Eastbound is clear
No, wait -- I think that's a bird on the track!
I used to wonder about RR signals like this -- what the heck does it mean when both the green and red are showing?? So, I posted a question on a UseNet group and as one might expect, got lots of replies. Among them 1 or 2 fairly lucid answers, such as this:
It means "Clear Signal", Proceed at authorized speed.
The aspect displayed, green over red, is simply one aspect that is used
for a Clear Signal. It means the same thing as a single green aspect, or
a green over red over red, where three signal heads are provided on the
In this case, the bottom head is called a marker, since it cannot display
anything but red. The reason the bottom head is provided is for light-
out protection: If the bulb in the top head should burn out, the crew on
an approaching train will still see the red, which would indicated a stop
is required. Otherwise, the red really has no effect on "Proceed"
If the bulb in the marker burn out, then the crew would see the single
green, and there would be no safety implication. (They would still have
to stop to report an improperly displayed signal, when they saw the non-
working head, but it really doesn't matter if they ran past it before