Some people are questioning the use of a long-term public-private partnership (P3) for the Maryland express toll lanes and American Legion Bridge replacement. Because P3s are complex, it’s not surprising that critics misunderstand this subject.

First, a long-term P3 involves the state (public partner) delegating to a competitively selected private partner the responsibility to design, build, finance, operate and maintain a major infrastructure facility. The long-term agreement assigns risks to the party best able to deal with each risk. Typically, cost overruns and late completion are among the risks the private partner accepts.

Second, there are two different kinds of P3, each financed differently. Maryland’s Purple Line light-rail project was financed based on annual payments of taxpayer money to the private partner, adjusted based on performance. In this kind of P3, some risks are transferred, but the risk of too few customers is retained by the state. The priva