Railway construction and operation requirements, structural and electrical clearances
Great Britain.Department of Transport.
London H.M.S.O.
1977
'These new sections represent the first stage of a complete revision and metrication of the "Railway construction and operation requirements for passenger lines and recommendations for goods lines of the Minister of Transport", 1950 (reprinted 1970) ... they supersede Paragraphs 51-56 (inclusive) and Appendix III of the 1950 edition of requirements, and also the separately published "Ministry of Transport, Railway electrification on the overhead system, requirements for clearances", 1966' - Introduction
Railroads