The Penobscot Narrows Bridge on Route 1 was reopened to traffic Monday night after authorities were forced to close it Sunday morning because large chunks of ice were falling on passing cars.

But after workers were unable to remove ice formations from the upper reaches of the bridge with the aid of a crane Monday afternoon, state officials left open the possibility they will have to close the bridge again if the ice starts to melt again this coming weekend.

The bridge, which spans the Penobscot River, connects Verona Island with the Waldo County town of Prospect.

The Hancock County Sheriff’s Office said five cars were damaged, including two that were totaled, by ice falling from the upper reaches of the cable-stayed bridge Sunday morning. Witnesses described the ice chunks as basketball-size and said they made a sound like thunder when they hit the pavement.

No one was hurt, but as a safety precaution the Maine Department of Transportation decided to close the 2,120-foot-long, two-lane bridge around 10:15 a.m. Sunday.

Engineers assessed the danger Monday morning and discovered that there was more ice compacted on the bridge than expected. The bridge remained closed throughout the day.

Ted Talbot, a spokesman for the MDOT, said agency officials spent part of Monday speaking with engineers who designed a similar cable-stayed bridge in Boston known as the Zakim Bridge.

That bridge had similar icing problems during one storm, Talbot said. Maine is considering somehow heating the cables on the Penobscot Narrows Bridge to prevent icing from occurring in the future, he said.

Talbot defended the Penobscot Narrows Bridge design. The bridge opened on Dec. 30, 2006. This was the first time it had to be closed.

“You don’t design a bridge for an ice storm,” Talbot said. “You design a bridge to hold the weight from ice and snow.”

When it warmed up Monday and more ice started to fall hundreds of feet from the top of the bridge to the road pavement, Talbot said state officials knew they had to do something.

The bridge is an integral commuter route for residents of the Bucksport area.

“It’s a very important bridge to the people of that area, but the detour they had to take (Sunday and Monday) is immense,” he acknowledged.

State officials hired the Cianbro Corp. to provide an industrial crane. The crane arrived late Monday afternoon, but its operators were unsuccessful as they tried to “nudge” off chunks of ice from the bridge’s cable system, Talbot said.

He said the ice that is frozen to some of the bridge’s upper cable supports is so solid that engineers feel confident the bridge will be safe for motorists to use.

“We’re confident the ice won’t fall,” he said.

Temperatures are expected to plummet to well below freezing this week, another factor that engineers considered before making their decision to reopen the bridge to traffic, Talbot said.

The National Weather Service is forecasting daytime high temperatures of 4 degrees on Thursday and 7 degrees Friday for the Bucksport region.

If it should warm up later in the week, however, the bridge may need to close again to give engineers more time to assess the falling-ice threat, Talbot said.

Dennis Hoey can be contacted at 791-6365 or at:

dhoey@pressherald.com