The new Walterdale Bridge will not be ready for traffic until the middle of 2017, city officials have revealed.

A report issued Thursday says concrete work cannot be completed by the contractor Acciona Pacer Joint Venture before the onset of winter.

The new river crossing was originally slated to open in November 2015. That was then pushed back to late 2016.

Mayor Don Iveson said construction crews are "racing against the weather" to complete construction. He also cited internal issues with sub-contractors as a reason for the delay.

"To be able to see it and not be able to cross it yet is frustrating," he told reporters on Thursday.

The penalty incurred by the contractor last June — $10,000 per day — is keeping the bridge on budget, he added.

That penalty rises to $17,000 per day at the end of October.

The city budgeted $155 million for the project. Iveson said the penalty hike will help the city meet the budget or come in under it

"This is an example where the city's contract is really serving citizens by putting fairly strict penalties in place for any delays," he said.

"While it's disappointing of course that the project is delayed, the city will get good value for money out of this replacement bridge in the fullness of time as the penalties accumulate."

The report says the bridge, which remains on budget, is the most ambitious project ever taken on by the City of Edmonton.

Deputy city manager Adam Laughlin said the bridge is a complex project that has seen a number of complications.

"This isn't building a Lego-type bridge," Laughlin said.