Risk management is of paramount importance for the success of tunnelling works and it is linked to the main excavation methods used: the Conventional Excavation Method (CEM) and the Tunnelling Boring Machine Method (TBM Method). Considering that there is no research showing univocally the advantages of one of the methods over the other, this work intends to conduct a comparative risk analysis between both methods. In order for this comparison to be as complete as possible, we present a risk evaluation analysing 11 risks and 4 risk factors. The end result will be a complete analysis of the existent risks, useful both for the technical and scientific community, something that has never been done before.