Centralized Traffic Control or Timetable & Train Order?
Mike sez…
by Mike Schafer & Bill Navigato
and, subsequently, operating ses- sions — need some form of traf- fic control. On real railroads, it was pretty much either timetable & train order (TT&TO, replaced today by radio-issued track war- rants) or Centralized Traffic Con- trol (CTC). For those of you who have just turned to Bill’s and my col- umn out of morbid curiosity to see what the village idiots are go- ing to squabble about today, and really don’t know much about train control, here’s some very basic descriptions. With TT&TO, which dates back to the 1800s, trains’ movements are governed by an employee timetable (ETT) and train class. If the schedule gets sufficiently messed up on ac-
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ailroad modelers who have sizable operating layouts —
count of very late-running trains or because a non-scheduled train has been thrown into the mix, the dispatcher issues train order(s) to the trains affected, through opera- tors at lineside stations. The op- erators then hand up the written train orders to the trains. Often, block-signal systems (ABS) add- ed protection to train movements within TT&TO territory and al- lowed for higher speed limits. CTC was developed in the 1920s and revolutionized rail traffic control. With CTC, the dispatcher could control a seg- ment of railroad — and it could be many miles — from a panel, remotely operating switches to set up “meets” at passing tracks between opposing trains. Track- side signals instantly indicated impending train routing to the lo- comotive crew. There was little or no need to wait for train orders to work their way through the sys- tem. CTC today remains widely used, although electronics has
Mike’s world Brandon Otterstrom, signaling guru for Mike Schafer’s I&StL, samples CTC dispatching on Phil Monat’s excellent Delaware & Susquehanna Railway in Bronx, New York, in April 2015. Schafer currently uses the old “Mother May I” method of dispatching until CTC can be implemented by Otterstrom. CTC will greatly streamline operations (and tone down the radio chatter) on the I&StL with its unusually complex track plan. Monat’s CTC system will serve as a prototype for the I&StL. — Mike Schafer photo
78 RAILROAD MODEL CRAFTSMAN
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