Comune di Milano and ATM Officially Complete Full 15-Kilometre Driverless Metro Line 4 Connecting Linate Airport

Historic East-to-West Rapid Transit Line Unites Milan's Urban Core

MILAN, Lombardy — In the most transformative expansion of Italian urban mass transit in decades, the Comune di Milano and regional transit operator Azienda Trasporti Milanesi (ATM) have officially opened the complete 15-kilometre alignment of Metro Line 4 (M4 Blue Line). The historic inauguration connects 21 brand-new underground stations stretching from Linate City Airport in the east through Milan’s historic center to the San Cristoforo FS railway hub in the southwest, creating a high-speed, zero-emission diagonal transit spine across Italy’s commercial capital.

Constructed by the SPV M4 public-private partnership consortium—including engineering and civil leaders Webuild, Hitachi Rail, and ATM—the multi-billion-euro project safely excavated beneath Milan’s priceless medieval monuments, Roman archaeological ruins, and underground canals without disturbing street-level cultural heritage.

State-of-the-Art Driverless CBTC Fleet Engineered by Hitachi Rail

The M4 Blue Line operates with industry-leading automated driverless technology designed to maximize safety, passenger volume, and energy efficiency:

• 47 Four-Car Automated Trainsets: High-frequency driverless metro trains engineered by Hitachi Rail Italy, operating at Grade of Automation 4 (GoA4) with automatic platform screen doors.
• Unprecedented 90-Second Headways: Advanced Communications-Based Train Control (CBTC) signaling permits train departures every 90 seconds during peak commuting periods.
• Capacity for 86 Million Annual Riders: The network is engineered to comfortably transport over 24,000 passengers per hour in each direction.
• Regenerative Braking Systems: The electric trains harvest kinetic energy during deceleration, feeding recovered power back into the third-rail electrical network to illuminate stations.
• Comprehensive Step-Free Accessibility: All 21 stations feature dual high-speed elevators, tactile paving paths, and zero-gap platform edges.

Crucial Interchanges at San Babila, Sant'Ambrogio, and San Cristoforo

The completion of the central tunnel sector delivers seamless cross-network connectivity:

Linate Airport to Central Duomo in 12 Minutes: The direct connection to San Babila Station (interchange with M1 Red Line) allows international business travelers and tourists to travel from airport baggage claim to the steps of the Milan Cathedral in just 12 minutes.
Sant'Ambrogio Interchange: Connects directly with the M2 Green Line, providing frictionless transit access to the Catholic University of the Sacred Heart and surrounding cultural quarters.
San Cristoforo Interchange: Interlinks with regional suburban rail lines (S9) and South Milan tramways, providing high-capacity commuter intercept before vehicles enter the congested inner ring road.

Removing 180,000 Daily Car Trips to Accelerate Milan's Climate Neutrality

Mayor Giuseppe Sala and European transport dignitaries praised the M4 as a monumental leap forward for urban decarbonization and clean air quality. By offering an ultra-fast alternative to private automobile travel along major ring roads and radial boulevards, Line 4 is projected to eliminate over 180,000 private vehicle trips each day, avoiding approximately 10,300 metric tons of carbon dioxide emissions every year.

Concurrently, surface street restoration along the M4 corridor has created over 240,000 square metres of newly pedestrianized public piazzas, protected cycleways, and landscaped green corridors. The M4 stands as a premier European infrastructure model uniting rapid airport connectivity, urban preservation, and climate-neutral mobility.