To maintain and renew traction rolling stocks, the causes of their deterioration which are closely connected with operational conditions should be identified. For this purpose, such parameters of rolling stocks as the performed work, speed, acceleration, mass, etc. should be properly determined. The first objective is to develop mathematical models to evaluate integrated criteria describing the deterioration of freight and passenger locomotives from technical and economical perspectives. The second goal is to compare the main criteria describing the process of deterioration of freight and passenger locomotives and the respective differences in the strategies of their renewal. Fuel consumption, engine oil consumption and terminal delays due to off-schedule locomotive maintenance were investigated. Each of these parameters may be used to determine the locomotive state (quality) from a particular perspective.