Train order

Train order operation, or more accurately timetable and train order operation, is a largely obsolete system by which the railroads of North America conveyed operating instructions before the days of centralized traffic control, direct traffic control, and the use of track warrants conveyed by radio. The system used a set of rules when direct communication between train dispatchers and trains was limited or non-existent. Trains would follow a predetermined operating plan, known as the timetable, unless superseded by train orders conveyed to the train from the dispatcher, through local intermediaries. Train order operation was a system that required minimum human overhead in an era before widespread use of technology-based automation. It was the most practical way for railroads with limited capital resources, or lines with limited traffic, to operate. To this day, a large number of short lines, heritage railways, and railroad museums continue to use Train Order operation for the aforementioned reasons.

On major railroads, train order operation has been almost completely replaced by more modern operating methods. The Long Island Rail Road in New York is the last major railroad in North America to use a "traditional" Train Order operating practice on parts of its Greenport and Montauk Branches, as well as Train Order forms for non-standard operation on the remainder of its system. While the last traditional long hand train order form was issued on September 3, 2012, timetable and train order operating practices remain in effect. The second to last train order holdout, the Chicago South Shore and South Bend Railroad, had retired its system in 2011.

Timetable and train order operation was widely used on North American railroads that had a single Main Track with periodic passing sidings. Timetable and train orders were used to determine which train had the right of way at any point along the line. A train which had the right of way over another train was said to be the superior train. Trains could be superior by right, by class or by direction. While a train dispatcher could establish "right" via train orders, the operating timetable established scheduled trains, their class and the superior direction. The "class" designation of a train equates to its priority with passenger trains having the highest, freight trains having less and Extra (unscheduled) trains having the least. In case of trains of the same class meeting the superior direction would then apply. On single track rail lines, the timetable specifies (explicitly or implicitly) the points at which two trains would meet and pass. It would be the responsibility of the inferior train to clear the main track a safe time before the superior train is scheduled to 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, the need to perform maintenance, and other contingencies required that railroads find a way to deviate from their established schedules.

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Wikipedia