Points in route control tables

[priyman]

All,

We had a study group and were failing to understand the points (detection) section of the control tables.

We determined that when you put down the points normal or reverse, the interlocking circuits would check point are set, locked and detected.

But in the box labled 'detected normal or reverse'; the check is that the route is set only when the points are detected? But isn't that repetition because you have already checked that they are set locked and detected?

I'll give you the example I'm thinking of 2004 paper - route 142B(M) requires;

Assuming this is a swinging overlap for sake of understanding;
I wrote:
212N, 211N, 207R, 206N,
(203N, 205R, 201N) or (203R, 202N).

Then I would enter 203 in the detection box as well.

But I see repetition, is there supposed to be this additional check (and if this was RRI - a double inclusion of relay contacts 203 RLR in the route locking circuitry) or am I misunderstanding something?

Any input would be welcomed,

thanks,

Priyank