In the months after opening in 1979, staff running the manual signal box that has guided as many as 4000 trains a day through central Sydney named it “malfunction junction”.

“There were lots of malfunctions in the early days. It was months before it settled down,” recalls Bob Scott, a former area controller who worked at the Sydney signal box for 15 years. “It was a very, very busy and a very complicated signal box.”

Retired signaller Bob Scott reflects on the closure of the signal box after almost 40 years. Credit:Wolter Peeters

Almost four decades later, controllers at the old brick signal box perched overlooking train lines near Redfern station will push buttons and turn rotary switches to shepherd trains through the city for the last time on Saturday.

To allow the transfer of signalling to a computer-based signal box at Homebush, the City Circle rail line in Sydney's CBD will be closed this weekend.