Montgomery County Executive Douglas M. Duncan yesterday proposed a large spending boost for transportation projects over the next six years, calling congestion on county roads "an increasing threat to the environment, to our economy and to our overall quality of life."

"It is not a question of whether to build more roads or use more mass transit--we have no choice but to do both," Duncan (D) said during his annual address on the state of the county.

Using the speech to outline his budget priorities for the coming fiscal year, Duncan listed the seven tax cuts he's pushed over the past five years and said now is the time to invest in the future. He wants to spend most of the estimated $83 million available for new programs on transportation projects, schools and conservation efforts, saying in an interview that he would not propose a tax cut in his next budget.

"We need to invest today because we have become one of the fastest-growing counties in the state," Duncan said. "And our popularity, while gratifying, is placing a heavy strain on our county's infrastructure."

To that end, Duncan proposed spending an additional $365 million over the next six years to expand bus service, build major roads ahead of schedule and improve intersections. In the plan's final year, the county would spend 50 percent more on transportation than it does today.

Many of the details of the plan, which Duncan dubbed the Traffic Relief Investment Program, will be filled out in the coming months as county officials draw up the budget for the fiscal year beginning July 1. But county officials said yesterday that the plan, if approved by the County Council, would add more buses to busy mid-county routes, speed along such major projects as the Montrose Parkway south of Rockville and commit more money to repairing neighborhood streets.

Duncan also said he would continue pushing for an intercounty connector, the proposed parkway that would join Interstate 270 and Interstate 95 north of the Capital Beltway. Gov. Parris N. Glendening (D) killed the $1 billion project this year.

Duncan's plan comes as State House leaders consider whether to commit a portion of Maryland's $1 billion surplus to transportation improvements.

In general terms, Duncan said Montgomery public schools would receive more money to hire teachers and improve staff development at a time when the system is slipping in statewide rankings based on standardized test scores. The budget to be proposed today by School Superintendent Jerry D. Weast seeks an estimated 7 percent increase in spending, which would consume most if not all money projected to be available for new programs.

Duncan endorsed parts of Weast's plan, and he said last night that he would use additional county money to expand a campus-based mental health program and to assign a police officer to each cluster of high, middle and elementary schools.

"As we work together to improve the quality of our schools, we have to do all we can to require a safe learning environment," Duncan said.

While much of his speech was devoted to transportation and education, Duncan also said he would begin a program to preserve forest land at a time when the county is experiencing rapid development.

The program's cost still must be worked out before Duncan submits his budget in March. But Duncan said he will form a forest conservation task force, comprising members from the public and private sectors, to help design a program that advisers say could allow more forest removal in some areas in exchange for guaranteed protections in others.

"We need to invest in the county's ecosystem and environment," Duncan said. "Clearly, to preserve our quality of life, we've got to ensure that the air is pure, the water is clean and the land is free from hazards."