When Porto Flavia became operative in 1924, it slashed ore production costs by up to 70 percent, allowing Vieille Montagne to gain a strong market share in a short time. The construction of Porto Flavia paid for itself in under two years, and was considered a technical marvel in the mining business. Other mine operators were not allowed to use the tunnel and harbor, still relying on manual labor or on longer railway routes.[6] The opening of Porto Flavia left many sailors from Carloforte without a job, damaging the nearby island economy.