FWC, FWP and RSO

[Peter]

1) Is my understanding correct!? 
2) At the point toe what is the difference between the Free Wheel Clearance and Switch Opening, are they not the same there?
2) The FWP, what's the impact of this not being set correctly? Does it though off the FWC which could result in a derailment?

You are basically correct. The FWP is all about the space between the back edge of the wheel that should pass between the open switch rail and its associated stock rail. The issue was about wheels hitting the open switch rail (flange back contact) and then putting stress into stretcher bars and other components because they open switch rail was being forced further open. Yes, at the front, the FWC and Switch Opening are the same measurement and although the standards talk about measuring FWC throughout the length of the switch, the fact that the opening at the front is typically in the range that you give means that there is always a requirement for it to be greater than the FWC min.

The attachment in the following post has the calculation for the values and was the response to the issue of repeat broken stretcher bars potentially caused by inadequate clearance and resultant flange back contact.

Peter