The problems were immense ​ — torrential rains, landslides, and mudslides, as well as tunneling through solid rock and, even more difficult, lithomargic soft soil, described as being like toothpaste.
यात पुष्कळ अडथळेही निर्माण झाले — मुसळधार पाऊस, भूघसरण तसेच कठीण खडकातून आणि सर्वात मुश्‍कलीचे म्हणजे टुथपेस्टसारख्या मऊ मातीतून बोगदे खणणे.