In planning, the dispatcher uses a record known as a TRAINSHEET, which appears somewhat as depicted in the following illustration. The track diagram is not represented on a trainsheet but is shown here to make the illustration more easily understandable. The trainsheet consists of a column in the center with the names of the stations on the dispatcher's territory, and blank columns in which the progress of trains is recorded by writing the times trains pass stations. In planning, the dispatcher writes the anticipated times in pencil to be readily available for comparison with the actual times trains pass these points.
The trainsheet is effectively a simulation and real-time model of the operation of the railroad. One of the important aspects of planning is the relationship of trains moving in opposite directions. For that reason, trains in each direction are separated by the station names in the center. Each column is read in the order that trains will pass stations; to the left of the stations column read down and to the right read up. Were one to follow the times of trains with their fingers or some other marker on each column, the relationship of the trains is readily apparent (see the example).
Another planning tool used by some computer assisted train dispatching software and by train dispatchers outside of the US is the stringline. The stringline plots distance against time. Trains in one direction rise on the graph left to right and in the other direction right to left. Where lines cross, trains in opposite directions meet or a train overtakes another in the same direction. The stringline illustration shows a simplified version of a stringline depicting the trains being discussed in these examples. In both cases the times represent the projected movement of trains before any dispatching decisions affect them.
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