Line S4 (Milan suburban railway service)

Line S4 is a commuter rail line serving Milan, Italy, and its surrounding metropolitan area. It is part of the Milan suburban railway service (Servizio ferroviario suburbano di Milano), operated by Trenord. The line runs from Camnago Lentate in the north to Milan Rogoredo, traversing the city via the Passante ferroviario, an underground railway tunnel crossing the city from northwest to southeast.

The S4 line offers frequent service, typically every 30 minutes during peak hours and every hour off-peak. It connects several municipalities in the Province of Como and the Province of Monza and Brianza to central Milan. Key stations served along the route, in addition to the termini, include: Saronno, Rescaldina, Rho, Milano Bovisa Politecnico, Milano Lancetti, Milano Porta Garibaldi, Milano Repubblica, Milano Porta Venezia, and Milano Dateo.

The S4 is an important component of Milan's public transportation network, providing commuters with a direct and efficient rail connection to major hubs within the city, including interchange stations for the Milan Metro (subway) and other suburban rail lines. Its operation helps to alleviate traffic congestion on roadways leading into Milan. Service frequency and station stops may be subject to change, so passengers are advised to consult Trenord's official website or mobile app for the most up-to-date schedule information.