- Train order operation
Train order operation is a system by which the railroads of
North Americaconveyed operating instructions before the days of centralized traffic control, direct traffic control, and the use of track warrants conveyed by radio.
Train order operation still exists on a few North American railroads, but has largely been replaced by more modern operating methods.
The term train order working is used in other regions of the world but the underlying details do not bear much similarity to North American methods of the past.
North American usage
In what was termed "timetable and train order operation", the operating
timetableestablished scheduled trains and their class. Class is a way of establishing superiority (priority) between different trains (e.g., passenger, through freight, and local freight). On single track, the timetable specifies the points at which two trains would meet or pass. The timetable thus provides the basic framework for train movement on a particular portion of the railroad. However, variations in traffic levels from day to day, unforeseen delays, need to perform maintenance, and so forth dictates that a way be found to vary from the schedules established by the timetable.
The train order provides the means to deal with these changes in operating conditions as they arise. Orders modify the timetable. Among the functions a train order can perform are:
* creating a train not provided for by the timetable (a so-called "extra").
* annulling a train provided by the timetable.
* creating "sections" of a schedule (in essence "cloning" a train's schedule and class when, for example, too much traffic exists to be handled by a single train).
* setting meeting points between extras since they have no timetable schedule.
* altering timetable meeting points (for example when one train is late and adhering to the timetable meeting point would cause delays for other trains).
* altering the schedule of a train to allow other trains to run with respect to the altered schedule rather than that given in the timetable.
* giving a train right over another train that ordinarily has timetable superiority.
* conveying warnings about temporary conditions such as temporary speed limits, track conditions or hazards which might affect the safety of trains or train crews.
Train orders were issued by the
train dispatcherresponsible for the portion of railroad concerned. They were conveyed to telegraph operators at outlying stations along the railroad via Morse telegraphor telephone; the receiving operators would copy the order onto onionskin forms designed for that purpose and would repeat the order back to the dispatcher so the dispatcher and other operators concerned could confirm correctness. As each operator repeated the order correctly, the dispatcher would give a complete time, along with the initials of the designated railroad official for that territory. After the order was completed, it was delivered by the operator to the concerned trains as they arrived or passed the delivery point. The operating time table indicated locations at which train crews could expect to receive train orders. If that same time table did not require that a train receive a "Clearance Form A" before departing, then a train order signal of some type was provided to advise train crews whether or not train orders were to be delivered. Delivery was accomplished by hand, if the train stopped, or by train order forks or hoops, either held by the operator as the train passed or mounted at trackside.
The train and engine crews addressed by the order were required to observe the instructions provided in the train order, the details of which were provided by the operating rule book.
Explanation of train order depicted in image
Use in other regions
Train order working is a system of controlling the despatch of trains, especially on
single lines, using telegraph messages.
On branch lines, these messages may be sent between the telegraph operators of the individual stations.
On busier lines, a central controller dispatches the necessary orders to the individual stations.
Train order station
A Train order station is a control point at which trains can be stopped and controlled through the use of train orders. A station requires the following:
*A siding or other track by which trains can pass each other
telegraphstation or other communications means for an operator to receive train orders
*A signal to indicate to trains whether there are train orders to be picked up
*A name to identify it on the orders
A train order station need not be at a passenger or freight station, nor does such a station have to handle train orders. In isolated areas train order stations may be required where there are no towns, in order to facilitate smooth operation. In denser areas passenger stations may be spaced more closely than train order stations.
A station is staffed by an operator who receives
train orders and gives them to trains as they pass. Upon receipt of an order, the operator makes copies and sets the signal to indicate to arriving trains that orders are to be picked up. Typically three indications are used:
* Proceed (green light and/or vertical blade): No orders; train may proceed
* Receive Orders (yellow light and/or diagonal blade): Pick up orders without stopping
* Stop (red light and/or horizontal blade): Stop to receive orders or to wait for another train to pass
Operators also record the passage of trains by their station.
Stations may not always be staffed, and when they are closed the signal is set to "proceed" and the switches lined to allow trains to pass without stopping. The system timetable indicates the stations and when they are staffed.
* [http://www.wx4.org/to/foam/sp/southwest/carrizozo_sub/a_directory.html Train orders on the Southern Pacific]
* [http://www.gatewaynmra.org/operate.htm Articles on North American prototype and model railroad operation]
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