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Milan’s New M4 Metro: Milan's new metro line

Metro M4 Milano , Italia - Webuild

Milan, evermore in the heart of Europe: east to west in just 30 minutes with the new M4 Milan line

The M4 or "Blue Line" is the new Milan metro line, an engineering project that is essential for developing the Lombardy capital and strengthening its position in Europe. Milan’s M4 will connect the city from east to west, passing through the historic centre and reaching Linate airport. From its two terminals, Linate and San Cristoforo, the Milan M4 line is 15 km long with 21 stations. Travelling between these two stations will only take 30 minutes.

The new metro line will be entirely underground, fully automated and driverless, allowing for the use of safer and more efficient driverless trains. The M4 will cross Milan's historic centre, allowing rapid travel along the east/west route of the city, significantly reducing road traffic.

In addition to the interchange with Linate airport, the work will have two interchange stations with the existing metro line: with the red line at San Babila station and with the green line at Sant'Ambrogio. The M4 will be connected to the suburban railway lines at the Forlanini FS, Dateo and San Cristoforo stations. Thanks to a short pedestrian connection to the outside that starts at Sforza Policlinico station, the work will also be connected to the yellow line at Missori station.

As the map of Milan’s M4, below, shows, the project involves building two single-track tunnels, one for each direction, 21 stations, 30 buildings and a workshop depot. The M4 Metro mainly falls within the perimeter of the Municipality of Milan, running for a small portion into the territory of the municipalities of Segrate and Peschiera Borromeo, near the eastern terminal.

Find out more about the Milan's M4 Metro Line Project

Fact Sheet of the Milan's M4 Metro Line
Milan East West – Milan’s new Metro - The work in numbers
Webcams in the construction site

Webcams in the construction site

Milan's M4 metro works can be followed live, in line with Webuild's pioneering spirit, which has always focused on innovation. The activities in Milan's M4, at the San Babila and Sant'Ambrogio construction sites can be followed live thanks to 4 webcams that show how Milan's new metro line is being built, in real time.

The construction sites live

July 4, 2023 - Inauguration of the San Babila Station of the new M4 metro line

Milan’s Linate airport is now just 12 minutes away from the city’s historic centre following today’s inauguration of the San Babila Station of the new M4 metro line. The Tricolore Station, which precedes San Babila along the line’s route from the airport, has also opened to the public. 

Present at the official ceremony, alongside Webuild Chief Executive Pietro Salini, were Italian Infrastructure and Transport Minister Matteo Salvini, and Milan Mayor Giuseppe Sala.

San Babila and Tricolore join the six stations of the M4 that are already in operation, running from Linate Airport to Piazzale Dateo, before heading to the centre via the Repetti, Stazione Forlanini, Argonne and Susa stops. Once fully completed, the line will have 21 stations and 15 kilometres of track, running across the city to connect the eastern end where the airport is located with the western end to the San Cristoforo terminus.


Read the press note


When the Milan M4 is open, it will be capable of transporting 24,000 people per hour, per travel direction. It is expected to be used by 86 million passengers per year, thanks to the train frequency: every 90 seconds during peak hours. In mobility terms, the M4 will significantly impact the city: when it is operational, Milan's total metro network will reach 118 kilometres, becoming the 6th largest infrastructure of this kind in Europe, by extension.

Metro M4 Milano

Milan's M4: sustainable mobility serving the city

Milan’s M4 Metro is a unique work, in mobility, environmental andsustainability terms, which will strengthen the Lombard city’s ecological footprint. 

Find out more

M4 Metro stops

The completion of work on the first Linate-Forlanini section brings the M4 project closer to a number that alone tells how the project will impact Lombardy's capital city. 12 minutes is the time that, once Milan M4’s entire route from Linate to San Babila is completed, it will take to connect the airport to the city centre on board the new "Blue Line" trains.

Linate is one of the metro’s two terminals, the ends of those 15 kilometres of track that, through 21 stations, run along the east-west direction of the city, reaching the other terminal at San Cristoforo. Thus, the M4 is also set to become the airport's metro line, a strategic infrastructure reducing distances in Milan and also bringing the city closer to the rest of Italy and Europe.

The completion of work on the first section is the first milestone in a long process that began in 2012. After the awarding of the tender and the first surface works, the first excavation at the Linate site dates back to 24 March 2014 and was completed a few months later, while on 8 April 2015 the excavation of the second tunnel, still on the Linate-Forlanini FS section.

After the Municipality of Milan approved the project for the central section, the tunnel excavations that cut the city in two also began in 2017. In September 2020, the excavations of the tunnels of the entire line were completed: 30 km for two tunnel pipes that connect, without interruption, Linate station with S. Cristoforo, along the east-west route.

M4 Metro: a premium supply chain that will change Milan's mobility

Construction of the M4 required a supply chain 1,196 companies, including suppliers and subcontractors, working to bring Milan closer to Europe in a project that will change Milan's mobility, encouraging the constant participation of the citizens. 

The supply chain that works with Webuild to build the M4 Metro – 99% represented by the best Italian companies – is almost entirely made up of companies from the Northern Italy (939), followed by 149 companies from Central Italy and 93 from the south. A large project in which the Lombardy region dominates, with as many as 635 companies active in the Milanese construction sites (53% of the total), followed by Emilia Romagna and Lazio.

Milano Est Ovest

Milano Est Ovest

Uno spazio narrativo fatto di storie, interviste e curiosità, per raccontare il cammino della M4 lungo tutte le sue stazioni. Il dinamismo della città, le sue dimensioni, le connessioni tra i suoi luoghi.

La Milano "sopra" e quella "sotto", in parallelo, da Est a Ovest.

Leggi articoli e storie su Milano Est Ovest

Milan's Metro: Some history and a few numbers

The Milan metro network currently consists of four lines (M1, M2, M3, and M5) and a railway link, where 5 suburban lines circulate. In total, there are 94.5 kilometres

The network is managed by ATM (Milan's Transport Company), owned by the Municipality of Milan, in charge of managing transport in Lombardy’s capital and in 51 Municipalities in the Province, serving an area with a total population of 2.4 million citizens.

ATM was founded on 22 May 1931 and in its first thirty years, it invested heavily in road transport development. In 1964, the first metro line in the city was opened: the M1 (the "Red Line") on the Lotto-Sesto Marelli route.

In October 1969, the M2, the "Green Line", was also opened. The M3, the “Yellow Line”, opened in 1990, while the M5, the “Lilac Line”, was opened in 2013 and is the city's first fully automated, driverless line. In 2014, new stations were opened on the M5 (Isola and Garibaldi FS). The line was completed in 2015.

Milan’s New M4 Metro: Milan's new metro line

Information material - Bridge project over the Strait of Messina
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