The Commonwealth Railways Act 1917 appointed a Commissioner who was to be in charge of all railways property and all moneys appropriated by Parliament. The existing securities granted by or to the Minister of State for Home Affairs or Works and Railways prior to this Act regarding Commonwealth railways were not affected. The Commissioner could delegate his powers, lease railway property, enter contracts (up to 5,000 pounds), refuse to carry dangerous or excessive weight goods, demand tolls, enter into agreements or contracts with the Postmaster-General, and connect with State railways. The Commissioner was deemed to be a common carrier subject to the appropriate obligations and privileges. His general duties were to "do all that is necessary or convenient for making, maintaining, altering or repairing and using the railways" and to "carry persons and goods".

The Commissioner had to prepare yearly estimates, quarterly and annual reports for the Minister and carry out matters of policy. A Plant and Stores Suspense Account and Railway Accident and Insurance Fund were established. The Commissioner had to supply information regarding proposed railway routes for the Parliament and when an Act authorised the construction of any railway, to acquisition land and close roads. Penalties and procedure were also set out in the Act. The Commissioner was empowered to make by-laws in accordance with the Act.

The railways officially taken over by the Commissioner were:
1. Trans-Australian Railway
2. Oodnadatta Railway
3. Northern Territory Railway
4. Federal Territory Railway
The Northern Territory Railway management was taken over on 1 July 1918. The Oodnadatta Railway was worked by the South Australian Railways Commissioner on behalf of the Commonwealth.

A Royal Commission was appointed on 8 February 1921 to inquire into the question of a uniform railway gauge (1) and its report was considered at a Premiers' conference in November 1921 and the Commissioner's recommendation of a uniform 4' 8 1/2" gauge was accepted (2).

The management of the Oodnadatta Railway was taken over by the Commissioner on 1 January 1926 (3). This line was renamed Central Australian Railway and Northern Territory Railway, the North Australia Railway in 1926. The Port Augusta - Port Pirie standard gauge railway was opened on 23 July 1937 (4). The Federal Territory Railway was re-named the Australian Capital Territory Railway (5).
By 1955 the Commissioner was in charge of the electric power plant and Railways Institute at Port Augusta (5).

The Commonwealth Railways Act, No. 99 of 15 November 1956 provided for the closing of railways if not longer required. By 1960 department provision stores operated at several towns on the Trans-Australian Railway route and at Darwin, to provide services for employees.

The Commissioner's report 1969-1970 stated that the east and the west coasts were linked by standard gauge rail and an "Indian-Pacific" express introduced for passenger traffic between Sydney and Perth. The Port Augusta-Whyalla Railway was opened on 6 October 1972 (6). The Annual Report of 1972-1973 states that a modern computing centre was opened on 21 March 1973 at Port Augusta. Forty-four by-laws were in force at 1 July 1975 as can be seen from The Australian National Railways Act 1917-1975. This Act, No. 26 of 1975 assented to on 18 April 1975, and proclaimed to commence on 1 July 1975, established an Australian National Railways Commission and abolished the Commonwealth Railways Commissioner. 
Mr K.A. Smith, the last Commissioner, became the Chairman of the Commission.

The Commissioners of Commonwealth Railways were;
(Nov) 1917-1929 (Nov): N.G. Bell
(Nov) 1929-1948 (Nov): G.A. Gahan
(Nov) 1948-1960 (Apr): P.J. Hannaberry
(Apr) 1960-1975 (July 1): K.A. Smith

References
1. Commonwealth Parliamentary papers, Session 1920-1921, Vol. V, pp. 759-841
2. Commonwealth Parliamentary papers, Session 1922, Vol II, p.1793
3. Commonwealth Parliamentary papers, Session 1926-1928, Vol V, p.14
4. Commonwealth Parliamentary papers, Session 1937-1940, Vol III, p.4
5. Commonwealth Parliamentary papers, Session 1956-1957, Vol III, p.934, p.957, p.961
6. Commonwealth Parliamentary papers, No. 22 Session 1974, p.12

Historical agency address
by1917-by1924: Russell Street, Melbourne 
by1924-  1930: Cnr Flinders Lane & Russell Street, Melbourne 
  1930-c 1967: 623 Collins Street, Melbourne 
  1967-  1975: 325 Collins Street, Melbourne

Legislation administered
Commonwealth Acts, No. 31 of 1917, Australian National Railways Act 1917-1975