N&W Signaling in 1928, 1932, 1939, 1940, 1941

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In 1954, the Signal Section of the Association of American Railroads published a lengthy series of technical manuals giving generic descriptions of all the types of circuits and signal equipment in use at that time.  The first volume of the series was titled "American Railway Signaling Principles and Practices; Chapter I - History and Development of Railway Signaling" (Chicago: Signal Section A.A.R.)  Although titled "Chapter I," this is a self-standing, 167 page soft cover book.  Pages 102-167 contain a magnificent chronology of signaling developments from 1832 to 1953.

The chronology deals, principally, with "firsts," and it is generally the fast, heavy traffic railroads (PRR, B&O, NYC, DL&W, P&R, AT&SF, B&M) which take credit for the "firsts."  Nonetheless, the N&W does receive five mentions.  Here they are...

1928 - "A Gill selector system, with audible answer-back, for central office selective control, was installed at Roanoke, Va., on the Norfolk & Western."  <<This was for Roanoke to North Roanoke on the Shenandoah Division.>>

1932 - "The first Union Switch & Signal Co. Model 31 car retarder installated in regular hump yard service was at the Portsmouth, Ohio, yard of the Norfolk & Western Ry."  (<<Car retarders were first introduced in 1924 at Gibson, Indiana, on the IHB RR.>>

1939 - "The first application of coded detector track circuits in interlocking was made by the Norfolk & Western Ry."  <<Wonder where...?>>

1940 - "The first installation of absolute permissive block signaling with three and four indictions with coded track circuits was made on the Norfolk & Western Ry. between Petersburg and Evergreen, Va."  << APB is for single track.  Could this be a reference to the Petersburg and Lynchburg belt lines...?>>

1941 - The first installation of speed control for car retarder operation was made on the Norfolk & Western Ry. at Roanoke, Va.  Model 31 electro-pneumatic retarders were used."  

As I type this, I am listening to "120 code" being made by a 1938-vintage DM coder, and at the receiving end being "played" on a type CD code detecting relay of the same time period.  Great stuff !

-- abram burnett
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