In the field of road and rail construction, due to the high concentration of temporary, financial and material investments, it is often possible to notice the redistribution of scarce budgetary funds to the detriment of infrastructure facilities that are of promising importance for the development of remote regions, industries and the economy of Russia as a whole. The aim of the study is to develop a three-level model of cash flows, results, effects and costs to assess the socio-economic efficiency of investments in the construction of promising railway lines. In this study, the concepts of perspective railway lines (PLL), socio-economic efficiency of investments are considered. A three-level model for assessing the socio-economic efficiency of investments in the construction of promising railway lines has been developed. The model takes into account the interests of all participants of the investment project and ensures the complexity of the socio-economic efficiency of the assessment. The authors propose a comprehensive criterion of socio-economic efficiency of investments: the payback period for each participant – investor. As tributaries are considered tax deductions on investment levels, the effects of growth in regional employment and net income from the transportation and sale of goods. The effect of the increase in the level of regional employment is formed by the total growth in real terms of wages in the region, due to the additional inflow of population for the project, as well as the increase in the purchasing power of the population as a whole, taking into account the redistribution of workers to new positions and places. The calculation of socio-economic efficiency of investments for the construction of the railway line «Polunochnaya – Obskaya», reflecting the high rate of return on investment for all levels of investment, the importance and profitability of the project as a whole. The calculations showed that the socio-economic efficiency of the project is achieved at all levels of investment for each of the participants. Further studies of the authors are planned in terms of identifying the main risk factors at the stage of the project, as well as the construction of a probabilistic model for assessing the socio-economic efficiency of investments in the construction of promising railway lines in terms of the risk of non-return on investment.