these are TBMs mainly built for digging vehicle tunnels, so small compared to TBMs used for subways and passenger rail, but still on the order of meters. I see

these are TBMs mainly built for digging vehicle tunnels, so small compared to TBMs used for subways and passenger rail, but still on the order of meters. I seem to remember their original machine was second hand and they used it as a template for their own machine. It might be capable of handling granite but I kind of doubt it.