The work studied and solved several issues, one of which was defining the reasonable roughness of the effective area at the wheel-rail pair, that provides their extended useful life period. 5 samples with different asperity in the range of Rz 1,322 to Rz 320 (the total number- 25) made from rails with different roughness, including rail withdrawn from service while replacement of the track structure at the open pit of SUEK company (Krasnoyarsk) were prepared for the study.As a result of the conducted theoretical and practical studies of wheel-rail tribosystem interaction for open-pit locomotives the study defined the rational value of the roughness while forming of the rails within Rz40 - Rz20 μm, which helps to reduce worn-in time of wheel-rail pair, which in turn will prolong the period of effective service of the open-pit railway transport. Detection establishment of rational roughness of wheel-rail working surfaces will allow for the theoretical forecast of the expected calculated value of the adhesion coefficient of locomotive‘s tire with the rail, and to increase its tractile efficiency.