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Germany updates: Railroad operator seeks modernization delay July 11, 2025, 2:35 AM ET (Deutsche Welle)

Because a railroad’s factory—its plant and train operations—may be spread out over thousands of miles and hundreds of communities, and because its trains use fixed tracks, unlike automobiles or airplanes, it has operating and service problems in some respects more complex than those of a major manufacturing installation. It is not surprising, therefore, that railroads have been among the pioneers in the use of improved methods of communication and control, from the telegraph to the computer and automation techniques.

Communications

Railroads were among the first to adopt the electric telegraph and the telephone, both for dispatching trains and for handling other business messages. Today, the railroads are among the larger operators of electronic communications systems.

Radio

Railroads began experimenting with radio at a very early date, but it became practical to use train radio on a large scale only after World War II, when compact and reliable very-high-frequency two-way equipment was developed. In train operations radio permits communication between the front and rear of a long train, between two trains, and between trains and ground traffic controllers. It also is the medium for automatic transmission to ground staff of data generated by the microprocessor-based diagnostic equipment of modern traction and train-sets.

In terminals two-way radio greatly speeds yard-switching work. Through its use, widely separated elements of mechanized track-maintenance gangs can maintain contact with each other and with oncoming trains. Supervisory personnel often use radio in automobiles to maintain contact with the operations under their control.

As the demand for more railroad communication lines has grown, the traditional lineside telegraph wire system has been superseded. As early as 1959, the Pacific Great Eastern Railway in western Canada began to use microwave radio for all communications, doing away almost entirely with line wires. Other railroads all over the world turned to microwave in the 1970s and ’80s. More recently many railroads have adopted optical-fibre transmission systems. The high-capacity optical-fibre cable, lightweight and immune to electromagnetic interference, can integrate voice, data, and video channels in one system.

Computers

A major reason for the growing use of microwave and optical-fibre systems was the tremendously increased demand for circuits that developed from the railroads’ widespread use of electronic computers.

Earlier, railroads had been among the leaders in adopting punched-card and other advanced techniques of data processing. In the 1970s and ’80s there was a strong trend toward “total information” systems built around the computer. In rail freight operation, each field reporting point, usually a freight-yard office or terminal, is equipped with a computer input device. Through this device, full information about every car movement (or other action) taking place at that point can be placed directly into the central computer, usually located at company headquarters. From data received from all the field reporting points on the railroad, the computer can be programmed to produce a variety of outputs. These include train-consist reports (listing cars) for the terminal next ahead of a train, car-location reports for the railroad’s customer-service offices, car-movement information for the car-records department, revenue information for the accounting department, plus traffic-flow data and commodity statistics useful in market research and data on the freightcar needs at each location to aid in distributing empty cars for loading. Tracing of individual car movements can be elaborated by adoption of automatic car identification systems, in which each vehicle is fitted with an individually coded transponder that is read by strategically located electronic scanners at trackside. Major customers can be equipped for direct access to the railroad computer system, so that they can instantly monitor the status of their freight consignments. Relation of real-time inputs to nonvariable data banked in computer memory enables the railroad’s central computer to generate customer invoices automatically. Data banks can be developed to identify the optimal routing and equipment required for specific freight between given terminals, so that price quotations for new business can be swiftly computer-generated.

Computers and microprocessors have found many other uses as a railroad management aid. For example, daily data on each locomotive’s mileage and any special attention it has needed can be fed by its operating depot into a central computer banking historical data on every locomotive operated by the railroad. In the past, many railroads scheduled locomotive overhauls at arbitrarily assessed intervals, but use of a computer base enables overhaul of an individual locomotive to be precisely related to need, so that it is not unnecessarily withdrawn from traffic. The same procedure can be applied to passenger cars. Systems have been developed that optimize economical use of locomotives by integrated analysis of traffic trends, the real-time location of locomotives, and the railroad’s route characteristics to generate the ideal assignment of each locomotive from day to day.

Computerization has given a railroad’s managers a complete, up-to-the-minute picture of almost every phase of its operations. Such complete information and control systems have proved a powerful tool for optimizing railroad operations, controlling costs, and producing better service.

Signaling

Railroad signals are a form of communication designed to inform the train crew, particularly the engine crew, of track conditions ahead and to tell it how to operate the train.

Methods of controlling train operations evolved over many years of trial and error. A common method in the early years was to run trains on a time-interval system; i.e., a train was required to leave a station a certain number of minutes behind an earlier train moving in the same direction. The development of distance-interval systems was a great improvement. In these so-called block systems, a train is prevented from entering a specific section of track until the train already in that section has left it.

Operation of single-track routes on the basis of a timetable alone, which was common on early lines in the United States, had the disadvantage that, if one train were delayed, others also would be delayed, since it was impossible to change the meeting points. By using the telegraph, and later the telephone, the dispatcher could issue orders to keep trains moving in unusual circumstances or to operate extra trains as required. This “timetable–train order” system is still used on many lines in the United States and Canada as well as in developing countries. It is often supplemented with automatic block signals to provide an additional safety factor, and radio is increasingly the means of communication between dispatchers and train crews.

Types of signals

The earliest form of railroad signal was simply a flag by day or a lamp at night. The first movable signal was a revolving board, introduced in the 1830s, followed in 1841 by the semaphore signal. One early type of American signal consisted of a large ball that was hoisted to the top of a pole to inform the engineman that he might proceed (hence, the origin of the term highball).

The semaphore signal was nearly universal until the early years of the 20th century, when it began to be superseded by the colour-light signal, which uses powerful electric lights to display its aspects. These are usually red, green, and yellow, either singly or in simultaneous display of two colours. The different colours are obtained either by rotating appropriate roundels or colour filters in front of a single beam or by providing separate bulbs and lenses for each colour. The number of lights and the range of aspects available from one signal can vary depending on its purpose. For instance, additional lights may be installed to the left or right of the main lights to warn a driver of divergence ahead from the through track. In Britain suitably angled strips of white lights are added to signals and illuminated when a divergent track is signaled. Red (stop or danger), green (track clear), and yellow (warning) have the same basic significance worldwide, but in Europe particularly they also are used in combinations of two colours to convey meanings that can vary from one railroad to another. Colour-light signaling is now standard on all but some minor rural lines of the world’s principal railways, and its use is spreading elsewhere.

Automated systems

The basis of much of today’s railroad signaling is the automatic block system, introduced in 1872 and one of the first examples of automation. It uses track circuits that are short-circuited by the wheels and axles of a train, putting the signals to the rear of the train, and to the front as well on single track, at the danger aspect. A track circuit is made by the two rails of a section of track, insulated at their ends. Electric current, fed into the section at one end, flows through a relay at the opposite end. The wheels of the train will then short-circuit the current supply and de-energize the relay.

In a conventional automatic block system, permissible headway between trains is determined by the fixed length of each block system and is therefore invariable. Modern electronics has made possible a so-called “moving block” system, in which block length is determined not by fixed ground distance but by the relative speeds and distance from each other of successive trains. In a typical moving block system, track devices transmit to receivers on each train continuous coded data on the status of trains ahead. Apparatus on a train compares this data with the train’s own location and speed, projects a safe stopping distance ahead, and continuously calculates maximum speed for maintenance of that headway. Moving block has been devised essentially for urban rapid-transit rail systems with heavy peak-hour traffic and on which maximum train speeds are not high; in such applications its flexibility by comparison with fixed block increases the possible throughput of trains over one track in a given period of time.

To ensure observance of restrictive signals, a basic form of automatic train control has been used by many major railroads since the 1920s. When a signal aspect is restrictive, an electromagnetic device is activated between the rails, which in turn causes an audible warning to sound in the cab of any train passing over it. If the operator fails to respond appropriately, after a short interval the train brakes are applied automatically. A refinement, generally known as automatic train protection (ATP), has been developed since World War II to provide continuous control of train speed. It has been applied principally to busy urban commuter and rapid-transit routes and to European and Japanese intercity high-speed routes. A display in the cab reproduces either the aspects of signals ahead or up to 10 different instructions of speed to be maintained, decelerated to, or accelerated to, according to the state of the track ahead. Failure to respond to a restrictive instruction automatically initiates both power reduction and braking. The cab displays are activated by on-train processing of coded impulses passed through either the running rails or track-mounted cable loops and picked up by inductive coils on the train. On some high-speed passenger lines the ATP system obviates use of traditional trackside signals.

Among other automatic aids to railroad operation is the infrared “hotbox detector,” which, located at trackside, detects the presence of an overheated wheel bearing and alerts the train crew. The modern hotbox detector identifies the location in the train of the overheating and, employing synthesized voice recording, radios the details to the train crew. Broken flange detectors are used in major terminals to indicate the presence of damaged wheels. Dragging equipment detectors warn crews if a car’s brake rigging or other component is dragging on the track.