More than 80 people have been working around the clock at Dundee rail station as part of the £1bn Waterfront regeneration.
A 56-hour closure of the Dundee to Aberdeen line was in place while contractors demolished the South Union Street Bridge at the site ahead of construction of a new station building next year.
Work started at 10pm on Christmas Eve and continues through Christmas Day.
The work is expected to finish at 6am on December 27.
Main contractor Sir Robert McAlpine, and its demolition contractor Keltbray, had more than 80 employees, a 120-tonne crane, a 250-tonne crane, two 75-tonne excavators, plus two at 45-tonnes and two seven-tonners, and other small plant on site for the operation.
The work will be completed before handing back to Network Rail before trains start again on Saturday.
The structure dated back to the late 19th or early 20th century and comprised a combination of cast and wrought iron beams with brick arches.
City development convener Councillor Will Dawson said: “This is yet another major step forward in the Waterfront project. This is quite a narrow timeframe and a great deal of planning has gone into this operation.
“The demolition will allow further development of the Waterfront, including the construction of the new railway station.”
A spokesman for Network Rail said: “We are assisting Dundee City Council in their plans and are also there to ensure that the railway line is still safe for operation after the work is complete.”
The work schedule included the installation of track protection, and protection for existing cables, signals and rail infrastructure.
The brick arches were broken out and steel beams craned out of the site. The demolition debris will be cleared from the track, before the removal of all the protection measures.
Finally, there will be an inspection of the site before it’s handed back to rail bosses.