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.
Probleeme oli tohutult: paduvihmad, maa - ja mudalihked, läbi kalju kaevandamine ning mis veelgi keerulisem, pehme savine pinnas, mida võrreldi hambapastaga.