The first tracks have been laid on a new freight link into Peel Ports' Seaforth Docks in Sefton.
The tracks for the £7.9m Olive Mount Chord project were laid from Olive Mount Junction to Edge Lane Junction in Liverpool using Balfour Beatty's giant new track construction machine.
Neil Scales, chief executive and director general of Merseytravel, said: "Work is progressing well and this is an important step forward in a nationally significant project that will help to improve access to the Port of Liverpool.
"It will mean better access for trains to and from Liverpool as well as a number of places in the north of England and beyond. Locally, it should also help reduce the number of lorries using the road network."
Contractor for the works, First Engineering, took possession of the rail line to lay the stretch of track from the Chat Moss line through the disused 1882 Olive Mount Tunnel up to a new exit on the Bootle Branch that carries freight trains to Seaforth Docks.
Work still in the pipeline on the project includes connecting the signalling to Edge Hill signal box.
Further north along the Bootle Branch, gauge clearance work is being carried out to the Spellow Tunnel and alterations will need to be made to the Sandhills signal box where the branch connects with Merseyrail's Liverpool to Southport line.
The new chord will be a single track along the centre line of the old double track tunnel. It will allow for 9' 6" deep sea container trains to eventually use the Chat Moss line to and from Manchester and the West Coast Main Line without the need to reverse in the Edge Hill area and along the busy Lime Street station.
The line, about a quarter of a mile long, has been closed for 20 years.
Merseytravel is client for the scheme and is acting on behalf of the Merseyside Local Transport Plan Partnership and The Northern Way.
Network Rail is project managing the scheme. There is also a contribution from the European Regional Development Fund. Peel Ports and Mersey Maritime sit on the project steering group along with train operator Freightliner.
The scheme is due to be completed by December 2008.