Milan Metro Line 4

The metro that brings Milan closer to Europe


Start of works


Progress status


Data updated to March 2022

Milan, Italy
SDG Obiettivi di sviluppo sostenibile
Climate action Climate action
Sustainable cities & communities Sustainable cities & communities

A driverless metro crossing Milan’s historic center, reaching Linate in a very short time

Milan’s M4 line metro will be entirely underground, and fully automated (driverless). It will connect Linate airport to Milan’s San Cristoforo railway station. Crossing Milan’s historic center, it will allow rapid movements along the city’s east/south-west route, and a significant reduction in road traffic.

Besides the interchange with Linate airport, the work will also have two interchange stations with the existing underground line: with the red line, at San Babila station; with the green line, at Sant’Ambrogio. It will be connected to the suburban railway lines in the Forlanini FS, Dateo and San Cristoforo stations.
The work will also be connected to the yellow line in the Missori station, thanks to a short pedestrian connection that starts from Sforza Policlinico station.

The project involves buildings two single-track tunnels, one for each direction, 21 stations, 30 structures and a workshop depot. It mainly develops within the perimeter of the Municipality of Milan, falling for a small portion into the territory of the municipalities of Segrate and Peschiera Borromeo, near the eastern terminal.

Supply Chain M4 Metro Line: Over 1000 companies pushing for a sustainable Milan

1,196 almost entirely Italian premium supply chain companies are participating with Webuild to build a metro designed to encourage citizens’ participation.

Technical data 



Line structures (emergency exits, etc)



The M4 is not merely technological excellence and design quality. The new metropolitan line of the Municipality of Milan, in fact, will significantly strengthen the sustainable footprint of the Lombard city, with significant environmental benefits: the line will allow a reduction in traffic in the city of approximately 180 thousand thousand per day, with an annual reduction in CO2 emissions of up to 75 thousand tons.

Advantages and benefits

Passengers per year


Daily avoidable car trips


Emissions of CO2 saved per year

75,000 t


Technology and innovation at the service of the city of Milan

To complete one of Europe’s most important underground sustainability projects and win an engineering challenge, the Group is working on 56 open construction sites. Some of them are located in the center of Milan, with 1,500 currently operational people. Realizing a strategic work for a city like Milan – crossing its historical heart, underground – also means putting technology at the service of the infrastructure, to preserve and protect Milan’s artistic and cultural heritage.

Webcam: live from the construction site

The Metro Line M4 construction sites are now streaming live. Currently, four webcams (two of them at the San Babila construction site, and two at the Sant’Ambrogio one) are streaming live images of the ongoing activities.

San Babila construction site

Webcam 1

San Babila construction site

Webcam 2

S. Ambrogio construction site

Webcam 1

S. Ambrogio construction site

Webcam 2