The article considers one of the neglected issues in the history of private railway construction in Asian Russia in early XXth century. The construction and initial operating period of the private railways in Siberia and Turkestan is seen through the prism of business development on the basis of the formation and functioning of contracting capital. Special attention is paid to the economic feasibility of the mechanism of interaction of the boards of private railway companies and major contractors, who had substantial assets for the satisfactory performing of the contract duties. The paper characterizes occupation, class, main activities and outlines the duties of the major contractors on the example of the Altai, Achinsk-Minusinsk and Semirechensk railway. The author examines the main ways and means of forming subcontractors’ units on private Railways Siberia, attempts to uncover the reasons for the lack of such entrepreneurial activity in the private Railways of Turkestan. The period of construction and preparation of railways were associated with significant difficulties due to the outbreak of the First World War. The author comes to the conclusion that private Railways in Asian Russia were dominated by the Russian European capital, guarded by large commercial banks.