1) instrument. Gauge refers to the shortest distance between the inner sides of two rail heads. The beam length of the rail flaw detection trolley must be calibrated strictly in advance, and the gauge can be obtained by adding the fixed length of the beam and the variable length measured by the gauge sensor, and then the measured gauge is compared with the design gauge.

2) Super high. After the lateral inclination is measured by the horizontal sensor installed on the rail inspection vehicle, the line superelevation is calculated by combining the measured gauge, so that the measured superelevation is compared with the designed superelevation. The liquid level sensor must be calibrated before each operation.

3) Plane and elevation

After measuring the three-dimensional coordinates of the prism on the track inspection trolley with a total station, combined with the calibrated geometric parameters of the track inspection trolley, the azimuth parameters of the trolley, the measured track gauge and the inclination angle measured by the horizontal sensor, the measured plane position and rail surface elevation at the corresponding mileage can be calculated, and then compared with the designed plane position and rail surface elevation at the mileage, the deviation can be obtained to guide the track adjustment.

4) mileage. After measuring the three-dimensional coordinates of the prism center on the track inspection trolley with total station, the point is projected on the design plane curve, and the mileage of the projected point is taken as the mileage of the current verification position of the track inspection trolley.

5) Positive vector. The chord lengths of 300 meters and 30 meters are taken to detect the long-wave irregularity and short-wave irregularity of the track respectively.