Europäisches Patentamt *EP001086874A1* (19) European Patent Office Office européen des brevets (11) EP 1 086 874 A1 (12) EUROPEAN PATENT APPLICATION (43) Date of publication: (51) Int Cl.7: B61L 3/06 28.03.2001 Bulletin 2001/13 (21) Application number: 99118757.6 (22) Date of filing: 23.09.1999 (84) Designated Contracting States: • Hungate, Joe B. AT BE CH CY DE DK ES FI FR GB GR IE IT LI LU Marion, IA 52302 (US) MC NL PT SE • Montgomery, Stephen R. Designated Extension States: Marion, IA 52302 (US) AL LT LV MK RO SI (74) Representative: Petri, Stellan et al (71) Applicant: WESTINGHOUSE AIR BRAKE Ström & Gulliksson AB COMPANY Box 41 88 Wilmerding, PA 15148 (US) 203 13 Malmö (SE) (72) Inventors: • Halvorson, David H. Cedar Rapids, IA 52405 (US) (54) Method and apparatus for controlling trains by determining a direction taken by a train through a railroad switch (57) An apparatus for determining the presence of are shown which are disposed on opposite sides of the a third rail disposed between parallel railroad tracks as rail vehicle. The radar detectors are coupled with an on- a train progresses along said parallel railroad tracks and board computing device and with other components of further for determining the relative direction of motion of an advanced train control system which can be used for said third rail with respect to said first two rails and fur- precisely locating the train on closely spaced parallel ther for determining the rate at which the third rail moves tracks and further for updating and augmenting position with respect to the first rails is disclosed, which is a low information used by the advanced train control system. power radar sensor disposed underneath the rail vehicle The system including GPS receivers and wheel tachom- and directed toward the rail on the opposing side of the eters for providing alternate sources of information for vehicle. In a preferred embodiment, two rail detectors position determination. EP 1 086 874 A1 Printed by Jouve, 75001 PARIS (FR) 1 EP 1 086 874 A1 2 Description typically lack the ability to sense the necessary move- ment of a train especially when a switch designed for BACKGROUND OF THE INVENTION high speed is being made from one parallel track to an- other at very low speeds. [0001] The present invention generally relates to rail- 5 [0006] Consequently, there exists a need for improve- roads, and more specifically relates to train controlsys- ment in advanced train controlsystems which overcome tems and even more particularly relates to automatic the above-stated problems. and remote sensing of rail switches. [0002] In the past, train control systems have been SUMMARY OF THE INVENTION used to facilitate the operation of trains. These train con- 10 trol systems have endeavored to increase the density [0007] It is an object of the present invention to pro- of trains on a track system while simultaneously main- vide a train control system having enhanced positive taining positive train separation. The problem of main- train separation capabilities. taining positive train separation becomes more difficult [0008] It is a feature of the present invention to include when parallel tracks are present. Often, parallel tracks 15 a train control system having capabilities for sensing the exist with numerous cross-over switches for switching direction a train takes through switches. from one track to another. It is often very difficult for elec- [0009] It is an advantage of the present invention to tronic and automatic systems such as train control sys- reduce the ambiguity of track occupancy which is often tems to positively determine upon which of several par- present when trains operate within a group of parallel allel train tracks a train may be located at any particular 20 tracks. time. For example, when tracks are parallel, they are [0010] It is another object of the present invention to typically placed very close to each other with a center- improve the position determination accuracy of trains. to-center distance of approximately fourteen (14) feet. [0011] It is another feature of the present invention to [0003] In the past, several different methods have include a sensor on board the train for sensing interme- been attempted to resolve the potential ambiguity of 25 diate tracks which exist between the wheels of a loco- which track, of a group of parallel tracks, a train may be motive as it passes between a switchpoint and a "cross- using. These methods have included use of global po- over frog" or other cross-track rails. sitioning system receivers, track circuits and inertial [0012] It is an advantage of the present invention to navigation sensors. These prior art approaches of de- provide additional information regarding train position termining which track is being used each have their own 30 which can be used to supplement and update other po- significant drawbacks. Firstly, standard GPS receivers sitional information, including GPS signals and for are normally incapable of positively resolving the posi- crosschecking a database. tion of the train to the degree of accuracy required. The [0013] It is yet another object of the present invention separation of approximately fourteen (14) feet between to provide information as to the type of switch a train is tracks is often too close for normal GPS receivers to pro- 35 passing through. vide a positive determination of track usage. The use of [0014] It is yet another feature of the present invention differential GPS increases the accuracy; i.e. reduces the to monitor the relative rate at which the intermediate uncertainty in the position determined. However, differ- track switches from predetermined positions on one ential GPS would require that numerous remotely locat- side of a locomotive to a predetermined position at the ed differential GPS transmitter "stations" be positioned 40 other side of the locomotive. throughout the country. The United States is not current- [0015] It is an advantage of the present invention to ly equipped with a sufficient number of differential GPS allow train control systems to determine the angle of a transmitting stations to provide for the accuracy needed switch as it is passed. at all points along the U.S. rail systems. [0016] The present invention is a method and appa- [0004] The track circuits which have been used in the 45 ratus for controlling trains by detecting intermediate rails past to detect the presence of a train on a particular track between the traveled rails, which is designed to satisfy also require significant infrastructure investment to pro- the aforementioned needs, provide the previously stat- vide comprehensive coverage. Currently, there are vast ed objects, include the above-listed features, and areas of "dark territory" in which the track circuits are achieve the already articulated advantages. The inven- not available. Additionally, these track circuits are sub- 50 tion is carried out in an "ambiguity-less" system in the ject to damage at remote locations and are susceptible sense that track ambiguity is greatly reduced by provid- to intentional sabotage. ing information on the passage of switches, the angle of [0005] The inertial navigation sensors proposed in the switches passed, and the direction taken by the train as past have included both gyroscopes and acceleration it passes through the switch. sensors. The gyroscopes are capable of sensing a very 55 [0017] Accordingly, the present invention is a method gradual turn; however, gyros with sufficient accuracy to and apparatus for determining the presence and orien- sense such turns are very expensive. Acceleration sen- tation of an intermediate track disposed between the sors, while they are less expensive than sensitive gyros, tracks over which a train is traveling. 2 3 EP 1 086 874 A1 4 BRIEF DESCRIPTION OF THE DRAWINGS interface 218, and locomotive ID module 220. Radio 202, antennas 204, 208, GPS receiver 206, wheel ta- [0018] The invention may be more fully understood by chometer 212, displays 214 and 216, brake interface reading the following description of the preferred em- 218, and locomotive ID module 220 are well known in bodiments of the invention, in conjunction with the ap- 5 the art. Onboard computer 210 is preferably a computer pended drawings wherein: using a P.C. architecture. The processor and operating [0019] Figure 1 is a plan view of a common parallel system and other details are subject to the desires of track configuration showing a turnout and two switches. the system designer. On-board computer 210 may in- [0020] Figure 2 is a block diagram of the train control clude a comprehensive rail track database. Coupled to system of the present invention. 10 onboard computer 210 via line 223 is turnout detector [0021] Figure 3 is an elevational view of a rail vehicle 222. Turnout detector 222 is described more fully in Fig- incorporating the sensors of the present invention show- ure 5 and its accompanying text. ing the orientation of the sensors with respect to the rails [0029] Now referring to Figure 3, there is shown a rail over which the rail vehicle travels. vehicle 300 of the present invention, including a first rail [0022] Figure 4a is an elevational view of a rail vehicle 15 sensor 302 and a second rail sensor 304. Second rail of Figure 3, as it passes over a right turn switch and an sensor 304 is shown oriented in a direction toward first intermediate rail is located between the rails over which rail 312, which is disposed beneath first wheel 322. First the rail vehicle travels. sensor 302 is shown oriented in a direction toward sec- [0023] Figure 4b is an elevational view of a rail vehicle ond rail 314, which is disposed beneath wheel 324.