Railway Signaling: U

NOTE:

Although all of these digitized articles are 60 or more years old, and likely have minimal commercial value today, the reader should bear in mind that material dated after 1923 remains under copyright by Simmons-Boardman Publishing.

These articles and the information contained therein may be freely reproduced or used in printed or electronic form for non-commercial or educational purposes, provided the copyright holder and original author (if known) are acknowledged, and provided that such publication also refers readers to the original document on this site.

Simply making interesting material available to those who share my interest in the railway signal systems of the past has been my sole objective in this long project.