The damage was the result of exposure to the weather, previous ''dodgy'' repair work and because the glass had bulged where tourists had leant on it waiting to be photographed, Mr Casey said.
The poor repair work had leadlight images of lions facing in the wrong direction and the omission of certain patterns from other windows it was originally designed to match, he said.
The toughened glass and double-glazing of the new window would easily handle the weight of a posing tourist, he said.
The window would be boarded up for about six weeks until the project was complete, he said.
Dunedin City Council asset manager John Varney said the budget for the restoration was between $10,000 and $12,000.
The window, installed in the early 1900s, had been ''buckled and bowed'' by leaning tourists and would be restored to its original condition, he said.
''There's an identical window on the opposite wall and hardly anyone sits on that because the light's not as good, so they sit on the window facing the tracks and it's sustained all the damage.''
