"Hidden" signal lamp failure

In this case I would suggest holding signal KR3276 at danger (using the replacement button) until KR3274 shows green. The headway will be reduced but it should avoid a following train from receiving a change of aspect.

If you're playing multiplayer then you could coordinate with the south panel and use KR3274 instead of KR3276 to determine when to release the next train.

" said:

In this case I would suggest holding signal KR3276 at danger (using the replacement button) until KR3274 shows green. The headway will be reduced but it should avoid a following train from receiving a change of aspect.

If you're playing multiplayer then you could coordinate with the south panel and use KR3274 instead of KR3276 to determine when to release the next train.

Does this happen in real life? If so does this happen as frequently as it does in the sim? Are bulb-out circuits really necessary, especially on automatic signals that are also protected by AWS?

" said:

In this case I would suggest holding signal KR3276 at danger (using the replacement button) until KR3274 shows green. The headway will be reduced but it should avoid a following train from receiving a change of aspect.

If you're playing multiplayer then you could coordinate with the south panel and use KR3274 instead of KR3276 to determine when to release the next train.

Does this happen in real life? If so does this happen as frequently as it does in the sim? Are bulb-out circuits really necessary, especially on automatic signals that are also protected by AWS?

Thanks for all the responses. My problem was that I couldn't see the signal to which it related to take the appropriate action. Would it be unprototypical for the signal lamp failure alert to specify the signal rather than the area?

" said:

" said:

In this case I would suggest holding signal KR3276 at danger (using the replacement button) until KR3274 shows green. The headway will be reduced but it should avoid a following train from receiving a change of aspect.

If you're playing multiplayer then you could coordinate with the south panel and use KR3274 instead of KR3276 to determine when to release the next train.

Does this happen in real life? If so does this happen as frequently as it does in the sim? Are bulb-out circuits really necessary, especially on automatic signals that are also protected by AWS?

Don't forget here that AWS will sound the same tone for both a cautionary aspecct (yellow, double yellow) as it would with a red aspect. Only a green aspect gets a different sound

An improperly displayed signal should be treated as if it is displaying it's most restrictive indication. Bulb out protection isn't necessary if the drivers simply follow the rules. In the remote chance that they fail to follow the rules the AWS would provide additional warning if the signal were was failing to display a restrictive indication. That should mitigate almost all the remaining risk.

" said:

An improperly displayed signal should be treated as if it is displaying it's most restrictive indication. Bulb out protection isn't necessary if the drivers simply follow the rules. In the remote chance that they fail to follow the rules the AWS would provide additional warning if the signal were was failing to display a restrictive indication. That should mitigate almost all the remaining risk.

"If" is a very deadly word. IF everyone followed the rules, IF that train didn't happen to be just there at the same time as the other one, IF that old wire hadn't just happened to touch the relay... Things are set up on the modern railway to mitigate against the IF - there should always be a second, or even third line of defence - just in case. After all, if Drivers never allowed their attention to wander we wouldn't need AWS; if Signalmen never allowed their attention to wander we wouldn't need interlocking.

I'm possibly over-generalising here, but I think that a significant proportion of railway accidents are caused by human error of some sort, whether that's a Driver missing a signal or the Signalman forgetting about a train or whatever. When I was a Signalman I sometimes got very stressed when the job was up the wall, and I made mistakes, but I had confidence that the interlocking would stop me from doing something that would kill people, and I still think that the Railway should have things like lamp-proving to try and mitigate the consequences of someone making a mistake. I would rather have 100 minutes of delay by stopping trains to talk them past a failed signal, than saving a few minutes and having a crash because someone made a mistake.


Kev

In the case that I experienced, a train received an adverse change of aspect because, although one of the lamps had failed, the signal in the rear did not switch to red all of the time, only when that particular light (one of the yellows) should have been displayed. This was driven by the proximity of one train to another and once two were the "right" distance apart for the signal in advance to change from red to the failed yellow aspect, the signal in the rear changed from yellow to red.

Given what is written above, should the signal in the rear not display a red aspect whatever the aspect of the signal in advance to prevent an ACOA?

In the case that I experienced, a train received an adverse change of aspect because, although one of the lamps had failed, the signal in the rear did not switch to red all of the time, only when that particular light (one of the yellows) should have been displayed. This was driven by the proximity of one train to another and once two were the "right" distance apart for the signal in advance to change from red to the failed yellow aspect, the signal in the rear changed from yellow to red.

Given what is written above, should the signal in the rear not display a red aspect whatever the aspect of the signal in advance to prevent an ACOA?

If the signal in front is lit, the signal in rear will show the appropriate aspect. If the signal in front is unlit, the signal in rear shows red. A lot of extra circuitry/code would be needed for the signal in rear to behave as you've suggested.