I think it's the sheer scale and character of the work that's the problem. if the system closes at 1:30am, and then reopens at 6, that's only 4 and a half hours to get the required equipment and people in there and get something done. Also, this particular stretch of track runs above ground right in the middle of a densely populated residential area. They can't be slinging 40-foot lengths of iron track and doing spot welds and hammering bolts in the dead of night. Just can't.
their problem for buying a property by a subway track, sorry