You could say "conventional excavation" but the author was obviously thinking of the English term "advance" when he used "avanzamento" in Italian rather than the more usual "scavo".

This the standard underground tunnelling terminology. The term for boring a tunnel with explosives is to "blast". The word "traditional" here is to indicate that they did not use a Tunnel Boring Machine, although if the ground was soft they would use roadheaders and bucket excavators, rather than blasting.

http://www.google.com/search?ie=UTF-8&oe=UTF-8&sourceid=desk...