03/26/2012 01:45 EDT | Updated 05/26/2012 05:12 EDT

Bird strike possible cause of falling glass

Falling glass has again disrupted street traffic in downtown Toronto.

The glass fell from the 16th floor of a building at 180 Queen St. W. at around noon on Monday.

Police from 52 Division have closed off a section of the busy street between University Avenue and St. Patrick Street to pedestrians, but are allowing vehicle traffic to go through. Police said mid-afternoon that it will probably take two to three hours until the glass is replaced and the roads are re-opened.

Over the weekend the corner of Bay Street and Adelaide Street was closed after glass fell from the newly built Trump Tower.

There were no injuries reported in either incident.

Police from 52 Division said the working theory is that a bird cracked the glass and a sudden drop in temperatures caused the pane to break.

But Doug Perovic, with the University of Toronto's Faculty of Applied Science and Engineering, said there is likely more to it than that.

"Birds shouldn't be shattering tempered glass ... so something else is not quite right," he said.

Ted Kesik, a professor of building science in the university's Faculty of Architecture, said there are normally three variables when glass breaks — design, workmanship and materials — but that increasingly climate is an issue.

However, he stressed that every incident is different and needs to be assessed individually.

Experts at the CBC weather centre said in this case the climate should not have been a factor. The temperature drop was not exceptional and Chinook winds hit buildings much harder in Calgary.