I imagine the rail on the Rockwood Wye is rather lightweight. The fact that it has a stub switch on the tail makes me think it might be 52 lb. Certainly not any heavier than 65 lb.
The big engines really need to tiptoe over that light iron around that sharp curve. Lots of good ties are a must. The summer I worked for the D&S, I was brakie on a work train that turned at Rockwood. I got the honor of lining the stub switch. A couple weeks later I was on another work train that turned at Elk Park. Once again I got to line the stub switch.
Such an honor....