Timetable and Train Order
Timetable and Train Order (in German: Timetable and Train Command) is the name of the traditional train control system on the North American railways . It is still widely used today by smaller railway companies and on branch lines with little traffic.
Procedure
Basics
The most important basis of train protection is driving at a certain time interval. All driving operations are based on a timetable . Precise clocks are therefore of particular importance to safety . In order to guarantee the following traffic protection, the following trains are only allowed to follow after a certain time interval, usually ten minutes. If the scheduled speed is not reached or if the train breaks down, appropriate safety measures must be taken by the staff of the train ahead. The train crew has to warn the following train with appropriate flares or bang capsules and flag signals placed on the track . For this reason, at the end of a train, a train terminal car called a caboose is carried. The following train must stop immediately and then drive the next mile only on sight, only then may it resume the permitted speed.
The counter- run protection is implemented in that a train has to wait for all scheduled counter-trains at a prescribed crossing point before it can continue itself.
Priority rules and driving rights
In the event of a delay, a system of priority rules “superiority rules” was created in order to keep subsequent delays as low as possible. Due to these regulations, the train crew can deviate from the timetable independently and, for example, move train crossings to other stations. There are basically two priorities: "class" and "direction" (direction of travel). The classes have priority over the direction of travel . For example, a train of a higher class has priority over a train of a lower class, regardless of the direction of travel of the second train. For trains of the same class, the prioritized direction of travel is always decisive.
As a result of these regulations, a driving service control of the operation of a route is largely unnecessary. However, the dispatcher ( dispatcher ) responsible for the respective route has the option of granting certain travel rights in order to keep the train traffic flowing. These orders are passed on by means of written orders (“train orders”). These are handed over to so-called train order stations during a train stop or when passing through. A signal indicates whether or not there is a corresponding command. With the introduction of train radio , the handing over of written commands has been largely stopped.
Additional trains that are not included in the timetable are marked separately by white flags or additional lamps and referred to as "extra". These rank after all scheduled trains.
If a scheduled train runs in several parts, all but the last part have a green flag or a green light at the top of the train. All parts together count as one train in the safety sense, i. H. the route is only considered free after the last part has been passed.
At larger railway junctions and crossing points, the signals set up are not used to regulate the sequence of trains. Only the authorization to drive in a limited section of the route ("interlocking limits") is displayed.
Block systems
In areas with a denser train sequence, additional block systems have been set up to increase performance and safety. The block system is to be understood as the generic term for driving at a distance , not necessarily as the technical safety system of the route block common in German-speaking countries . Such a block system only applies to the continuous main track of a line. As is customary in Germany, no distinction is made between route section (route block) and station (route).
In the manual block system, the security is carried out by prescribed reporting procedures; in the automatic block system, appropriate blocks are released or blocked by technical devices that check that the block sections with track circuits are free . In most cases, the rules of the "Timetable and Train Order" still apply, the block system is only viewed here as an additional safety system.
Need for modern procedures
In order to meet the requirements of rail customers, from the second half of the 20th century, the company began using more and more special trains and reducing scheduled trains. This led to an imbalance in favor of the special trains. However, the advantages of the traditional "Timetable & Train Order" system were largely lost. From the mid-1980s onwards, a procedure comparable to that of the German train control operation was used . The train crew receives the necessary driver's license from central dispatchers. The backup is also carried out using computer-aided processes. With the introduction of this procedure, the end-of-train wagons became obsolete, as the end-of-train control is ensured by electronic detectors (“end-of-train device”) and the train operations are now monitored by the dispatcher.
Web links
- Article by Dr.-Ing. Jörn Pachl on the US operating procedures ( Memento from September 27, 2007 in the Internet Archive ) (PDF; 687 kB)