In July 2012, the municipal government of Rio de Janeiro launched the bidding process of a Public-Private Partnership (PPP) for developing a light-rail transport system (or VLT, which stands for Veículo Leve sobre Trilhos). The PPP comprised the construction of a network of light rail vehicles in downtown and the port areas of the city of Rio de Janeiro. An overview of global infrastructure is presented, and PPP contracts arise as a relevant alternative of infrastructure development especially in emerging countries. The VLT project characteristics and the methodology of economic valuation of the concession are described in this work. The valuation is based on the Real Options Theory, where the demand is the stochastic variable. This work proposes the analysis including the demand guarantee option proposed in the contract. The results are compared using the Net Present Value (NPV) analysis in a range of scenarios, with sensitivity analysis on two of the main concerns of the Project: volatility and demand floor levels for guarantees.