COMSA, whose legal name "Legal name (company)") is COMSA Corporación de Infraestructuras, S.L., is a Spanish corporation headquartered in Barcelona, ​​Catalonia.[1]​.

It has a railway operating company license from the State Railway Safety Agency for goods on the General Interest Railway Network since 2024,[2]​ and a Single Safety Certificate since 2025.[3]​ It had previously operated in the railway freight transport market through COMSA Rail Transport, a subsidiary that it sold in 2018 to SNCF.

It was founded as José Miarnau Navás Construction Contractor in 1891, in Reus, by the railway worker José Miarnau Navás, focusing its activity on railway infrastructure, such as the construction of the La Sagrera station in Barcelona.[4]​ After the founder died in 1934, the company changed its name to Hijos de José Miarnau Navás.[5]​ After the war ended Spanish civil, the company diversified with road and building projects, one of its most notable works of those years being the reconstruction of the Amposta suspension bridge. In 1964 it changed its name to Construcciones Miarnau, and again, in 1976, to COMSA.[6]​ It participated in works such as the first Barcelona Ring Belt, the doubling of track on the San Vicente de Calders-Molins de Rey line, the construction of the first Madrid-Seville high-speed line, and the Palau Sant Jordi. In 1982, Comsa developed the Rapid Track Renewal Train (TRR), the only one in Spain that represented a first-rate technological innovation.[7]​.

After its merger with Estudios, Montajes y Tendidos Eléctricos (EMTE) in 2009,[8]​[9]​ it was renamed COMSA EMTE, but in 2015 it was integrated into the COMSA corporation, which was organized into three business areas:[10]​.

In 2023, it won a competition organized by the Israeli occupation authorities for the construction of the Blue Line between West Jerusalem and certain illegal settlements, such as Gilo.[11]​.