Until 1985, FRA rules required signals to be directly above or to the right of the track governed. This led to innovative (and model-genic) signal bridges, two arm signal masts, and dwarf signals.
Two Arm Mast:
Signal Bridge:
Current rules do not, and the preferred signal placement (for double track), is to the field side of the track governed.
Modern Field Side Placement:
Signals are placed so the train will stop before the clearance point of any turnouts involved.
Nick
Take a Ride on the Reading with the: Reading Company Technical & Historical Society http://www.readingrailroad.org/
My new 8X5 in N is progessing slowlyand finally time to finish the wiring. Am about to wire in all the DCC switch decoders and the signals to indicate switch status (neat NCE Switch Kat feature), but not sure what should be the correct placement for the signals in terms of were on the track, left or right of approach and distance it should be rom the track. Any help would be apprecaited.