Project manager Stephen Townley said: “The problems we have had are it is an extremely aggressive environment down there.

“Electricity from the third ‘live’ rail causes corrosion in the metal and with the Mersey being so near, there is lots of water.

“The decline of Liverpool’s heavy industry has also not helped because the water is not being drawn off any more, leading to a raising of the water table.”

He said the new concrete, more advanced than the 1970s slabs which the original tracks are laid on, together with springy plates holding the rails in place, gave the repaired section a 75-year design life.

He also said there are no plans to do any more slab track renewal in the near future.

Mr Townley said: “As far as track slab renewal goes for Network Rail, this is the last scheduled for the foreseeable future.

“We have other projects in the North West, including bridge reinforcement, but this is the last major project scheduled for the city area.”

He said the line to Hunts Cross was closed because a replacement bus was “more reliable” than running trains on a closed line.