The study consists of carrying out a socio-economic cost-benefit analysis of the improvement project of the A-4 (E-5) motorway, framed in the Adaptation, Reform and Conservation Plan of the Andalusian corridor. It will be based on official evaluation methodologies and parameters. In the analysis, the following will be taken into account: 1) investment, operation and maintenance costs of the project. 2) Operational costs of light and heavy vehicles (Depreciation, maintenance and conservation, fuel consumption and tire expense). 3) Savings in travel time. 4) Externalities of road safety (accidents) and environmental effects (CO2 emissions, pollutants). Once the results are obtained, sensitivity and risk analyses of the most relevant parameters will be carried out, and the results of the evaluation will be synthesized.