Results are given on laboratory tests of the flat drains to determine the compressibility characteristics needed in the drainage structure design, A change in the drain thickness and working section was evaluated under the static and dynamic loading both in the free state and in the soil body medium. In the course of tests, velocities of the deformation development and recovery were registered. The compressibility data are complemented by the results of the compressibility in the soil medium under the action of stamp. Study of peculiarities of the drain performance in the road structure has allowed an approach to drainage embedment specifications to be changed on the basis of considering the water-and-temperature regime of cuts exposing the ground water levels.