About... Disrupters and Progress
Railroads in the early 1800's pulled passenger and freight cars on wooden rails or stringers using horse power, and since that time, the entire railroad industry has gone through hundreds or thousands of improvements. Most of these were changes by trial and error, inventions that had a goal of improving service and safety and reducing the cost per mile for moving people and goods.
The end result of most of these improvements was a reduction in labor costs, which make up the buik of expense for railroads. Some of these were significant. As an example, the move to diesel locomotives, led to the elimination of firemen on all locomotives and many, many maintenance jobs in roundhouses. In fact, the roundhouses themselves were eliminated by the diesel locotive. Another example was telemetry and the invention of the federal read end device to remotely monitor train status on the last car. Along with block signaling, this resulted in the loss of conductors and flagmen in cabooses at the back of the train, and all but eliminated the caboose itself and the weight it added to the train.