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Design Coefficient of Friction is a dimensionless number that is defined as the ratio between friction force and normal force. It is a crucial parameter in road design and vehicle safety calculations.
The calculator uses the formula:
Where:
Explanation: This formula calculates the required coefficient of friction needed for a vehicle to stop safely within the available stopping sight distance, accounting for the driver's reaction time.
Details: Accurate friction coefficient calculation is essential for road safety design, determining appropriate road surface materials, and ensuring vehicles can stop safely within the designed sight distances.
Tips: Enter vehicle speed in m/s, stopping sight distance in meters, and break reaction time in seconds. All values must be positive, and SSD must be greater than (Vb × t) for valid results.
Q1: What is a typical value for coefficient of friction in road design?
A: Typical values range from 0.3 to 0.6 for dry pavement, depending on surface material and conditions.
Q2: How does vehicle speed affect the required coefficient of friction?
A: Higher speeds require higher coefficients of friction to maintain the same stopping distance, as kinetic energy increases with the square of speed.
Q3: What factors influence break reaction time?
A: Reaction time varies by individual but typically ranges from 1.5 to 2.5 seconds. It can be affected by age, fatigue, distractions, and alcohol consumption.
Q4: How does this calculation account for different road conditions?
A: The calculated coefficient represents the minimum friction required. Actual road conditions (wet, icy, etc.) may require higher design coefficients for safety.
Q5: Can this formula be used for all vehicle types?
A: While the basic principles apply, different vehicle types (cars, trucks, motorcycles) may have different braking characteristics that should be considered in detailed design.