TY JOUR TI Statistical Analysis of Failures in the Traction Drive Systems of the Moscow Metro Electric Rolling Stock KW subway KW electric rolling stock KW traction drive KW statistical analysis KW failures KW operation KW maintenance JO Bulletin of scientific research results AU Kul'kov, A.A. AU Nikonov, D.D. AU Gryaznova, E.L. PY 2026 IS 2026 PB FSBEI HE "Emperor Alexander I St. Petersburg State Transport University"