A processor that powers the electrical control panel on the Casco Bay Bridge caused the power failure that affected gates on the bridge Monday afternoon and led to a massive traffic jam on the Portland and South Portland sides of the Fore River span.

The power loss prevented bridge operators from raising the gates that keep traffic flowing after a ship has passed under the bridge.

At the time of the power loss, police on both sides of the river issued warnings to motorists to avoid using the bridge. Power was restored by 4:30 p.m.

Ted Talbot, spokesman for the Maine Department of Transportation, said an electrician conducted a diagnostic exam of the bridge’s electrical system and determined that the processor malfunctioned. A spare processor was installed and traffic was flowing smoothly by Monday evening.

Workers try to repair the gates of the Casco Bay Bridge. The problem was blamed on a processor that powers the electrical control panel causing the power failure.

“The processor failed. Everything in the electrical world has a life span and due to the complexity of the bridge’s operating system, we will always need to have a spare part,” Talbot said.

The Casco Bay Bridge, which is 4,748 feet long, opened in 1997, replacing the aging Million Dollar Bridge. In October 2015, the state announced it was seeking bids to privatize the maintenance and operation of the new bridge. It gave the contract to Florida Drawbridge Inc., which staffs the bridge with two tenders around the clock, according to Talbot.

Those bridge tenders lower and raise traffic gates on the bridge when ships pass through the structure’s 285-foot-wide drawbridge section. Talbot said tenders are needed at all times because ships often show up at all hours with little advance notification.

“We’ve been very pleased with that company’s performance and have no regrets,” Talbot said.

Motorists are stranded and rerouted as the gates on the Casco Bay Bridge are stuck on Monday afternoon. Staff photos by Jill Brady

Talbot said the first power failure occurred about 3:35 p.m., but affected only the northbound side of the bridge – the span that carries traffic from South Portland into Portland. The southbound side of the bridge lost power around 4 p.m.

Monday’s loss of power is not related to two mechanical malfunctions that occurred on the bridge last Thursday and Friday, Talbot said.

On Thursday afternoon, a gate-locking mechanism malfunctioned, and a gate could not be raised from the down position for 14 minutes. On Friday afternoon, the gate-locking mechanism failed again, this time for 16 minutes.

“We were able to disable the locking mechanism and raise the gate,” Talbot said Monday. “But those situations were unrelated to what happened today.”

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

[email protected]

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