The show kicks off with a dynamic taster of what the series has in store - namely the inside story of a crack team building a trailblazing, fully-automated metro system costing $50 billion, by far the biggest and most advanced new railway opening anywhere on the planet in 2019. A dramatic scene with our main characters dealing with a crisis gets the ball rolling.

Another super challenge looms, perhaps the greatest of the entire project - digging two tunnels beneath Sydney Harbour.

In the early planning stages, the team actually considered dropping pre-fabricated tunnel sections down onto the floor of the harbour one by one, lowering them from barges, which was the way the road tunnel under the harbour was built.