1. The Essentials of Train Operation Methods of Control- OCS and CTC
ECHO
FOXTROT
GOLF

2. Overview of Train Operation
Movements (Trains, transfers or engines) operate on the main track between terminals utilizing one of two methods of control.
OCS (Occupancy Control System), or CTC (Centralized Traffic Control)
OCSis commonly referred to as “Dark Territory” as there are no wayside signals to
govern movements and the RTC has no “real time” display to see the progress of the movement.
This system utilizes Clearances issued by the RTC to the movement over the radio system or by telephone, and written down by the crew, instructing the movement to proceed from/to defined locations such as Station name signs or mile signs. A computer is used by the RTC to track and record all of these clearances and protect against any conflicting movements
Example: A train is given a clearance to proceed from “ABLE” to “DELTA”. The green line represents the portion of the main track the train is now authorized to use.
ABLE
BAKER
CHARLIE
DELTA
ECHO
The RTC will ask for a location report from the train at certain locations, which releases the track behind the movement so it can be used by another train.
Example: The RTC calls the train and asks for a location report. The train responds “Clear of CHARLIE at 0830”. This now allows the RTC to issue a clearance to another train behind CHARLIE e.g. train No. 2 (Orange line) is issued a clearance between ABLE and BAKER.
ABLE
BAKER
CHARLIE
DELTA
ECHO
When the first train is approaching DELTA, the crew will contact the RTC and request another clearance to take them further. The RTC will “Supersede” the first clearance giving the train additional track ahead.
Example: “Clearance No. 1 is superseded. Proceed from CHARLIE to ECHO.” The first train now has operating authority between CHARLIE and ECHO.
ABLE
BAKER
CHARLIE
DELTA
ECHO 2

3. Meeting an opposing train
When two movements are authorized opposing one another, they must pass one another at a designated “Siding”. The clearances will state which movement will go into the siding, and which will go down the main track.
Example: Train No.
1’s
(Green) clearance states
“ Proceed from ECHO to
FOXTROT…. Take siding at FOXTROT
Train No.2’s
(Red) clearance states “Proceed from GOLF to siding west switch
FOXTROT. (Red line) W E
ECHO
FOXTROT
GOLF
When the two trains arrive at the end of their operating authorities, one will be in the siding, and the other will be on the main track.
ECHO
FOXTROT
GOLF
The RTC will then issue each of the trains a clearance to take them further based on each train identifying the other train as having arrived.
Example: Clearance to Train No. 1(Green) “Do not leave until train No. 2 arrives at FOXTROT…. Proceed from FOXTROT to GOLF.”
Clearance to Train No.2 (Red) “Do not leave until train No. 1 arrives at FOXTROT … proceed from FOXTROT to ECHO.
ECHO
FOXTROT
GOLF
When switching is to be performed, a train can be given a “work” Clearance to move in both directions until the clearance is cancelled.
Example: To train No. 1. “ Work between ECHO and GOLF”
ECHO
FOXTROT
GOLF 3

4. CTC
Centralized Traffic Control (CTC) is a system by which movements are governed by signal indication routing them in one direction on main track, through turnouts in and out of sidings arranging meets, and through crossovers.
Indications on CTC signals are affected by the conditions in the track ahead, as well as the indication on the next signal. The RTC has no knowledge of the indication displayed on a CTC signal other than it being a “Stop” indication, or a “Permissive” indication.
The RTC requests a routing for a movement, then requests a signal. The RTC computer cross checks the RTC’s request, then, depending on the track conditions ahead, and the indication of the next signal, an indication will be displayed on the signal in the field.
Some of the conditions which will not allow a permissive signal to be displayed in the field are:
A broken rail; An open switch;
Equipment present on the track ahead prior to the next signal; or Blocking applied by the RTC to protect various situations.
Signals are normally erected to the right of the track in which they govern, but can be to the left of the track as long as by placing it there, it does not put it to the right of another track.
Dummy Masts
At some locations where there is not enough room to place signals to the right or left of the track in which they govern, the signal mast may be equipped with a Dummy Mast, or both signals erected on one mast.
Main Track
Siding 4

5. There are five different controlled signal head configurations.
These signals are divided up into two categories. Control signals and Non control signals.
CONTROLLED SIGNAL
Definition:
A CTC block signal which is capable of displaying a Stop indication until requested to display a less restrictive indication by the RTC.
These are CTC signals which the RTC controls and can block in the “STOP” indication. A written authority is required to pass these signals when displaying a “stop” indication. They are found where a “Controlled location” is present, and the RTC can route trains in different directions.
There are five different controlled signal head configurations.
3 head high mast
2 head high mast
3 head dwarf
2 head dwarf single head dwarf
CONTROLLED LOCATION
A location in CTC the limits of which are defined by opposing controlled signals.
Controlled Location
Controlled Location
Multi-track Controlled Location 5

6. A block in CTC between consecutive controlled locations or points.
CONTROLLED BLOCK
A block in CTC between consecutive controlled locations or points.
Controlled Block
Controlled Location
Controlled Location
NON CONTROL SIGNALS - Sometimes called intermediates.
These are CTC signals which the RTC does not control. Their indications work automatically and are governed only by the conditions in the block ahead, as well as the indication on the next signal.
No authority is required to pass these signals when displaying all red (a “stop and proceed” indication), and most have been equipped with an “R” marker plate on the mast which makes them a “restricting” signal when displaying all red.
These signals are found between “Controlled locations”. There are two different non control signal head configurations. R R
2 head staggered high mast
single head high mast
On CN, these signals can only display a limited number of indications.
Stop and proceed (Or restricting when equipped with an “R” plate as shown); Clear signal;
Advance clear to stop, slow, Medium, or limited signal; Clear to stop signal;
Clear to slow signal; Clear to medium signal; or Clear to Limited signal. 6

7. Direction indicators (Rule 440)
Some signals in CTC have been equipped with a white illuminated directional arrow indicator on the signal mast. This directional arrow is only illuminated when the next signal is permissive, and the dual control switch is lined in the direction of the arrow.
e.g. if the advance signal to a siding is indicating “Clear to stop” and the arrow indicator is illuminated and/or flashing, it indicates that the next signal is permissive and the route at the controlled location is lined in the direction of the arrow.
Speeds
There are five defined speeds that CTC signals can communicate:
“Limited Speed”a speed not exceeding 45 MPH
“Medium speed” a speed not exceeding 30 MPH
“Slow speed”
a speed not exceeding 15 MPH
“Diverging Speed” a speed not exceeding 25 MPH
“Restricted speed” a speed which permit stopping within ½ the range of vision of equipment and in no case exceeding “Slow Speed”. When
moving at restricted speed, be on the lookout for broken rails. When a broken rail is detected, the movement must be stopped immediately and must not resume until permission is received from the RTC or signalman. 7

8. Sequencing
Signals in CTC reflect a “spaced sequence” as to what is ahead. You cannot get a “clear” signal on one signal, then a “stop” signal on the next one. Depending on the length of the Controlled block between signals, you may have advanced information of a stop signal two blocks ahead…. but in all cases… at least one block ahead.
Each signal contains information as to the indication of the next signal. In CTC, it is very important to know the territory you are operating in as the lengths of the blocks between signals vary and are not uniform. Great consideration has been given as to the indications that can be displayed on any given signal and the distance to the next signal. 8

9. RULE 27 SIGNAL IMPERFECTLY DISPLAYED
This rule has an application to govern the action to be taken when a block or interlocking signal is observed to be imperfectly displayed, or the sequence of signals does not follow normal progression.
(a) Except as provided in paragraph (b), a fixed signal which is imperfectly displayed, or the absence of a fixed signal where one is usually displayed, must be regarded as the most restrictive indication that such signal is capable of displaying. An imperfectly displayed signal must be communicated to the proper authority as soon as possible.
(b) Where a block or interlocking signal is observed with one or more lights extinguished, and at least one light remains displaying either green or yellow, movements may proceed reducing to slow speed through turnouts, when practicable, preparing to stop at the next signal.
EXCEPTION: If a solid yellow is displayed on the bottom position and the remaining positions are red or extinguished, the movement must immediately reduce to RESTRICTED speed.
(c)When a signal is known or suspected of being damaged, it must be regarded as displaying the most restrictive indication that can be given by that signal.
(d)When a block or interlocking signal displays an indication that is in other than normal progression in relationship to the indication of the advance signal to that signal, the movement must stop immediately consistent with safe train handling practices and contact the RTC or signalman for further instructions.
(e) Repairs to damaged signals must not be made by other than qualified employees. Signals that have been knocked over must not be re-erected by other than an authorized employee. If it is known or suspected that a signal bungalow has been damaged, such fact must be reported to the RTC immediately.
Rule 27(b) Reduce to slow speed through turnouts when practicable, be prepared to stop at next signal. And advise RTC.
Rule 27(a) and (c) Stop. Obtain authority to proceed. And advise RTC.
Rule 27(b) Exception - Proceed at restricted speed. And advise RTC. 9

10. Other definitions used in CTC operation:
ADVANCE SIGNAL
A fixed signal used in connection with one or more signals to govern the approach of a movement to such signal.
BLOCK
A length of track of defined limits, the use of which by a movement is governed by block signals.
BLOCK SIGNAL
A fixed signal at the entrance to a block to govern a movement entering or using that block.
CENTRALIZED TRAFFIC CONTROL SYSTEM (CTC)
A system in which CTC rules apply.
DUAL CONTROL SWITCH
A switch equipped for powered and hand operation.
SPRING SWITCH
A switch equipped with a spring mechanism arranged to restore the switch points to normal position after having been trailed through.
TRAILING END
The tail end of the last piece of equipment in a movement in the direction of travel.
FIXED SIGNAL
A signal or sign at a fixed location indicating a condition affecting the operation of a movement.
CONTROLLED POINT
A signal location in CTC consisting of controlled signal(s) in one direction only.
CONTROLLED SIGNAL
A CTC block signal which is capable of displaying a Stop indication until requested to display a less restrictive indication by the RTC.
Operating on other than signal indication
Authorities other than signal indication are used to accommodate when a signal cannot be given, or the track is to be shared by other equipment or a foreman performing track work.
Remember: Some of the conditions which will not allow a permissive signal to be displayed in the field are: A broken rail; An open switch; Equipment present on the track ahead prior to the next signal; blocking applied by the RTC to protect various situations. 10

11. These are considered the KEY non signal rules used in CTC and are:
Written authority for a train or transfer to pass a stop signal.
(Ref Rule 103.1(b) (iii))
Rule 564(d) - Governs movements past a stop signal at “reduced speed” when a
known condition is preventing the signal to be displayed in the field.
(Ref Rule 103.1(b) (iii))
Rule 566 -
Written authority for a train or transfer occupy the track between two
(Rule 577)
control signals exclusively, and move in either direction until the
authority is cancelled.
Rule
When issued with a Rule 566 authority, it gives permission to use
(Rule 577.1)
certain Dual Control Switches in hand position, and suspends the
indication on the signal governing movement over those switches.
(Mostly used when switching at a controlled location.)
Rule 567 -
Written authority for a train or engine to occupy the track between
(Rule 577)
two control signals jointly with another train or transfer, and move in
either direction until the authority is cancelled. (Requires both trains
or transfers to have a written understanding as to each others
movements.)
Rule
Written authority for a train or transfer to occupy the track between
(Rule 567.2)
two control signals when a Foreman already holds an authority on
that portion of track. (requires verbal permission from the Foreman
prior to moving)
Rule 568 -
Authority to enter the main track or siding in CTC at a hand operated
switch.
Rule
Stop signal passed without authority.
Rule 573 -
Governs reverse movements within CTC.
Rule 576 -
Switching at a controlled location 11

12. TGBOs and DOBs
In addition to requiring clearances or signal indication to operate on a main track, all movements must obtain and be governed by either a Tabular General Bulletin Order, (TGBO) or a Daily Operating Bulletin (DOB).
The TGBO and DOB contain “General Bulletin Orders” which modify or restrict the operating parameters that are found in the Time Table. TGBOs are addressed to a specific train, while DOBs can be used by all movements within DOB limits.
TGBO
TGBO’s contain all track conditions a specific movement will encounter for its routing, as well as any movement specific GBO’s which may be in effect.
Example of a TGBO address: Q
Q= Quality service (100 series trains such as intermodal);
111 = the trains ID
number,
3 = the CN Region the train originates, 1 = the “First” train of that ID
number to operate on the date; and 10 = the date the train is scheduled to operate.
It is imperative that the correct TGBO for the movement is obtained from the GBO delivery system (fax memory or CNiNet web site). If the wrong TGBO is printed by mistake, the RTC must be contacted and will instruct you to destroy it.
The TGBO also has a “Routing” section titled “Applicable On”. You must verify that the “applicable on” section covers all of the trackage you will operate over to your destination.
In order to show verification that the TGBO’s movement I.D. is correct, and that the “Applicable On” portion covers the trackage you will use, you must initial next to both of these items.
Next you must verify that each page of the TGBO is legible and contains all of the items. As each page is verified, initial the bottom. On the last page of the TGBO, when it is verified that all items are present and legible, sign the bottom.
The TGBO will be automatically retired, and no longer valid when you arrive at your destination.
DOB (For use when trip will remain entirely within DOB limits)
The Metro Toronto DOB for example, can be used by all non TGBO addressed movements within DOB limits, and therefore does not have an address. The CN Regional Special Instructions indicates the limits of various DOBs on the Great Lakes. The date however is the important aspect of a DOB. CN Great Lakes DOBs are effective from 0300 to 0259 each day. It is imperative to verify that the DOB is correctly dated, then as with the TGBO, verify that each page of the DOB is legible and contains all of the items. As each page is verified, initial the bottom. On the last page of the DOB, when it is verified that all items are present and legible, sign the bottom. 12

13. Rule 43 slow track protection
GBO’s within the TGBO or DOB will indicate slow track protection as per rule 43. You will be required to comply with these Temporary slow orders.
Example: Due to track conditions do not exceed 30 MPH between mile 43.3 and mile 43.5 Ruel sub.
Yellow flags are placed in each direction 2 miles prior to the location of the slow track condition as an advanced warning to train crews. Green flags are then placed at the point where the train may increase to normal speed after the entire train has passed.
Rule 142 states - Crew members within physical hearing range are required to remind one another of the restrictions contained in GBO and clearances in sufficient time to ensure compliance.
Rule 42 Planned Protection of track work
Rule 42 protection of track work is used extensively on CN for Planned work, especially in CTC. Rule 42s will be highlighted on your TGBO or DOB with a black Vertical line.
Rule 42s are in effect between the time stated in the GBO, and run between whole mileages or other defined locations. No part of a movement may enter, move, or be moving within the limits of the Rule 42 between the times stated in the GBO without first having permission from the Foreman.
e.g. A rule 42 is in effect between the hours of 0800 and 1600 between mile 85 and mile 83 Bala sub., with Foreman Gary Cadaret.
Coming south at 1000 hrs, you will encounter Foreman Cadaret’s Yellow over red flag 2 miles north of mile 85. A call to obtain permission to pass through the limits must be made:
e.g.“CN Foreman Gary Cadaret this is 498 over” “ 498 this is CN Foreman Gary Cadaret over”
“ 498 approaching your red flag mile 85 what are your instructions over”
“ 498 you may pass my red flag mile 85 and proceed through my entire limits with no restrictions, whistle and bell passing work crews over..”
“ OK for 498 to pass Foreman Gary Cadaret’s red flag mile 85 and proceed through the entire limits with no restrictions… whistle and bell passing work crews … is that correct over.”
“ That is Correct 498… Foremen Gary Cadaret out.” “ Thank you Foreman Cadaret…498 Out”
Rule 142 states - Crew members within physical hearing range are required to remind one another of the restrictions contained in GBO and clearances in sufficient time to ensure compliance. 13

14. Rule 44 Unusual track signal conditions.
The following is a summary of Rule 44 conditions and requirements when Rule 42 or Rule43 flags are not displayed, displayed outside the times indicated, or are displayed in the wrong location.
-If flags for a Rule 43 are not displayed, this will be indicated in the GBO. (Normally slow orders which will be repaired within the day… flags must be displayed within 24 hrs.)
-If flags for a Rule 42 are not displayed between the times stated in the GBO, the movement will be governed as if they were in place. Such condition must be immediately reported to the RTC.
-The Yellow Rule 43 flags and the yellow over red Rule 42 flags will be located 2 miles from the beginning of the slow order or the Rule 42. If not possible, or if deemed necessary, they may be placed closer or farther than the 2 miles, or to the left of the track in which they govern, and the GBO will so indicate. -
If flags for a Rule 43 are encountered without having a GBO indicating a
Rule 43 being in effect, the movement must reduce to
10 MPH and
immediately contact the RTC.
-If flags for a Rule 42 are encountered without having a GBO indicating a Rule 42 being in effect, STOP at once and contact the RTC.
-If the yellow over red flag and or red flag is encountered for a Rule 42 one half hour before, or one half hour after the times shown, contact the Foreman named in the GBO. If the Foreman can be contacted, the train may proceed on instructions from the Foreman.
-If the yellow over red flag is encountered for a Rule 42 more than one half hour before, or more than one half hour after the times shown, contact the RTC. The RTC may instruct you to contact the Foreman named in the GBO and be governed by his instructions. The movement may proceed on instructions from the Foreman. 14

15. Radio broadcast requirements
On CN, there are requirements to make radio broadcasts to the airwaves at various intervals.
In OCS, a member of the crew on all trains must initiate a radio broadcast on the designated standby channel between one and three mile from the next station or interlocking. This broadcast must include the next requirement to protect against another train, transfer or Foreman if the restriction is between the upcoming station and the next station or interlocking.
e.g. You are approaching NOVAR, and you have a protect against Foreman Smith between HUNTSVILLE and MARTINS.
“CN 498 One mile to Novar… no restrictions.” Your next call approaching Huntsville would be:
“CN One mile to Huntsville… protect against Foreman Smith between Huntsville and Martins.”
In single track CTC, a member of the crew on all trains and transfers must initiate a radio broadcast to the airwaves on the designated end to end standby channel stating the name of the signal displayed on the advance signal to the next controlled location or interlocking.
e.g.
“CN 498…. Clear signal to Brechin” or
“CN 498 ….Clear to Stop signal at Brechin”
Rule 34 Fixed signal recognition and compliance
The following signals/operating signs must be communicated in the cab of a locomotive between crew members:
Block and Interlocking signals; Rule 42 and 43 signals; One mile sign to interlockings; One mile sign to Hot box detector; Stop sign;
OCS begins sign;
Red signal between the rails;
Stop signal displayed by a flagman; and
A switch not properly lined for the train or affected movement.