In which case if not underground railway what about underground toilets? I seem to recall seeing some in London but can't recall where.
Otherwise what else would need such large strong beams?
Jean
I am separated from this job by not only a century or so but by the physical tyranny of 19 000 kilometres. So, although having some engineering background, I hold back from appearing too authoritative.
However, I would make these suggestions:
I am struck by the complete absence of tools - apart from the ladder.
I don't think any of the pictured timber is permanent. The supporting beams certainly aren't - they're well above road level.
I think the two capstan screws merely suspend the formwork decking (planking beneath their feet) from the crossbeams.
It is possible that the work (which I would guess would probably be sewerage) is fairly much done and that it has all taken place below their feet, under the decking.
Wouldn't it be nice if there was a readi-mix truck just waiting around the corner ready to pour concrete on top of that planking. Then we could take all that timber away underneath, leaving a beautifully strong lid, just under street level. Then we could stop bothering that music teacher with all our dust and blasphemy.
PS. That great grandad of mine from Limerick (below), swears they're digging for gold.