In 2008, the Indian highway authority granted a contract to a private company, a subsidiary of L&T Infrastructure Development Projects, to establish a six-lane toll road beginning in the state of Tamil Nadu, running north from the city of Chennai. By the government’s reckoning, the highway was supposed to be finished three years later at a cost of about $65 million. But difficulties in acquiring land led to delays and cost overruns. Two years ago, the company defaulted on its loans. The road has yet to be completed.

That Mr. Trump will find investors for his plans may be taken as a given. Be it Japan, Europe or North America, central banks have maintained rock-bottom interest rates in an effort to spur recovery from the worst financial crisis since the Great Depression. As a result, money managers are on the prowl for investments offering a decent rate of return.

“Infrastructure investment, which typically yields 3 to 4 percent, looks relatively attractive,” said Linda Yueh, a visiting senior fellow at the London School of Economics.

But others question why the United States needs to involve private money. The American authorities can tap vast and sophisticated bond markets, with municipal bonds exempt from federal taxes.

“The borrowing costs for the U.S. government are zero,” said Mark Weisbrot, a co-founder of the Center for Economic Policy and Research in Washington. “There’s simply no reason to turn to private capital and all the complications, uncertainties, and opportunities for corruption and bad outcomes that you add to the mix.”

China provides a textbook case of what happens when the state invests aggressively in infrastructure. From 1992 to 2013, China allocated about 8.6 percent of its economic output toward infrastructure projects, according to an analysis by the McKinsey Global Institute. In 2013 alone, China spent $829 billion on infrastructure, more than the United States, Canada and Western Europe combined.

Inefficiency has added to the cost of many projects. Corruption has erected no shortage of white elephants. Still, China’s huge expansion demonstrates the benefits of the state guiding infrastructure spending.