Société Marseillaise du Tunnel Prado Carénage Société Marseillaise du Tunnel Prado Carénage (ALTPC.PA) operates and maintains urban toll tunnels in Marseille, France, including the core 2.5 kilometer Prado-Carénage tunnel that connects the city's southern districts and the A50 motorway to the east with the northern A55 motorway via the city center; the Prado Sud tunnel linking to southern neighborhoods; the Louis Rège (or Rege) tunnel connecting Prado Avenue to the Prado-Carénage tunnel; and the Schloesing access road. The company, founded in 1989 and headquartered at 3 Avenue Arthur Scott, Marseille, provides financing, construction, upkeep, marketing, and operational services for these infrastructure assets under concessions, primarily serving local vehicular traffic to enhance urban mobility in the Transportation and storage sector with a focus on support activities for transportation. Major shareholders include Eiffage and Vinci Concessions, whose groups recently finalized a concession extension project for the Prado-Carénage tunnel via a 2017 amendment with Aix Marseille Provence metropolis, incorporating a new EUR 60.5 million financed access road on Schlœsing boulevard; entered exclusive negotiations in 2021 for a simplified tender offer followed by squeeze-out at EUR 23 per share; and appointed Julien Thomas as Directeur Général in May 2025.