In the tunnels being excavated under the streets of Milan for the new M4 metro line, has been celebrated the feast day of Saint Barbara. On December 4, which marks the martyrdom of the patron Saint of miners and all those who perform tunnel work, activity throughout the project came to a halt. It was done in remembrance of the martyr as well as to pay tribute to those who work on large civil infrastructure projects. Two brief moments of reflection were held: the first at Manufatto Argonne and the second at the project’s base camp of via Gatto/Forlanini. The decision to celebrate the feast day on site was not casual, as explained Pietro Salini, Chief Executive of Salini Impregilo. «The M4 … is one of the most important projects in sustainable mobility in Europe. It is an example of teamwork, of Italian excellence in construction, of a successful collaboration among companies, public administration and financial institutions».
The new Milan metro
The virtuous collaboration on the development of the new metro line commissioned by the city will provide residents a service that is unique in terms of sustainable mobility.
Once up and running, the Milan Metro Line 4 (M4) will make it possible to reach the city centre from Linate airport in just 12 minutes. It will take a 30 minutes to travel the full length of the line of 15 kilometres (9.3 miles). Along its east to south-west axis, the line will intersect with two
metro lines and three commuter rail lines. It will have 21 stations and a fleet of 47 bidirectional cars.
About 1,500 people work on the project, and they are keeping up a sustained pace. Civil works are 60% complete, while the entire project is 50% complete. According to forecasts, a first section of the line will be operational in 2021 from Linate to the Forlanini FS train station. Another section will open so that trains from Linate can arrive at the central San Babila station in December 2022. The entire line should be open all the way to the outlying San Cristoforo FS train station by July 2023.
Once finished, Milan’s new subway line will be able to transport 86 million people every year, removing up to 16 million vehicles from the streets of Milan each year.
TBMs near the Navigli canals
Construction of the M4 enters a new phase as it approaches the Navigli network of canals. The tunnel-boring machines (TBM) are to keep digging until next spring. They are passing below the Waldensian Church on Via Francesco Sforza, the Basilica of Sant'Ambrogio, the Ca 'Granda, the Columns of San Lorenzo, and the Torre Merlata building on the corner of Via San Vittore and Via Carducci. And this is just a part of the impressive historical and artistic heritage that workers and technicians are protecting as they build this strategic piece of infrastructure.
Protecting Milan’s heritage
To protect Milan’s architectural and artistic heritage, the company responsible for the project (owned by the city and a group of companies led by Salini Impregilo and Astaldi) has adopted a technical protocol for underground work that combines preventive analysis with continuous monitoring. These procedures were tested by Salini Impregilo when it built Cityringen, Copenhagen’s new driverless metro inaugurated on September 29 by Queen Margrethe II. Before that, it had done them along the B1 Line in Rome.
Digging beneath a crowded urban centre entails an exceptional commitment to monitoring and analysis, both in the design and in the execution of the works. In the case of the M4, the tunnels are being dug at a greater depth than Cityringen or the B1. The technicians are adopting a procedure calling for archaeological assistance during the excavation of stations and relics, an activity that proceeds even after the superintendent’s office gives the go-ahead.
Technicians have collected every architectural and structural piece of information about the buildings that could be potentially affected by the excavations. This has allowed them to identify any critical issues which could require special measures. Inspections revealed that Casa Silvestri and Palazzo Serbelloni, among others, needed special care. For Villa Necchi Campiglio, which houses an important collection of valuable art and design objects, an agreement was signed guaranteeing insurance coverage for the museum and its collection. The agreement called for a detailed inventory of the entire collection, and some works judged to be at a higher risk for their age or materials received temporary packaging.
Moving historic monuments to safety
Priceless historic buildings and monuments received special care. Certain monuments were even moved out of the TBM’s path to avoid any risk of damage, such as the Column of Verziere in Largo Augusto; the statue of Cesare Correnti in Piazza della Resistenza Partigiana; the medieval wall in Via Francesco Sforza; and the Madonna della Rassegnazione. These monuments will be returned to their original locations after cleaning and restoration, as required by the culture ministry.
The excavations have uncovered numerous finds of historical and scientific value for archaeologists and the culture ministry, such as the ancient Roman cemetery near the Basilica of Sant’Ambrogio.
This safeguarding of the city’s heritage was made possible by Salini Impregilo’s experience gained over the years in the construction of underground projects. During the digging of Copenhagen’s Cityringen, the TBMs came within 1.5 metres of the foundations of some historic buildings. During work on Rome’s B1 Line, the underground areas needed to be frozen during an important discovery.
In Thessaloniki, Greece, an ancient Roman road was discovered during the construction of the city’s first metro line. It is in the process of being safeguarded.
Progetto Italia and the M4
The M4 is being built by a consortium of companies led by Salini Impregilo and Astaldi. They are joining forces to become a single group under Progetto Italia, a plan by Salini Impregilo supported by an investment by state-backed lender Cassa Depositi e Prestiti. Milan’s M4 line is a first testing ground for this partnership between the two companies working on a complex project that will have a significant impact on the quality of life in Italy’s business capital.