PURPOSE: To equalize the concrete thickness of the right and left slope of a curvilinear waterway by a method wherein a deflection due to a tyre difference is detected by fitting a steering sensor in a lining machine and a cylinder for adjusting the caterpillar width of a waterway lining machine is expanded.

CONSTITUTION: When a trimming groove 5 is curved, the center of a car body 20 deflects from the center of the groove 5 to the right hand because of the tyre difference of catapillars 21, 22 of a waterway lining machine 2. In accordance therewith, the center of a lining machine 6 also deflects from the center of the groove 5 to the right hand. In accordance with this deflection, a steering sensor 81 emits a signal. This signal is sent to a catapillar control system, and when the signal is discriminated as a value more than a given value, cylinders 23, 24 are expanded by a same stroke simultaneously. Accordingly, the grounding position and the catapillar width of the catapillars 21, 22 do not vary but only the car body 20 is moved to the left direction, therefore, the lining machine 6 is also moved to the left direction. In this way, the center of the car body 20 and the lining machine 6 is made to coincide with the center of the groove 5, as a result, the concrete thickness of both slopes 50, 51 can be made equal.