Fewer people are expected to ride Downeaster trains in the current fiscal year because of anticipated construction delays, according to the rail authority that operates the passenger service.

Work crews replaced 2,000 rail ties over the summer and will replace an additional 28,000 ties this fall and next spring, said Patricia Quinn, executive director of the Northern New England Passenger Rail Authority.

Passengers made a record 537,000 trips on the Downeaster during the fiscal year that ended June 30, even though the service posted its worst-ever on-time performance because of the construction delays.

Those delays will be even worse this fiscal year, which began July 1, prompting the rail authority to predict that ridership will fall to 519,000 passengers, a decline of 3 percent.

The ties will be replaced along the route between Portland and the Massachusetts/New Hampshire border, Quinn said. Crews with Pan Am Railways, which owns the railroad, will install the ties. The freight rail company is paying for the labor, and the Downeaster is paying an estimated $2.3 million for the ties and ballast.

Quinn said the work will continue this fall until the ground freezes up, and then crews will start again in the spring and work until June.

She said the project, which has been planned for years, has been delayed, first because of difficulty getting the ties and then because Pan Am crews were busy replacing ties elsewhere on its rail system.

She said tie replacement is similar to routine maintenance work performed on highways.

“It’s like filling in the potholes,” she said. “It’s something that is ongoing.”

Work began on Oct. 14 on the section of the line between Exeter, New Hampshire, and the Massachusetts border.

As a result of the work, all trains may experience delays of 30 to 50 minutes, and some trains that operate in the middle of the day are being canceled. Some of those trains are being replaced by a motor coach that operates between Portland and Boston, with a single stop in Wells.

Weekend train service will not be affected by the construction.

The service impacts will change as construction proceeds, Quinn said. Delays and cancellations will be posted on the service’s website, amtrakdowneaster.com.