Link: Copy link
Thanks again Richard:rsullivan wrote: Mr. Ed(nhhe52). I recalled wrong. I read New Haven Railroad 1925 Rule Book and here are the correct meanings. The red blade with white stripe and round end is an interlocking signal. The red blade with white stripe and pointed end is an automatic block signal. The red blade with white stripe and squared end is a train order, manual block, controlled block, or a drawbridge signal. A distant signal is the forked-end yellow with black chevron stripe blade. These are described on pages 88 and 89 of that book. I doubt they changed thoughout the years.
New Haven Railroad Rule Book 1925 pic 8.jpg
I also found a nice website that explains a lot about semaphore signals and devices at http://www.railroadsignals.us/signals/s ... L_DRAWINGS_. The picture at the top appears to be of two upper quadrant short blade automatic block signals positioned as clear to proceed attached to a catenary bridge for eastbound trains on the Harlem Branch it appear at Oak Point Yard. It has a link to the 1930 US&G Catalog of Mechanical Drawings.
Hope the corrections about the semaphore blades reached you before they were permanently ingrained in your memory.
Still haven't found the Shoreliner issue yet.
Richard H. Sullivan, Jr. member #3967
Statkowski wrote: What was the purpose of these double stacked signals? Is the upper semaphore for the signal at the point of the signal and the lower semaphore for the signal for the block ahead?
Ed (and any others curious about such):
What follows is a broad, simplified version of what really happened.
Way back when automatic block signals were first installed, semaphore signals were lower-quadrant things that displayed one of two aspects - go and stop. The top blade (red in color with a pointed end) on two-blade applications was for the immediate block ahead, and showed either green or red. The bottom blade (yellow in color with a fishtailed end) showed whether the next signal was cleared off or not, and showed either green or yellow. The engineer was thus informed about not only the immediate block in front of him, but also the one following that.
When they converted over to upper-quadrant signals capable of displaying three aspect (red, yellow or green), the bottom signal became an extension of the indication given by the top signal. It was no longer an approach indicator for the next signal, but ended up giving the engineer far more information than the old system. With a combination of top and bottom, the engineer now knew not only the condition of the block immediately in front of him, but the block beyond that, and the block beyond that.
Red (horizontal blade) over Red = Stop and proceed. The immediate block ahead is occupied, but you can proceed slowly, preparing to stop short of the obstruction, once you've made your initial stop.
Yellow (diagonal blade) over Red = Approach. The immediate block ahead is clear, but the block beyond that is not. Slow down in anticipation of that next signal.
Yellow over Yellow = Advance Approach. The immediate block ahead is clear, so is the block beyond that, but the third block may not be. Slow down a little in anticipation of that third block.
Yellow over Green (vertical blade) = Approach Medium. The immediate block ahead is clear, so is the block beyond that, but the third block may not be. Plus, you might be making a crossover or diverging move at the next signal. Slow down in anticipation of that upcoming possible diverging move.
Green over Red = Clear. The immediate block ahead is clear, so is the block beyond that, plus the one beyond that. No need to slow down until maybe the next signal.
With the switch from two-aspect semaphores to three-aspect semaphores, you can readily see that the information about the line ahead increased from two signal blocks to three, and thus allowed the trains to run faster.
Thanks John:jkasey wrote: Richard & all others,
There is an article on signals by the late Peter Lynch in Shoreliner Vol 31-Issue 1-pages 15-23. Richard, are you using an index that I help put together over the years? I took it upon myself to continue an index that another NH modeler gave up to devote more time to family. I'm glad that it is being put to good use. Just curious.