(11-09-2010, 02:39 PM)priyman Wrote: Peter,
I had a go at representing it in the way you have outlined... see attached!
thanks again,
priyank
You confused me somewhat re what you were intending
a) You didn't actually say which route
b) I think that you made a mistake re lie of 207
c) I think you interchanged your column headings.
I have therefore tried to interpret what you meant to put and made some assumptions; a bit like using redundancy in a message to perform error correction. Of course for safety critical communications shouldn't do this, but instead use the parity bits to decide whether to accept / reject it.
Let me know if I "have got the wrong end of the stick"......
I have made amendments and reattached here. I have shown my amendments in Red and my deletions in Green; obviously if writing in the exam you'd write the Red as if it were Black and totally ignore the Green (pretending it to be invisible).
Actually to be pedantic the 2nd presentation applies only to RRI which operates by establishing the new overlap before permitting the hinge to swing and hence the switchover from one to the other is effectively instantaneous, only taking the changeover of the point NLR/RLR. In SSI etc, the decision to swing the hinge is made on the availability of the new overlap and therefore when the set position of the hinge points is changed, the point detection for the new overlap may not yet be established- it ALL has to be bridged out whilst all the required points are moving. However suggest this is distinction is too deep for IRSE Exam purposes!
PJW