BOSTON — AROUND 20 or 25 percent of union carpenters are out of work on average in the United States. In New England, the proportion is 60 percent.That's one reason why Sigurd Lucassen, president of the United Brotherhood of Carpenters and Joiners, calls for the nation's policymakers to adopt a "national development strategy to rebuild America." "We have got a nation falling down around our ears," says the head of the largest construction union in the country, with about 600,000 members in the US and Canada. He wants his members and other workers to be employed rebuilding the nation's infrastructure - its highways, bridges, schools, water treatment facilities, and so on. The union's "ready to rebuild America" campaign was launched in June. Since then Mr. Lucassen, with the help of a public relations firm, has been talking to the press around the country. One commonly asked question, he notes in an interview, concerns how to get the money for an expanded public works program when the federal budget is already nearly $350 billion in deficit. He replies that President Bush did find the money for the Gulf war, coming to the help of the Kurds, and other overseas activities. "We got a great president," he says. "He is solving the problems of the world." But in this country, millions are unemployed, he adds. "They are tax users, not payers." A 1 percent reduction in unemployment would provide "$30 billion in new federal revenues." Lucassen argues that the nation can't afford not to fix up the country's infrastructure. Economic studies show that money spent on such projects boosts productivity. Employees spend less time commuting to work. Transportation companies can move goods faster. Maintaining the present condition of highways and roads through 1995 would provide 500,000 more jobs, he holds. Constructing and repairing water and sewer facilities would create 250,000 more jobs. Maybe, says Lucassen, the government should divide the budget in two parts, with one for capital and maintenance projects, and the other for operations. The capital budget would normally be in the red. "We ought to have a Marshall Plan for the United States," he says.