10,000 people have scrambled to get a spot in the City Rail Link open day on November 17.
The underground walking tour tickets were snapped up within an hour of going online at 12pm today as the public are keen to grab a first glimpse at the construction.
Ewart Barnsley of City Rail Link says the interest in the underground tunnel walk has "exceeded our expectations".
"There has been unprecedented response with 10,000 bookings made within the hour."
The City Link Rail is unable to host more than 10,000 people for the open day. The Waterview Tunnel open day in 2017 hosted 42,000 people but Barnsley has said there are "a lot more health and safety concerns to consider" with the City Rail Link project.