With an increase in the weave length up to 100 m, the unevenness of the distribution of longitudinal and flexural stresses at the interstice distance will increase, which is caused by factors of a purely operational nature. In these conditions, there is a need to conduct constant monitoring of the stress-strain state of the track. The article presents stress tensometry formulas based on the acoustoelasticity effect, using subsurface, longitudinal and shear ultrasonic waves. In the calculation relationships, the influence of the ambient temperature between the time of the inspection is taken into account. The results are confirmed experimentally. Methods for controlling and calculating the longitudinal and flexural stresses in rails are proposed, based on the results of ultrasonic strain gauging.