Method and apparatus for tracking trains through multiple false track circuit occupancies

2 67~0-5 IIEI~!OD ~ID APPARArll;~EOE~ rRACKINQ r_ AINS THROUG~IJIJITIPI.E FALSF rRACK_CIRCUIr OCCUPANCIES BACKGROUND OF r~lE INVENTION FIE~LD O~_THE INVENTION The present invention relates to central control .systems for monitoring the location of a plurality of trains within a transit system. ~lore particularly the present invention relates to a centralized electronic control system which utilizes interlocking circuits ancl false occupancy correction factors to monitor train locations.

Central tracklng systems monitor a number of trains along a transit system by assigniny train desiynators to individual trains and section designators to individual seetions of the track throuyhout the transit system and by monitoring the occupancy of those track sections by the various trains in the system. If a particular traln is in a ~1 ~ ~ 1 r~ 3 -- 3 - particular track section, that seation iB said to be occupied. The presence of a tra;in within the section will trigger a sensor in th~ track, a:lerting th~ contral ~y~tem which will alert tha central control computer that that portion of the track i~ occupied. However, it occasionally arises that a section of the track system will indicate occupancy when in faat that portion of the track system is not occupied, this i5 referred to as a false occupancy.

A false occupancy occurs when a track circuit signals an occupancy at a location where the central control system does not expect an occupancy to occur. In situations where track circuits on both sides of a newly received accupancy signal were previously unoccupied, the control system doeæ not expect an occupancy to occur. The central control system will therefore classify this type of an occupancy as a potential false occupancy.

A false occupancy can be caused by a variety of different factors, such as input/output (I/O) failure, signal wire failure or an external event that may cause a track to become shorted or the track circuit to become shorted. In a train control system with automatic train control, a false occupancy will not allow other trains to proceed through the falsely occupied section of track as long as the cause of the occupancy indication signal is unknown.

2Q~ t7~32~ The methods utilized hy existing track control systems present limitations in the prescnce of ~alse occupancie~.

Once a false occupancy has been located at a particular track section, a train cannot be tracked through the section. The presence of the false occupancy will obscure tracking o~ the train. There is a maximum number oP ~alse occupancies that can be accommodated by a system. When a system becomes overloaded with a greater number of false occupancies, train tracking becomes impossible.

S~MM~RY OF T~E I~VENTIO~ It is an object of khe present invention to provide a method for monitoring track occupancy signals which can accommodate any number of false occupancy signals.

It is another object of the present invention to provide a method for monitoring track occupancy signals which can monitor trains as they pass throuyh portions of the track which register false occupancies.

It is a further object of the present invention to provide a method for central track control which monitors a plurality of track sections o~ a transit system for determining train location within a system and for monitoring and accommodating false occupancies, which can be implemented on existing central track control systems.

S f,7~f;~-5 Thec:e anc1 other ohjects of l;he present invention are aeco~plished l~y prot~:lc1inq a ce~ al track control system wl1lcl-l asslgns individual codes to false occupar1cies in a ~rain location tah].e, monitors the approclch of actuaL trains to the false occupancy si~es, replaces the false occupaney eod~ with the approaehincJ traln number as the train crosses throuyh the false oceupancy site, stores the false oceupaney code in an lndexecl location and restores the false occupaney code af-ter the train has passed the false oceupancy site.

In aceordanee with the present invention, there i.5 provided a method for tracking a plurality of trains through a transit system having a track with a plurality of intereonneeted sections, comprisil1g the steps of: asslgning a unlque train designator to eaeh train, assigning a unique section designator to each of said traek see-tions, monitoring eaeh traek seetion, deteeting an oeeupancy signal from any of said SeCtiollS, analyzing the oeeupaney signal to identify any train occupaney, correlating the designator of eaeh identified train with the seetion designator of the oeeupied traek section, analyzing the oeeupancy 20 . signal to identify any erroneous detection, assigning a false oceupaney c1esignator to any erroneous deteetion, correla~ing the false oeeupaney designator with the section designator of the track section of the erroneous deteetion, in~ereorrelating eaeh train desi.gnator and false oeeupaney designator whieh are eorrelated to adjaeent traek seetions.

In aeeordance with another aspeet of the invention there is provided apparatus for traeking a plurality of trains through a transit system having a traek with a plurality of interconneeted . .

. ., Sa 67~0-S~ sections, comprlsing: mearls for assigrlinq a uniclue traln designator to each ~rai.n, Ineans for assiqnincJ a unique section designator -to each of said trac:k sectlonsr means for monitoring each track section, ~nealls for detect:LncJ an occupancy signal from any of said sections, means for analyzincJ the occllpancy si~Jnal to iclentify any traln occupancy, means for correlating the de.signator of each iclentified traln with -the section designator of the occupied track section, means for analyzing the occupancy signal to i~entify any erroneous detectlon, means for assigning a false occupancy des.tgnator to any erroneous detection, means for correlating the false occupancy designator with the section designator of the track section of the erroneous detection, means for intercorrelating each train designator and false occupancy designator which are correlated to adjacent track sections.

In accordance with another aspect of the invention, there is provided apparatus for tracking a plurality of individually identifiable trains through a transi-t system haviny a track with a plurality of interconnected, independently identifiable sections, comprising: means for receiving signals 2~ from said track sections and for analyzing said signals to identify any train occupancy signals indicative of the presence of a train within a signaling track section and to identify any false occupancy signals from a signaling track section, coding means connected to said receiving means for generating a train occupancy code corresponding to each identiiied train occupancy, and for generating a false occupancy code correspondiny to each false occupancy signal, first and second memory register means indexed to said track sections and conne~ted to said coding means, means ~` 5)~ 67~ 5 for storincJ eacll t~ain occupancy code in said flrst memory register means at a :Loca~ion indexed to the train-signaLing track sectloll, means for stori.ng each false occupancy code in said flrst memory register mealls at a location indexed to tlle false--signaling track section, means for shifting said false occupancy code to said second memory reyister means at a location indexed to khe false-signaling track section, and for shi.fting said train code to said false occupancy index location in said first register.

BRIEF DESCRIPTION OF THE DRAWINGS The i.nvention will now be described with reference to the following drawings illustrating an exemplary embodiment thereof.

Figure 1 :is a schematic diagram of a transit system and a central control system therefore.

DETAILED DESCRIPTION OF AN EXE_PLARY EMBODIMENT As illustrated in Figure 1, each track 10 of the transik sys~em is divided into a number of circuits or sections, 1-5. The track sections are independently connected to a vital interlocking mechanism 7 which detects the actuation of the sensors 8 stationed along the track system at the boundaries 2 ~ ~ r~ '`3 2 ~3 of the various track sections. An I/0 interface 9 links the interlocking mechanism 7 with the cen~ral computer 10. A~ a train passes along the track into and out of a particular section, its location is noted and the central computer S system 10 records the occupation of the particular section by the particular train.

In the system according to the present invention, the individual trains are tracked in a table, each train designated by an assigned number or code. As a train is detected within the system, a code corresponding to the train is stored in a train location table. The codes can be arbitrar~ly assigned to individual trains or specifically assigned by the system operator. In thi~ manner, the location of each train as it p~a~ses through the transit system is continuously monitored.

The system of the present invention also keeps track of the occurrence of false occupancies.

As false occupancies are determined, they are given a special code and stored within the train location table.

When a track circuit on either side of a false occupancy location becomes occupied with a train, the original false occupancy designation number is shifted from the train location table to a false occupancy location table at a position indexed to its position in the train location ~ t~ J f~ table. The number vf the adjacent train i~ sub~tituted into the train location table at the f~ormer position of the f~lse occupancy nun~er. The entry in the train location table at the index location of ~ fals0 occ:upancy code number is thereby replaced with the train c:ode number of the train on the occupied track circuit next to the false occup~ncy location. In this manner the train designator is recorded both at its location and at the adjacent location where the ~alse occupancy was previously recorded~ In the case whsre false occupancies occupy adjac~nt track circuit locations, ~he actual train number is substituted ~or all of the false occupanaies ~imultaneou~ly as the train occupies a circuit position adjacent either end of the false occupancies. Once the train has passed through the false occupancy locations, and the train is now occupying a non-adjacent section on the other side of the false occupancy or occupancies, the train location is only recorded at this section and the special false occupancy numbers are shifted back into the train location table and removed from the ~al e occupancy location table. With the above described recordation method, the real train number is always associated with at least one physical track circuit and is never hidden behind a false occupancy code identi~ier which may have occupied the track circuit before the train.

r~ ~ 8 - The following charts illustrate a number of examples o~ the operation o~ the present invention with one, two, and three false occupancies respeatively. Table I consists o~ a series of seven frames, illustrating the proyre~sion from no trains or false occupancies to one ~alse occupancy, with the travel of a train from track section 1 through track section 5.

In each of the frameæ, the status of track sectLons 1-5 is indicated by the designations in the train loaation column and the false locatlon column, re~pectively. In the first frame there are no train occupancy indications or false occupancy indications detected by the central monitoring system. Frame 2 indicates the detection of a false occupancy in track section number 3. This false occupancy detection has been arbitrarily assigned number 999 and is indicated by the 999 at the location indexed by track section 3 in frame 2.

In frame 3, the approach of train number 10 has been detected and indicated by the designation "10" in index position 1 corresponding to track section 1 in the train location table. As the train lO approaches track section 3 which has the false designation 999, the train designator 10 is moved to track section 2 as indicated in frame 4. Once the train has reached the occupancy location of track J section 2, the adjacent track section false occupanoy 999 is replaced with an occupancy deslgnator "10", and the ~al~e occupancy designator 999 is moved to the false occupancy location colu~n as illustrated in frame 4.

Next, as the train leaves track section 2, the "10" designator is removed from the train location column in the index position corresponding to track section 2, but is maintained in the index 3 position.

The train 10 is presumed to have travelled into track section 3, however, as this track section is pxoviding a false occupancy designation, the system cannot detect the pre ence of train 10 in track circuit 3. Therefore, ths designator "10" is left in this location on the presumption that this is now the true location of train 10.

In frame 6, train 10 has been detectPd in track section 4 and the designator "10" is therefore added to the train location column of the table at index position 4. The train designator 10 is maintained at index position 3 where the false occupancy signal is still being received. As the train leaves track section 4 and is now detected at track section 5, the designator 10 is moved to the appropriate index position 5, as indicated in frame 7 of table 1, and the train designator 10 at track index location 3 is replaced with the falsa occupancy designator 999 in the train location column.

2 ~ ~ r~ 9 The false location colu~n is then emptied and no longer indicates detection of any false occupancies, as the ~alse occupancy detection is now indicate~ in the train location table.

TABLE l Frame Track Train False Circuit Loc. Loc.

0 0 2 0 0 15 I 3 0 4 0 0 0 Track Train False Circuit Loc. Loc.

0 ~ O 2 0 0 25II 3 999 0 ~alse occupy.

4 0 0 0 0 Track Train False Circuit Loc. Loc.

1 10 0 real train occup.

2 0 0 III 3 999 0 false occup.

4 0 0 0 0 Track Train False Circuit Loc. Loc.

a o 2 100 real train occup.

IV 3 109g9 Palse & real occup.

4 0 0 S O O Track Train False Circuit Loc. Loc.

1 0 0 2 0 0 V 3 10999 ~alæ~ & real occup.

4 0 0 0 0 Track Train False Circuit ~oc. Loc.

1 o 0 2 0 0 : VI 3 10 ~ 999 false & real occup.

4 10 0 real train occup.

0 0 Track Train False Circuit Loc. Loc.

1 0 0 2 0 0 VII 3 999 0 false occup.

4 0 0 0 real train occup.

Table II similarly illustrates the progression of a train through 6 track sections or circuits, wherein false designations have been detected at track sections 3 and 4 and have been given designators 999 and 998, respectively.

The ' :

3 2 ~ - ~2 train again, is illustrated as entering track section 1 passin~ through track sections 3 and 4 and exiting track section 8.

As can be observed, the desiLgnators for fal~e train occupancy are switched to the designator corresponding to the train once the train has approached and occupies the adjacent track section. This sw:;tched designation is maintained until the train leaves the adjacent section as it moves away from the false designating seation. The fals~ designators are moved to the false location column of the table as the train passes through the fal~e zones and are replaced after the train has left as described above.

TABLE II Track Train False Circuit 10c. Loc.

0 0 2 ~ 0 3 0 0 4 0 0 0 6 0 0 Track Train False Circuit Loc. Loc.

0 0 2 0 0 3 999 0 false occup.

4 998 0 false occup.

o 0 6 o 0 - 13 Track TralnFalse Circuit LOC.~oc.

1 10 0 real train occup.

2 0 0 3 ggg 0 false oc~up.

4 998 ~ ~alee occup.

0 0 6 0 0 Track TrainFalse Circuit Loc.Loc.

1 0 0 2 100 real train occup.

3 10999 false & real occup.

4 10998 -false & real occup.

0 0 6 0 0 ~rack TrainFalse Circuit Loc.

Loc.

0 0 2 0 ~ 0 3 10999 false ~ real occup.

4 10998 fal e & real occup.

3~ 5 0 0 6 0 0 Track TrainFalse Circui~ Loc.

Loc.

0 0 2 0 0 3 1099g false & real occup.

4 10998 ~alse & real occup.

0 0 O O Track Train False Circuit Loc. Loc.

0 0 2 0 0 3 10999 false & real occup.

4 10998 ~alse & real occup.

100 real train occup.

6 0 0 Track Train False Circuit ~oc. Loc.

1 0 0 2 0 0 3 999 0 false occup.

4 998 0 false occup.

0 0 6 10 0 real train ocaup.

Table III illustrates the passage of a train in a manner similar to Tables I and II, however, seven track sections are illustrated and three adjacent false occupancy detections are illustrated.

The method of indicating the approach and passage of the train through the false occupancy track sections is the same that explained above.

% ~3 ~ ~ 15 TABLE I~ Track Train False Circuit Loe. Loc.

0 0 2 0 0 3 0 o 4 0 0 o 0 6 0 0 7 0 0 Traek Train False Circuit Loc. Loe.

0 0 2 0 0 3 999 0 false oeeup.

4 998 0 ~alse oeeup.

997 0 false oeeup.

6 0 0 7 0 0 Traek Train .

False Circuit Loe. Loe.

1 10 0 real train oeeup.

2 0 0 3 999 0 false oeeup.

4 998 0 false oeeup.

997 0 ~alse oeeup.

6 0 0 7 0 0 Traek Train False Circuit Loe. Loe.

0 0 2 10 0 real train oeeup.

3 10 999 false oeeup.

4 10 998 false oeeup.

997 false oeeup.

6 0 0 7 0 0 2 0 ~L 1 ~ 2 ~ - 16 Track Train False circuit Loc~ Loc.

o o 2 0 0 3 lO999 false & real occup.

4 lo998 ~alse & real occup.

10997 falee & real occup.

6 0 0 7 o 0 Track Train False Circuit Loc. Loc.

0 0 2 0 0 3 10999 false & real occup.

4 10998 false & real occup.

997 ~alse ~ real oacup.

6 0 0 7 0 0 Track TrainFalse Circuit Loc.

Loc.

0 0 2 0 0 3 10 999 false & real occup.

4 lO998 false & real occup.

10997 false ~ real occup.

6 0 0 7 0 0 Track TrainFalse Circuit Loc.

Loc.

l 0 0 2 0 0 3 lO999 false ~ real occup.

4 10998 false & real occup.

10997 false & real occup.

6 100 real train occup.

7 0 0 ~ 7t~J ~ 3 TrackTxain False Circuit Loc.

Loc.

5 1 0 0 2 0 0 3999 0 false occup.

499~ 0 false occup~ 5997 0 false occup.

lo 6 0 0 710 0 real train occup.

The change in the software necessary to implement the present invention into existing cenkral control computer~ for transit systems requires the addition of the handling of a false location column within the train monitoring and location indication tables. In this manner, the location of a train will always be associated with a physical track location, and will not be masked by ~alse occupancy detection indications.

It will be understood that the above description of the present invention is susceptible to vario~s modifications, changes and adaptations, and the same are intended to be comprehended within the meaning and range of eguivalents o~ the appended claims.