As part of this line the tracks ran under Parramatta Road through a sandstone arched overbridge designed by the engineer William Randle.

[1] In 1854 the private company was taken over by the government, due largely to a lack of funds and increasing political pressure to complete the first sections as promised.

[1] The most recent sections of the tunnel are concrete and were constructed c. 1990s when the new Department of Immigration office tower was built in Lee Street.

Parts of the tunnel extensions (the brick vaulted sections) have since been propped using steel frames and braces to support the increasing weight of the road traffic above.

It was constructed by the Sydney Railway Company, the private interest group that formed in 1848 with the backing of the New South Wales Legislative Council.

Opened in 1855, it has a direct and tangible link to the first phase of railway construction in NSW and to the Darling Harbour Goods Yard.

The various extensions to the overbridge which together form the current tunnel demonstrate the changing technologies and designs used in railway engineering.

The overbridge has a strong connection to the original Sydney Station and is a rare example of the first phase of railway construction in NSW.

[1] Railway Square road overbridge was listed on the New South Wales State Heritage Register on 2 April 1999.