Congruence (manifolds): Difference between revisions

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Congruences in Riemannian manifolds: Further cleanup after http://en.wikipedia.org/w/index.php?title=Congruence_%28manifolds%29&diff=next&oldid=360457878 More of http://en.wikipedia.org/wiki/Special:Contributions/99.188.101.147 may be suspect ...
 
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[[Image:Feste Fahrbahn FFBögl.jpg|thumb|Track equipped with LZB loops.
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Notice the second cable on the lower part of the left rail.]]
 
'''Linienzugbeeinflussung''' (or '''LZB''') is a [[cab signalling]] and
[[train protection system]] used on selected German and Austrian railway lines
as well as the [[AVE]] in Spain. 
In [[Germany]], the system is mandatory on all lines where trains exceed speeds of
{{convert|160|km/h|abbr=on}} ({{convert|200|km/h|abbr=on|disp=or}} in Spain), but it is used on some slower lines to increase capacity. The [[German (language)|German]] Linienzugbeeinflussung translates to
''continuous train control'', literally: ''linear train influencing''.
It is also called ''linienförmige Zugbeeinflussung''.
 
== Overview ==
In Germany the standard distance from a distant [[Railway signal|signal]] to its home signal is {{convert|1000|m}}. On a train with strong brakes, this is the  [[braking distance]] from 160&nbsp;km/h.  In the 1960s Germany evaluated various options to increase speeds, including increasing the distance between distant and home signals, and cab signalling. Increasing the distance between the home and distant signals would decrease capacity.  Adding an additional aspect would make the signals harder to recognize.  In either case, changes to the conventional signals wouldn't solve the problem of the difficulty of seeing and reacting to the signals at higher speeds.  To overcome these problems, Germany chose to develop continuous cab signalling.
 
The LZB cab signalling system was first demonstrated in 1965, enabling daily
trains at the International Transport Exhibition in Munich to run at 200&nbsp;km/h. 
The system was further developed throughout the 1970s, then released on various
lines in Germany in the early 1980s and on German, Spanish, and Austrian
high-speed lines in the 1990s with trains running up to {{convert|300|km/h|abbr=on}}. 
Meanwhile, additional capabilities were built into to the system.
 
LZB consists of equipment on the line as well as on the trains. A 30–40&nbsp;km segment of track is controlled by a LZB control center.<ref name="GermanSignalling">Signalling System for German High Speed Lines, by H. Uebel, Standard Elektrik Lorenz A.G., Stuttgart, Germany, presentedin the "1989 International Conference on Main Line Railway Electrification", p 36-39.</ref>
The control center computer receives information about occupied blocks from [[track circuit]]s or [[axle counter]]s and locked routes from interlockings.
It is programmed with the track configuration including the location of points, turnouts, gradients, and curve speed limits.  With this, it has sufficient information to calculate how far each train may proceed and at what speed.
 
The control center communicates with the train using two conductor cables that run between the tracks and are crossed every 100 m.  The control center sends data packets, known as telegrams, to the vehicle which give it its movement authority (how far it can proceed and at what speed) and the vehicle sends back data packets indicating its configuration, braking capabilities, speed, and position.
 
[[Image:Ice2 mfa on lzb.jpg|thumb|right|360px|Main console of an [[DBAG Class 402|ICE 2]] train in LZB mode. The current, the maximum and the target speed is 250&nbsp;km/h. The target distance is 9.8&nbsp;km]]
 
The train's on-board computer processes the packets and displays the following information to the driver:
* <u>Current speed</u>: locally derived from speed sensing equipment - shown with a standard speedometer
* <u>Permitted speed</u>: maximum allowed speed now - shown with a red line or triangle on the outside of the speedometer
* <u>Target speed</u>: maximum speed at a certain distance - shown with LED numbers at the bottom of the speedometer
* <u>Target distance</u>: distance for target speed - shown with LED bars showing up to 4000 m, with numbers for longer distances
 
If there is a long distance free in front of the train the driver will see the target speed and permitted speed equal to the maximum line speed, with the distance showing the maximum distance, between 4&nbsp;km and 13.2&nbsp;km depending on the unit, train, and line.
 
As the train approaches a speed restriction, such as one for a curve or turnout, LZB will sound a buzzer and display the distance to and speed of the restriction.  As the train continues the target distance will decrease.  As the train nears the speed restriction the permitted speed will start to decrease, ending up at the target speed at the restriction.  At that point the display will change to the next target.
 
The LZB system treats a red signal or the beginning of a block containing a train as a speed restriction of 0 speed.  The driver will see the same sequence as approaching a speed restriction except the target speed is 0.
 
LZB includes [[Automatic Train Protection]]. If the driver exceeds the permitted speed plus a margin LZB will activate the buzzer and an overspeed light.  If the driver fails to slow the train the LZB system can apply the brakes itself, bringing the train to a halt if necessary.
 
LZB also include an [[Automatic Train Operation]] system known as AFB (Automatische Fahr- und Bremssteuerung, automatic driving and braking control), which enables the driver to let the computer drive the train on auto-pilot, automatically driving at the maximum speed currently allowed by the LZB.
In this mode, the driver only monitors the train and watches for unexpected obstacles on the tracks.
 
Finally, the LZB vehicle system includes the conventional [[Indusi]] (or PZB) train protection system for use on lines that aren't LZB equipped.
 
== History ==
=== Choice of cab signalling ===
In the 1960s the German railways wanted to increase the speeds of some of their railway lines.  One issue in doing so is signalling. German signals are placed too close to allow high-speed trains to stop between them, and signals may be difficult for train drivers to see at high speeds.
 
Germany uses distant signals placed {{convert|1,000|m|ft|abbr=on}} before the main signal. Trains with conventional brakes, decelerating at {{convert|0.76|m/s2|abbr=on}}, can stop from {{convert|140|km/h|mph|abbr=on}} in that distance. Trains with strong brakes, usually including electromagnetic [[track brake]]s, decelerating at {{convert|1|m/s2|abbr=on}} can stop from {{convert|160|km/h|mph|abbr=on}} and are allowed to travel that speed. However, even with strong brakes and the same deceleration, a train traveling {{convert|200|km/h|mph|abbr=on}} would require {{convert|1,543|m|ft|abbr=on}} to stop, exceeding the signalling distance.  Furthermore, as energy dissipated at a given acceleration increases with speed, higher speeds may require lower decelerations to avoid overheating the brakes, further increasing the distance.
 
One possibility to increase speed would be to increase the distance between the main and distant signal. But, this would require longer blocks, which would decrease line capacity for slower trains. Another solution would be to introduce multiple aspect signalling.  A train traveling at {{convert|200|km/h|mph|abbr=on}} would see a "slow to 160" signal in the first block, and then a stop signal in the 2nd block.
 
Introducing multi-aspect signalling would require substantial reworking for the existing lines, as additional distant signals would need to be added onto long blocks and the signals reworked on shorter ones. In addition, it wouldn't solve the other problem with high-speed operation, the difficulty of seeing signals as a train rushes past, especially in marginal conditions such as rain, snow, and fog.
 
Cab signalling solves these problems.  For existing lines it can be added on top of the existing signalling system with little, if any, modifications to the existing system.  Bringing the signals inside the cab makes it easy for the driver to see them.  On top of these, the LZB cab signalling system has other advantages: * The driver is immediately aware of signalling changes. :This allows a driver to stop slowing down if a signal at the end of a block improves. 
It also allows the control center to instantly signal stop in the case of dangerous conditions such as a derailment or avalanche.
 
* The driver can electronically "see" a long distance down the track, allowing him or her to drive the train more smoothly.
* A train following a slower train can "see" the slower train well in advance, coasting or using regenerative braking to slow and thereby saving energy.
* It can signal a variety of speeds.  (Conventional German signals in the 1960s could only signal {{convert|40|or|60|km/h|mph|abbr=on}} for turnouts. Modern conventional German signals can signal any {{convert|10|km/h|mph|abbr=on}} increment, but LZB can signal even finer increments.)
* It allows the track to be divided up into a large number of small blocks if necessary to increase capacity.
* It enables a more capable [[Automatic Train Protection]]
* It enables the AFB Automatic Train Operation system.
 
Given all of these advantages, in the 1960s the German railways chose to go with LZB cab signalling instead of increasing the signal spacing or adding aspects.
 
=== Development ===
 
The first prototype system was developed by German Federal Railways in conjunction with Siemens and tested in 1963.  It was installed in Class 103 locomotives and presented in 1965 with {{convert|200|km/h|mph|abbr=on}} runs on trains
to the International Exhibition in Munich. From this Siemens developed the LZB 100 system and introduced it on the Munich-Augsburg-Donauwörth and Hanover-Celle-Uelzen lines, all in Class 103 locomotives.<ref name="LZB80">
Continuous Automatic Train Control and Cab Signalling with the LZB 80, by H. Sporleder, Siemens, AG, published in the
"1989 International Conference on Main Line Railway Electrification", p 40-46.</ref>
The system was overlaid on the existing signal system. All trains would obey the standard signals, but LZB equipped
trains could run faster than normal as long as the track was clear ahead for a sufficient distance.
LZB 100 could display up to {{convert|5|km|mi|abbr=on}} in advance.
 
The original installations were all hard-wired logic. However, as the 1970s progressed SEL developed the computer
based LZB L72 central controllers and equipped other lines with them.
 
By the late 1970s, with the development of microprocessors,
the 2-out-of-3 computers could be applied to on-board equipment.
Siemens and SEL jointly developed the LZB 80 on-board system
and equipped all locomotives and trains that travel over {{convert|160|km/h|mph|abbr=on}}
plus some heavy haul locomotives.  By 1991, Germany replaced
all LZB 100 equipment with LZB 80/L 72.<ref name="GermanSignalling"/>
<ref name="LZB80"/>
 
When Germany built its high-speed lines, beginning with the
Fulda-Würzburg segment that started operation in 1987,
it incorporated LZB into the lines.  The lines were divided into
blocks about {{convert|1.5|to|2.5|km|mi|abbr=on}} long, but instead of having a signal
for every block, there are only fixed signals at switches
and stations, with approximately {{convert|7|km|mi|abbr=on}} between them.
If there was no train for the entire distance the entry
signal would be green.  If the first block was occupied it
would be red as usual.  Otherwise, if the first block was free
and a LZB train approached the signal would be dark and the
train would proceed on LZB indications alone.
 
The system has spread to other countries.  The Spanish equipped
their first high-speed line, operating at {{convert|300|km/h|mph|abbr=on}}, with LZB. 
It opened in 1992 and connects Madrid, Cordoba, and Seville. 
In 1987 the Austrian railways introduced LZB into their systems, and with the
23 May 1993 timetable change introduced Euro City trains running {{convert|200|km/h|mph|abbr=on}}
on a {{convert|25|km|mi|abbr=on}}-long section of the Westbahn between [[Linz]] and [[Wels]].
 
Siemens continued to develop the system, with "Computer Integrated Railroading",
or "CIR ELKE", lineside equipment in 1999.  This permitted shorter blocks and
allowed speed restrictions for switches to start at the switch
instead of at a block boundary.  See [[#CIR ELKE|CIR ELKE]] below for details.
 
=== Development timeline ===
 
{| class="wikitable"
|- class="hintergrundfarbe6"
! width="80" | Date || Description || width="130" | Control centers / Length
|-
| align="center" | 1963 || Testing on [[Nuremberg–Bamberg railway|Forchheim–Bamberg line]] ||
|-
| align="center" | 1965 || 200&nbsp;km/h presentation trips on the [[Munich–Augsburg railway|Munich–Augsburg line]] installed in [[DB Class 103|Class 103]] locomotives<ref
    name="bachtech-2006-1-24">''Der ICE – ein Produkt des Systemverbundes Bahn''.
    In: [[Deutsche Bahn]] AG: (http://www.db.de/site/shared/de/dateianhaenge/publikationen__broschueren/bahntech/bahntech200601.pdf)
    ''bahntech'', Nr. 1/06], S.&nbsp;24&nbsp;f.</ref> ||
|-
| align="center" | 1974–1976 || Operations testing on the [[Wanne-Eickel–Hamburg railway|Bremen–Hamburg line]] || 3 controllers / {{convert|90|km|mi|abbr=on|disp=or}}
|-
| align="center" | 1976 || Expanded the trial to the [[Hamm–Minden railway|Hamm–Gütersloh line]]. ||
|-
| align="center" | 1978–1980 || S-Bahn pilot project in Madrid ([[RENFE]]) || 1 controller / {{convert|28|km|mi|abbr=on|disp=or}}
|-
| align="center" | 1980–1985 || Operations start on some [[Deutsche Bundesbahn|Deutschen Bundesbahn]] (DB) lines || 7 controllers / {{convert|309|km|mi|abbr=on|disp=or}}
|-
| align="center" | 1987 || Operations start on new high-speed lines [[Hanover–Würzburg high-speed railway|Fulda–Würzburg]] and [[Mannheim–Stuttgart high-speed railway|Mannheim–Hockenheim]] || 4 controllers / {{convert|125|km|mi|abbr=on|disp=or}}
|-
| align="center" | 1987 || [[Austrian Federal Railways]] decides to introduce LZB ||
|-
| align="center" | 1988–1990 || Further expansion to new routes in Germany || 2 controllers / {{convert|190|km|mi|abbr=on|disp=or}}
|-
| align="center" | 1991 || Commissioning of the remainder of the [[Hanover–Würzburg high-speed railway]], the [[Mannheim–Stuttgart high-speed railway]] and additional routes || 10 controllers / {{convert|488|km|mi|abbr=on|disp=or}}
|-
| align="center" | 1992 || Opening of the [[Madrid-Sevilla high-speed rail line]] in Spain || 8 controllers / {{convert|480|km|mi|abbr=on|disp=or}}
|-
| align="center" | 1992 || First section [[Western Railway (Austria)|Wien–Salzburg]] route in Austria || 1 controller / {{convert|30|km|mi|abbr=on|disp=or}}
|-
| align="center" | 1995 || Commissioning of the [[Madrid]] C5 [[Cercanias]] (suburban rail) line || 2 controllers / {{convert|45|km|mi|abbr=on|disp=or}}
|-
| align="center" | 1998 || Commissioning of the [[Hanover–Berlin high-speed railway]] and expansion of the [[Nuremberg]]-[[Würzburg]] route, paired with electronic interlockings.  || 6 controllers
|-
| align="center" | 1999 || Commissioning of the [[#CIR ELKE|CIR ELKE]] pilot project on the [[Mannheim–Karlsruhe–Basel railway|Offenburg–Basel line]], with CE1 system software || 4 controllers
|-
| align="center" | 2001 || Commissioning of the [[#CIR ELKE|CIR ELKE]] pilot project at [[Achern]] || 1 controller
|-
| align="center" | 2002 || Commissioning of the [[Cologne–Frankfurt high-speed rail line]] using [[#CIR ELKE-II|CE2]] system software || 4 controllers
|-
| align="center" | 2003 || Commissioning of the upgrades to the [[Cologne–Aachen high-speed railway|Cologne–Düren(–Aachen)]] rail line (LZB with CE2-Software)|| 1 controller / {{convert|40|km|mi|abbr=on|disp=or}}
|-
| align="center" | 2004 || Commissioning of the upgrades to the [[Berlin–Hamburg Railway|Hamburg–Berlin line]] (LZB with CE2 system software)|| 5 controllers
|-
| align="center" | 2004 || Commissioning on the upgrades to the [[Munich S-Bahn]] using (CE2 software and shorter blocks) || 1 controller
|-
| align="center" | 2006 || Commissioning on the upgrades to the [[Anhalt Railway|Berlin–Halle]]/[[Leipzig]] line where LZB (CE2) and [[European Train Control System|ETCS]] are combined for the first time. || 4 controllers
|-
| align="center" | 2006 || Commissioning of the [[Nuremberg–Munich high-speed railway]] (LZB with CE2 system software with turnout extension) || 2 controllers
|}
 
== Line equipment ==
=== Cable loops ===
[[Image:Lininenleiter im Gleis mit Kreuzungsstelle.jpg|thumb|Cable loop]]
 
The LZB control center communicates with the train using conductor cable loops.
Loops can be as short as 50 meters long, as used at the entrance and exit
to LZB controlled track, or as long as {{convert|12.7|km|mi|abbr=on}}. Where the loops are longer
than {{convert|100|m|ft|0|abbr=on}} they are crossed every {{convert|100|m|ft|0|abbr=on}}. At the crossing the signal [[phase angle]]
is changed by 180° reducing electrical interference between the track
and the train as well as long-distance radiation of the signal.
The train detects this crossing and uses it to help determine its
position. Longer loops are generally fed from the middle rather than an end.
 
One disadvantage of very long loops is that any break in the cable
will disable LZB transmission for the entire section, up to {{convert|12.7|km|mi|abbr=on}}.
Thus, newer LZB installations, including all high-speed lines,
break the cable loops into {{convert|300|m|ft|0|abbr=on}} physical cables. Each cable is fed from
a repeater, and all of the cables in a section will transmit the
same information.
 
[[Image:LL-Verlegung.png|thumb|640px|center|Short loop cable configuration.]]
 
=== LZB route center (central controller) ===
 
The core of the LZB route center, or central controller, consists of a
2-of-3 computer system with two computers connected to the outputs and
an extra for standby. Each computer has its own power supply and is in
its own frame.<ref name="LZB80"/> All 3 computers receive and process inputs
and interchange their outputs and important intermediate results.
If one disagrees it is disabled and the standby computer takes its place.
 
The computers are programmed with fixed
information from the route such as speed limits, gradients, and the
location of block boundaries, switches, and signals.  They are linked
by LAN or cables to the interlocking system from which they
receive indications of switch positions, signal indications, and
track circuit or axle counter occupancy.  Finally, the route center's
computers communicates with controlled trains via. the cable loops
previously described.
 
=== Other equipment ===
 
[[Image:LZB Bereichskennzeichnungswechsel.jpg|thumb|right|Start of LZB sign]]
[[Image:LZB-Blockkennzeichen.jpg|thumb|Sign indicating a new (virtual) LZB block]]
* ''Repeaters'': Repeaters connect individual {{convert|300|m|ft|0|abbr=on}} long loop sections to the primary communication links, strengthening the signal from the route center and sending the vehicle responses.
* ''Fixed loops'': Fixed loops, typically about {{convert|50|m|ft|0|abbr=on}} long, are placed at the ends of the controlled section. They transmit fixed telegrams which allow entering trains to receive an address.
* ''Isolation cabinets'': A long communication link will consist of multiple individual cables connected in "isolation cabinets" which serve to prevent the low-frequency voltage which is coupled from the catenary from accumulating on the cable.
* ''Signs'': Signs indicate the LZB block boundaries (if not at a signal) and the entrance and exit from the LZB controlled area.
 
== Vehicle equipment ==
 
The vehicle equipment in the original LZ B80 designed consisted of:<ref name="LZB80"/>
 
* ''Computers'': The on-board equipment centered around a 2-of-3 computer system. The original LZB 80 design used 8085 microprocessors programmed in assembly language. The programs were interrupt driven, with interrupts generated by a 70 ms clock, the track receivers and transmitters, the serial interface, and also within the program itself. Interrupts triggered comparison and output programs. Peripheral equipment was arranged around the computers with all interfaces electrically separated and all grounds tied to the cabinet frame which was tied to the vehicle chassis.
* ''Redundant power supply'': The computers and peripheral equipment were supplied with a redundant power supply based on two identical voltage transformers. Each was capable of supplying the power necessary for all of the equipment. They were normally alternately switched, but if one failed the other would take over. On-board batteries could also supply temporary power.
* ''Odometry'': The vehicle speed and distance traveled is measured on two independent channels by two pulse generators mounted on different axles. Each is linked to a separate micro-controller based unit used to correct any inaccuracies. The central logic polls the two units as well as an accelerometer,compares the values and checks for plausibility.
* ''Receiver'': Two pairs of receiving [[antennas]] are each fed to selective, self-regulating [[amplifiers]] whose output is fed to a [[demodulator]] and then a serial-parallel transformer. The received telegrams are then fed byte by byte to the central logic computer. The receivers also indicate transition points and whether the signal is present.
* ''Transmitter'': The 2 out putting computers feed serial-parallel transformers.  They are compared after conversion, and transmission is only allowed if they are identical. Only one signal is actually transmitted, with the transmitter transmitting the two signals at 56&nbsp;kHz with the signals displaced by a 90° phase angle.
* ''[[Emergency brake (train)|Emergency brake]] connection'': The computers are connected to the brake via a relay. A computer command or loss of current will release the air from the brake pipe applying the emergency brake.
* ''INDUSI horn connection'': The horn signalling the driver is also connected by a relay.
* ''[[Serial interface]]'': A serial interface is used to connect the rest of the components, including the driver inputs, display unit, logger, and the automatic drive and brake control (AFB) to the computers. Telegrams are transmitted cyclically both from and to the computers.
* ''Driver input unit'': The driver inputs train related data such as the type of braking (passenger/freight), braking potential, maximum train speed, and train length on the driver interface unit. This is then displayed to the driver to verify that it is correct.
* ''Modular cab display (MFA)'': The modular cab display shows the relevant speeds and distances to the driver as described in the [[#Overview|overview]].
* ''Automatic drive/brake control'': When enabled by the driver, the automatic drive/brake control unit (AFB) will drive the train following the permitted speed. When not operating on an LZB equipped line, i.e. under INDUSI operation, the AFB acts as a "cruise control", driving according to the speed set by the driver.
 
The equipment in newer trains is similar, although the details may vary. For example, some vehicles use radar rather than accelerometers to aid in their odometry.  The number of antennas may vary by vehicle. Finally, some newer vehicles use a full-screen computer generated "Man-machine interface" (MMI) display rather than the separate dials of the "Modular cab display" (MFA).
 
== Operation ==
=== Telegrams ===
 
LZB operates by exchanging telegrams between the central controller and
the trains.  The central controller transmits a "call telegram" using
[[Frequency-shift keying]] (FSK) signalling at 1,200 bits per second on a 36&nbsp;kHz&nbsp;±&nbsp;0.4&nbsp;kHz.
The train replies with a "response telegram" at 600 bits per second
at 56&nbsp;kHz ±&nbsp;0.2&nbsp;kHz.<ref name="TSI_HSR_CommandControl">
Directive 96/48/EC, Interoperability of the trans-European
high speed rail system, Draft Technical Specification for Interoperability,
Part 3, annexes to the TSI, "Control-Command and Signalling" Sub-System,
19.05.2006.
</ref>
 
==== Call telegram format ====
 
Call telegrams are 83.5 bits long:
* Start sequence: Synchronization: 5.5 bits, Start element + baker code: 3 bits
* Address: Section ID: A-E, A1-A3, Location: 1-127 or 255-128
* Vehicle information: Travel direction: up/down, Braking type: passenger/freight, Brake curve number: 1-10, A-B
* Braking information: Distance to brake application: {{convert|0|–|1550|m|ft|0|abbr=on}}
* Nominal distance XG: {{convert|0|–|12775|m|ft|0|abbr=on}}, Target information, Distance: {{convert|0|–|2700|m|ft|0|abbr=on}}, Speed: {{convert|0|–|315|km/h|mph|abbr=on}}
* Display information, Signal information: 3 bits, Additional information: 5 bits
* Auxiliary information: Group identity: 1-4 - Indicates response type required, Line identity: new high-speed/normal main lines, Central controller type: LZB 100/72
* [[Cyclic redundancy check]] (CRC): 8 bits
 
One might note that there is no "train identification" field in the telegram. Instead, a train is identified by position. See [[#Entry into LZB, zones and addressing|Zones and Addressing]] for more details.
 
==== Response telegram format ====
 
There are 4 types of response telegrams, each 41 bits long. The exact type of telegram a train sends depends on the "Group identity" in the call telegram.
 
The most common type of telegram is type 1, which is used to signal a train's position and speed to the central controller. It contains the following fields: {LZB p3}
* Synchronization and start sequence: 6 bits
* Group identity: 1-4 - Indicates response type
* Vehicle location acknowledgement: number of zones advanced = ±0, ±1, ±2
* Location within zone: {{convert|0|–|87.5|m|ft|0|abbr=on}} (in {{convert|12.5|m|ft|abbr=on|disp=or}} increments)
* Braking type: passenger/freight
* Brake curve number: 16 possible brake curves
* Actual speed: {{convert|0|–|315|km/h|mph|abbr=on}}
* Operational and disgnostic information: 5 bits
* Cyclic redundancy check (CRC): 7 bits
 
The other telegrams are used primarily when a train enters the LZB controlled
section. They all start with the same synchronization and start sequence
and a "group identity" to identify the telegram type, and end with the
CRC. Their data fields vary as follows:
* Type 2: Vehicle location acknowledgement, location within zone, braking type, brake curve number, maximum train speed, train length
* Type 3: Railway, train number
* Type 4: Locomotive/train series, serial number, train length
 
=== Entry into LZB, zones and addressing ===
 
Before entering an LZB controlled section the driver must enable the train by entering the required information on the [[#Driver Input Unit|Driver Input Unit]] and enabling LZB. When enabled the train will light a "B" light.
 
[[Image:LZB-Topologie.png|thumb|450px|LZB Topology]]
 
A controlled section of track is divided into up to 127 zones, each {{convert|100|m|ft|0|abbr=on}} long.
The zones are consecutively numbered, counting up from 1 in one direction and down from 255 in the opposite.
 
When a train enters a LZB controlled section of track, it will normally
pass over a fixed loop that transmits a "change of section identification" (BKW)
telegram. This telegram indicates to the train the section identification
number as well as the starting zone, either 1 or 255.
The train sends back an acknowledgement telegram.
At that time the LZB indications are switched on, including the "Ü"
light to indicate that LZB is running.
 
From that point on the train's location is used to identify a train.
When a train enters a new zone it sends a response telegram with the
"vehicle location acknowledgement" filed indicating that it has advanced
into a new zone.  The central controller will then use the new zone
when addressing the train in the future. Thus a trains address will
gradually increase or decrease, depending on its direction, as it
travels along the track. A train identifies that it has entered a new
zone by either detecting the cable transposition point in the cable or
when it has traveled {{convert|100|m|ft|0}}.<ref name="LZB80"/>
A train can miss detecting up to 3 transposition points and still
remain under LZB control.
 
The procedure for entering LZB controlled track is repeated when a train transitions from one controlled section to another. The train receives a new "change of section identification" telegram and gets a new address.
 
Until the train knows its address it will ignore any telegrams received.
Thus, if a train doesn't properly enter into the controlled section
it won't be under LZB control until the next section.
 
=== Speed signalling ===
 
The main task of LZB is signalling to the train the speed and distance
it is allowed to travel.  It does this by transmitting periodic call
telegrams to each train one to five times per second, depending on
the number of trains present.  Four fields in the call telegram are
particularly relevant:
* Target distance.
* Target speed.
* Nominal stopping distance, known as "XG" (See below).
* Distance to brake application point.
 
The target speed and location are used to display the target speed
and distance to the driver.  The train's permitted speed is calculated
using the trains braking curve, which can vary by train type,
and the XG location, which is the distance from the start of
the {{convert|100|m|ft|0|abbr=on}} zone that is used to address the train.  If the train is
approaching a red signal or the beginning of an occupied block
the location will match the location of the signal or block boundary.
The on-board equipment will calculate the permitted speed at any
point so that the train, decelerating at the deceleration
indicated by its braking curve, will stop by the stopping point.
 
A train will have a parabolic braking curve as follows:
 
: <math>V_{\rm permitted} = \sqrt{ 2 \cdot decel \cdot (XG-dist)} </math>
 
where:
* decel = deceleration
* dist = distance from beginning of {{convert|100|m|ft|0|abbr=on}} zone
 
Where a train is approaching a speed restriction the control center will
transmit a packet with an XG location set to a point behind the speed
restriction such that a train, decelerating based on its braking curve,
will arrive at the correct speed at the start of the speed restriction.
This, as well as deceleration to zero speed, is illustrated with the
green line in the "Permitted and supervised speed calculation" figure.
 
[[Image:LZB Speed Calculation.png|thumb|500px|left|Permitted and supervised speed calculation]]
 
The red line in the figure shows the "monitoring speed", which is the speed
which, if exceeded, the train will automatically apply the emergency brakes. 
When running at constant speed this is {{convert|8.75|km/h|mph|abbr=on}} above the permitted speed
for transited emergency braking (until speed is reduced) or {{convert|13.75|km/h|mph|abbr=on}} above the permitted speed for continuous emergency braking.
When approaching a stopping point, the monitoring speed follows a braking
curve similar to the permitted speed, but with a higher deceleration,
that will bring it to zero at the stopping point. When approaching a speed
restriction, the monitoring speed braking curve intersects the speed
restriction point at {{convert|8.75|km/h|mph|abbr=on}} above the constant speed.
 
[[Image:ICE3 LZB decel.png|thumb|ICE full-service braking and LZB deceleration]]
 
Deceleration rates are more conservative with LZB than with conventional German
signalling. A typical passenger train braking curve might have a "permitted
speed" deceleration of {{convert|0.5|m/s2|ft/s2|abbr=on}} and a "monitoring speed"
deceleration of {{convert|0.71|m/s2|ft/s2|abbr=on}} 42% higher than the deceleration for the
permitted speed, but lower than the {{convert|0.76|m/s2|ft/s2|abbr=on}} required to stop from
{{convert|140|km/h|mph|abbr=on}} in {{convert|1000|m|ft|0|abbr=on}}. The ICE3, which has a full service braking deceleration of {{convert|1.1|m/s2|ft/s2|abbr=on}} below {{convert|160|km/h|mph|abbr=on}}, dropping to {{convert|0.65|m/s2|ft/s2|abbr=on}} <!-- ? --> by {{convert|300|km/h|mph|abbr=on}},
has a LZB target speed deceleration of only {{convert|0.68|m/s2|ft/s2|abbr=on}} to {{convert|120|km/h|mph|abbr=on}}, {{convert|0.55|m/s2|ft/s2|abbr=on}} between {{convert|120|and|170|km/h|mph|abbr=on}}, and {{convert|0.5|m/s2|ft/s2|abbr=on}} at higher speeds.<ref name="ICE3 brake">"The Linear Eddy-Current Brake of the ICE 3"
by Dr.-Ing. Wolf-Dieter Meler-Credner and Dipl.-Ing. Johannes Gräber,
published in Railway Technical Review (RTR), April, 2003</ref>
 
In between the permitted speed and monitoring speed is a warning speed,
normally {{convert|5|km/h|mph|abbr=on}} above the permitted speed. If the train exceeds that speed
LZB will flash the "G" light on the train's display and sound a horn.
 
=== Leaving LZB ===
 
About {{Convert|1700|m|ft|0|abbr=on}} before the end of the LZB controlled section the central controller
will send a telegram to announce the end of LZB control. The train will flash
the "ENDE" light which the driver must acknowledge within 10 seconds. 
The display will normally give the distance and target speed at the end of
the controlled section, which will depend on the signal at that point.
 
When the train reaches the end of LZB control the "Ü" and "ENDE" lights
go off and the conventional INDUSI (or PZB) system takes over automatic
train protection.
 
=== Special operating modes ===
 
Special conditions not covered by the full LZB system or failures can put LZB
into one of the special operating modes.
 
==== Crossover to opposite track ====
 
As a train approaches a crossover to a normally opposite direction track
the display will flash the "E/40" light.  The driver confirms the indication
and the permitted speed drops following the braking curve to {{convert|40|km/h|mph|abbr=on}}.
When the crossover section is reached the displays are switched off
and the driver can proceed through the crossover at {{convert|40|km/h|mph|abbr=on}}.
 
==== Drive by sight signal ====
 
German signalling systems have a "drive by sight" signal that consists
of 3 white lights forming a triangle with one light at the top.  This signal,
labeled "Zs 101", is placed with a fixed line side signal and, when lighted,
permits the  driver to pass a fixed red or defective signal and drive by sight
to the end of the interlocking no faster than {{convert|40|km/h|mph|abbr=on}}.
 
When approaching such a signal in LZB territory the "E/40" light will be
lit until {{convert|250|m|ft|0|abbr=on}} before the signal, then the "E/40" will go dark and
"V40" will flash.  The "V40" signal indicates the ability to drive by sight.
 
==== Transmission failure ====
 
If data exchange is interrupted, the trains distance measurement system
fails, or the train fails to detect 4 or more cable transposition points
the LZB system will go into a failure state. It will light the "Stör"
indicator and then flash "Ü". The driver must acknowledge the indications
within 10 seconds.  The driver must slow the train to no more than {{convert|85|km/h|mph|abbr=on}} or lower; the exact speed depends on the backup signalling system in place.
 
== Extensions ==
=== CIR ELKE ===
 
CIR-ELKE is an improvement on the basic LZB system.
It uses the same physical interface and packets as standard LZB
but upgrades its software, adding capabilities and modifying some procedures.
It is designed to increase line capacity by up to 40% and to further
shorten travel times. The name is an abbreviation of the English/German project title
''<u>C</u>omputer <u>I</u>ntegrated <u>R</u>ailroading - <u>E</u>rhöhung der <u>L</u>eistungsfähigkeit im <u>K</u>ernnetz der <u>E</u>isenbahn''
(Computer Integrated Railroading - Increase Capacity in the Core Railway Network). Being an extension of LZB it is also called LZB-CIR-ELKE further abbreviated into LZB-CE.
 
CIR-ELKE includes the following improvements:
* ''Shorter blocks'' - CIR-ELKE blocks can be as short as {{convert|300|m|ft|0}}, or even shorter for S-Bahn systems.  The Munich S-Bahn system has blocks as short as {{convert|50|m|ft|0}} at the beginning of the platform, allowing a train to pull into the platform as another is leaving and making it capable of running 30 trains per hour.
* ''Speed changes at any location'' - The standard LZB system required that speed restrictions start at block boundaries. With CIR-ELKE speed  restrictions can start at any point, such as at a turnout.  This means a train doesn't have to slow down as soon, increasing average speeds.
* ''Telegram evaluation changes'' - In order to increase safety on a system with shorter intervals between trains CIR-ELKE sends identical telegrams twice. The train will only act on a telegram if it receives two identical valid telegrams. In order to compensate for the increase in the number of telegrams CIR-ELKE sends telegrams to non-moving trains less frequently.
 
=== CIR ELKE-II ===
 
The original LZB system was designed for permitted speeds up to {{convert|280|km/h|mph|abbr=on}}
and [[Grade (slope)|gradients]] up to 1.25%. The [[Cologne–Frankfurt high-speed rail line]] was designed
for {{convert|300|km/h|mph|abbr=on}} operation and has 4% gradients; thus, it needed a new
version of LZB, and CIR ELKE-II was developed for this line.
 
CIR ELKE-II has the following features:
* Maximum speed of {{convert|300|km/h|mph|abbr=on}}.
* Support for braking curves with higher decelerations and curves taking into account the actual altitude profile of the distance ahead instead of assuming the maximum down slope of the section. This makes operation on 4% gradients practical.
* Support for target distances of up to {{convert|35000|m|ft|0|abbr=on}} to a stopping or speed restriction point. If there is no such point within that distance the system will display a target distance of {{convert|13000|m|ft|0|abbr=on}} and a target speed of the line speed.
* Support for enabling the [[Eddy current brake]] of the ICE3 trains. By default, the eddy current brake is enabled for emergency braking only. With CE2 it is possible to enable it for service braking, too.
* Signalling voltage or phase changes.
* Audible warning signals 8 seconds before the point of braking, or 4 seconds for the Munich S-Bahn, instead of {{convert|1000|m|ft|0|abbr=on}} before or with a {{convert|30|km/h|mph|abbr=on}} speed difference done previously.
 
== Malfunctions ==
 
The LZB system has been quite safe and reliable; so much so that there have
been no collisions on LZB equipped lines because of the failure of the
LZB system. However, there have been some malfunctions that could have
potentially resulted in accidents. They are:
 
* On June 29, 1991, after a disturbance, the train driver had the LZB system off and passed a stop signal with two trains in the tunnel at Jühnde on the Hanover-Würzburg high-speed line.
* On June 29, 2001, there was nearly a serious accident at the Oschatz crossover on the Leipzig-Dresden railway line. The crossover was set to diverging with a {{convert|100|km/h|mph|abbr=on}} speed limit but the LZB system displayed a {{convert|180|km/h|mph|0|abbr=on}} limit. The driver of ICE 1652 recognized the diverging signal and managed to slow down to {{convert|170|km/h|mph|0|abbr=on}} before the crossing and the train did not derail. A software error in the LZB computer was suspected as the cause.
* A similar near-accident occurred on November 17, 2001 in Bienenbüttel on the Hamburg-Hanover rail line. In order to pass a failed freight train an ICE train crossed over to the opposite track going {{convert|185|km/h|mph|abbr=on}} through a crossover that was rated at {{convert|80|km/h|mph|abbr=on}}. The suspected cause was the faulty execution of a change to the  interlocking system where the crossover speed was increased from {{convert|60|to|80|km/h|mph|abbr=on}}. Without that speed restriction the LZB system did continue to show the {{convert|200|km/h|mph|abbr=on}} pass-through line speed on the in-cab display - the train driver applied the brakes on recognizing the line-side signal lights set to diverge and the train did not derail.
* On April 9, 2002 on the [[Hanover-Berlin high-speed rail line]] a fault in the LZB line center computer brought four LZB controlled trains to a stop with two trains in each line direction being halted in the same signalling block (Teilblockmodus - divided block control). When the computer was rebooted it signaled {{convert|0|km/h|mph|abbr=on}} to the trains in front and {{convert|160|km/h|mph|abbr=on}} to the following trains. The drivers of the following trains did not proceed however - one driver saw the train in front of him and the other driver double-checked with the operations center which had warned him prior to departure, so two possible collisions were averted.
 
== Routes ==
{{Empty section|date=September 2010}}
== Equipped lines ==
=== DB (Germany) ===
The following lines of '''[[Deutsche Bahn]]''' are equipped with LZB, allowing for
speeds in excess of 160&nbsp;km/h (providing the general suitability of the track):
 
* [[Augsburg]] - ''[[Dinkelscherben]]'' - [[Ulm]] (km&nbsp;7.3 ­ km&nbsp;28.5)
* [[Berlin]] - ''[[Nauen]]'' - ''[[Glöwen]]'' - ''[[Wittenberge]]'' - ''[[Hagenow Land]]'' - ''[[Rothenburgsort]]'' - [[Hamburg]] (km&nbsp;16.5 - km&nbsp;273.1)
* [[Bremen (city)|Bremen]] - [[Hamburg]] (km&nbsp;253.9 - km&nbsp;320.1)
* [[Dortmund]] - [[Hamm|Hamm (Westf)]] - [[Bielefeld]] (except for the station of Hamm)
* [[Frankfurt am Main]] - ''[[Gelnhausen]]'' - [[Fulda]] (km&nbsp;24.8 - km&nbsp;40.3)
* [[Hannover]] - ''[[Stadthagen]]'' - [[Minden]] (km&nbsp;4.4 - km&nbsp;53.4)
* [[Hannover]] - ''[[Celle]]'' - [[Uelzen]] - ''[[Lüneburg]]'' - [[Hamburg]] (km&nbsp;4.0 - km&nbsp;166.5)
* [[Hannover]] - ''[[Göttingen]]'' - ''[[Kassel|Kassel-Wilhelmshöhe]]'' - ''[[Fulda]]'' - ''[[Würzburg]]'' (km&nbsp;4.2 - km&nbsp;325.6)
* [[Karlsruhe]] - ''[[Achern]]'' - ''[[Offenburg]]'' - ''[[Kenzingen]]'' - ''[[Schallstadt|Leutersberg]]'' - ''[[Weil am Rhein]]'' - [[Basel|Basel Bad. Bf.]] (km&nbsp;102.2 - km&nbsp;270.6)
* ''[[Köln]]'' - [[Aachen]] (km&nbsp;1,9 - km&nbsp;41,8)
* [[Köln]] - ''[[Düsseldorf]]'' - [[Duisburg]] (km&nbsp;6.7 - km&nbsp;37.3 and km&nbsp;40.1 - km&nbsp;62.2; Düsseldorf main station is not equipped)
*[[Köln]] - ''[[Troisdorf]]'' - ''[[Montabaur]]'' - [[Limburg a.d. Lahn]] - [[Frankfurt am Main]] (km&nbsp;8.7 - km&nbsp;172.6)
*[[Leipzig]] - ''[[Wurzen]]'' - [[Dresden]] (km&nbsp;3.6 - km&nbsp;59.5)
*[[Lengerich (Westfalen)|Lengerich (Westf)]] - [[Münster (Westfalen)|Münster (Westf)]]
*[[Lehrte]] - [[Stendal]] - [[Berlin-Spandau]]
*[[Mannheim]] - [[Karlsruhe]]
*[[Mannheim]] - ''[[Vaihingen an der Enz]]'' - [[Stuttgart]] (km&nbsp;2.1 - km&nbsp;99.5)
*[[München]] - ''[[Augsburg]]'' - [[Donauwörth]] (km&nbsp;9,2 - km&nbsp;56.3 and km&nbsp;2.7 - km&nbsp;39.8; Augsburg main station is not equipped)
*[[Nürnberg]] - [[Allersberg]] - ''[[Kinding]]'' - [[Ingolstadt]]-Nord ('''ABS:''' km&nbsp;97.9 - km&nbsp;91.6; '''NBS:''' km&nbsp;9.0 - km&nbsp;88.7)
*[[Nürnberg]] - ''[[Neustadt an der Aisch]]'' - [[Würzburg]] (km&nbsp;34.8 - km 62.7)
*[[Osnabrück]] - [[Bremen (city)|Bremen]] (km&nbsp;139.7 - km&nbsp;232.0)
*[[Paderborn]] - [[Lippstadt]] - ''[[Soest, Germany|Soest]]'' - [[Hamm|Hamm (Westf)]] ('''Strecke 1760:''' km&nbsp;125.2 - km&nbsp;180.8; '''Strecke 2930:''' km&nbsp;111.5 - km&nbsp;135.6)
*Zeppelinheim bei Frankfurt/Main - [[Mannheim]]
 
'''Note:''' ''italics'' indicate the physical location of an LZB control center.
 
=== ÖBB (Austria) ===
The [[West railway (Austria)|West railway]] (Vienna–Salzburg) is equipped with LZB in three sections:
 
*[[Sankt Pölten|St. Pölten]]–[[Ybbs an der Donau]] (km&nbsp;62.4–km&nbsp;108.6)
*[[Amstetten, Lower Austria|Amstetten]]–[[Sankt Valentin|St. Valentin]] (km&nbsp;125.9–km&nbsp;165.0)
*[[Linz]]–[[Attnang-Puchheim]] (km&nbsp;190.5–km&nbsp;241.6)
 
=== RENFE (Spain) ===
 
* [[Madrid]] - ''[[Córdoba, Spain|Córdoba]]'' - [[Sevilla]] (9 Centers / 480&nbsp;km), operational since 1992.  Since 2004, the terminus Madrid­Atocha is also equipped with LZB.  In November 2005, a branch line to Toledo was opened. (20&nbsp;km).
* Cercanías Madrid line C5 from Humanes over Atocha to Móstoles-El Soto.  It is 45&nbsp;km&nbsp; long with  2 LZB centres and 76 Series 446 vehicles.
* All EuskotrenBideak network with the exception of the Euskotran network.
 
== Non-mainline uses ==
 
In addition to mainline railways, versions of the LZB system are also used
in suburban (S-Bahn) railways and subways.
 
=== Dusseldorf, Duisburg, Krefeld, Mülheim an der Ruhr ===
 
Tunnels in the Düsseldorf and Duisburg U-bahn (subway) system, and some of
the tunnels in the Mülheim an der Ruhr U-bahn are LZB equipped.
 
=== Vienna (Wien) ===
 
With the exception of line 6, the entire [[Vienna U-Bahn]] is equipped
with LZB since it was built and includes the capability of automatic driving with the
operator monitoring the train.
 
=== Munich ===
 
The [[Munich U-Bahn]] was built with LZB control.
During the regular daytime the trains are automatically driven with
the operator simply starting the train. Stationary signals remain
dark during that time.
 
In the evenings from 9:00&nbsp;p.m. and on Sundays the operators drive the
trains manually according to the stationary signals in order to remain
in practice.
 
There are plans to automate the placement and reversal of empty trains.
 
=== Nuremberg ===
 
The [[Nuremberg U-Bahn]] U3 line uses LZB for fully automatic (driverless)
operation. The system was jointly developed by [[Siemens]] and [[VAG Nuremberg]]
and is the first system where driverless trains and conventional trains
share a section of line. The existing, conventionally driven U2 line trains
shares a segment with the automatic U3 line trains. Currently, an employee
still accompanies the automatically driven trains, but later the trains
will travel unaccompanied.
 
After several years of delays, the final three-month test run was successfully completed on April 20, 2008, and the operating licence granted on April 30, 2008. A few days later the driverless trains started operating with passengers, first on Sundays and public holidays, then weekdays at peak hours, and finally after the morning rush hour which has a tight sequence of U2 trains. The official opening ceremony for the U3 line was held on June 14, 2008 in the presence of the Bavarian Prime Minister and Federal Minister of Transport, the regular operation began with the schedule change on 15 June 2008. The Nuremberg U-bahn plans to convert U2 to automatic operation in about a year.
 
=== London ===
 
The [[Docklands Light Railway]] in east London uses the [[SelTrac]] technology which was derived from LZB to run automated trains. The trains are accompanied by an employee who closes the doors and signals the train to start, but then is mainly dedicated to customer service and ticket control. In case of failure the train can be driven manually by the on train staff.
 
== European Train Control System ==
 
Different European countries currently have a variety of train signalling
systems. In order to standardize operations and allow a train to pass through
Europe without switching locomotives or needing to be equipped with
many signalling systems Europe has developed the
[[European Train Control System]] (ETCS). The European Union has required
that European nations adopt ETCS, which is currently in its initial
implementation phases. It is supposed to eventually replace all national systems.
 
LZB is considered a "Class B" system within ETCS. A train can be equipped with
a LZB "Specific Transmission Module" (STM) which allows ETCS on-board equipment
to communicate with LZB ground equipment. In addition, lines can be
dual-equipped with both ETCS and LZB, allowing trains equipped with either
system to traverse the line at full speed. The line from Jüterbog to
Halle/Leipzig is dual-equipped.
 
== References ==
 
<references/>
 
==See also==
 
* [[Automatic Train Protection]]
* [[Train protection system]]
* [[European Train Control System]]
 
{{Commons category|Linienzugbeeinflussung}}
 
[[Category:Train protection systems]]
[[Category:Railway signalling in Germany]]

Latest revision as of 09:20, 22 February 2014

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