In growing numbers, rich families are investing in infrastructure, putting their money to work on remote mountaintops, bustling harbors and across deserts the world over. This broad category covers the structures and systems needed to keep economies running and growing. So think highways, public transit, power plants, telecom backbones─and don't forget schools, hospitals, dumpsites and ports. 'We see it all the time,' says Alan Harter, of Pactolus Private Wealth Management, a registered investment adviser in McLean, Va.

Most wealthy families get into infrastructure the same way other investors do: indirectly. They buy stock in multinationals whose wares and services generally accompany development─outfits like Caterpillar, Haliburton and IBM . But some are making direct investments. These hands-on deals can involve private-investor groups that come together to build or buy projects and operate them over a relatively long period.

The Presidio Parkway, a six-lane toll road that will connect the city of San Francisco to the Golden Gate Bridge, is one project that some private investor groups are considering. In another case, Citi Infrastructure Investors, Ullico and J.P. Morgan Asset Management Infrastructure Investments Group have been looking at putting money into Chicago-area projects. One deal calls for spending up to $225 million to reduce energy consumption at municipal facilities. The savings initially would be used to pay back the private investors with interest.

Some of the infrastructure investors─Harter calls them 'uber bulge bracket families'─still run businesses that made them rich. Infrastructure is central to their wealth-building strategies; securities can account for as little as 15 percent of their portfolios, says Harter. Some are still steamed about the stock market in 2008, which saw the average U.S. millionaire's securities portfolio shed about 30 percent of its value, according to research firm Spectrem Group. This distrust sometimes extends to other alternatives. 'Our clients look distastefully on blind-pool' investments such as hedge funds, says Harter, whose firm manages about $430 million.

They also want in on growth in emerging markets, where many of these projects are occurring. But they want to get in on it first-hand, in keeping with a post-2008 move toward assets you can hold or walk on─gold, collectibles like wine and art, and types of construction and real estate that seem likely to produce cash over long periods.

But there's a bigger impetus for this burgeoning interest in infrastructure investing, says David Friedman of Wealth-X, a marketing consultancy to firms with rich customers: The families involved tend to think they're better at making money than garden-variety investment managers. 'They want their wealth managers to hedge risk around a liquid portfolio' in the name of capital preservation, says Friedman. But to generate steadier and bigger returns over time 'they want to put risk capital in things they know.'

So a family that's willing to plunk down $15 million to go thirds on a container dock in Djibouti is apt to know something about piers already, or the Horn of Africa, or both─or be in close cahoots with people who do. For these projects, cash-out doesn't come in 10 years and it's not predicated on a sale. These investors measure investment return in terms of cash flow through the operating life of a project, or for an agreed-on period that's likely to span decades, says Harter. Indeed, one U.S. family is eight years into a multi-country waterworks deal that has yet to pay a dime, says Norman Anderson, of CG/LA Infrastructure, a Washington, D.C.-based firm that develops projects around the world.

This kind of patience calls for deep pockets. Management fees and the occasional need to retain local experts can also add to the cost. But David Doll offers a reservation beyond hefty antes and long lockdowns. 'These deals are fraught with 'translation errors,' ' says Doll, who runs Sequent Asset Management in Houston, an investment-advice firm for the ultra-rich that manages $400 million. 'You're talking about different accounting standards, different business practices.' Unstable local governments can be another risk.

Given all the complications, direct infrastructure strikes Anderson as an expensive way to get an 8 percent or 12 percent return on investments─the standard range, he says. You also don't get a break on the toll, even if you own the road.