The Trump administration’s proposal to repair and expand America’s roads, bridges, ports and airports includes the expanded use of public-private partnerships (P3s). Under P3s, state and local governments award franchises to private companies that agree to pay for and manage the infrastructure in exchange for the companies receiving toll payments from future users. A number of P3 projects currently operate in the United States, and they are common in other developed nations.

Despite the growing embrace of these projects by policymakers around the world, the Trump proposal is being met with skepticism. For example, the New York Times dropped this article last week ahead of Trump administration efforts to promote the proposal. According to the article, “experts agree” that “there is little hard evidence” that such projects produce long-term benefits to the public as compared to traditional government-provided infrastructure. (That “agreement” came as news to many transportation experts.)

At heart, the article charges that P3 programs are “win/​no lose” proposals for the private firms: if the projects prove popular, the firms profit—sometimes handsomely, to the detriment of consumers. But if the new infrastructure doesn’t get many toll-paying users, the financial losses from the projects fall on taxpayers.

To illustrate this, the NYT cites California State Route 91, one of the first P3s in the United States. Initially intended to reduce congestion, the project awarded a private company the right to build and operate a special four-lane toll road in the middle of the highway. The road was “congestion priced,” meaning the tolls fluctuated in order to limit use just enough to guarantee the free flow of traffic.

The original lease on the road included a noncompete clause that limited the state’s ability to add additional lanes to the non-P3 part of SR-91 or to build parallel infrastructure. This resulted in heavy congestion on the old lanes, pushing motorists onto the toll lanes and producing a financial windfall for the toll company. That ultimately prompted Orange County to buy out the toll company for $207 million in 2003.

However, the SR-91 problem is not inherent to P3s. It arose as a result of the conditions under which the franchise was arranged. Traditionally, P3s have been awarded through negotiations between private companies and transportation authorities, leading to high initial private investments and uncertainty about demand for the road. That risk, in turn, encourages toll road companies to want protections like the noncompete clause.

But there are ways to reduce the risk to the private companies while also protecting taxpayers and infrastructure users, as transportation experts Eduardo Engel, Ronald Fischer, and Alexander Galetovic explained in Regulation back in 2002. The authors suggest using a particular type of auction to award highway projects: a Present-Value-Revenue (PVR) auction. In a PVR auction, it is understood that the private company will only operate the road for a time, and then it will be returned to the public. Regulators set a maximum toll level that motorists will be charged to use the road. Private companies then bid on the amount of toll revenue, measured in present value terms, they would want to receive before the road is returned to the public. The lowest PV bid wins. The winner collects revenues and pays for the maintenance of the road until it has earned the revenue that it bid in present value, regardless of whether it takes five years or 50. Thus, the term of the franchise is variable depending on road usage; if usage is less than expected, the lease extends. If usage is greater than expected, the lease is shorter-term. The private company won’t “lose,” but it won’t make a windfall either.

PVR auctions provide resilience against shocks, such as lower-than-expected traffic. They also provide the basis for governments to buy back roads. For PVR franchises, a fair buyout is simply the difference between what the company has earned to date and the total revenue it bid to earn in present value.

In the case of SR-91, a PVR auction would have reduced the risk of the investment, and therefore would have precluded the need for risk-reducing contract obligations like the noncompete clause. If difficulties still arose, the government would have been better equipped to buy back the road for a more reasonable price.

Written with research assistance from David Kemp.