BANGOR – The Maine Supreme Judicial Court ruled Tuesday on a disputed railroad crossing that is key to an affordable housing project proposed for the city’s historic but deteriorating waterworks complex on the banks of the Penobscot River.

In a unanimous decision, the state’s law court ruled that the state Department of Transportation did not exceed its authority when it approved in 2003 a public railroad crossing at the site of the waterworks building on State Street.

Maine Central Railroad had asked the law court to reverse a decision that granted the city of Bangor, owner of the waterworks, a public crossing on State Street. Oral arguments in the case were heard on Oct. 19 of last year.

In a ruling written by Justice Robert W. Clifford, the law court determined that the disputed railroad crossing was “sufficiently public” in nature to justify its classification as a public at-grade crossing.

The waterworks property, vacant since the 1970s, is the focus of Shaw House Development Inc.’s $6 million redevelopment plan. The developer aims to convert the complex, a collection of century-old brick buildings, into efficiency units for low-income adults. The project won’t work without a railroad crossing to provide vehicular and pedestrian access to the waterworks site.

Shaw House Development Inc. is a for-profit subsidiary of Shaw House Inc., the nonprofit group that runs a shelter for homeless teens on Union Street.

Efforts Tuesday to reach representatives of the railroad were unsuccessful.

On Tuesday, project coordinator Doug Bouchard hailed the law court’s decision as another victory in Shaw House’s effort to turn the waterworks into 35 efficiency units for low-income adults.

“I’m just glad that this phase [of the legal dispute over the crossing] is over,” Bouchard said Tuesday. “We are glad that the court ruled in our favor.”

With the crossing issue laid to rest, the project faces one more legal challenge.

Last fall, the railroad filed a civil lawsuit in Penobscot County Superior Court challenging the city’s decision last August to take the land needed for the crossing by eminent domain. The city paid $500 for the land, an amount typically paid in such cases, Assistant City Solicitor John Hamer said at that time.

In its civil suit, the railroad alleged that the city did not follow proper procedures when it took the land, that it paid too little for it, and that the taking should not have occurred until after the law court ruled.

That case is still pending, according to Bouchard.

Bouchard said he hopes that the issue is resolved soon, so that construction can begin in May.

“We are expecting a decision within six or eight weeks. If that happens, we are assuming that the decision will come down in our favor,” he said, adding that, to date, project supporters have prevailed at each step in what has become a protracted legal battle.

Shaw House initially planned to start work in the spring of 2003. Instead, the project became mired in a legal morass.

In the meantime, the city is doing what it can to keep the project viable.

Last month, city councilors granted Shaw House a 20-year lease for the waterworks because the nonprofit needed to show “sufficient control” of the site in order to hold onto a U.S. Department of Housing and Urban Development grant that is part of the project budget.

In addition to helping meet the need for affordable housing, the project, city officials believe, would preserve the historic complex that has been deteriorating rapidly for the past several years.