The commuters didn't ask questions when mysterious notices appeared offering free rides to the Silver Spring Metro station. When the shuttle buses started arriving at their apartment buildings north of White Oak in Montgomery County two months ago, they were ready to hop on board.

"It's free, it's clean, it's dependable," said a secretary who was one of a dozen or so people waiting for one of the shuttle buses last Friday morning. She, like the 27 others who use the service, used to drive her car down traffic-clogged Rte. 29 to the subway station, but now she leaves it at home. "You don't have to pay $1.50 a day to park in Silver Spring," she said. "It's better than Metrobus."

Her daily free commute is the gift of developer Jay Alfandre -- a man the White Oak commuters never heard of -- and his partners, Beltway Limousine Co. Alfandre wants to build an office building about a mile south of the apartments, but county planners told him the roads already were too crowded to accommodate another development. So he has promised to run the van service indefinitely in an effort to reduce traffic before returning to the planners later this month to get his proposal approved.

Indeed, builders wanting to tackle the Montgomery County Planning Board these days find they have to tackle rush-hour traffic first. Traffic is so bad in some parts of the county that a virtual building moratorium is in effect along much of the important I-270 and Rte. 29 corridors.

So if he wins permission to build, Alfandre expects a van pool arrangement to be part of the deal. His is not an isolated case. Other builders and developers have organized ride-sharing schemes and built commuter parking lots.

Still more builders and developers have banded together to form "road clubs," to pool their money to pay for road improvements, new roads, new bridges, intersections and traffic lights. In exchange, the county gives them permission to build offices, apartments and houses.

The shift of more responsibilities to the developers was not a conscious move by the county, according to officials, but it is a byproduct of efforts to control growth. Nonetheless, they concede, at a time when Montgomery County's population has expanded rapidly and its budget become more constrained, some of the burden of expensive road building has been unloaded onto the developers.

Most builders remain adamant that paying for public roads is the government's job. "I don't like being put in this position," said Alfandre, who complained that almost all his projects now involve road improvement work. "But it's a business decision."

Yet the builders are forking out money for roads and van pools. Observed Jeff Zyonts, research coordinator for the county planning board, "That's the only way things are getting approved." And because under county law developers cannot get approval for projects when the roads are considered inadequate, the builders are often the ones to propose the new road clubs, according to county planning board chairman Norman Christoller. "There's a tendency on the part of the development industry to complain about them on the one hand," he said, "and to beg us for them on the other."

Builders, for example, are contributing $750,000 and giving land for road improvements along Rte. 28 north of Rockville and paying the total $1.8 million for expanding a one-mile section of Rte. 118 in Germantown. Builders' contributions are expected to pay for roughly $5 million of the planned $30 million Great Seneca Highway between Rockville and Germantown, according to county officials.

The county is negotiating with about 30 builders who want to form a "super road club." The builders have offered to split the cost of $187 million in road improvements in Germantown -- the largest such scheme ever proposed in this area. In exchange, they would receive permission to build thousands of offices and apartments. Developers in Fairfax already know how the system works. In the case-by-case planning and zoning process there -- known as the "proffer" system -- they have long found themselves proffering public road projects. But as development continues to be a booming business, they have found themselves proffering more.

For instance, developers of the recently announced Centennial Gateway commercial and residential complex, in Fairfax Center near Fair Oaks, have promised $5 million for highway interchanges.

The county has collected $28 million for road improvements, including construction of a portion of the Springfield Bypass, from developers of the nearby Fair Lakes development, west of Fairfax City.

Developers in Prince George's County, where traffic jams are rarer, so far have not been expected to cough up money for public road projects. But Don Spicer, an assistant to county executive Parris Glendening, said officials are talking to developers about participating in road projects. In Montgomery, builders said they learned quickly how the system works.

When Rockville builder John Pettit started planning 1,950 houses near the intersection of Snoffers School Road and Rte. 124 in the Gaithersburg area, county officials told him the intersection was not big enough to handle the traffic.

So Pettit formed a "road club" with three other developers planning projects in the area and offered to rebuild and widen the intersection. The project was approved, 600 houses have been built, and the intersection improvements are in the engineering stage.

The project cost, he said, comes to about $1 million. He said it will add $300 to $500 to the cost of each house. "I have reservations," he said. "I hate to keep adding on to the price. It's the people buying houses that are paying for it. The cost is being passed through to the ultimate consumer."

But he said he knows this is only the beginning of major road projects he will have to do. "They have already set the pattern," he said. "If you want to build here, that's what you are going to have to accept."

The increased cost for housing, however, has raised some concerns. "The fees keep getting tacked on and tacked on, and it's making it more and more difficult for builders to produce affordable housing," said Stanley Halle, president of the Suburban Maryland Building Industry Association. "There's no end to the charges that keep getting added on."

The road clubs and developer-sponsored van-pooling arrangements are new to Montgomery County: The first was negotiated about five years ago when development began outpacing county and state road building, and few are completed. Their long-term impact remains a subject of speculation and controversy.

Developer David Weiss charged these road clubs are "the result of the public sector not meeting its obligations to the public . . . . They can't provide everything immediately when it's needed, but it's their responsibility to provide it." But Weiss said county officials seem aware of the problem and are willing to work with developers on it.

County council member Scott Fosler said road clubs and van pools may tackle traffic. But the development they allow, he said, could cause shortages of other public facilities, such as schools and fire houses.

Indeed, road clubs have developed without any action by the County Council. "The problem is that this gets done incrementally, without any thought given to it," Fosler said. The council, he complained, "never sat down and discussed what the policy should be."

Rather than wait and hope that the state or county would expand the road system, builders started volunteering to do it themselves. "It's really a product of necessity more than anything," said John J. Clark, a transportation planner with the Montgomery County government.

Most of the road and ride-sharing schemes remain in the planning stages, but Clark and other county officials seem certain of success. "The potential is so great," Clark said, "not only to solve current problems but for whatever future traffic is going to be."

Yet zoning attorney Charles Dalrymple said the process is so disorderly that getting subdivisions approved is like playing Monopoly: "I'll give you two right-turn lanes and a signal six miles from the site, and you'll give me approval."

The system "is not real intelligent," he added, "but it does get improvements made. I don't think I've had many cases where the developer says, 'Nope, I'm not going to make the improvements.' "

There remains an enthusiasm for the opportunities for development that road clubs and van-pooling schemes have opened up.

When developers started planning the Knightsbridge development -- 2,200 apartments near Briggs Chaney Road and Rte. 29 -- they realized that traffic on Rte. 29 was nearing the saturation point. But aided by zoning lawyers John W. Neumann and James Tavel, they came up with an idea that, as Neumann put it, "probably greased the way."

First, they promised to build a five-acre, 400-vehicle commuter parking lot on Rte. 29, open to anybody who chose to use it. Second, they promised to start a commuter-van pool operation with one van for every 100 residents.

The parking lot has been built and the van pool operation is scheduled to begin next year, after the first 600 apartments are occupied. Under a 50-year agreement, each resident is to pay $84 a year toward the commuter bill, while users pay the remaining half. The plan, and the dollar amounts, can be renegotated with the county each year.

"I think it's a great idea," said Neumann. "I want to see this kind of thing done more and more. We can't just keep pouring cement."