City crews returned to Lake Shore Boulevard West on Tuesday morning to repair the area where a chunk of concrete fell from the Gardiner Expressway the day before.

Concrete crumbled onto the road as crews used a hammer to chip away at loose material on the underside of the Expressway. A 10-pound (4.54-kilogram) piece of concrete fell onto the westbound lane of the busy road, between Bathurst Street and Dan Leckie Way. Traffic was delayed as two westbound lanes were briefly closed in the afternoon.

"It's a little bit scary but fortunately nobody got hurt so hopefully they'll fix the problem and make sure it's addressed in the future," one driver told CTV Toronto as he was stopped underneath the Expressway.

While the highway is about a half-century old, it's still structurally sound, according to Mike Laidlaw, the city's acting manager of structures and expressways.

"What you're seeing here is more of a cosmetic, superficial covering of the concrete. That's what's coming off," said Laidlaw. Road crews will continue to inspect the area on Tuesday and Wednesday.

Officials said the Expressway supports tens of thousands of trucks and cars each day. When it was first built in the 1950s, the city didn't use salt on the roads. Today, the salt can make its way into reinforcing bars on the highway, causing them to expand and crumble.

In a similar incident, concrete fell onto Lake Shore Boulevard West in January 2007.

Crews will begin to make major repairs and replace sections of the Expressway in the next two to three years.

With files from CTV Toronto's Michelle Dube.