Between 30,000 to 40,000 people packed the city's Castello plaza, one of the largest in the capital of Piedmont region, in the first large-scale demonstration in favour of the TAV Lyon-Turin railway.
The protest came after Turin city authorities, lead by the anti-establishment Five Star Movement (M5S), in September approved a motion demanding a halt the project. The Piedmont regional government has ruled in favour of the TAV.
Italian and French transport ministers are expected to meet on Monday to discuss the project.
“Turin is closing itself off, this is why we thought we have to do something as citizens,” Giovanna Giordano and Patrizia Ghiazza, two of the organisers, told reporters. “Turin has come out onto the streets to say yes many times.”
Supporters see the train project as a potential source of growth for the region and northern Italy.
Elected in 2016, Turin Mayor Chiara Appendino of the Five Star Movement said on Saturday that “the door is open and will remain open” in a blog post showing a photo of her office door.
The Lyon-Turin project would involve construction of a 57.5 kilometre tunnel between Maurienne valley and Susa valley, to cut travel time between the two cities to two hours from current four hours.
Luigi Di Maio, political chief of the M5S, has called for complete renegotiation of the project, which he dismisses as a waste of public money.
France's Transport Minister Elisabeth Borne told the national assembly on Monday the government remains determined to complete the project.
The EU has attempted to push the two countries to advance. The total cost of the tunnel is estimated at €8.6 billion, 40 percent financed by the EU, 35 percent by Italy and 25 percent by France.
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