He persuaded the New South Wales legislature to pass an Act on 27 July 1852 requiring all railways in the colony to be of 5 ft 3 in (1,600 mm) gauge.

After Sheilds resigned due to difficulties, a Scot named James Wallace was appointed.

The Sydney Railway Company encountered many troubles: engineers came and went; real estate required became expensive and difficult to acquire; money, supplies and manpower ran short, partly because of a gold rush.

Eventually the property of the Sydney Railway Company was transferred to the government of New South Wales on 3 September 1855.

It was not until 1955 that the Up and Down Main Lines were also electrified to coincide with the opening of the Blue Mountains electrification programme.

The line consists of three pairs of electrified tracks, six in total, which head west through the Inner Western suburbs of Sydney to Strathfield.

A bit further west is Lidcombe, where there is another triangle junction, connecting the suburban tracks to the Main Southern railway line.

Speed limits on the route vary between locations and tracks (main, suburban or local).