TY JOUR TI Technical Maintenance Analysis of the Automatic Locomotive Signalling in the Metro System KW Metro system KW automatic locomotive signalling KW train devices KW maintenance KW digital protection KW failures KW lack of frequency KW generator of a comprehensive test of the speed control system JO Proceedings of Petersburg Transport University AU Shvoyn, A.I. AU Kuz'min, V.S. AU Zhuhin, N.O. PY 2025 IS 22 PB FSBEI HE "Emperor Alexander I St. Petersburg State Transport University"