Category:Microtunnel boring machines
It should not display full-size Tunnel boring machines (TBM) which should be in the upper Category:Tunnel boring machines, or directional drilling machines which should be in Category:Drilling machines.
The main feature of Microtunnelling is that the hydraulic driving jacks remain in the insertion pit, and push the whole-length pipe assembly including the cutting head; whereas full-size TBM driving jacks are on the machine and only push the machine, bearing against the last tunnel section built.
Note that the largest Microtunnel machines and tunnels can be accessed by personnel (up to 2m diameter).
Also see Category:Geotechnical engineering