To calculate the minimum value of ruling radius of horizontal curves?

Question

Answer

Minimum Value of Ruling Radius of Horizontal Curves in Civil Engineering

In civil engineering, horizontal curves are used in road design to help drivers navigate turns safely. The minimum value of the ruling radius of horizontal curves is an important factor in determining the safety and comfort of driving on a road. The ruling radius is the radius of the largest circle that can be drawn tangent to both the inside and outside edges of a horizontal curve.

Factors Affecting Minimum Value of Ruling Radius

Design Speed: The design speed of a road is the maximum safe speed at which a vehicle can travel on it. A higher design speed requires a larger minimum value of the ruling radius to ensure safe driving.

Superelevation: Superelevation is the banking of a road at a curve to counteract the centrifugal force experienced by a vehicle. A higher superelevation allows for a smaller minimum value of the ruling radius.

Lateral Friction: Lateral friction is the resistance to sideways movement on a road. A higher lateral friction allows for a smaller minimum value of the ruling radius.

Grade: Grade is the slope of a road. A steeper grade requires a larger minimum value of the ruling radius to ensure safe driving.

Calculation of Minimum Value of Ruling Radius

The minimum value of the ruling radius can be calculated using the following formula:

Rmin = (V²)/(127f)

Rmin: Minimum value of the ruling radius in meters

V: Design speed of the road in kilometers per hour

f: Coefficient of lateral friction

The coefficient of lateral friction can be determined using the following formula:

f = tan(α)

f: Coefficient of lateral friction

α: Angle of friction between the tire and the road surface

Conclusion

The minimum value of the ruling radius is an important factor in ensuring the safety and comfort of driving on a road. It is determined by factors such as design speed, superelevation, lateral friction, and grade. The calculation of the minimum value of the ruling radius involves the use of formulas that take into account these factors.

Answer

Minimum ruling radius is radius below which we not goes because in future if we want to increase speed of vehicle then we need to changes max super election and super elevation is depends on radius distance if we provided radius less then we need to redesign again to provide max super election therefore IRC suggest Radius should not the particular value so that redesign not required this limited value is known as minimum ruling radius

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