Timelapse footage of work to upgrade the Glasgow Subway has been released by operator Strathclyde Partnership for Transport (SPT).
It shows track being removed and replaced at the sole junction on the six-mile underground railway, which links it to the train depot at Govan.
Delays to the work have extended the system’s month-long closure for around two weeks, with services now expected to resume in mid-August.
Problems have included the removal of old concrete taking longer than expected, but has SPT denied claims it was replaced with the wrong type.
Flooding of the junction caused by heavy rain flowing down the tracks from the depot has also hampered progress.
The Subway has been closed since 2 July and was due to have re-opened next Monday.
Other work being carried out during closure of the 120-year-old system - the third oldest in the world after London and Budapest - includes a facelift for Cessnock Station and tunnel repairs between Hillhead and Buchanan Street stations.
An SPT spokeswoman said: “The video link shows some of the work captured by timelapse cameras in the north and south turnout chambers, where the trains come in and out.
“The beginning of the video shows the removal of the running rail, live [electrified] rail and track.
“This is followed by concrete coring and breakout, and then clean down in both chambers prior to installing and setting out the new track system and rail installation.
“The video then cuts to ramp activities, showing the removal of track, and plant and equipment moving materials in and out of the chambers.”
The shutdown was arranged for the quietist time of the year, during the school holidays, with buses replacing trains.