A developer's request to take some of the car trips allotted to one future development and move them to another has sent Montgomery County planners huddling to work out a policy for the complicated matter.

For the past several years, the county has been dividing the number of future automobile trips among the owners of undeveloped property along some traffic-choked roads and highways, planners said.

The developer is one of several to put up $800,000 collectively to make improvements on Route 118, which runs along their properties, planners said. In return for the funds for the road improvements, the planning board allotted the developers car trips based on the size of their properties and intended use.

The improvements to the road are now under way, and developers are starting to apply to the planning board for final approval of their projects, said Bud Liem, transportation coordinator for the county.

"We have studies that state a certain number of car trips will be generated per 1,000 square feet of development, depending on whether it's commercial, residential, retail or whatever," Liem said. "It's an excellent planning tool to know how many car trips you are going to have to deal with and who is responsible for what."

The developer, Stanley Martin Communities Inc., under the name Northlake Medical Associates, wants to build a medical clinic and doctors' offices on 3.3 acres in a residential section of Germantown, according to a staff report.

Because residential development generates less traffic than a medical clinic, the developer proposes to build a smaller office building on an adjoining parcel of land he owns and transfer the allotted car trips from that property to the medical clinic.

The office building would be reduced by 64,615 square feet to allow the requested 26,800 square feet of medical clinic, said Stephen P. Elmendorf, attorney for the developer.

"This would benefit the county because the medical clinic will generate less traffic in the morning rush hour than a larger office building would," he said.

The planning board, which heard the request last week, voted to defer the matter until members could make a policy decision about the transfer of road trips.

But planning board Chairman Norman L. Christeller said that he and other board members have serious reservations about the trip-transfer request and that he doubts the board will agree to it.

"We can't be put in the position of approving this for one developer and then have someone else come in and demand the same thing," he said.

Christeller said he envisions the possibility of developers "hoarding trips" -- getting approval for a certain amount of car trips for one property, then parceling the trips out to other developments in the area.

"It might encourage people to grab up trips and hoard capacity, which would make it next to impossible to plan for an area," he said.

This is not the first time the county has faced such a question. Last fall, the same developer asked permission to transfer allotted car trips from one residential property to an adjacent residential property. The board agreed, after the developer legally combined the properties into a single parcel.

Christeller said the developer may be allowed to do the same thing in the case of the medical clinic. He said that if the developer combines the commercial and residential properties into a single commercially zoned parcel, the board may readjust his car-trip allotment.

"There is a way this might be done," Christeller said. "But it should be done in a way that does not set a precedent."

Elmendorf, however, countered that a decision granting his client's request to transfer trips from one property to another may not result in a precedent.

"No case is a precedent unless the body that makes the decision views it as a precedent," he said.