Apennine Base Tunnel

The Apennine Base Tunnel, alternatively known as the Grand Apennine Tunnel, is a railway base tunnel 18.5 kilometres (11.5 mi) long on the Bologna-Florence Direttissima line in central Italy. At the time of its completion, the Apennine Base Tunnel was the world's second longest tunnel after the Simplon Tunnel, and the longest built with double track; presently, it is the 16th longest tunnel in the world. The tunnel was opened on 21 April 1934; compared to the old Porrettana railway over the mountain range, its completion enabled an alternative route that was 35 kilometres (22 mi) shorter. Running between the stations of San Benedetto-Castiglione and Vernio-Montepiano-Cantagallo, it has a length of 18.5 kilometres (11.5 mi), a peak height of 328 metres (1, 076 ft) above sea level and a maximum incline of 1.2%.

Tunnel data from Wikidata (CC0). Summary from Wikipedia (CC BY-SA).