[citation needed] 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 18.507 kilometres (11.500 mi), a peak height of 328 metres (1,076 ft) above sea level and a maximum incline of 1.2%.

[1] Around 1902, a special commission established by the Upper Council of Public Works examined the route studies and selected Protche's proposal, allegedly due to the alignment's more favourable terrain criteria, such as gradients and stability, best satisfied requirements the line.

Accordingly, the Bologna–Florence high-speed railway was constructed during the 1990s; its completion has seen some passenger traffic being drawn away from the older Bologna-Florence Direttissima line and the Apennine Base Tunnel alike.

[1] Between 29 October 2001 and 20 May 2014, the Apennine Base Tunnel was subject to safety-orientated engineering works; these were largely centred around implementing modern fire-suppression equipment and associated emergency systems.