What Is A Vertical Curve, Why Do Railways Need To Set Up Vertical Curves
Jul 08, 2023| Usually, in order to adapt to the ups and downs of the terrain and reduce the cost of construction projects, the longitudinal section of the railway is connected by continuous straight sections with different slopes due to different terrains. Because of this, a slope change point is formed at the junction of the slope section and the slope section. If the lines of each slope section are connected into a broken line, it means that there must be a "knuckle" on the line. When the vehicle passes this "knuckle", The relationship between the vehicle and the track is shown in the figure below.
If the angle of the "knuckle" is very small (the difference between the slopes of two adjacent slopes is very different), then when the train passes through the slope change point, the entire train will be distributed on different slopes, which will cause coupler stress to occur. Changes are prone to breakage or decoupling.
How to set the vertical curve?
1. The allowable speed is not greater than 160km/h. When using circular vertical curves, if the algebraic difference between adjacent slopes is greater than 3‰, vertical curves should be set. The radius of the vertical curve should not be less than 10000m, and the difficult section should not be less than 5000m.
2. When the allowable speed is greater than 160km/h and the slope algebraic difference is not less than 1‰, a circular vertical curve should be set. The radius of the vertical curve should not be less than 15000 m, and the length should not be less than 25m.
3. Vertical curves must not overlap with vertical curves and transitional curves, and must not invade turnouts, regulators and exposed bridge decks.
4. Depending on the speed, the radius of the vertical curve is different, as shown in the figure.
how to mark
The starting position of the vertical curve is marked "SQ L = vertical curve length" on the rail waist, the position of the slope change point is marked "SB R = vertical curve radius" on the rail waist, and the end position of the vertical curve is marked "SZ" on the rail waist L=vertical curve length", the size of the mark is the same as that of the curve mark, and the color is red and white.