All I can say is, this looks like trouble, and you'd better have lots of money to handle it.
I have worked as an estimator and project manager for a pipeline construction company for a lot of years, and we ran into a similar situation on a project in the middle of a city street about 15 years ago. There were commercial buildings on each side of that street, which did not help. The hard rock is only the beginning of your problem -- the shale is possibly the most treacherous thing to excavate, as it may be difficult to cut, but then, once you get about 10-15 feet down, the shale may fracture and huge blocks break off and fall into the ditch, without any warning. This is especially dangerous because you have to excavate that hard rock down below--and that cannot be readily done without creating a whole bunch of vibration that will make those top layers want to cave into the ditch. Adjacent (and not so adjacent) structures can be affected. I'd have to say that this situation was the most dangerous place to dig that I have ever seen.
Our solution was expensive, but may be necessary in your case: pre-drill soldier piles (H-piles) about 5-10 feet deeper than your trench goes into that hard rock, then drop in lagging (either trench plates, or wood) to brace the walls of the excavation. You probably will need an excavator-mounted hoe-ram to break the rock.
Good luck!
PS I make my living as an estimator, and I am not green enough to offer an off-the-top-of-my-head price on this one.