You can't blame Toronto drivers for feeling a wee bit shell shocked about the piece of concrete that rained down without warning on the Gardiner Expressway Thursday morning.
After all, it's happened before.
Earlier this year, the roles of this accident-waiting-to-happen were reversed, and it was the crumbling Gardiner Expressway that was the focus of concern.
It was January 27th, a Saturday night, when a 6.5 kilogram chunk of solid material fell off the bottom of the roadway and right in front of a startled motorist at York and the Lake Shore.
Somehow, as in Thursday's incident, it missed.
Crews shut down the area for part of that weekend to check for more problems. But they didn't find any, a fact that didn't calm the nerves of those who had to traverse the underpass when rush hour began that Monday.
And it's not just Toronto that has concerns that what goes up must one day come down.
A public inquiry is underway in Quebec, after an overpass collapsed onto the highway in Laval on September 20, 2006. Five people - including a pregnant woman - were killed in that incident and six more were injured.
A few months later in Ottawa, on December 11th, a businessman driving under a train overpass was stunned when a piece of concrete a half a metre wide came loose and crashed through his windshield.
The 44-year-old was shaken up but wasn't hurt.
These incidents and others have many calling for more frequent inspections of the crumbling infrastructure in major cities.
Weather, salt, age, accidents, neglect and poor construction are just some of the reasons why the roads sometimes give way.
Crews generally do a good job in keeping them in a good state of repair but their unpredictability still makes them a concern.
Because of the sheer number of bridges in Toronto (which the city says stands at 530), the Gardiner only gets a thorough going over once every two years. But after what happened at the beginning of the year, officials agreed to move up that timetable to 2008.
The city normally spends about $10-12 million a year maintaining its streets and overpasses.