It sounds like a great opportunity. Governments worldwide are spending more than $1 trillion a year to build roads, power grids and more. Now comes a host of exchange-traded funds the baskets of stocks or other securities that trade as a unit focusing on infrastructure, too, making it easy for individuals to get in on the action.

But it turns out more than a few analysts are skeptical about these types of ETFs. For starters, two of the biggest are loaded with utilities; they account for over a third of the iShares S&P Global Infrastructure Index ETF and a whopping 88 percent of the SPDR FTSE/Macquarie Global Infrastructure 100 ETF. Utilities are certainly spending billions on projects, but it could take years for those projects to make money. Meanwhile, those stocks are dragging down returns. The iShares ETF is up just 15.8 percent this year, and the SPDR ETF is up 3.4 percent, well below the performance of the broader stock market. Utilities play a big role in infrastructure and deserve to be in an index, says Jerry Moskowitz, director of business development for FTSE Americas.

A better option, some pros say, is to buy the ETF that focuses on Chinese bridge builders and other companies in emerging economies. Those economies are growing at three times the pace of developed Western economies, according to CIBC World Markets. Chinese stocks make up 15 percent of the PowerShares Emerging Markets Infrastructure Portfolio; its top holdings also include the Brazilian mining giant Vale. Only 2.5 percent of the PowerShares ETF is invested in utilities. Expenses are high, though $75 for every $10,000 invested, more than other infrastructure ETFs.