Fairfax County Executive J. Hamilton Lambert ordered a review yesterday of whether the county should buy property where four houses are being built in the path of a proposed access ramp to the Springfield Bypass -- a purchase that could cost county taxpayers $1 million.

Lambert asked his staff to examine whether the county should stop the construction of the four $300,000 houses by purchasing the land on the proposed ramp site in central Fairfax County.

"The developer is sitting there with approved plans to build, and we know there's going to be an interchange there," said county transportation director Shiva K. Pant. "It's prudent to somehow try to acquire the land. It'll cost a lot more if we wait until the houses are built and people have moved in -- then we would have to buy the houses and pay relocation costs."

Under state law, a landowner must be compensated for the value of the land and any improvements on it when the government acquires it for public use.

The four houses already under construction are part of a 25-acre project that would include 23 houses. The developer, James P. Brehony, has halted construction but will not say if he will resume work.

Brehony bought the property for $702,000 in October and received building permits for his project from Fairfax County, even though most of the houses he planned to build were directly in the path of a cloverleaf ramp tentatively planned to link Ox Road (Rte. 123) with the Springfield Bypass.

According to county officials who have met with him, Brehony apparently did not know about the proposed ramp when he started construction. John T. (Til) Hazel Jr., the prominent Fairfax County developer who sold the land to Brehony, apparently did not tell him about the ramp when they negotiated the land sale.

A spokesman for Hazel has said that Hazel's firm did not inform Brehony of the ramp because it had not been given final approval.

Brehony could not be reached for comment yesterday. He declined earlier to comment on the matter.

Although the proposed route for the $200 million, cross-county Springfield Bypass has been approved, no construction date has been set because most of the road remains unfunded, including the segment that would sweep through Brehony's property.

The ramp never has been incorporated into the county's master plan, although it was recommended in studies of the bypass as long ago as 1981.

Asked yesterday if the county could have avoided the current tangle involving Brehony's land, Lambert said, "How could you catch it? Nobody had finalized the plans . . . . We had no way of knowing whether that ramp was going to be required or not."

The construction of the houses was discovered last month by a highway engineer who noticed work under way on the property.

County officials maintain that even if they had been aware earlier of the conflict between Brehony's project and plans for the ramp, they could not have stopped construction because Brehony's project already had been approved and met zoning requirements.

Lambert said the county may have several options for obtaining the money to buy Brehony's property. He said it could come from the county's general fund, or from a reserve in the county budget for road improvements. He said the county also could consider whether it could use funds from the $135 million road bond approved last fall in a referendum.

A decision on the property is scheduled to be made by the county Board of Supervisors at its next meeting on June 23.