PURPOSE: To obtain the device which has a simple constitution and does not require foundation work, by detecting shearing stress which is applied to rails by the rolling stock, computing the stopping position of the rolling stock, displaying the presence or absence of abnormality, and computing and displaying the weights of the rolling stock and the load.

CONSTITUTION: Four strain gages 6 are arranged at both side parts 2a and 2b of the rail 2 which are located at the positionss separated by equal distance l1 from the intermediate point between specified sleepers 4 and 5 in the direction of the rail. Thus a shearing stress detector A is constituted. Strain gages 6 are likewise arranged at the rail 3, and a shearing stress detector B is constituted. An operator, which comprises a strain difference computing circuit and a stopping position computing circuit, judges the suitability of the stopping position of mixed pig iron car, and computes the sensitivity of the detectors A and B, is provided. An average value computing circuit which computes the average value of the loads, a received pig iron computing circuit, and a circuit which computes the total weight of the mixed pig iron car are provided.