by charlesriverbranch
I was at Anderson/Woburn the other day waiting for a train to Maine. A Lowell-bound train had just departed, and the signals showed red over red. After a few minutes they changed to yellow over red, but a few minutes after that they changed to yellow over green. Then, shortly before my train arrived, they changed to green over red.
I know that green over red means clear, and yellow over red means that the next block is clear but the one after that is occupied; but what does yellow over green mean?
I know that green over red means clear, and yellow over red means that the next block is clear but the one after that is occupied; but what does yellow over green mean?