From Linate to Dateo, Milan gets on board the M4

The cars stop at the platform, the security doors open, then close again a few seconds later, and the train pulls away. The distance from Milan’s Linate Airport to Piazza Dateo is 5.6 kilometres (3.5 miles), for a total of six stops on the first section of the M4, the new subway line that will connect Milan’s business airport with the city centre and then to San Cristoforo at the far end of the city’s trendy canal district.

The first part of the new line will open on November 26: the journey from the airport to downtown will now take just a matter of minutes, transforming Milan into one of Europe’s most accessible metropolises by air. Work continues on the rest of the line, which will reach a total length of 15 kilometres (9.3 miles) dotted by 21 stations. It will cross the historic city centre in just 29 minutes, linking the east and western areas of Italy’s business and financial capital, transporting up to 24,000 people every hour, 86 million a year.

“Because of its characteristics, this line represents Milan’s gateway to Europe and Europe’s gateway to Milan,” explained Renato Aliberti of Webuild, Ceo of M4 S.p.A.

The goal of the metro is just that: to create a fast and sustainable connection to the city centre, a link that at various points intersects other metro lines as well as regional rail lines, significantly increasing the capacity of the city’s sustainable mobility system.

The tunnels for the new subway line run right under the foundations of historic buildings, calling for innovative construction techniques. “The excavation never stopped during the construction of the tunnels,” Guido Mannella, project manager Metro Italia, Webuild, explains. “We set up four shifts to cover the 24-hour day during the excavation phases, and worked on holidays. By maintaining these rhythms, we were able to excavate about one and a half million cubic metres of earth, which corresponds to about 75,000 truck trips: 75,000 trucks put one behind the other would cover the distance from Milan to Rome.”

Labour and sustainability went hand in glove because, in order to reduce the impact on the city, the excavated earth was transported along the same tunnels where the subway will run, to deposits located on the outskirts of the inhabited areas.

Now that the tunnels are completed, the focus shifts to building the stations. Site manager Fabio Guanella is busy in the downtown stations: veritable canyons more than 30 metres (98 feet) deep that widen suddenly before your eyes as you walk from San Babila, Santa Sofia and De Amicis.

“When they gave me this assignment,” he says, “the Group said, ‘let’s start building Line 4.’ So I started to look at the first drawings, the first floor plans, and we started to do the first surveys and then to figure out where the metro would run. At the beginning, it seemed almost impossible. We said: ‘but a station won’t fit here, between these two buildings’… and yet thanks to the designers and the commitment of the entire staff, step by step we are building an important work of infrastructure. Every time I see it I say: ‘ha, we’ve come a long way.’”

The stations connect some of Milan’s historic buildings, schools, museums and landmarks.

In Piazza San Babila, for example, the canyon is long and deep, and the excavations open right at the edge of the walls of the buildings in this busy area. This is where Alessandra Ciancaglini works, who started her career on the M4 construction site and is now in charge of project scheduling.

“I arrived first,” she admits, “I worked on the tender, and from there we began to set up the work ahead.”

Ciancaglini works for Webuild, the group that is building the M4, and she has been on the construction site for over 10 years. Her experience onsite has been punctuated by milestones in her personal life.

“I remember when I started in December 2010,” she says, “I had recently returned from maternity leave. Then the actual construction started in 2012, so we can say that my daughter grew up with her mom working for the Milan subway.”

Since 2012, much has been accomplished. The tunnels have been completed, the construction of the stations is in an advanced state, and the first section from Linate Airport to the Dateo stop will soon be handed over to Milan’s residents.

This achievement was made possible by relying on the work of more than 1,500 people and 1,300 supplier companies, and a very high degree of innovation.

In the excavation phases, advanced technology was deployed to protect Milan’s artistic and historical heritage. Some monuments were even moved to avoid any risk of damage when the Tunnel Boring Machines were passing beneath them. These include the Verziere Column with the Statue of the Redeemer in Largo Augusto; the Bust of Cesare Correnti in Piazza della Resistenza Partigiana; the medieval wall in Via Francesco Sforza; and the Monument of the Madonna of the Resignation. These monuments will be replaced in their original position after the cleaning and restoration required by the Culture Superintendent’s office. This ability to safeguard the artistic heritage is due to Webuild’s long experience in the construction of metro lines over the years. To build Copenhagen’s Cityringen, in some places the digging machine excavated at a depth of just 1.5 metres (5 feet) below the foundations of historic buildings. In some areas of Rome, it was necessary to freeze the ground to safeguard existing buildings during the construction of the B1 subway line. Then there’s the Thessaloniki metro in Greece, where instead a project is underway to safeguard an ancient Roman road discovered during the construction of the city’s first line.

And so specific techniques have been used in the excavation of the stations in Milan’s centre (San Babila, Sforza Policlinico, Santa Sofia, De Amicis, Sant’Ambrogio), where digging machines with a diameter of 9.15 metres (31 feet) across were used, to incorporate the passenger disembarkation platforms inside the tunnel, thereby reducing the volume occupied by the stations to the minimum.

This technological leadership has allowed — and is still allowing – the construction of a strategic work for Milan, which will have a significant impact on the city’s mobility while also contributing to the redevelopment of many areas of the metropolis.