Derailment

A derailment is a railway accident in which a rail vehicle track leading his train, the track leaves. To the contrary, the re-railing or railing, i.e. the proper placement of a rail vehicle on the rail (s ).

For the railways of the Federal Republic of Germany defined the Federal Railway Office: " A gaffe is the sliding or lifting of a railway vehicle off the road, even if it itself aufgleist again, or the two-lane running of a railway vehicle. " This corresponds to the definition of the UIC, the with this definition, a vehicle describes as " derailed vehicle ." For in the vehicle regulations of UIC (AVV " General Contract of Use for Wagons " and RIC " Regolamento Internazionale delle Carrozze " ), is required in a derailed vehicle a special investigation of the rolling stock concerned. In Germany the derailment of the dangerous events in railway operation counts.

Following this EBA definition is the responsibility of the German Federal Railway Authority a rail vehicle already then as derailed when the constant contact between the wheel flange and / or tread of the wheel lost to two rail heads went, even if any of the target state ( leadership of the flange at the running edge of the rail heads ) will be recovered. That is already considered lifting a wheel off the road as derailment, is related to the usual in the past Achsgleitlagern. The mostly loosely inserted in the axle box bearing shell can slip when the load from its nominal position and be functional.

In the following, the terms are chosen which are appropriate for the structures under the aegis of the Federal Railway Office in Germany railways. In other railways in Germany or in other German-speaking areas, other terms may be possible.

Causes

Unintentional derailment

Vehicle -related causes

Rail vehicles can be derailed if they have too high a speed for the roadway geometry (curve radius, superelevation, switch type, etc.). Furthermore, can cause errors on the vehicle ( for example, wheel and axle errors Sollmaßabweichungen to the wheel flanges, broken axle bogies and defects ) to the derailment. Not properly secure goods or exceedingly unbalanced load balancing can freight cars from the track.

Operator -related causes

To derailment can occur when the driver, for example, signals are not observed, driving too fast or in the wrong direction anfährt ( forward or backward ). To the train driver braked before a final track with buffers, it can also come to the derailment when doing the end of the track is over. While maneuvering, the process operation as well as when driving on narrow curves vehicles can buffer and derail it. Here, the buffer between two vehicles over or slide next to each other and pry the affected vehicles from the track.

Error, the operator of the railway infrastructure, such as Dispatcher and switch guards, for example, in the following cases lead to derailments

• A switch is changed while a rail vehicle passes over it. The process is " two-lane drive called ".
• Unlawful behavior of signal interference.
• The understanding especially when maneuvering is not unique.
• A necessary command is not given or ambiguous.
• The necessary conditions for allowing a train or shunting were not met.
• Unintentional raising the vehicle ( that is with raised eg when unloading a container tilted the carriage ) during loading and unloading and derailing the same at weaning.
• Crossing of a brake, because it " bounces " the wheel over the obstacle ( Applies even if the vehicle then right again stands on the track). Chocks that are seen in the moving vehicles, cause if they get on the point end into a centerpiece, sure to derailment because they tilt in the heart and the press about running wheel sets from the track.
• Verbremsen and driving over a track or end financial statements.

Improper operation of vehicles technically related derailments can be promoted. So often heavy acceleration or braking on damaged rail tracks, with responsibility for a derailment. This means that previously several trains without problems could run over the damage, only the additional - by accelerating / braking triggered - dynamic forces enabled the derailment.

Infrastructure -related causes

The trouble-free operation of rail vehicles is ensured by the proper track geometry. Therefore, any unacceptable variations in the location and condition of tracks, switches can included, lead to derailment. Such deviations from the nominal geometry are:

• Worn and defective rails;
• Soft is not in final position;
• Foreign objects of any kind, including railway -related such as buffers, usually light space;
• People or animals in the track;
• Temperature-related track buckling;
• Other intolerant track width changes;
• More intolerant track axes changes (eg due to washouts or earthquakes).

As a rule, however, does not lead to a derailment that tailgating a blunt traffic switch, which is located in the wrong location. The course has been designed for this trailing of switch blades, but only one derailment of the ride, but damage to the blades, crossing closures and transmission parts, can not be avoided. Too much speed and the affected switch is mechanically locked, it may yet come to a derailment, because the tongue can not follow fast enough due to the locking mechanism and the inertia of the movement. The tailgating does not work by design of high-speed switches and other types of points (eg with movable core ), as malpositioned heart pieces of principle and drives are not high-speed switches due to trailable large retaining force. To prevent derailments on turnouts, the end position is checked when setting a route in the switchboard and secure the switch against relocation.

On particularly dangerous places in the rail network (eg before railway bridges ) guide rails are attached as derailment. These are additional indoor, lack of space in the track outer rails that derailed wheelsets lead and make it difficult to leave the tracks.

Intended derailment

A derailment is caused intentionally, but in practice simply avoided to prevent further damage to unintended vehicle movement. This can either be specified in local guidelines for maneuvering and driving trains ( conceivable in slope stations ) or where a decision in an individual case, depending on the individual situation. Course Preference decisions, is the uncontrolled running vehicle kinetic energy soft, so gradually withdrawn as a consequence.

Derailment devices such as sand turnouts and track locks belong to the edge precautions. To force a redirection or even derailment of vehicles that perform an illegal movement.

The necessary derailment by raising the rail vehicle using hoist or crane for maintenance or repair purposes is not a dangerous event or incident within the meaning of the above definitions.

Follow

Sometimes vehicles with axles derailed many kilometers are carried in the course before the derailment is noted primarily for freight. This generally gives rise great damage to the railway facilities ( infrastructure, cable etc ).

By derailing the rail vehicle in question is greatly slowed. This usually leads to the fact that the vehicle breaks off from the forward part, as the vehicles are decelerated behind, together with the derailed vehicle due to the automatic action of the railway brake by opening of the main air line. The front brakes pulling part, normally by the, by the train separation, open air main, also. The critical case is when the derailment remains unnoticed and the clutch does not tear. The train can be many kilometers to go until it eg comes through jamming in turnout areas to the actual disaster, with the appropriately serious consequences for passengers and property.

If derailed vehicles or lost cargo protrude into the next track, it may there come to a result there derailments traffic -efficient vehicles. Another consequence event of a derailment on electrified lines and stations is damage to the overhead line equipment, including the catenary masts.

For rapid detection of derailments on-board detectors can be used. What is new is the development of infrastructure- side prototypes. In both cases, the amount may be reduced at the derailment when it is detected early and immediate countermeasures are effective.

Even seemingly harmless lapses can lead to structural damage to the vehicle. Because with every derailment, one must assume that the vehicle was overloaded at points, for example when a wheel disc suddenly the entire burden of carriage axis (or more ) must commence. In addition, the load receiving often does not take place in the angle to which the wheel disc is adapted to be load bearing. This may mean that after the derailment are no longer the two wheel disks in parallel. Also, the springs can move, so they no longer are in the right position or are not performed correctly. Therefore, should not be put back into service even slightly derailed vehicles before running a capability study was performed. Without such continued operation be the same most vehicles (even if only one axis was derailed ) banned again.

Similarly, the state of the infrastructure and, where appropriate, the catenary system must be checked and repaired.