I think I know what you mean. Been studying directional drilling of shale gas seams, where instead of drilling vertical wells down to the seam they can drill a well down and then horizontally through the seam, then fracture it extracting the gas. I know it's not the same thing, but what might have been very difficult in the 80s might technologically be possible now. However given the infrastructure that's been put in place now, it's difficult to just abandon it as a bad job. It's a bit frustrating to see how long these developments take. St peters Sq has been shut for years and I don't think it's due to fully re-open until August or September.Worked on a couple of schemes for an underground system in Mcr in the eighties....basically its a non starter. Far too much under there to go through, and the city centre doesn't have the area to go deep and back up again...if that makes sense. I would offer a Chicago style metrolink above ground as a possibility..