Southern Pacific through freight RVME-M arrives at Medford, Oregon on the evening of May 11, 1990. Exposed on Kodachrome 25 using a Nikon F3 with f2.0 135mm lens. Slide scanned with a Nikon LS-5000 at 4,000 dpi and processed with Lightroom to remove dust.
I exposed this view of Southern Pacific’s RVME-M (Roseville to Medford, Manifest) arriving at Medford, Oregon.
This was one of many Kodachrome slides exposed on an exceptionally productive trip to SP’s Siskiyou Line with Brian Jennison in May 1990.
For more Siskiyou photos, click HERE to see my earlier post.
A very good question; the answer is ‘no’ and ‘yes’, depending on how deeply you wish to consider it.
In common Southern Pacific practice in the modern era (say post 1920) when used as automatic block signals, the US&S Style B mechanism only allowed for each blade to display two aspects (horizontal for the most restrictive, angled down for the least restrictive). To get three aspects you needed two blades.
However, in an earlier era (lets just say pre-1920, but that is not an absolute date) the lower quadrant semaphore was capable of displaying three aspects in rare instances.
As I understand it, the reason the signals continued to be made with three roundels (lenses) was so that crews would see the more restrictive (yellow or red) color as soon as the signal started to drop or if the signal became stuck in a half-way position.
Further complicating matters; the US&S Style B mechanism, often associated with the company’s two position lower quadrant semaphore, could in fact be applied to a three position signal. However, this wasn’t an especially efficient device for three position blades, so US&S developed the Style S mechanism for three-position automatic semaphores (circa 1908).
Also, the three position lower quadrant semaphore blade could be applied as a train order signal, which were covered under a complete different set of rules than automatic block or interlocking signals.
Those lower quadrant signals are fabulous. Looked back at some of your earlier posts also for more. One question, did they have a three position option?
I think that’s a book I need, despite having had to cut back on purchases – nowhere to put the stuff!
A very good question; the answer is ‘no’ and ‘yes’, depending on how deeply you wish to consider it.
In common Southern Pacific practice in the modern era (say post 1920) when used as automatic block signals, the US&S Style B mechanism only allowed for each blade to display two aspects (horizontal for the most restrictive, angled down for the least restrictive). To get three aspects you needed two blades.
However, in an earlier era (lets just say pre-1920, but that is not an absolute date) the lower quadrant semaphore was capable of displaying three aspects in rare instances.
As I understand it, the reason the signals continued to be made with three roundels (lenses) was so that crews would see the more restrictive (yellow or red) color as soon as the signal started to drop or if the signal became stuck in a half-way position.
Further complicating matters; the US&S Style B mechanism, often associated with the company’s two position lower quadrant semaphore, could in fact be applied to a three position signal. However, this wasn’t an especially efficient device for three position blades, so US&S developed the Style S mechanism for three-position automatic semaphores (circa 1908).
Also, the three position lower quadrant semaphore blade could be applied as a train order signal, which were covered under a complete different set of rules than automatic block or interlocking signals.
I chronicle some of this in my book on Classic Railroad Signaling. See: http://www.quartoknows.com/books/9780760346921/Classic-Railroad-Signals.html
Those lower quadrant signals are fabulous. Looked back at some of your earlier posts also for more. One question, did they have a three position option?