The objective reality of the modern conditions of track operation is a continuous increase in train mass. Retrospective analysis shows that the average weight of trains on Russian Railways for the period from 1940 to 2015 is increased from 1301 to 3960 tons. In 2015 weighting rate of trains on most areas of the network is set to 6300 tons, and in certain areas - 7100 tons, formed from cars with axle load of 25 ton/force. Creating high-power locomotives allows in certain areas, such as the Trans-Siberian railway, passing the trains with weight up to 9000 tons. The article discusses the impact of driving conditions of heavy trains (running in the maximum traction mode, locomotive braking and during coasting) on formation of track deterioration on operating section of trains, part of which included cars with higher axle loads of up to 27 ton. Researches was carried out at the Oktyabrskaya railway (direction Kovdor - Murmansk). It is found that the number of deviations in the track geometry at the Kovdor - Pinozero section before operating cars with increased axial loads in areas with traffic on the maximum traction mode were higher by about 1.5 times, and in the areas of application of locomotive braking by about 1.7 times higher than in areas with coasting motion. When cars with higher axle load were introduced into the operation the greatest negative impact on the criterion of track geometry deviations were subjected to areas with traffic at maximum traction mode, and especially the braking areas, where the number of deviations has increased relative to areas with coasting in 2 - 2.5 times (during summer months).