2006 CTs ROUTE & ASPECTS

[merlin89]

My attempt at 2006 layout CTs

[PJW]

My attempt at 2006 layout CTs

A very good set of CTs; see attached scans.

Main comments
1. Look at swinging overlaps. If there are facing points in a simple swinging overlap (i.e. no further point conditions / opposing) then ther hinge points won't feature in the availability (they will either be free to go N or free to go R so it is meaningless. However where there are further condittions then yes the hinge points will feature: in one lie with one set of conditions and in the other lie wither witthout any conditions or with a different set of conditions- obviously anything common to both will be included elsewhere in the route availability expression.
You tend to get it more right at the aspect level but in the TCs clear be careful to ensure that the track over the hinge points is included constantly (i.e. as if it were a route track, since common to both overlaps) also that the tracks in one lie are conditioned out by the points being in the other and vice versa.
I haven' bothered to refine your answer in a few respects as I think the laaw of diminishing returns applies in the exam; just be aware for example that you stated 122A(M) requires opposing route locking from 175 to be normal, but of course one of the advantages of the swinging overlap is that 222 can be R whilst there can be a move taking place from 175 and then 159D(S) so to b 100% you'd need to condition this opposing locking according to the overlap hinge points.

2. Be sure to include the word "or" where necessary; a list separated by commas implies AND. Conversely in your route locking (as Reubem has pointed out in a recent post for 2008 CTs) you have but a superfluous "or". If either (or indeed both) of the platform tracks is occupied for the relevant time, then this bypasses the locking on both of them.

3. The trouble with listing trasks as overrun protection is that would often need conditioning out by route away etc if the line bi-directional; I think that it is probably better just to list the signals where a SPAD would endanger your route, conditioned out by relevant point conditions when SPAD would be directed elewhere and thus not endanger.

4. You should state your practices; seems to be relatively modern NR using SSI. In this case you ought to be showing "better aspects" for Warning routes, to cover the situation in which the signal has already cleared before route step up could take place and thus the (W) would show YY or G if forward signal clears appropriately.

5. For 171A you have required 234 set locked and detected R. Not actually wrong but think what you would have done if doin the CTs for 164B; I expect you would have demanded N. However would you really want to stop those two routes being used simultaneously. There is probably not a large risk of a SPAD at 168 but I think I'd prefer it to go via 234N rather than R (whch is probably why the layout has defined the normal lie as it has); reasons:
a) the speed on the branch is lower, probably less traffic,
b) keeps to the outside of the layout,
c) it is further before it becomes foul of 171A than 164B at the diamond; indeed CG is foul of moves over 233R but clear of moves over 235N.
Hence I'd have a hard call (but probably set and lock though not detect) for 164B but just soft call with 171 which means call them if they are free but set the route anyway even if not free, get the protection a goodly % of the time but don't hold them in that position if another route has a greater need.

6. For some unknown reason you have suggested that (W) routes do not prove TPWS at red exit signal; incorrect!

7. Overall though a very good set ocf Control Table, but your biggest mistake was NOT DOING A CT FOR 147A(S)- always read the question paper carefully

I'll try to look at some of your other attempts sometime, but rather pushed for time at present