First = A Big Thx to Member / Contributor Eric Schmelz for this superb semaphore shot at Polly NM ! This list existed primarily as an adjunct to the CLEAR BLOCK quarterly publication, which has now ceased publication as of August 2008. The List now serves as the primary forum of what was the Railway Signaling Technical and Historical Society, formerly the RR Signal Special Interest Group (Signal SIG). This group of over 1700 members studies railway signaling and operations, including: the historic and present day methods, equipment, devices, wiring and modeling simulations / applications. The members share interests including: interlocking and signal system rules and operation, signal and track charts, signal and machine hardware collecting, studying prototype towers and operations and replicating them accurately for model railroad applications and usage. We also have another storage area for great photos and files at Railway-Signaling2. A BIG THX to all who contribute and help out here ! New members are always welcome. Founder and one of the moderators, Bill Strassner, who started in the PRR Signal Dept June 1965.