Track Warrant Control on the Pacific & Eastern
Track Warrant Control (TWC) is a verbal authorization system defined by the General Code of Operation Rules (GCOR), used to authorize trains to occupy Main Tracks outside of Yard Limits. TWC can be used as a stand-alone dispatching and safety system in unsignaled territories, or can be supplemented with Automatic Block Signaling (ABS) to increase flexibility and traffic capacity.
The Track Warrant permits a specific train to occupy a specific piece of Main Track between named locations. The Track Warrant also contains information of its own validity; when comes in effect and in some cases when it becomes void.
A Track Warrant is issued in the following steps, usually using radio:
The Track Warrant is not in effect until the "OK" time is shown on it. If the Track Warrant restricts train movement or previously granted movement authority, the dispatcher can not consider the Track Warrant to be in effect until his "OK" has been acknowledged by the train crew member.
The Track Warrant form varies somewhat from railroad to railroad. Below is shown the form used on the Pacific & Eastern.
The upper 2 lines identify the Track Warrant by a number, a date, the train in question and the location of the train when the Track Warrant is issued.
After this follow 10 standard instruction fields plus one field for non-standardized instructions. Only some of the instruction fields are used in a given Track Warrant. The instruction field is numbered, and each field has a box to the right of the number. A check-mark in this box marks the instruction field as being in use of this Track Warrant. A typical instruction would then be: "Check Box 1, Track Warrant NO. 234 Is Void."
The instruction fields are described in detail in the following sections.
The 3rd line from the bottom holds information on the "OK" time and dispatcher initials. The 2nd last line states that the Track Warrant has been received and the name of the crew member who copied it. The last line it used to note when Limits are reported clear to the dispatcher.
The start point in the Track Warrant is normally referred to as the First Named Point, while the end of the Limits are referred to as the Last Named Point. The named points may be any point that can be exactly identified, such as switches, mile posts or Stations.
Pacific & Eastern Track Warrant
NO: ____________ _________20_____
To: _______________ At: _________________
1 * Track Warrant NO. ________is VOID.
2 * Proceed from___________________to____________________
3 * Proceed from___________________to____________________
4 * Work Between__________________and___________________
5 * Not in effect until arrival of ____________at_________________
6 * This authority expires at ________________________________
7 * Hold Main Track at last named point
8 * Clear Main Track at last named point
9 * Between _________________and _________________make all
movements at restricted speed. Limits occupied by train,
engines, men or machines.
10 * Do not exceed ____MPH between __________and___________
11 * Other specific instructions: ______________________________
OK __________ M Dispatcher ___________
Reported Clear at _______M By _____________
An important part of a Track Warrant is to define when it is in effect. Unless boxes 1, 5 or 6 indicates differently, Track Warrant is in effect as soon as the dispatcher has checked its correct reception by the train, and remains in effect until the train has reported the Limits clear.
A Track Warrant may be limited in time. A typical use for
this would be a window for a work train or a local switch job necessitating to foul the Main Track.
Though a Track Warrant usually assigns a section of Main
Track to one train only, it is sometimes necessary to be a little more
Adapted form Carsten Lundsten (http://www.lundsten.dk/us_signaling/twc/index.html)