Signal stop case
As a signal stop event at the one referred to railways , the automatic return falling of a signal from the travel expenses to the maintenance position after the train is completely or partly passed to it.
The start signal of a route at the beginning of a specified route can basically only show "travel" as long as the first vacancy detection section monitored by the track vacancy detection is reported as clear. With driving of the first, as a support case portion or erasing section designated area behind the start signal in the start signal "Halt" would fall. This can lead to undesirable effects that must be countered in the course of planning such systems.
While the normal stop caused by the train passing the signal is referred to as a regular stop , in rare cases there are irregular stops in which a signal showing the way is withdrawn for other reasons.
In addition to this safety-related core function, the signal stop is also of major importance for train tracking. By means of a target / actual comparison of the time of the signal stop, the movement of a train can be tracked and the arrival, departure and transit times can be deduced. These times are used, for example, in scheduling systems and for traveler information.
Stall criteria
When a train passes a starting signal of a route that indicates the route , this must be immediately set to "Stop" in order to cover the train . If a track vacancy detection system is available, the stopping position takes place by driving on the first vacancy detection section continuously monitored for the route. This section is called the hold section or the delete section .
Alternatively, the halt can also take place with a time delay. Route-dependent maneuvering and blocking signals generally fall into the stop position immediately after the first vehicle has passed the signal location during maneuvering. Consideration of train control devices is not necessary, apart from exceptions such as the use of light blocking signals as entry signals on the opposite track. The fact that the locomotive passes such signals during a pushed shunting run when they have already returned to a stop position is not critical due to the fact that the top is occupied by a shunting attendant.
Another possibility is a delayed activation of the train control. Furthermore, further track switching means connected to the signal box can also trigger the stop position.
Entry form signals in mechanical interlockings must remain in the driving position until the train with the end of the train has passed the signal train termination point. The relay group for triggering the electrical route key lock , which forces the train to participate in the back block, is switched on by the travel position of an entry form signal . Resetting such a signal too early would lead to a block disturbance.
Only in the case of electrical interlockings is there an automatic signal stop for almost every signal; In the case of mechanical interlockings, only the main signals on tracks that are approved for passages, as well as group exit signals and associated distant signals, need to be equipped with the necessary wing or disk couplings. Mechanical track blocking signals are generally not equipped with wing clutches, regardless of whether they are set mechanically or electrically.
The signal stop is triggered either by the occupancy information of the track vacancy detection systems or via rail contacts by interrupting the coupling or monitoring circuit. In the case of light signals, the stop occurs via a circuit in the relay system of the interlocking; in the case of form signals, an electrical coupling is released that connects the signal wing to the signal drive, whereby the signal wing can fall back into the stop position due to gravity, which is what gives this term its name Has.
history
Since form signals can also be seen from behind, a main signal that fell back while the train was in a stop position was considered withdrawn in the past. For this reason, among other things, baggage cars built up to around 1950 had a high-level driver's seat with a roof structure for monitoring trains, routes and signals. Exit and block signals from junction points, which were equipped with wing couplings for the self-covering of trains even before the First World War, were therefore switched in such a way that they only stopped when the route setting field was unblocked, when the last axle had left the isolated rail of the route clearance . This circuit variant still occurs today in interlockings that have not been modernized. There are similarly acting circuits in electromechanical interlockings . When the interlocking was modernized around 1970, the stop was usually changed over to the first axis being used by the train.
At the Deutsche Reichsbahn , from around 1965 the firefighting bursts for new signal boxes were preferably arranged at the level of the signal location. In particular from the driver's cabs of steam locomotives you could still see the signal deletion in some places, which initially led to irritation for the locomotive personnel. Only when the lines were increasingly equipped with PZB equipment were these extinguishing bursts about twenty to thirty meters behind the signal locations.
Fall prevention
When the regular signal stop occurs depends on the type of signal. While in many subway and light rail networks of the signal stop event takes place directly driving past the Zugspitze at the signal, the signal cancellation when must gauge railways done so late that have passed through the gap device even in the worst case, recording bodies of vehicle equipment of the train control system. Otherwise there could be an unintentional emergency braking . In the case of newly built systems at Deutsche Bahn, the section that triggers the stop usually begins at least 50 m behind the main signal, the section in between is referred to as the stop prevention section or non-stop section . The track clearance of this section is only checked punctually when setting the route. If the extinguishing section adjoining the halt prevention section is occupied, the halt is triggered. This is referred to as stop criterion 1 .
The length of the stop prevention section must be at least the greatest possible distance between the first axle of a vehicle and its antenna of the train control system (e.g. vehicle magnet of the PZB ).
In order to prevent that trains which are shorter than the stopping prevention section would not trigger a stopping position. In order to ensure follow-up protection even for short trains, the stop must occur at the latest when the section in front of the signal has been cleared. This is referred to as stop criterion 2 .
The maximum length of the stop prevention section may be 400 m in Germany, since driving according to operational rules must be 400 m beyond the main signal. In the case of block signals that are used purely for train sequence control and which are not followed by a danger point within a distance of no more than 200 m, the track switching means that causes the signal to be deleted should generally follow 50 meters after the signal location. Different values are documented internationally, for example at least 25 m for ÖBB , but 0 to 6 m for RENFE (as of 1995).
A special feature is the exit from train station tracks, which can be occupied by several trains. If the entire length of the first departing train comes to a stop in the stop prevention section, the signal that does not stop causes a hazard, as the driver of the second train could interpret the "drive" signal as valid for him. In such cases, the signal should stop after 50 meters, but at the latest after the shortest possible length of the first train.
Regular and irregular signal stop case
A basic distinction is made between the regular signal stop case and the irregular signal stop case. The regular stop corresponds to the regular operating sequence, in which a signal from the train ( caused by the train ) stops.
On the other hand, an irregular stop occurs when the integrity of a route that has already been set is jeopardized. For example, due to a fault in an element such as a switch, regardless of whether it is flanking protection or in the route, or a flank protection violation due to impermissible journeys that endanger an adjacent train route .
Unintentional driving past signals indicating stop can result from errors in the vehicle technology (e.g. brake failure), errors in the safety technology (premature signal stop) and driving errors by the driver ( sliding , braking, disregarding / mixing up signals). In Germany in 2014, main signals showing stop were accidentally run over 470 times. It can also be triggered by interventions by the dispatcher (manual stop position or auxiliary resolution). Technical fail-safe reactions such as B. Power failures can cause an irregular halt.
In the event of an irregular stop, the train concerned must be brought to a standstill even if it has already passed the route's start signal. If the train in question is between the pre-signal and the main signal, the required braking distance is usually not reached, so that it can usually no longer be brought to a stop before the main signal showing "stop".
Stop evaluation
With ETCS comes the holding case assessment , i. H. the distinction between regular and irregular halts is of particular importance. An irregular stop immediately before a signal-controlled train drives past leads to an emergency brake using the comparatively simple PZB that takes effect in fractions of a second. In operation with ETCS level 2 or 3 , on the other hand, several seconds pass before the interlocking stop is transmitted via various interfaces and processed by the ETCS on-board device. For example, Deutsche Bahn assumes a delay time of 2.5 s between the request for the irregular stop and the processing of the corresponding reaction on the ETCS on-board device.
This results in cases in which, in the event of an irregular stop with conventional train control (e.g. PZB), an emergency brake is triggered when the train passes the signal, while with ETCS it would have already passed the signal due to these delays. An ETCS emergency stop order related to the signal would not reach the train until after the signal - all other things being equal - and would therefore have no effect per se.
If the interlocking is able to transmit an irregular stop to the ETCS center with sufficient reliability , it can stop a train that has already passed the signal behind it with an unconditional emergency stop. Many signal boxes are not able to do this. There is therefore the risk that an actually irregular halt will be assessed as a regular halt and a safety reaction will therefore not take place.
In order to achieve the same level of security with such interlockings in ETCS operation as with conventional train control, the ETCS control center must therefore use the last, i. d. Usually triggered by passing a group of balises at the signal, evaluate the position report where the train is and, if necessary, send a location-dependent or location-independent emergency stop order ( Conditional / Unconditional Emergency Stop ) to the train, if necessary also shortly after the to stop irregularly stopped signal. The implementation differs depending on the infrastructure operator and RBC supplier.
A location-dependent emergency stop order leads to an emergency brake if the minimum safe front end of the train is still in front of or so close behind the signal that, taking into account the ETCS transit time delays, it can be assumed that the train is under conventional train control would have been force-braked when driving past the signal.
Due to inaccuracies in the ETCS odometry , there may be unwanted emergency brakes on short, slow-moving trains if the vehicle triggers a regular stop early by passing the signal with the last axle (stop criterion 2) , which is the minimum safe stop from the ETCS point of view Zugspitze is just before the signal. Relocating the axle counter a few meters behind the signal can help.
When ETCS was introduced in Hungary, it turned out to be problematic that the stop section was usually directly at the signal, so the signal is set to "stop" after the first axis has passed. Regular unintentional emergency braking would have been the result. To solve the problem, consideration was given to reporting the signal stop to the ETCS control center with a delay or bringing forward the reference point for the relevant train position. Since the first variant was considered to be problematic from a safety point of view, the ETCS control center was configured to transmit a preferred distance to the on-board unit in the event of emergency stop orders.
After a hazard that occurred in Switzerland in 2019 due to the interaction of the stopping situation assessment and incorrectly set vehicle odometry, an immediate measure u. a. the stall assessment is deactivated on several affected RBCs.
Stop assessment is to be used in the Gotthard and Ceneri base tunnels from 2020 .
Others
The signal stop triggers a train running message and train number forwarding in computer-aided systems . This point in time differs from the points in time for arrival, departure or transit contained in the timetable. In the event of deviations, such as trips on command, corrections by the operator may be necessary. As a rule, however, departure, arrival and transit times can be determined approximately from the time of the signal stop.
On the Dutch high-speed line HSL Zuid , a signal stop is triggered automatically after a certain time after a train stops unexpectedly in the tunnel.
Individual evidence
- ↑ a b c d e f g h i j k l m Ulrich Maschek: Securing rail traffic . 4th edition. Springer Vieweg, Wiesbaden 2018, ISBN 978-3-658-22877-4 , p. 25 f., 101, 131, 143 f., 257, 300 .
- ^ Colin Bailey: European Railway Signaling . Ed .: Institution of Railway Signal Engineers. A & C Black, London 1995, ISBN 0-7136-4167-3 , pp. 113 .
- ^ A b c Karl Schnabel, Sándor Vajda: Introduction of ETCS Level 2 in Hungary by Thales . In: signal + wire . tape 107 , no. 5 , 2015, ISSN 0037-4997 , p. 12-18 .
- ^ Frank Tasch: Rules of procedure for driving trains . In: Your train . No. 12 , 2015, ISSN 0948-7263 , p. 14-18 .
- ↑ Ulrich Maschek: Driving past signals indicating stop . In: Your train . No. 2 , 2016, ISSN 0948-7263 , p. 28-33 .
- ↑ Sonja-Lara Bepperling, Charles Fermaud, Rainer Beck: systematic and random errors for risk analysis ETCS . In: signal + wire . tape 106 , no. 7 , 2014, ISSN 0037-4997 , p. 25-28 .
- ↑ Study on the introduction of ETCS in the core network of the Stuttgart S-Bahn. (PDF) Final report. WSP Infrastructure Engineering, NEXTRAIL, quattron management consulting, VIA Consulting & Development GmbH, Railistics, January 30, 2019, p. 259 f. , accessed April 22, 2019 .
- ↑ Security-relevant incident with ETCS L2 on the Lausanne - Villeneuve route . In: Eisenbahn-Revue International . No. 7 + 8 , July 2019, ISSN 1421-2811 , pp. 410 .
- ↑ Ramon Gander: SBB discovers errors in train protection and takes immediate action. In: sbb.ch. Swiss Federal Railways, July 18, 2019, accessed on July 20, 2019 .
- ^ Walter Fuß, Dagmar Wander, Patrick Sonderegger, Leif Leopold ,: Railway safety technology in Swiss tunnels . In: signal + wire . tape 111 , no. December 12 , 2019, ISSN 0037-4997 , p. 44-50 .
- ^ Heidi Holland-Nell, Thomas Ginzel, Jörg Demitz: Further development of the railway operations laboratory of the TU Dresden . In: signal + wire . tape 99 , no. November 11 , 2007, ISSN 0037-4997 , p. 23-27 .
- ^ Bob Janssen: Reliable operation on the HSL Zuid high-speed line . In: Railway technical review . No. October 10 , 2009, ISSN 0013-2845 , p. 550-554 .