The city expects the Calgary Zoo bridge on 12th Street S.E. to be removed later this week, after heavy winds hampered work by construction crews Wednesday.

"It's probably the most complex and critical event of our project," said Katherine Hikita, a structural engineer with the city.

A new bridge is being built just west of the old span, which links Inglewood and the zoo.

A crane from Saskatchewan will be used to lift out the steel truss section of the old bridge.

"It is a 108-year-old bridge that's been in service for that long, so it's a pretty big event," Hikita said.

An artist rendering of the 12th Street S.E. bridge replacement, which is scheduled to open in late 2017. (City of Calgary)

'A lot of preparation'

Hikita said removing the old bridge in one piece is the best way to do the job and not risk any of it falling into the river.

"We've done a lot of analysis. We actually built a 3D computer model to figure out the best way to lift this bridge out and how it should behave as we start lifting it, so we've done a lot of preparation to get ready for this moment," she said.

The crane will place the bridge on the south side of St. George's Island and then it will be dismantled.

Old bridge to live on

Parts of the old bridge will be incorporated in a display of public art that will be installed nearby.

Hikita says the bridge will be removed in the next couple of days, depending on weather.

"We are going to be lifting it out as soon as the weather conditions cooperate and we get a little less wind going on," she said.

The new bridge is scheduled to open to traffic in late 2017.