For those unfamiliar with the area I'll summarise the work, from west to east:
- At Roby junction a new turnout will be installed in the Up line, linking it to the new Up Chat Moss Slow. The existing Up line becomes Up Chat Moss Fast.
- The fourth line is already in place from Roby Junction to the east end of Huyton station.
- Immediately east of Huyton station, the new line will run over the pedestrian tunnel, already extended to accommodate it.
- Next comes Huyton Telephone exchange. The LNWR-era stone wall will be demolished and a strip of the car park taken over, to fit the fourth track in.
- Continuing east, the wall at the back of Huyton Bus Station will also need to go, and a narrow strip of land will be taken.
- Here, at Huyton Junction, track changes will be necessary (See diagram.) to connect the fourth track into the junction. This will include removing some track laid in 2014.