Purpose. The main purpose of this paper is to analyze the existing methods for surveying curves in a plan, to study the influence of the errors in measuring plan parameters on the permitted speeds of motion, to develop re-commendations for reducing road disturbances by bringing the parameters of curves to the standards that operate in Ukraine in the directions of accelerated and high-speed train traffic. The problem of restructuring the curves was not so acute until there was a need to increase the speed of motion and technical condition monitoring of the track plan. Unreliable determination of the curves parameters leads to unjustified restrictions in the speed of motion or to large volumes of straightening operations. Methodology. The methodology used in the paper provides for a comprehensive and detailed study of different ways of railway curves survey, aimed at developing and obtaining the optimal solutions for the railway track plan. To date, there are different methods of survey the actual geometry of the railway track. To carry out research in various sections of complexity and for a long time of the railway track operation, the most convenient, first of all, considering the regularity of arrivals, there is a tape of the track-measuring car. However, this method is used to assess the state of the railway track, and not to determine the exact geometric position. Thus, when trying to determine the actual outline of the track unevenness using a track-measuring tape, a number of difficulties arise. When forming a mathematical model of the existing plan, the assumption is used: it is considered that three adjacent points on the curve are located along the circumference. The work of track renewal trains is based on this principle. As a result of track renewal operations with the aim of reducing the volume of flattening, the curve does not correspond to the initial passport data. Findings. The results of the work come out of the analysis of different approaches and methods of surveying the plan of the line, the parameters influence of the curves on establishing the permissible speed of motion. The recommendations received in the work will help to increase the efficiency of design decisions and the quality of railway track reconstruction as a whole. Originality. Scientific approaches to assessing the state of curves, studying the influence of their parameters on the permissible speed of trains, have been further developed. The system of criteria for assessing the state of curves that affect the accumulation of track disturbances in the plan is supplemented. Practical value. The results obtained will be useful for carrying out measures to improve speed, improve the smoothness of train traffic and the level of travel comfort on curved track sections, especially in the areas of accelerated and high-speed train traffic.