Infrastructure offers a unique category of investment opportunities that can share characteristics of private equity, public equity and real estate investments. Most of the investment opportunity in economic infrastructure focuses on transportation and utility infrastructure assets, including existing brownfield assets and the development of new greenfield projects. Transport assets include toll roads, airports, sea ports, railroads and parking lots. Utility infrastructure includes gas and electric utilities, oil and gas pipelines, solar farms, cell towers, and related assets. There are seven elements that describe infrastructure investments: