ROCKLAND, Maine — The future of the Brunswick to Rockland railroad line will be decided over the next 18 months.

The line is viewed as important both for local industries to move freight less expensively and for tourist-related businesses that benefit from the influx of visitors.

Maine Eastern Railroad has operated the 56-mile-long rail line for the past 10 years. Its contract with the state was to expire in October 2013, but the company agreed to continue running through December 2014, according to Nate Moulton, director of rail programs for the Maine Department of Transportation, which owns the line.

The line has experienced a significant drop in freight and passenger traffic during the past few years, the transportation official acknowledged, and the company has cut back significantly on its passenger excursion service this summer.

The 15-month extension on the contract allows the state to solicit proposals, beginning this fall, from other railroad companies interested in operating the Brunswick to Rockland line after 2014, said Moulton. He expects there will be interest and that Maine Eastern can also submit a proposal to continue service.

During the next year, the state will study the demand for passenger and freight customers along the route.

The contract between Maine Eastern and the state, which owns the rail line, requires the company to carry freight, although it had encouraged them to also operate passenger service. Maine Eastern is responsible for maintaining the lines. Maine Eastern would only pay the state if its revenues from the line exceeded a certain amount which it has yet to attain, Moulton said.

The line has been operating since May 1990, five years after Maine Central Railroad abandoned the spur. The state spent $30 million in the early 1990s to upgrade the line to be able to handle passenger trains, which resumed running on the Rockland line in 2004.

Passenger service during the past 10 years has been limited largely to summer excursion trips. The amount of traffic grew during the past decade, reaching a peak of nearly 19,000 people in 2008, according to prior statements by Maine Eastern.

Rail advocates had expressed hope that the extension of Amtrak commuter rail service from Portland to Brunswick last year could eventually be extended to Rockland.

The opposite has occurred, however.

Maine Eastern was running two trips a day between Brunswick and Rockland until this year. In April it announced that it would reduce the trips to once a day between the two midcoast Maine cities.

But since that announcement, Maine Eastern has reduced its passenger schedule even further. Except for a few trips in June and July, regular excursion service will not begin until Aug. 21 and run once a day Wednesday through Saturday until Oct. 12. That is a dramatic change from past years, when the service would start on Memorial Day weekend.

Lorain Francis, the executive director of Rockland Main Street, said that downtown merchants were very disappointed when the 2013 schedule was announced by Maine Eastern.

“The passengers from the trains have been important, steady customers for the downtown throughout the summer,” Francis said. “They have been an important part of the downtown economy along with visitors who come by car or cruise ships, large and small.”

Maine Eastern laid off several of its Maine workers earlier this year, including its vice president for passenger operations.

The state also owns the railroad station in Rockland, located at the intersection of Union and Pleasant streets. Maine Eastern leases the station and then subleases much of the space to the Trackside Station restaurant. Moulton said the state is stepping in and is negotiating with Trackside’s owners to extend the lease directly with the state.

The historic building was constructed in 1917-1918 and served as a train station until 1959, when commuter passenger service ended to Rockland. The city of Rockland acquired the building and used it for municipal offices until 1996. The state then purchased it from the city and renovated it extensively in 2006.

The largest source of revenue for Maine Eastern has been its freight service and Dragon Products is by far its largest customer.

During the construction boom of 2005-2006, Dragon needed two barges at its Rockland waterfront facility to handle the daily shipments of cement from the plant that would then be shipped to southern New England. That traffic had fallen by half with the recession, Moulton said.

There was an increase last year and a projected further increase in shipments this year, the transportation official said.

Ray DeGrass, the plant manager for Dragon, said that the rail line is important both because shipping cement by rail is more economical than trucking it over the highways but also because it avoids having thousands of trucks loaded with cement on the highway.

The cement plant sends rail cars about five miles on the line from its Thomaston plant to its dock on Rockland’s South End waterfront, where a barge is then filled and product shipped to the Boston market. He said the barge makes about 40 trips to the Boston market each year, carrying a combined 160,000 tons of cement.

If not for the rail line, the company would have about 5,000 trucks on the road, mostly during the busy summer tourist season when roads are already heavily used, he said.

Dragon also uses the rail line to ship cement south and then north to Quebec.

Another customer of Maine Eastern is Dica Perl Minerals, formerly known as Chemrock, on Buttermilk Lane in Thomaston. Maine Eastern also does some business with Bath Iron Works.

Telephone and emails were left with Maine Eastern’s parent company Morristown and Erie Railway Inc. in New Jersey. No return messages have been received.