al aspects that can be included to make route signaling more robust. Together, these variations tend to minimize the differing complexities between the two systems. We will start by examining Speed Signaling and then cover Route Signaling. Figure 2 (page 58) shows typi- cal aspects, names and indications used with speed signaling. It may seem overpowering at first; how- ever, after reviewing it aspect by aspect, it really becomes easier to grasp. For example, clear, ap- proach, restricting, stop and pro- ceed, and absolute stop remain identical to route signaling, except that with speed signaling the “Re- stricting” is achieved with the low- est head displaying a solid yellow with all heads above red. In addition to the basic Ap- proach — indicating be prepared to stop at next signal — speed sig- naling requires Approach Medium, Approach Limited, and Approach Slow to be added in, designating approach next signal at Medium, Limited, and Slow speeds, respec- tively. That leaves four aspects for handling movements through the diverging route, one each at Me- dium and Limited speed (aptly named Medium Clear and Limited Clear) and one each at Medium and Limited speed prepared to stop at the next signal, aptly named Medium Approach and Limited Approach.
signaling is also the “standard” adopted by the Northeast Oper- ating Rules Advisory Committee (NORAC). Typically, route signaling is con- sidered easier to understand and to implement. Therefore, many modelers prefer to make use of route signaling, and it is what you mainly read about in the model press. However, if you are model- ing one of the Eastern roads, I rec- ommend that you give serious con- sideration to implementing speed signaling.
As we will see later on, there are simplifications that can be worked into the implementation of speed signaling. Also, there are addition-
It is important to note that flash- ing aspects, when used, always de- fine less restrictive indications. For example in Figure 2, Approach Limited is less restrictive than Ap- proach Medium. This is for safety reasons in the event that if a flasher unit sticks on, the system defaults to the more restrictive aspect. Similarly, if the unit sticks in the off condition, the signal displays an invalid aspect whereby “standard operating Rule 27 applies” which typically reads as, “A signal imper- fectly displayed, or the absence of a signal at a place where a signal is usually shown, must be regarded as the most restrictive indication that can be given by that signal.” A
corresponding saying among pro- totype train crews is “a dark signal is a red signal.”
Important Point:
A flashing aspect is always “less restricting” than if the light is illuminated continuously or dark.
Although extensive, it should be pointed out that aspects shown in Figure 2 are typical and if freelace modeling should be adequate, and likely more than adequate, for your application. However, if prototype modeling it is always best to check with your railroad’s Rule Book and Special Instructions to deter- mine the specific aspects used in the era and location being mod- eled. Likely, they will include varia- tions from those shown in Figure 2. For example, some railroads use a green-over-red dwarf denot- ing Clear while others use the as- pect for Medium Clear and others Slow Clear. Additionally, flashing aspects tend to be found more fre- quently on more modern updated applications and may well not exist on railroads employing a long es- tablised signaling system.
Speed Signaling Application Examples
Figure 1 illustrates various ex- amples of different track arrange- ments and turnout alignments and the correspondingly generated sig- nal aspects for speed signaling. In every case, Turnouts 3 and 7 are considered to be Medium Speed Turnouts (No. 16 prototype, cor- responding to No. 8 model) and Turnout 5 Slow Speed (No. 12 prototype, corresponding to No. 6 model). In Figure 1a, the dispatcher or tower operator has Train A aligned to proceed on the main track up to Signal 8R, supposedly to wait for an opposing train to enter the siding for a meet. Signal 8R is at “Stop,” Signal 4R is at “Approach,” and intermediate Signal 246 is at “Approach Medium,” providing two full block lengths, plus the
FEBRUARY 2016 55
Meet at Dillard Extra 3718 West holds on main track while Train 511, the Riddle Turn — a local serving towns of Drain, Roseburg, and Riddle — needing to clear the main track, crosses over to the east end of the Riddle-Dillard siding. Once clear, the dispatch- er lines the crossover for main track and clears the corresponding mast signal for Extra 3718 West to continue its run. Note, route signaling employs a two-headed dwarf searchlight signal on the siding where the upper head corresponds to the route continuing on the siding and the lower head taking the divergent route across the crossover onto the main track. Similarly, the two-headed mast signal back by the rear of the two tank cars — the signal just accepted by the 511 crew — performs the same function for eastbound traffic on the main track.
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