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Railroad Traffic Control Systems
Here you will find information on the 2 most common types of Railroad Traffic Control methods used. This has been put together based on information I gathered listening to my scanner and researched in part on the web, and through discussion with control operators. If any inaccuracies are found please Email Me
Centralized Traffic Control: Centralized Traffic Control (CTC) is a system that uses 'Block Signals' to break up the RR Lines into sections called 'Blocks', and a Control Operator to give trains permission through a certain Block, or group of Blocks, commonly used in areas of heavy traffic. Often times the signals can manage traffic smoothly as long as all train operators get permission from the operator and proceed through the blocks on green signals.
Signals have different meanings depending on where they are used, such as on a single line (ie between Co Rd 492 and Co Rd 550), with no switches between blocks, red means stop, green means proceed, and yellow means caution. Red signals require the operator's permission to pass, unless it's a red signal to mark the end of the main and the beginning of a yard, they must contact the yardmaster (or carman in some cases) to enter the yard, and then are under his/her control. A red signal to leave a yard is generally back into CTC Operator's territory and must be contacted once again. Green signals will usually show up along the way when given permission through a few blocks at a time, unless there is a train ahead, you will only have a green signal when the lead train is completely clear of the next block in front of it. Yellow is caution on single tracks, usually when a block has a restricted speed, or when there are track crews out. I don't recall ever seeing traffic when the signals were yellow on the 'single-line' but I believe when there is, it's at a reduced speed.
In areas of power switch tracks, signals work differently. Generally, for the 2 single tracks meeting up at the switch, there will be one signal on each track, green if the switch is set in your favor, red if it is set to the parallel track, in which case you must stop. If you are approaching a switch, there will be 2 signals, If both are red, there is a train in the next block and the train will have to stop. If the top light is green, and the bottom is red, the switch is set to the straight track. If the top is red and the bottom light is yellow, it means the train will take the curved, or diverging track. Often times the control operator will give them a command 'proceed on signal indication', meaning when they have clear signals they can go to the next block, and then another train can follow as soon as the first block is clear and so on. If the blocks are small, 2 trains can safely travel in the same direction, and one thats trying to go against the flow of traffic, off a switch will get a red signal and stop until the tracks clear, then it's track will get switched and a clear signal will allow that train to head where the first 2 came from.
Sometimes there is a signal tower with 3 lights on it. Red, Yellow, and Green. Works similar way as the previous section mentioned, red will mean stop, green means straight path, yellow means curved path when approaching the switch. When coming to the switch from one of the branch tracks, Red means stop, Yellow means caution, and Green means clear.
This may not have been the most help as I wrote it all in my own words, but I hope it was of some help in understanding CTC and signals. All my info was basically from the LS&I's system of operations and what I have seen while near the tracks or heard on my scanner.
Track Warrant Control: Track Warrant Control is a method of 'written instructions' given by a dispatcher, copied and repeated by train crews, to show their movement permission. Each warrant has several lines, each with it's own set of instructions to be checked as requested by the dispatcher. Warrant locations are known as 'Stations' or Mileposts, and there are several 'station' points along the main lines. Warrants vary from railroad to railroad, but mostly remain the same. I created this Example Track Warrant to help in explaining, while going over the lines.
The top section is all pretty simple, 'Number' is the track warrant number, which will depend on who's giving it. The LS&I uses numbers that are 'day, month, and number for the day'...ie on Dec 1st the numbers will be 120101, 120102, 120103 and so on. CN just goes up in sequential order. The Ore Sub is around 700 and something currently...ie 738, 739. 'Date' is just that, the date. 'To' signifies Job Name and Lead/Tailing engine number and direction, and 'At' is the Stationpoint or Milepost location of the train. Here is a brief CN example... "Track warrant Number 745, seven four five, Dated December 1st 2002 To the WC 7525 South At Partridge".
From there, the dispatcher will then give the train operator his instructions by having him 'check' certain line boxes, each with their own set of instructions, to show the train's movement allowance. I will go over the commonly used lines and their meanings, then give a continued example of the started warrant above (use example warrant link above to follow along if you like).
Line 01: "Track Warrant Number ### Is Void" simply means the active warrant with the number stated is no longer valid, and those warrant limits are no longer useable by that train
Line 02: "Proceed From (location) To (location) On (type) Track" is just a simple instruction line to give a train permission from one stationpoint to another, on stated track (usually 'Main' track is referred). Line 3 is a duplicate of this line
Line 04: "Work Between (location) And (location) On (type) Track" differs from line 2 in that 'work between' means the train is entitled to backup moves, and traveling between location points several times...thus 'Working' the area
Line 07: "Not In Effect Until The Arrival Of (train) At (location)" train's authority is not valid until the named train arrives at the stationpoint mentioned
Line 08: "Hold Main Track At Last Named Point" means when you arrive at the last location point on the warrant, stay on the main track when calling the dispatcher for the next warrant
Line 10: "Clear Main Track At Last Named Point" means the train must take the siding track upon arrival of the last stationpoint before contacting the dispatcher to continue
Line 13: "Do Not Exceed (speed) MPH Between (location) and (location)" is a speed restriction, to the named speed between the MP or Location Points named. Line 14 is a duplicate of this line
Line 22: "(number) Items Checked, (line #), (line #)" is a sum up of all the boxes that are supposed to be checked, including itself, just to 'make sure' none were missed when the dispatcher assigned the instructions"
Now after the brief example from the top section, the next part would go something like this... "Check Line 2, proceed from Partridge to Escanaba on main track, check Line 7, Not in effect until the arrival of the WC #7512 North at Partridge, check Line 22, 3 items checked, 2, 7 and 22"
The bottom section OK'd At is read by the dispatcher after the train crew reads back the warrant, then the dispatcher gives the OK time and zone. Disp. is the dispatchers initials, and Copied By is the Engineer's initials, or Relayed To is the initials of the guy who wrote it down, relayed by the Engineer.
I hope this was most helpful, and remember, I threw all this info together myself, so if something is inaccurate or hard to follow, please let me know and I will try to fix this, or if you feel I should list 'ALL' the lines instead of the common ones, input is always welcome.
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