PORTLAND (AP) – A new barge service designed to transport containerized cargo between Portland and New York Harbor gets under way next month.

The weekly service is being offered by Columbia Coastal Transport and represents an extension of its service between Boston and New York.

Columbia was attracted to Portland by Sprague Energy’s plan to build a waterfront facility to ship products from Maine’s paper mills to New York Harbor, where they can then be shipped worldwide.

If successful, the new barge operation would put Portland on the leading edge of a new transportation mode called “short sea shipping.”

The new sea link allows shippers to avoid the region’s increasingly congested highway system, said Martin Toyen, a transportation consultant who is helping Bridgeport, Conn., set up a daily barge service to New York Harbor.

“It’s the swing of the pendulum,” Toyen said. “What’s happening is that shippers are looking at the economics and realizing that water is becoming economically viable.”

The U.S. Maritime Administration has been pushing for the development of a short sea shipping system to help reduce the growing freight congestion in the nations rail and highway systems. Some states, including Massachusetts, view the creation of such a system as part of a “smart growth” strategy to reduce congestion without building more highways.

The service in Portland would be the fifth one to be put in place since the initiative began, said Mark Yonge, a Florida transportation consultant and a member of the Short Sea Shipping Cooperative, a private group that is promoting the use of waterways and ocean for transporting cargo.

“This is fantastic,” he said of the new Portland service. “For years we’ve been doing studies on short sea shipping, but we have reached a time now where we need to see some action. Here’s someone who has taken it upon themselves to do just that. I applaud them.”

Sprague plans to pack containers at Merrill’s Marine Terminal, which has rail access, and truck the containers to the International Marine Terminal, where longshoremen will load them onto the barge.

The port currently handles 2,300 loaded containers a year, a figure that Sprague estimates could eventually increase tenfold as a result of its expansion. Officials also believe that the barge service will generate more business for Maine railroads because paper mills will send products to Portland on freight cars rather truck them to New York.