Faced with E-ZPass customers who are upset about being overcharged all winter because of damaged sensors at the Kennebunk toll plaza, the Maine Turnpike Authority is promising refunds.

And because officials cannot determine who was overcharged, the turnpike authority will provide refunds to all motorists who were billed for driving vehicles with three axles through that poll plaza from Dec. 1 to April 1, whether the tolls were correct or not.

Although some turnpike employees knew that the sensors had been damaged by a snowplow in early December, they thought the sensors weren’t working at all so no one was being charged for three axles, said Peter Mills, the authority’s executive director. The workers didn’t know that some drivers were being charged extra for hauling trailers they didn’t have.

“We had no idea we would be overcharging people,” he said. “We thought we would be undercharging people. We are happy to do that now to make sure everybody is square with us.”

Mills said he wasn’t aware of the problem at the northbound toll plaza until it was reported in the media Wednesday.

The northbound turnpike on-ramp in Kennebunk has two toll lanes. From around Dec. 1 to April 1, the E-ZPass-only lane was closed so workers could make improvements, including replacing old-style sensors in the pavement with modern ones that can’t be damaged by snowplows. The sensors determine how many axles a vehicle has so the correct toll can be charged.

Tolls are higher for a three-axle vehicle, typically a two-axle car or truck pulling a one-axle trailer. The difference ranges from 25 cents to $2.30, depending on how far someone drives on the turnpike. Mills said it’s 40 cents to 50 cents in most cases.

The difference is what will be refunded to E-ZPass users.

Mills said the sensors were damaged by a plow during a snowstorm shortly after Dec. 1. He said he doesn’t know how many people were overcharged.

He said turnpike authority workers assumed the sensors weren’t working at all, which typically happens after sensors are hit by a snowplow. But because only one lane was open during the construction project, the authority couldn’t close the lane and replace the sensors, a job that takes several days.

Turnpike spokeswoman Erin Courtney said Wednesday that officials didn’t learn about the overcharges until last week, when a customer called to report extra charges to an E-ZPass account.

Mills said Thursday that several people called the turnpike authority during the winter to complain about being overcharged and most likely received refunds, as is typical when customers complain. He said the calls were infrequent, and the pattern was never reported to higher-ups.

“Unfortunately, it should have hit my desk a littler earlier,” he said.

Several people contacted the Portland Press Herald on Thursday and said they had complained to the turnpike authority over the winter about being overcharged at the Kennebunk on-ramp.

Some, like Erica Tibbetts of Kennebunk, had complained multiple times. She said she first contacted the turnpike authority about the problem on Jan. 15, then two friends who had been overcharged also called. Although the authority refunded her each time, its inability to solve the problem angered her.

She said she is pleased that the turnpike authority will provide refunds, but thinks it’s overdue. The refunds will appear next week as credits in customers’ E-ZPass accounts.

“I think it’s great they are doing that because it seems they knew about it and weren’t doing anything,” she said. “If it hadn’t come out in the news, they wouldn’t have given any credit unless they were specially asked for it.”

Mills said the old sensors, with 30-year-old technology, will be replaced by new sensors at every toll plaza over the next few years. He said the new sensors, buried below the pavement grade, work better in cold-weather states like Maine.

The new sensors also are more sensitive, to capture data from vehicles traveling at highway speeds. In a high-speed toll lane in New Gloucester, for example, the sensors have captured data from police cars going 100 mph, he said.

In Kennebunk, the new sensors have been installed in the E-ZPass lanes northbound and southbound, and are now being installed in the cash lanes. When the project is completed next month, Mills said, there will be new sensors in six of the turnpike’s 19 toll plazas.

Tom Bell can be contacted at 791-6369 or at:

tbell@pressherald.com