2010 Signal Control Table

[kirandas]

Hi

I have tried to attempet the 2010 signal Control Table.Can any one please check and let me know my drawbacks.

Iam finding difficulty to clacualte the approach release time dealys and sectional route locking release time delay. Kindly explain the concept.

Regards

Kirandas

[PJW]

I won't be able to respond to the first part for a couple of days as I have other calls on my time, but the second part is quicker for me.
.
The concept is that we need for release of overlap locking to be convinced the train has been on the berth track of the signal for such a long time that it must actually have stopped. For approach release it depends on the type of signal, but broadly we wish to ensure that the train is sufficiently close to the signal (hence not yet stopped but moving relatively slowly) that can see the aspect and in particular the route indicator clearly. For a Warning class route it is similar but more to do with having controlled down to a relatively low speed that adequately mitigates the risk of the short overlap beyond the following signal.

Re the calculation of specific times I suggest you look at the attachment on a post relating to time values. Then if there are any remaining doubts having studied this, ask more specifically.

Hi

I have tried to attempet the 2010 signal Control Table.Can any one please check and let me know my drawbacks.

Iam finding difficulty to clacualte the approach release time dealys and sectional route locking release time delay. Kindly explain the concept.

Regards

Kirandas

[Zaphod]

Hi

I have tried to attempet the 2010 signal Control Table.Can any one please check and let me know my drawbacks.

Iam finding difficulty to clacualte the approach release time dealys and sectional route locking release time delay. Kindly explain the concept.

Regards

Kirandas

Hi,

In my opinion you have made a very good job of it. In particular the flank protection seems to be really well done.

I remember seeing this layout in the exam last year and nearly having a panic attack! It's very complicated compared to previous years.

A few things that I spotted:

473B(M):
I think that 488D(M) and 488D(C) are also opposing routes here, because once they are on track circuit BM, there are no longer any point conditions to lock 473B(M) against them.

You have included a YY aspect but the route box indicates this can't be shown.

488B(W):
I would expect the approach control conditions for 488B(W) to be different from that for 488B(M). Otherwise, there is no point in distinguishing between the two classes of route and you might as well just have the main route and turn the restricted overlap into a reduced overlap. So the warning route should probably have a time condition associated with the approach control.

(This probably makes the difference in approach locking time between 488B(M) and 488B(W) acceptable. If the approach release conditions were the same I would expect the approach locking time to be the same too.)

488B(C):
In general I think that the call on routes in the station area would probably require only one of the track circuits to be occupied. So in this case, only ES would need to be occupied for the call-on, and ER should be clear. I admit this is not universally true, but if you assume it to be true it makes things simpler! So everywhere where you have got the requirement for ER to be occupied, I would remove it.

In the route locking it is important that brackets are shown around the 'OR' conditions. So in this case I would make it
CS, ET, ER, (ES ----OR---- ER --- 30s)
This is because it could otherwise be interpreted that the ER occupied condition trumps all of the other track circuits.

Also here, you have got 488B(M) and 488B(W) as opposing routes for 488B(C) but with no route locking. I would say that route locking is required here, bearing in mind that a train using one of these routes might come to rest in the platform and then have another train called-on behind it.

And the same comment about making the approach control more restrictive applies. In fact I think that the call-on route should be even more restrictive than the warning route. This is because the call-on route has an obstruction in it. At least the warning route has an overlap, even if it's a relatively short one!

468C(S):
You have chosen not to provide an overlap for this route. This is fine as long as the principles you're working to allow it. However, if you'd chosen to provide an overlap, the routes from 455 would no longer be opposing, which would make the route locking controls much simpler.

I would make the same comment about calling-on. This would probably only happen if half the platform were occupied; in this case track circuit CP being occupied.

You have included brackets here for the route locking but I don't think they are in the right place. A train using route 455C(M) would need to clear track circuits BG and CR. It would then need to EITHER come to a stand on CP OR continue through the route clearing CP and CN. The overlap track circuit CM does not need to be shown. The brackets should be arranged to make it clear that the 'OR' condition only applies to the second part. In this case:
BG, CR, (CP, CN ---- OR ---- CP --- 30s)

I'm not sure about your last wheel replacement conditions. Why do FM, FN and EN have $40 applied to them? I would have thought that your entry in the designated column would suffice. However, I don't see why the signal would stay clear while FM is occupied. By the time the train has cleared FL, the train is well past the signal and the driver of any propelling train won't be able to see it. So I would just have this entry as "FL".

[Peter]

Also here, you have got 488B(M) and 488B(W) as opposing routes for 488B(C) but with no route locking. I would say that route locking is required here, bearing in mind that a train using one of these routes might come to rest in the platform and then have another train called-on behind it.

I have not been able to look at what was posted yet, but this comment caught my eye in Zaphod's post. It is correct to put the M and W as opposing the C (and indeed the other 2 combinations of these 3), but there is no release condition for it as it is not held once the first train has taken its route since the other routes are in the same direction. This is no different to over-setting a following route from any other signal.

[Zaphod]

Also here, you have got 488B(M) and 488B(W) as opposing routes for 488B(C) but with no route locking. I would say that route locking is required here, bearing in mind that a train using one of these routes might come to rest in the platform and then have another train called-on behind it.

I have not been able to look at what was posted yet, but this comment caught my eye in Zaphod's post. It is correct to put the M and W as opposing the C (and indeed the other 2 combinations of these 3), but there is no release condition for it as it is not held once the first train has taken its route since the other routes are in the same direction. This is no different to over-setting a following route from any other signal.

Oops! Sorry about that - post edited accordingly.

[kirandas]

Hi all

Thank you for your valuable suggestions. Iam looking into the comments and will come back for any clarification.