Today I understand the crossrail TBM is being dismantled. London is, as far as I am aware mainly clay, whilst the Pennines are a mixture of various types of hard stone. I have some questions 1. Can a TBM be reused on another project - ie what is a TBM's projected lifespan and what governs that lifespan? 2. Does it need a different cutting head to go through hard stone or does it need recourse to explosives etc? 3. What speed can a TBM make cutting through London clay and Pennine stone? 4. What would it cost in general terms to make say a 15 mile tunnel through the pennines and how long would it take? 5. Can a TBM be sent through an existing tunnel to widen it to say UIC gauge, eg Standedge or if not, is there a more practical solution to tunnel widening?