Hi All

[adobe]

Hi All,
I am working as a signalling designer in one of the UK Railway Company and this is my first forum entry.
First of all, I would like to say warm thanks to forum admin for accepting me as forum member.
I have joined a railway 10 years ago in the signalling design process working on several multi-disciplinary remodelling and renewals schemes rail projects.
I would like to know the situation where an automatic signal provided with a replacement facility operated from NX panel in Signal Box, can have an Entrance/Exit button.
I would much appreciate if anybody could look please into my issue and replay.
Kind Regards,
Adobe.

[Peter]

Hi All,
I am working as a signalling designer in one of the UK Railway Company and this is my first forum entry.
First of all, I would like to say warm thanks to forum admin for accepting me as forum member.
I have joined a railway 10 years ago in the signalling design process working on several multi-disciplinary remodelling and renewals schemes rail projects.
I would like to know the situation where an automatic signal provided with a replacement facility operated from NX panel in Signal Box, can have an Entrance/Exit button.
I would much appreciate if anybody could look please into my issue and replay.
Kind Regards,
Adobe.

The signal normally has a button like any signal that would be an entrance or an exit, but the function is effectively pull to replace the signal, push to return to automatic.

An automatic signal can obviously be an exit from a controlled signal and hence if it is a valid exit when the entrance is selected, the button would take on the function as the exit when pressed.

Peter

[nionita]

Hi Peter,

Thank you very much for your prompt answer.
I have a special situation (please see the attachment) where before the level crossing protecting signal is an automatic signal with replacement button facility.
I understand an automatic signal can be an exit from a controlled signal but why it is still require an entrance button if it has a separate replacement button?

Thanks again.
Adobe

[PJW]

I agree with what the other Peter wrote initially, but would clarify (as per your diagam) that the Replacement control button is offset to the track on the control panel rather than being in line with it.

I don't actually know answer to your specific case- I am not familiar with the MCB with Obstacle Detectors (don't have any on the Underground!). I guess though that the clue is that the overlap extends across the crossing so perhaps there is some locking imposed by that outer signal; i.e. it may be plated as an Auto signal to denote it is passable by driver's authority, but from a signal engineering locking perspective it may be treated as a controlled signal.

However I am a bit confused because
a) never used to regard a level crossing in the overlap as something which should be ocked (unless very close), and
b) I thought that NR had decided to plate all signals as non-passable nowadays, regardless of whether they are auto signals from a signalling engineeering perspective.

Hence very keen to earn the correct answer from someone more up to date with mainline practice than I currently am.

Hi Peter,

Thank you very much for your prompt answer.
I have a special situation (please see the attachment) where before the level crossing protecting signal is an automatic signal with replacement button facility.
I understand an automatic signal can be an exit from a controlled signal but why it is still require an entrance button if it has a separate replacement button?

Thanks again.
Adobe

[Peter]

I think you need a new "L" key on your keyboard PJW!

[PJW]

I think you need a new "L" key on your keyboard PJW!

ActuaLLy you are right, on my netbook I do have to push sLightLy extra hard for the L to appear; generaLLY not a probLem but exacerbated by attempting to type with it LiteraLLy on my lap when on the Reading RaiLair bus on the way to Heathrow.
I was aware of it and corrected the majority the moment I made the post, but I see that I missed a coupLe- I was anyway short of time as the bus had aLready Left the M4 to go to T5.
For some reason though when I updated post then it actuaLLy decided to add as a new one in the thread rather than repLace the earLier one and I had not reaLised, so have now gone back to delete the one with many Ls missing!

Hopefuly this post is OK now that I am in Lucknow and using a tabLe. There is a Lesson here re systems engineering when there are some components working just on the Limits of toLerance, which can Lead to intermittent operation when something eLse is sub-optimaL.

[dorothy.pipet]

I've had a quick look at the scheme plans where MCB-ODs have been commissioned (not a project I was involved in myself). In that case the overlap at the crossing is a POL ending before the crossing; the protecting signals are all controlled (with auto button); the previous signals are all distants and the previous stop signals all controlled. Not all that helpful as a comparison really.

It does seem to me that something doesn't add up with that sketch. I'm tempted to say either the Entrance/exit symbol is incorrect or the button should be an (A) - is there some way you can double check these?

[PJW]

Certainly worth investigating.
I am back from India after the Bank Hoiday and will be in a better position to do so after then.

I've had a quick look at the scheme plans where MCB-ODs have been commissioned (not a project I was involved in myself). In that case the overlap at the crossing is a POL ending before the crossing; the protecting signals are all controlled (with auto button); the previous signals are all distants and the previous stop signals all controlled. Not all that helpful as a comparison really.

It does seem to me that something doesn't add up with that sketch. I'm tempted to say either the Entrance/exit symbol is incorrect or the button should be an (A) - is there some way you can double check these?

[yass100]

Hi...
Nice to meet you,. i hope i will remain in this forum as a positive member of this community.. I found this forum is a good for discussion..