The General Accounting Office is seeking to learn if U.S. requirements are causing costly unnecessary delays in several rapid transit construction projects, including Washington's Metro, according to GAO spokesman Gerald Killian.

Specifically, the congressional watchdog agency is investigation whether the Urban Transit Administration, an agency of the federal Department fo Transportation, is taking too long to approve construction grants for the projects, Killian said.

About 80 per cent of the cost of such rapid-transit projects is paid for out of federal funds; while 20 percent of the funding comes from state and local governments.

Among the cities with projects under GAO investigation, aside from Washington, are Baltimore Philadephia, Buffalo, Denver, Miami and San Juan, Killian said.

The GAO started its investigation after Sen. Charles McC. Mathias (R-Md.) asked the agency to find out if the federal approval process was costing taxpayers millions of dollars by delaying rapid transit projects and thus driving up costs, Killian said.

Mathias, a member of the Senate's transportation subcommittee, said last May that UMTA's "alternative analysis" process aimed at reducing administrative and construction costs on Metro "has actually resulted in higher cost due to delay and inflation."

Theodore C. Lutz, Metro's general manager, said the alternative analysis process has added between $50 million and $100 million to the cost of Metro, which eventually is expected to exceed $6 billion.

he impact of the GAO's study on Metro may be negligible, since the subway's construction is in such an advanced stage that any changes resulting from the GAO investigation are unlikely to have much impact on it, Killian said, "unless they extend the subway further."