Tools that provide quantifiable ratings and / or certifications of infrastructure projects’ degree of sustainability. These ratings / certifications are based on well-defined and structured sets of quantitative indicators. Most rating systems work with a third-party certification process that assigns scores based on a project’s performance against the set of indicators. While some can be universally applied to infrastructure in all sectors, many rating systems address specific sectors like waste, transport, or renewable energy. Rating systems provide guidance for decision making across several lifecycle phases: during Project Planning and Design phases they can be used to compare different alternatives; during Construction and Operation they can serve as benchmarks to quantify a project’s progress in terms of sustainability.