The Fairfax County planning staff wants to strengthen its arsenal against potential commercial development along Leesburg Pike, west of the Tysons Corner area to the Loudoun County line.

The staff is asking the county Board of Supervisors and Planning Commission members to restrict future development along the north and south sides of the busy thoroughfare to residential use. The matter is scheduled for Planning Commission consideration in March.

The county's present land-use plan, which is considered the guide for zoning decisions, basically sets the Dulles Airport Access Road as the barrier against the westward spread of large-scale, Tysons-Corner-style development. But the staff wants the board to adopt amendments stiffening the language in the land plan.

The proposal would limit future development to residential use, along with development such as churches that are allowed in residential neighborhoods under special-use permits handled by the county's Board of Zoning Appeals.

The proposed amendments are almost certain to win support from the Great Falls and McLean citizens associations and Reston-area residents.

Supervisor Nancy Falck (R-Dranesville) supports the proposal, saying, "It would strengthen the existing land-use plan by reinforcing what is currently planned for low-density residential development."

Falck said the staff proposal resulted from a recent "study of the goals of the comprehensive plan" and how effective the plan has been as a tool for decision-making.

William Keefe, head of the county's comprehensive plan branch, called it an effort to clarify the plan as it relates to commercial development along Rte. 7. Rather than deal with specific parcels all along the corridor, "we will be talking broad policy issues here," he said.

Although official statements said this proposal is needed to strengthen the existing code, developers said they believe the county is making sure its position calling for more residential development is based on enforceable policies.

Last year, several major challenges to the land-use plan along the corridor sparked strong opposition from those who live in the neighborhoods on both sides of Rte. 7.

Although the Planning Commission killed the proposals during its 1985 review of the comprehensive plan, several proposals concerned residents. One of those called for expansion of the existing Hazelton Labs facility at Rte. 7 and Towlston Road, which exists by special permit. The county last year denied the firm's request to expand and set up corporate headquarters for its international operations.

The commission also killed an effort to change the land-use plan for 98 acres immediately northwest of the Dulles road and fronting on Rte. 7. NVLand, the McLean-based firm that owns the site, immediately filed a rezoning request for the same property but has yet to file development plans.

In recent weeks, several residential rezoning bids calling for either cluster residential developments or planned-development housing projects have been filed with the county for land along Rte. 7.