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Tom:
After looking at the photo, I didn't realize until now that this eastward signal had a lunar associated with it. I looked at a CB&Q alignment chart from 1967, and discovered that the eastward signal at the Milwaukee double track mainline crossing also had
a lunar associated with it.
These absolute signals controlled not only the interlocking, but the intermediate block beyond the interlocking to the next signal. The red searchlight with lunar lit would be displayed if the interlocking was not occupied (and not lined up), but the intermediate
block was occupied. I'm guessing that Burlington wanted to do this because of the amount of mainline activity associated with Savanna Yard. Without the lunar, the train could only be advanced through the un-occupied interlocking by being 'talked by' the
signal.
The signal rule, which changed from 501-J in the 1950's, to 501-I in the 1960's, changed in Name from 'Stop and Proceed' to 'Permissive'. Under the latter rule, the stop was no longer required, but the train was still required to operate at restricted speed
through the entire block. Burlington was the only railroad under the BN Merger that did not require the train to stop, and the rule was changed back to 'Stop and Proceed' after 1970.
Other than at Savanna, the only territories that had extensive use of the lunars was from Chicago to Aurora and Aurora to Galesburg. While the train was, under the above rule, required to operate at restricted speed, Chicago to Aurora also had cab signals.
Under those circumstances, and with the short block spacing particularly east of Downers Grove, a train starting up from an interlocking (control point) under rule 501-I could be out-paced by a faster train just ahead, resulting in the cab signal 'picking
up' to 'Approach', allowing a faster operation to quickly resume.
Glen Haug
From: CBQ@groups.io <CBQ@groups.io> on behalf of Tom Mack via Groups.Io <thommack=yahoo.com@groups.io>
Sent: Wednesday, May 15, 2019 6:21 AM
To: CBQ@groups.io
Subject: [CBQ] Question on Rule 501I - Permissive Signal
Hopefully a ex-CB&Q employee can help me with this one. Rule 501I (501"eye") was a permissive signal - "Proceed at restricted speed through entire block". It was either a red signal with a milepost number plate or a red signal with a lunar. Here are my
questions:
1. I found a photo of a single red searchlight with a lunar signal at Savanna at the single track MILW diamonds on the Q just south of the double-track MILW diamonds. This MILW track was a MILW branchline that went south, and was probably not all that busy.
If I am reading Rule 501I correctly, the lunar was used so that the signal could be set to Permissive for this diamond if the dispatcher decided to do so by lighting the lunar. Otherwise, if the dispatcher left the lunar off (unlit), the signal became a 501J
Stop - "Stop before any part of train or engine passes the signal". Is this correct that a lunar would cause the signal to become either 501I or 501J depending on the dispatcher lighting the lunar? (A signal with a permanent milepost number plate would always
be 501I.)
1a. BTW, in the BN Signal Aspects and Indications dated July 1, 1974 it appears 501I became 501J - Stop and Proceed.
2. Since the Q did not have a "Stop and Proceed", did a train have to stop first at a Rule 501I signal before proceeding at Restricted Speed, or did it just roll through the red signal at Restricted Speed?
3. Assuming number 2 above is that the train did not have to stop, in actual practice, how did Restricted Speed differ from the speed through a Rule 501E "Approach" (yellow) signal?
Thanks!
--
Tom Mack
Cincinnati, OH
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