N&W Train Order Signals - "Calling On"

nw-mailing-list at nwhs.org nw-mailing-list at nwhs.org
Sat Sep 16 16:45:45 EDT 2006

To my previous post dealing with "Calling On Signals," I should have included the 1905 rule on "permissive signals," which seems to pre-date the concept of "interlocking."

It is Rule 712, and is included under that section of the Rule Book captioned "Rules Governing the Operation of Telegraphic Block." By the fact of its inclusion in a section so named, it is apparent that the concept of "interlocking" had not yet matured in the minds of the framers of the N&W book... if, indeed, they had any interlockings at all !

Rule 712 states (and here I have preserved the original capitalizations in the text):

"A permissive block arm, painted GREEN, is placed on the signal mast below the block arm at stations named by special instructions, where it is desired to move trains under permissive block without the use of PERMISSIVE BLOCK CARD.

"A horizontal position of the permissive arm or a green light displayed signifies caution, and indicates that a preceding train is in the block.

"When it is desired to allow a train to enter a block under permissive signal, the block arm will be lowered when the train approaches, and the GREEN arm will remain in horizontal position.

"When the block is clear, both the block and the GREEN arm will be lowered as the train approaches.

"When a block is controlled by a permissive block arm, freight trains may be permitted to enter same, five minutes apart.

"No train will be permitted to enter such block while there is a passenger train therein, and no passenger train will be permitted to enter such block while there is any train therein, except as provided in Rule 705." <Rule 705 simply states that the train dispatcher will issue Permissive Block Cards, so it appears that passenger trains could be operated under a permissive block so long as the train dispatcher issued a permissive block card.>

At any rate, the "green permissive arm" mentioned in Rule 712 of the 1905 Rule Book does not seem to be aimed at a situation where "Calling On" signals are used at interlockings, but rather at certain "telegraph block stations" which, due to traffic, frequently had to advance trains under permissive block indications. As worded, the1905 rule seems to apply more fittingly to simple telegraph block stations than to interlocking situations. The green permissive arm allowed the operator to do his work from inside the station (where he may have to stay close to the telegraph sounder,) rather than go outside and hand up permissive cards. But, now 101 years after the fact, who really knows the exact situation(s) the rule was addressing, and how it was applied...?

One other thing about the 1905 rule cries out for comment, and that is the old principle that "the engineman must see the signal changed to a proceed indication." Many railroads had that rule. It was a guard against telegraphers and levermen falling off to sleep and failing to restore a signal to Stop behind a passing train, with the unseemly consequences that a following train may soon come along and accept the signal which had been displyed for the previous train. When one realizes that there was no "Hours of Service Law" in 1905, and that the regular tour of duty for telegraphers and levermen was twelve hours per day, six or seven days per week, he can better understand why that particular rule is in the book !

Also, the fact that the block arm and the permissive arm are "lowered" indicates that the N&W was using lower quadrant semaphores. All as one would expect, given that the year was 1905.

Give me a one-way ticket on a time machine !

-- abram burnett
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