On Metro-North Railroad going westbound out of New Haven station, the five (straight) tracks are in a cut with stone retaining walls (about 30 feet high) on either side and there are four overpasses within a half mile of the station. At the south side beneath the overpasses, the clearance between the (load-bearing) retaining wall and the car side narrows to between one foot and, at most, eighteen inches. I'm amazed that the New Haven Railroad was willing to build it this close. But they didn't dare do it on curves...
MELGAR
