The controversial Albert "Tibby" Cotter bridge, a walkway designed for sports fans and cyclists for greater access over Anzac Parade to the Sydney Cricket Ground, was expected be completed for Friday's World Cup match between South Africa and the West Indies.

Instead, NSW Roads Minister Duncan Gay cut the blue ribbon to open the bridge but said it was never expected to be "completely finished" even by the time of Australia's first match at the SCG next Sunday.

Mr Gay also defended a $13 million blow-out in costs as well as his refusal to release detailed costings of the $38 million project to sections of the media and more importantly, the Heritage Council of NSW, which Mr Gay said would be "better off looking after their own home" when asked if he would release the costings.

"We didn't believe any of this was essential [changes to the structure]," Mr Gay said. "They were the rules and we had to adhere to them.

"It was the delay in the approvals which forced our time span. We had to remove one of the key supporting structures and it meant hundreds of tonnes of extra steel, concrete and redrawings and hence the cost blew out."

As for the unexpected surge in costs for the 420-metre-long structure, Mr Gay insisted it was worth every cent.

"It's still a valuable piece of infrastructure, if we thought the cost had blown out too much we would not have gone ahead with it," Mr Gay said. "We would have rather not have it [extra costs] but I think everyone's got to agree the final bridge is just exceptional."

Mr Gay's viewpoint is in contrast to that of Professor Lawrence Nield, chairman of the NSW Heritage Council, who told Fairfax Media three weeks ago, "the requirements of the Heritage Council would not have produced a cost increase".

Meanwhile, Minister for Sport Stuart Ayres has defended the bridge's location. He said he was confident people would walk further from Central Station to the bridge just so they could get an "experience".

"For 100 years we have made that walk as hard as we possibly can, by making people walk up hill and down dale," Mr Ayres said. "I think we will look back on this bridge and say to ourselves, "why did we not do it earlier'?"