In the early days of railroading, train movements were more or less controlled by a few rules giving superiority to a train on a particular section of track. Train "dispatching" did not exist. Trains could not advance from one station to the next without first verifying the arrival of in-bound trains. This resulted in major delays in the movement of trains, and more importantly increased the probability of collisions. The carnage on early railroads was incredible.
In the 1850s the telegraph was adopted by US railroads to improve the efficiency and safety of train movements. Prescott(3) summarizes this nicely:
"The use of a telegraph is a most important auxiliary in working the road, as, by the rules in force, trains moving in one direction possess positive rights to run without regard to time, or without reference to any opposing train; and an opposing train upon reaching a point whence, by the time-table, it should be met and passed by a train having the right to the road, is not permitted to leave until the arrival of such train; but by the use of the telegraph, conductors* in such cases may be immediately communicated with, and directed to move forward, without the slightest danger of collision. Without the telegraph, under such circumstances, they would be obliged to remain stationary, or proceed slowly at the most imminent risk. A single track railroad may be rendered more safe and efficient by a proper use of the telegraph than a double-track railroad without its aid; as the double track can only obviate collisions which occur between trains moving in opposite directions, while the telegraph may be used effectually in preventing them either from trains moving in an opposite or the same direction. In moving trains by telegraph, nothing is left to chance. Orders are communicated to the conductors and engineers of the opposing trains, and their answers returned, giving their understanding of the order, before either is allowed to proceed. It would occupy too much space to allude to all the practical purposes to which the telegraph is applied in working the road, and it may suffice to say that without it the business could not be conducted with anything like the same degree of economy, safety, regularity, or despatch."
Thus by the time the San Juan extension was completed in 1880, telegraphic control of railroads was considered an essential feature of railroad operations. Later, the telephone was introduced as a supplement and eventually a replacement for the telegraph.
Other Railroad Communications
On the Narrow Gauge the transmission of "consists" (a list of what loads and/or empties are in the train) was an important issue according to Norwood: "An abbreviated consist was sent from terminals to Alamosa, Montrose, or Salida to permit transfer forces to plan in advance for standard gauge transfer forces and machinery. These consists were transmitted by Morse telegraph and showed train handling, departure time from terminal, car number, contents, and destination." (4) On the Narrow Gauge, weather reports were especially important. Sometimes operators were stationed at the remote Osier depot for the purpose of reporting weather and snow conditions. Cumbres was maintained for the same purpose at all times in addition to being an important train order delivering station. The railroad used its communication facilities for all kinds of routine communications such as orders for materials, summoning of doctors, etc.
*This was not strictly true; on until the use of two-way radios was direct contact with engineers and conductors possible. Using the telegraph and telephone, the agent-operator did the actual communicating, and the information was passed to the trainmen using train orders.
3. "History, Theory, and Practice of the Electric Telegraph", by George B. Prescott.
4. "Rio Grande Narrow Gauge Recollections", by John B. Norwood, page 82. Heimburger House Publishing Company, 1986.