How to calculate the turning radius of a road.
In road construction and planning, the turning radius is an important parameter that determines the trajectory and safety of the vehicle in the curve. This article will explain how to calculate the turning radius of a road and help you understand how to determine the appropriate turning radius.
1. Definition of turning radius.
The turning radius is the minimum turning radius that a vehicle can achieve at a curve, usually the inscribed circle radius. In road construction and planning, the size of the turning radius depends on factors such as the design speed of the road, the width of the road, the type of vehicle, and the speed of travel.
Second, the calculation method of the turning radius.
1.The turning radius is calculated based on the design speed.
According to the road design code, roads with different design speeds require different turning radii. Here are some common formulas:
1) The formula for calculating the minimum radius (rmin) of the circular curve without superelevation section is:
rmin = v2 / g * 15.4
Where: v is the design velocity (km h) and g is the acceleration due to gravity (981 m/s2）。
2) The formula for calculating the minimum radius (rmin) of the circular curve with superelevation is:
rmin = v2 / g * 15.4 * 1.155 * tan2(φ / 4)
Where: is the superelevation slope (expressed as radians).
2.The turning radius is calculated based on the vehicle type.
Different types and sizes of vehicles require different turning radii. In general, larger vehicles require a larger turning radius to ensure safe driving. Generally, large vehicles have a turning radius that is about 20% larger than that of small vehicles.
3.The turning radius is calculated based on the driving speed.
The speed at which the vehicle travels also affects the required turning radius. In general, the faster you travel, the greater the required turning radius. As a result, vehicles traveling on highways require a larger turning radius for safety.
3. The value range of the turning radius.
Depending on the type of road and vehicle type, the range of turning radius varies. Generally speaking, the turning radius of urban roads is between 10 and 20 meters, and the turning radius of highways needs to be larger. At the same time, different types of vehicles require different turning radii, with larger vehicles requiring a larger turning radius.
Fourth, the impact of turning radius on traffic safety.
The appropriate turning radius can ensure the smooth trajectory of the vehicle in the curve, reduce the roll and skidding of the vehicle, and improve the safety and comfort of driving. If the turning radius is too small, the vehicle is prone to accidents such as collisions and rollovers at curves;If the turning radius is too large, the vehicle needs a longer distance to complete the turn, which is easy to cause traffic congestion and safety hazards.
5. Summary. The turning radius of a road is an important parameter in road construction and planning, which determines the trajectory and safety of the vehicle in the curve. When determining the turning radius, factors such as the design speed of the road, the width of the road, the type of vehicle, and the driving speed need to be considered. A suitable turning radius can ensure the safety and comfort of the vehicle in the curve, and improve the efficiency and safety of the road.