Price was the main decider in awarding the $1.3 billion Waterview project, according to Robert Jones, Leighton Contractors' alliance project director.
"I think it's purely and simply a competitive tender and price," Jones said, indicating the rival Fletcher Construction consortium had offered to do the work for less.
He was commenting after Friday's announcement the Fletcher consortium won the contract for the connection tunnels and Great North Rd interchange in Auckland, a decision by the NZ Transport Agency which left Leighton the loser in the tender for New Zealand's biggest roading project.
Jones said Leighton had spent about $18 million and at one point had 140 people working on its bid.
"That's the way it goes. You go into these bids obviously very hopeful that you have something extra special but at the end of the day, it's price-dominated.