 = Median/5
• D. R2 = Median/4

Answer: (C)

The recommended formula for the nose radius R2 for a median opening is R2 = Median/5. This recommendation is based on design standards for roadway configurations, where the nose radius is critical for providing adequate sight distance, ensuring vehicle maneuverability, and improving safety at median openings.

Using a radius equal to one-fifth of the median width strikes a balance between maximizing the opening for vehicles and minimizing the potential for conflicts with opposing traffic. An appropriately sized nose radius helps in accommodating turning movements and enhances the overall flow of traffic, reducing the risk of accidents.

In roadway design, particularly at intersections and median openings, adhering to established guidelines, such as this radius formulation, is essential for creating safe and efficient transportation systems. This ratio is derived from empirical data that suggest the optimal turning arc that vehicles can navigate comfortably. Proper application of this formula leads to improved traffic operations and safety metrics.