Each signal unit may display one, two or three colors.
This comes from the early days when the blade on a semaphore signal was called an arm. Each signal unit is commonly referred to as an arm. Signals controlled by the dispatcher do not have number plates and are two or three unit signals. These signals are usually operated automatically within the CTC system and their aspect determined by train location and track condition. Intermediate signals (signals with number plates) generally govern movements between interlockings and are commonly spaced at one train length apart. Not all signals in CTC territory are controlled by the dispatcher. meaning "on sheet." When this circuit becomes occupied by a train the dispatcher will show on his train sheet that this train is by the location that corresponds with that particular circuit. The dispatcher calls this same circuit the O.S. The detection circuit (track circuit) within the interlocking limits is known as the detector track circuit. When a less restrictive indication than "stop" is displayed, a signal is said to be "cleared." The track between the outer opposing signals is referred to as the interlocking limits. These signals display stop (rule 292) as their most restrictive indication. The definition of an interlocking is: "An arrangement of signals and signal appliances so interconnected that their movement must succeed each other in proper sequence and for which interlocking rules apply." Each signal governing entrance to an interlocking is called an interlocking signal or home signal. In contemporary railroading this is called a control point (CP).
#Train dispatcher 3.5 territories code
The control codes are sent to the field equipment via the code line to control the corresponding signals and switches.Įach end of a siding controlled by the dispatcher is called an interlocking. The control machine provides a means for the dispatcher to monitor wayside conditions and to initiate the control codes thru push buttons and levers. More so than the dispatcher's phone circuit and is the first to be repaired if major damage to the pole line occurs. This circuit is the most important pair of wires on the pole line. The code and carrier system allows the CTC system to operate over only two line wires, known as the code line.
A direct-wired arrangement would require one pair of wires for each controlled signal and switch within the CTC territory, and would not be economical. Because the distance between the control machine and the field locations in CTC territory usually extends a number of miles, the system is controlled by code and carrier equipment.
#Train dispatcher 3.5 territories install
The economics alone of eliminating telegraph offices and interlocking operators made it justifiable to install CTC.ĬTC is defined as "a block system under which train movements are authorized by block signals whose indications supersede the superiority of trains for both opposing and following movements on the same track." CTC provides centralized control for signals and switches within a territory of defined limits, controlled from a single control console known as a control machine. Compared to timetable and train order operations this was a vast improvement, not to mention CTC greatly reduced the danger of human error. On average CTC saved trains 42 seconds per mile and permitted passenger trains to make up lost time without delaying other trains.
The priorities were established according to traffic density and savings. Beginning in the mid-30's the railroads continued construction from one division to another as time and money became available. Hope you enjoy this information and happy model railroading!Īn early signal engineer once said, "The art of signaling may be quite truly termed the art of saving seconds safely." You could say that the railroad industry took this idea and ran with it purchasing CTC for much of their busy mainlines. CTC and signaling in general is such an involved subject, that I will try keeping simple, yet I do not want to leave out any key points. All information is of a general description and does NOT focus on one particular prototype, but instead on standard practices used throughout the railroad industry. This information is intended to give one a better understanding of how Centralized Traffic Control (CTC) operates. Part 2 Clearing a Signal at an Interlocking
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