Multiple sources confirm that the Brenner Base Tunnel is the project slated to become the longest railway tunnel in the world. One web search explicitly states, 'Once the Brenner Base Tunnel is completed, it will be the longest railway tunnel in the world.' Another web search mentions the tunnel 'will become the longest underground railway connection in the world.'

The evidence confirms the tunnel connects Austria and Italy, as the Brenner Pass is described as forming the border between Italy and Austria, and the tunnel is located beneath the Brenner Pass. The connection of Austria and Italy via the Brenner Railway is also noted as a major line connecting the two countries.

Multiple sources provide conflicting length data (55 km vs 64 km), but they consistently state that the tunnel is designed to be the longest underground railway line in the world. One web search specifies a total length of 64 km and confirms it 'will, in future, be the longest underground rail connection.'

The evidence confirms Herrenknecht's machines have been used in major global tunneling projects. Specific mentions include tunneling beneath the Bosporus (Istanbul), and the use of TBMs in the context of the Himalayas, confirming the scope of their work in these regions.