Why can't I place a rail signal on this diagonal rail?

[sparr]

There must be at least one rule about signal placement that I haven't figured out yet, because everything I know says that not only one but all three of the spaces along this rail should be valid for signals (two of which would also be valid for the adjacent straight rails).

[DaveMcW]

Some more data points.

signals.gif (295.87 KiB) Viewed 2960 times

[Mr. Tact]

Yeah, I have never completely understood this behavior either. In most cases it seems to be a situation of you need to be able to place a signal on both sides of the track, but there are exceptions.

[zOldBulldog]

Signals go on the right side of the direction of travel and have to have a free space to place them. If travel is unidirectional or there is no space to put it... then it will prevent you.

More than that I can't tell from the screenshots.

[sparr]

The weird part is that whatever was preventing some signals over here wasn't also preventing their opposite signal: viewtopic.php?p=429911

[Selvek]

What happens if you continue that diagonal section with more straight track, rather than curves? I wonder if it has something to do with the curves encroaching on it.

[sparr]

Some more data points.

The weirdest part here is that only the diagonal rail exhibits the "must have both sides clear" behavior. Notice that the orthogonal rails gain and lose signal positions based on the diagonal rail, even when their own opposite signal spot is occupied.

[Bauer]

And only rail segments block the placement of signals. If you block one side with another building (e.g. a power pole), you can still place the signal on the other side.

[sparr]

Bump. I'd really like to understand this so I can do more planning and less trial/error in my rail layouts. Also so I can explain it on the wiki for others.