Employees at Italy’s largest stainless steel plant blocked the motorway between Milan and Naples for several hours on Thursday.
The A1 is the most important main road in Italy.
Workers are angry at plans by German owners ThyssenKrupp to cut around 550 jobs and halve production.
The stainless steel plant in Terni in central Italy is one of the most modern in Europe, but has been making losses for several years.
ThyssenKrupp blames it on the poor state of the market and structural oversupply.
It wants to save 100 million euros in annual costs and says that if it doesn’t succeed it will close one of the furnaces at the site in 2016.
Italy is Europe’s second-largest steel producer after Germany.