Detection of foreign material on a railroad track

Abstract

The present invention relates to a method for detection of foreign material on a railroad track segment comprising: - determining a reference current value of a transmitted and / or received current corresponding to an unoccupied state of said segment; - detecting an occupied state with at least two changes of current value of said transmitted and / or received current, during a vehicle passage on said segment, representative of the inbound and outbound of said railway vehicle, - detecting a fall of foreign materials comprising: - determining an after occupancy current value of said transmitted and / or received current after expiration of said passage, - determining the absolute value of the difference between said after occupancy and said reference current values, - if the absolute value of the difference is higher than a predetermined threshold, identifying a fall, - alerting about the presence of foreign materials.

Description

[0001] Detection of foreign material on a railroad track

[0002] The present invention concerns a method for detection of foreign material on a railroad track, said method being implemented by a monitoring system disposed trackside of said railroad track, said monitoring system disposed trackside of said railroad track having a transmit monitor and a receive monitor electrically coupled to conductive components of said railroad track that is configured to be travelled by plural railway vehicle systems, said monitoring system being configured to monitor said railroad track by measurements of transmitted current injected into the conductive components at a first location; and / or of received current at a first location that represents at least a portion of the transmitted current from a second location that is conducted through the conductive components of the route, said first location and second spaced-apart location being associated to a segment of said railroad track to monitor.

[0003] The present invention also relates to a non-transitory computer-readable medium including a computer program comprising software instructions which, when executed by a computer, implement said method for detection of foreign material on a railroad track.

[0004] The present invention also relates to a corresponding monitoring system disposed trackside of said railroad track for detection of foreign material on a railroad track.

[0005] The most common form of railway vehicle detection used by railroads for the last decades have been track circuits, which use the rails as conductors, applying a voltage or current to the rails at one end of track section (i.e. track segment) and receiving a voltage or current at the opposing end of the same track section.

[0006] If the received voltage or current is above a predetermined threshold, said track section is said to be unoccupied, and a signal is used to indicate an unoccupied state of said track section. Conversely, if the received voltage or current is below a threshold, said track section is considered in an occupied state and a signal is used to indicate said occupied state and requires railway vehicle to slow or stop before entering the track section.

[0007] It has to be noted, that an occupied state of the segment corresponds to the absence of both a railway vehicle and of foreign materials on said on said segment of the railroad track

[0008] However said occupancy could be the result of at least one broken rail or any of the wires associated with the track circuit equipment that may have been disconnected, a breakdown of a track circuit equipment itself, a presence of a train through its axles blocking the signal from reaching the receiver of the track circuits.

[0009] Moreover, railway vehicles often carry goods, which are likely to leave behind foreign material (i.e. debris) on said track section, and if such foreign material (i.e. debris) is electrically conductive (e.g. metal banding used to secure materials), it can also impact the detection operated by said track circuits leading also to a detected occupied state.

[0010] In other words, a track circuit reacts when there is a railway vehicle present on the track section it is monitoring or when conditions of the track section change.

[0011] False detection of an occupied state, especially related to the presence of foreign material, can significantly reduce the traffic flow and require maintenance personnel to travel (walk or drive at slow speed) to the considered track section to remedy the issue.

[0012] In other words, this will restrict subsequent railway vehicle (e.g. train) movements through the track section, delaying operations.

[0013] Maintenance personnel will also be required to travel to the site to investigate and remedy the issue. Indeed, current state of art technology cannot differentiate this debris from a train.

[0014] The maintenance personnel has no idea what is causing the unintentionally occupied track section, as there are many items that can lead to this false detection as listed above

[0015] Due to the nature of the track circuit design, there are indeed multiple failures, which can cause a track section to be incorrectly determined as occupied.

[0016] Therefore, the maintainer may have to spend considerable time investigating the root case. In the case of debris, they may need to walk or travel at low speed along the track to find the issue. In other words, the investigative process can take hours such that no railway vehicles are allowed to use said track circuit during the time of the investigative process.

[0017] This means that operations may not be restored for many hours, losing valuable opportunities for revenue. Valuable potential revenue is thus lost and unnecessary maintenance costs are incurred. It can be noted that from railroad maintenance records, it is estimated that debris on the track causes occupied states of track sections at least three thousand times per year in North America resulting in as much $10,000,000 in lost revenue due to railway delays, and costs railroads up to $300,000 annually in unplanned maintenance.

[0018] To solve this problem, a prior art solution is provided by US 10, 252, 735 B2 and is based on the simultaneous monitoring of changes to both transmitted and received currents only when the track section is unoccupied, which results in undesirable delays in detection of debris on the track.

[0019] The present invention aims to solve the above-mentioned problem. For this purpose, the invention relates to a method for detection of foreign material on a railroad track, said method being implemented by a monitoring system disposed trackside of said railroad track, said monitoring system disposed trackside of said railroad track having a transmit monitor and a receive monitor electrically coupled to conductive components of said railroad track that is configured to be travelled by plural railway vehicle systems, said monitoring system being configured to monitor said railroad track by measurements of:

[0020] - transmitted current injected into the conductive components at a first location; and / or

[0021] - received current at a first location that represents at least a portion of the transmitted current from a second location that is conducted through the conductive components of the route, said first location and second spaced-apart location being associated to a segment of said railroad track to monitor; wherein said method comprises the following steps:

[0022] - determining beforehand a reference current value of said transmitted current and / or of said received current, said reference current value corresponding to an unoccupied state of said segment;

[0023] - detecting an occupied state of said segment by detecting at least two changes of current value of said transmitted current, and / or of said received current, during a time period corresponding to a railway vehicle passage on said segment, said at least two changes of current value being respectively representative of the inbound and of the outbound of said railway vehicle on said segment,

[0024] - detecting a fall on said segment of foreign materials from the railway vehicle during said time period, said detecting comprising:

[0025] - determining an after occupancy current value of said transmitted current and / or of said received current after expiration of said time period,

[0026] - determining the absolute value of the difference between said after occupancy current value and said reference current value,

[0027] - if the absolute value of the difference value is higher than a predetermined threshold, identifying a fall on said segment of foreign materials from the railway vehicle during said time period,

[0028] - alerting about the presence on said segment of foreign materials.

[0029] In other words, the wayside detection provided by the present invention proposes to monitor the transmitted and / or received current during a time period corresponding to a railway vehicle passage, and is thus dependent on the railway vehicle passage and based on a comparison of current levels (i.e. values) before and after railway vehicle passage to determine that the railway vehicle leaves behind foreign material (i.e. debris) on said monitored track section.

[0030] Moreover, according to the present invention, a foreign material can be detected by monitoring data at a single location of the track segment, that way no information needs to be exchanged between spaced apart ends of the track segment, which makes the solution easier to implement.

[0031] Such method for detection of foreign material on a railroad track may include one or more of the following features, considered alone or in any technically possible combination:

[0032] - when using measurements of said received current, the fall on said segment of foreign materials involves that said after occupancy current value is less than said reference current value of said received current;

[0033] - when using measurements of said transmitted current, the fall on said segment of foreign materials involves that said after occupancy current value is higher than said reference current value of said transmitted current;

[0034] - the detecting of an occupied state of said segment comprises, using said transmitted current, the determining of the type of railway vehicle move between an outbound move and an inbound move on said segment;

[0035] - said railway vehicle move is:

[0036] - an outbound move on said segment when the reference current value of said transmitted current is changed instantaneously to a value both greater than said reference value and greater than a predetermined current threshold;

[0037] - an inbound move on said segment when the reference current value of said transmitted current is changed instantaneously to a value both greater than said reference value and less than said predetermined current threshold;

[0038] - said railway vehicle move is:

[0039] - an outbound move on said segment when the value of said transmitted current decreases relative to time consistent with expected train speeds;

[0040] - an inbound move on said segment when the value of said transmitted current increases relative to time consistent with expected train speeds;

[0041] - said method further comprises estimating the location of said fallen foreign materials on said segment by using a reference curve of said transmitted current, as a function of time, said reference curve being obtained beforehand during a prior reference time period wherein said segment is successively unoccupied, occupied during a railway vehicle passage on said segment without any fall of foreign materials on said segment, and once again unoccupied after said railway vehicle passage;

[0042] - estimating the location of said fallen foreign materials comprises:

[0043] - using said reference curve, determining the falling instant wherein, when said segment is in occupied state, the value of said transmitted current is equal to the after occupancy current value; - using said falling instant and a known velocity of said railway vehicle for estimating the distance travelled by said railway vehicle between the start of the occupied state and said falling instant;

[0044] - said reference curve is associated to the type of railway vehicle move as determined during the detecting of an occupied state during which said fall on said segment of foreign materials from the railway vehicle is detected.

[0045] The present invention also relates to a non-transitory computer-readable medium including a computer program comprising software instructions which, when executed by a computer, implement said method for detection of foreign material on a railroad track.

[0046] The present invention also relates to a corresponding monitoring system disposed trackside of said railroad track for detection of foreign material on a railroad track, said monitoring system disposed trackside of said railroad track having a transmit monitor and a receive monitor electrically coupled to conductive components of said railroad track that is travelled by plural railway vehicle systems, said monitoring system being configured to monitor by measurements of:

[0047] - transmitted current injected into the conductive components at a first location; and / or

[0048] - received current at a first location that represents at least a portion of the transmitted current from a second location that is conducted through the conductive components of the route, said first location and second spaced-apart location being associated to a segment of said railroad track to monitor; wherein said monitoring system comprises also a monitoring module with one or more processors configured to:

[0049] - determine beforehand a reference current value of said transmitted current and / or of said received current, said reference current value corresponding to an unoccupied state of said segment;

[0050] - detect an occupied state of said segment by detecting at least two changes of current value of said transmitted current, and / or of said received current, during a time period corresponding to a railway vehicle passage on said segment, said at least two changes of current value being respectively representative of the inbound and of the outbound of said railway vehicle on said segment,

[0051] - detect a fall on said segment of foreign materials from the railway vehicle during said time period, by:

[0052] - determining an after occupancy current value of said transmitted current and / or of said received current after expiration of said time period,

[0053] - determining the absolute value of the difference between said after occupancy current value and said reference current value, - if the absolute value of the difference value is higher than a predetermined threshold, identifying a fall on said segment of foreign materials from the railway vehicle during said time period,

[0054] - alert about the presence on said segment of foreign materials.

[0055] The invention and its advantages will be better understood upon reading the following detailed description of a particular embodiment, given solely by way of a nonlimiting example, wherein this description is made with reference to the appended drawings, wherein:

[0056] - figure 1 is a flowchart of a method for detection of foreign materials on railroad track according to the invention;

[0057] - figure 2 illustrates the impact of a foreign material on the transmitted and / or received currents.

[0058] The method 10 for detection of foreign materials on railroad track according to the invention is implemented by a non represented monitoring system disposed trackside of said railroad track, said monitoring system disposed trackside of said railroad track having a transmit monitor and a receive monitor electrically coupled to conductive components of said railroad track that is configured to be travelled by plural railway vehicle systems.

[0059] Said monitoring system is configured to monitor by measurements of:

[0060] - transmitted current injected into the conductive components at a first location; and / or

[0061] - received current at a first location that represents at least a portion of the transmitted current from a second location that is conducted through the conductive components of the route, said first location and second spaced-apart location being associated to a segment of said railroad track to monitor.

[0062] Specifically, according to the present invention, said monitoring system comprises also a monitoring module with one or more processors configured to:

[0063] - determine beforehand a reference current value of said transmitted current and / or of said received current, said reference current value corresponding to an unoccupied state of said segment;

[0064] - detect an occupied state of said segment by detecting at least two changes of current value of said transmitted current, and / or of said received current, during a time period corresponding to a railway vehicle passage on said segment, said at least two changes of current value being respectively representative of the inbound and of the outbound of said railway vehicle on said segment,

[0065] - detect a fall on said segment of foreign materials from the railway vehicle during said time period, by: - determining an after occupancy current value of said transmitted current and / or of said received current after expiration of said time period,

[0066] - determining the absolute value of the difference between said after occupancy current value and said reference current value,

[0067] - if the absolute value of the difference value is higher than a predetermined threshold, for example 500 milliamperes, identifying a fall on said segment of foreign materials from the railway vehicle during said time period,

[0068] - alert about the presence on said segment of foreign materials.

[0069] Optionally, the monitoring system comprises an information processing unit, not shown, for example made up of a memory and a processor(s) associated with the memory.

[0070] According to this option, the monitoring module is made in the form of software, or software brick, executable by the processor(s). This module is configured to implement, automatically (that is to say, without human intervention), dedicated processing operations described hereinafter.

[0071] The memory of the monitoring system is then configured to store a monitoring software. The processor is then configured to execute the software applications from the monitoring software.

[0072] In a variant that is not shown, the monitoring module is made in the form of a programmable logic component, such as an FPGA (Field Programmable Gate Array), or in the form of a dedicated integrated circuit, such as an ASIC (Application Specific Integrated Circuit).

[0073] When the monitoring system is made in the form of one or several software programs, i.e., in the form of a computer program, it is further able to be stored on a medium, not shown, readable by computer. The computer-readable medium is for example a medium suitable for storing electronic instructions and able to be coupled with a bus of a computer system. As an example, the readable medium is an optical disc, a magnetic-optical disc, a ROM memory, a RAM memory, any type of non-volatile memory (for example, EPROM, EEPROM, FLASH, NVRAM), a magnetic card or an optical card. A computer program including software instructions is then stored on the readable medium.

[0074] Figure 1 is a flowchart of a method 10 for detection of foreign materials on railroad track according to the invention

[0075] According to a first step 12, the method 10 for detection of foreign materials on railroad track comprises a first determining step DET USRCV consisting in determining beforehand a reference current value of said transmitted current and / or of said received current, said reference current value corresponding to an unoccupied state of said segment. Then, a step 14 is implemented wherein detecting an occupied state of said segment by detecting at least two changes of current value of said transmitted current, and / or of said received current, during a time period corresponding to a railway vehicle passage on said segment, said at least two changes of current value being respectively representative of the inbound and of the outbound of said railway vehicle on said segment. Inbound movement is defined as entry of the train at the end of the track segment opposite the track circuit and moving towards the monitoring system. Outbound movement is defined as entry of the train at the end of the track segment same as the track circuit and moving away from the monitoring system.

[0076] Optionally, said step 14 of detecting an occupied state of said segment comprises, using said transmitted current, a step 16 of determining of the type of railway vehicle move between an inbound move I and an outbound move O on said segment.

[0077] According to an optional aspect, an outbound move of the railway vehicle on said segment is determined when the reference current value of said transmitted current is changed instantaneously to a value both greater than said reference value and greater than a predetermined current threshold as illustrated later by figure 2, and an inbound move on said segment is determined when the reference current value of said transmitted current is changed instantaneously to a value both greater than said reference value and less than said predetermined current threshold. In another embodiment, inbound moves may be determined by increases in transmitted current versus time and outbound moves may be determined by decreases in transmitted current versus time consistent with train speeds.

[0078] On figure 1 , the arrow 18 corresponds to the case wherein an outbound move is detected, whereas the arrow 20 corresponds to the case wherein an outbound move is detected.

[0079] Said method comprises also another essential step 22 of detecting a fall on said segment of foreign materials FM from the railway vehicle during said time period. Said detecting step 22 is implemented independently of the above option consisting in determining the type of railway vehicle move. In other words, regardless the type of railway vehicle move, said step 22 is always performed (i.e. in both cases of inbound or outbound move).

[0080] Said detecting comprises:

[0081] - determining an after occupancy current value of said transmitted current and / or of said received current after expiration of said time period,

[0082] - determining the absolute value of the difference between said after occupancy current value and said reference current value, - if the absolute value of the difference value is higher than a predetermined threshold, for example 500 milliamperes, identifying a fall on said segment of foreign materials from the railway vehicle during said time period.

[0083] If no fall on said segment of foreign materials FM is detected, according to the arrow 23, the method returns to the first step 12 of determining beforehand a reference current value of said transmitted current and / or of said received current, said reference current value corresponding to an unoccupied state of said segment.

[0084] On the contrary, if a fall on said segment of foreign materials FM is detected, according to the arrow 24 a further step 26 of alerting A about the presence on said segment of railroad of foreign material FM is then implemented according to the present invention.

[0085] Optionally and independently of the above option consisting in determining the type of railway vehicle move, said method 10 further comprises a step 28 estimating the location of said fallen foreign materials on said segment by using a reference curve of said transmitted current , as a function of time, said reference curve being obtained beforehand during a prior reference time period wherein said segment is successively unoccupied, occupied during a railway vehicle passage on said segment without any fall of foreign materials on said segment, and once again unoccupied after said railway vehicle passage.

[0086] More precisely, according to an optional aspect, estimating 28 the location of said fallen foreign materials comprises:

[0087] - using said reference curve, determining the falling instant wherein, when said segment is in occupied state, the value of said transmitted current is equal to the after occupancy current value;

[0088] - using said falling instant and a known velocity of said railway vehicle for estimating the distance travelled by said railway vehicle between the start of the occupied state and said falling instant.

[0089] As an optional extra, said reference curve is associated to the type of railway vehicle move as optionally determined 16 during the detecting 14 of an occupied state during which said fall on said segment of foreign materials from the railway vehicle is detected.

[0090] Once said optional location is estimated and provided for example to a maintainer, according to the arrow 30 the method is reiterated.

[0091] Figure 2 illustrates the impact of a foreign material on the transmitted and / or received currents, in the view A when the railway vehicle move is an inbound move, and in the view B when the railway vehicle move is an inbound move.

[0092] Indeed, the current(s) (i.e. transmitted and / or received current) monitored by the monitoring system according to the present invention, and as represented by the ordinate axis 32 react(s) at each end when there are railway vehicle present or when the track section changes over time, time being represented by the abscissa axis 34.

[0093] Such curves, have been built and obtained when developing analytics solutions related to track circuit data (detecting rail buckles, insulated joint failures, etc.), and while collecting data, events with debris (i.e. foreign material) on the track were captured.

[0094] On figure 2, in view A associated to an inbound move, as a railway vehicle moves through a track section (i.e. track segment), the received current is represented, by the solid curve 36 when leaving behind a foreign material on said track, and without leaving behind a foreign material on said track by the dotted curve 38, the transmitted current is represented by the solid curve 40 when leaving behind a foreign material on said track, and without leaving behind a foreign material on said track by the dotted curve 42.

[0095] Similarly, in view B associated to an outbound move, as a railway vehicle moves through a track section (i.e. track segment), the transmitted current is represented by the solid curve 44 when leaving behind a foreign material on said track, and without leaving behind a foreign material on said track by the dotted curve 46, the received current is represented, by the solid curve 48 when leaving behind a foreign material on said track, and without leaving behind a foreign material on said track by the dotted curve 50,

[0096] In other words, the graphs in figure 2 show the normal trajectory of the track circuit currents in dashed lines 38, 42, 46, 50, subsequently called “reference curves”, while the solid lines 36, 40, 44 and 48 illustrate an example of what happens when foreign material (i.e. debris) is left behind by the railway vehicle (e.g. a train).

[0097] As can be seen in both views A and B, initially the transmitted and / or the received current are relatively constant as the values are dictated by only the track conditions (i.e. rail and ballast resistance) in the unoccupied state.

[0098] When a railway vehicle (e.g. a train) initially enters the monitored track section, the received current 36 or 38 in view A or 48, 50 in view B, at both ends drops to nearly zero as the axle from the railway vehicle (e.g. a train) prevent transmitted current at one end from reaching the other end.

[0099] The transmitted current increases at both ends and will increase with the larger increase coming at the end where the train entered considered as in an outbound move as illustrated in view B, the transmitted current is relatively constant as the length of the railway vehicle (e.g. a train) passes over the segment, with the current limited by only the resistance of the wires connected to the track.

[0100] Once the rear of the railway vehicle (e.g. a train) passes this end, the transmitted current decreases as the resistance between the transmitter and the rear of the railway vehicle (e.g. a train) increases relative to its distance. At the end opposite from where the railway vehicle (e.g. a train) entered considered as in an inbound move, the transmitted current will begin increasing as the resistance between the transmitter and the front of the train decreases relative to its distance. Eventually the transmitted current will be relatively constant as the length of the railway vehicle (e.g. a train) passes over the considered monitored segment, with the current limited by only the resistance of the wires connected to the track.

[0101] Once the train leaves the track section without leaving behind any foreign material on the considered monitored track segment, the transmitted 42 and 46 and received currents 38 and 50 at both ends should return to their values before the railway vehicle (e.g. a train), as long as track conditions have not changed in the relatively short period of time for the railway vehicle (e.g. a train) to traverse the section.

[0102] As illustrated by curves 36 for the received current with an inbound move, 40 for the transmitted current with an inbound move, 44 for the transmitted current with an outbound move and 48 for the transmitted current with an outbound move, when the railway vehicle (e.g. a train) leaves behind debris from its cargo such as metal banding, iron ore, etc. If the debris is conductive, it impacts the track circuit operation adversely and the track section may be incorrectly be determined as occupied.

[0103] In the case of a railway vehicle (e.g. a train) leaves behind debris, that would adversely impacts operations, figure 2 shows the reaction of the track circuit currents.

[0104] The reaction is initially the same as a normal move as represented by dotted curves in figure 2 38, 42, 46, 50 which are thus merged with curves 36, 40, 44 and 48 representing the impact of the fall of a foreign material on the monitored track segment. However, once the debris is dropped onto the track at ti on view A and at t2 on view B, the end observing the outbound move on view B will show the transmitted current 44 as relatively constant, at a value higher than that before the arrival of the train, while the end observing the inbound move on view A will continue to show an increasing transmitted current 40.

[0105] The rear of the train can no longer be seen at the outbound end as the debris (i.e. the foreign material) is preventing it. The front of the railway vehicle (e.g. a train) however, can still be seen from the inbound end as the debris is not yet seen. Once the train leaves the track section, the transmitted current at the inbound end will also be relatively constant, at a value higher than that before the arrival of the train.

[0106] Thus, as can be seen in both views, and as optionally used by the present invention, when using measurements of said transmitted current, the fall on said segment of foreign materials involves that said after occupancy current value is higher than said reference current value of said transmitted current. At both ends the received current will be relatively constant, but at a lower value than that before the arrival of the train.

[0107] Thus, as can be seen in both views, and as optionally used by the present invention, when using measurements of said received current, the fall on said segment of foreign materials involves that said after occupancy current value is less than said reference current value of said received current.

[0108] These signatures can be detected by the appropriate algorithm of figure 1 as previously described, and immediate notification (i.e. alert) can be sent to maintenance personnel identifying the exact issue.

[0109] Furthermore, the level in view A and I2 in view B of transmitted current at each end where it goes relatively constant can be used to locate the foreign material.

[0110] For most moves of railway vehicle (e.g. a train), the level of transmitted current as it moves through the track section is relatively linear and repeatable. Using knowledge of the relationship between transmitted current and location of the front or rear of the railway vehicle (e.g. a train), the location of the foreign material (i.e. the debris) can be estimated as shown in figure 2. For example, the transmitted current will increase (for inbound moves) to 50% of its overall change throughout the move when the front of the train is through 50% of the track segment. Also for example, the transmitted current will decrease (for outbound moves) to 75% of its overall change throughout the move when the rear of the train is through 75% of the track segment. For even better accuracy in locating foreign material, methods that incorporate changing track conditions may be used to dynamically understand the relationship between transmitted current and location of the front or rear of the railway vehicle as specified in US 11 ,577,763.

[0111] Thus, differently from the previous cited patent US 10,252,735 B2, the present invention involves the movement of railway vehicles (which allows for faster detection of foreign materials), and provides furthermore the ability to locate the foreign material (i.e. debris) left behind.

[0112] A person skilled in the art would understand that the invention is not limited to the embodiments described, nor to the particular examples of the description, the above- mentioned embodiments and variants being suitable for being combined with one another so as to generate new embodiments of the invention.

[0113] The present invention is specific to the railway domain as it uses data from existing wayside track circuits. The present invention thereby proposes to provide railroads with immediate detection and identification of foreign material (i.e. debris) on the railroad track, and optionally and advantageously can also approximate the location of the foreign material (i.e. debris) that causes train delays. In addition, using data available from existing track circuits, makes the solution economically feasible as no sensors or additional equipment is required.

[0114] This information allows the railroads maintainers to understand exactly the problem and remedy required, supporting faster restoration of service avoiding lengthy train delays and expensive maintenance investigations. The present invention allows thus maintenance personnel to restore operations much faster than they are currently able. The amount of time required to restore operations is thus significantly reduced, and lost revenue opportunities are minimized.

[0115] In other words, the present invention provides a novel and cost-effective method to automatically detect, identify and locate foreign material (i.e. debris) that has been left on the track by passing railway vehicle (e.g. a train) for the purpose of restoring operations more quickly.

[0116] Thus, the present invention permits to eliminate the above cited lost revenues and unplanned maintenance activities through a detection method that monitors each track circuit data continuously, and can detect and identify foreign material left behind on the track, and also that can optionally provide an approximate location of the foreign material left behind.

Claims

CLAIMS1 A method for detection of foreign material on a railroad track, said method being implemented by a monitoring system disposed trackside of said railroad track, said monitoring system disposed trackside of said railroad track having a transmit monitor and a receive monitor electrically coupled to conductive components of said railroad track that is configured to be travelled by plural railway vehicle systems, said monitoring system being configured to monitor said railroad track by measurements of:- transmitted current injected into the conductive components at a first location; and / or- received current at a first location that represents at least a portion of the transmitted current from a second location that is conducted through the conductive components of the route, said first location and second spaced-apart location being associated to a segment of said railroad track to monitor; wherein said method comprises the following steps:- determining beforehand a reference current value of said transmitted current and / or of said received current, said reference current value corresponding to an unoccupied state of said segment;- detecting an occupied state of said segment by detecting at least two changes of current value of said transmitted current, and / or of said received current, during a time period corresponding to a railway vehicle passage on said segment, said at least two changes of current value being respectively representative of the inbound and of the outbound of said railway vehicle on said segment,- detecting a fall on said segment of foreign materials from the railway vehicle during said time period, said detecting comprising:- determining an after occupancy current value of said transmitted current and / or of said received current after expiration of said time period,- determining the absolute value of the difference between said after occupancy current value and said reference current value,- if the absolute value of the difference value is higher than a predetermined threshold, identifying a fall on said segment of foreign materials from the railway vehicle during said time period,- alerting about the presence on said segment of foreign materials.2.- The method according to claim 1 , wherein when using measurements of said received current, the fall on said segment of foreign materials involves that said after occupancy current value is less than said reference current value of said received current.3.- The method according to claim 1 or 2, wherein when using measurements of said transmitted current, the fall on said segment of foreign materials involves that said after occupancy current value is higher than said reference current value of said transmitted current.4.- The method according to anyone of the preceding claims, wherein the detecting of an occupied state of said segment comprises, using said transmitted current, the determining of the type of railway vehicle move between an outbound move and an inbound move on said segment.5.- The method according to claim 4, wherein said railway vehicle move is:- an outbound move on said segment when the reference current value of said transmitted current is changed instantaneously to a value both greater than said reference value and greater than a predetermined current threshold;- an inbound move on said segment when the reference current value of said transmitted current is changed instantaneously to a value both greater than said reference value and less than said predetermined current threshold.6.- The method according to claim 4, wherein said railway vehicle move is:- an outbound move on said segment when the value of said transmitted current decreases relative to time consistent with expected train speeds;- an inbound move on said segment when the value of said transmitted current increases relative to time consistent with expected train speeds.7.- The method according to anyone of the preceding claims, further comprising estimating the location of said fallen foreign materials on said segment by using a reference curve of said transmitted current, as a function of time, said reference curve being obtained beforehand during a prior reference time period wherein said segment is successively unoccupied, occupied during a railway vehicle passage on said segment without any fall of foreign materials on said segment, and once again unoccupied after said railway vehicle passage.

8. -The method according to claim 7, wherein estimating the location of said fallen foreign materials comprises:- using said reference curve, determining the falling instant wherein, when said segment is in occupied state, the value of said transmitted current is equal to the after occupancy current value;- using said falling instant and a known velocity of said railway vehicle for estimating the distance travelled by said railway vehicle between the start of the occupied state and said falling instant.9.- The method according to claims 4 and 7 wherein said reference curve is associated to the type of railway vehicle move as determined during the detecting of an occupied state during which said fall on said segment of foreign materials from the railway vehicle is detected.10.- A non-transitory computer-readable medium including a computer program comprising software instructions which, when executed by a computer, implement a method for detection of foreign material on a railroad track according to anyone of the preceding claims.11 .- A monitoring system disposed trackside of said railroad track for detection of foreign material on a railroad track, said monitoring system disposed trackside of said railroad track having a transmit monitor and a receive monitor electrically coupled to conductive components of said railroad track that is travelled by plural railway vehicle systems, said monitoring system being configured to monitor by measurements of:- transmitted current injected into the conductive components at a first location; and / or- received current at a first location that represents at least a portion of the transmitted current from a second location that is conducted through the conductive components of the route, said first location and second spaced-apart location being associated to a segment of said railroad track to monitor; wherein said monitoring system comprises also a monitoring module with one or more processors configured to:- determine beforehand a reference current value of said transmitted current and / or of said received current, said reference current value corresponding to an unoccupied state of said segment;- detect an occupied state of said segment by detecting at least two changes of current value of said transmitted current, and / or of said received current, during a time period corresponding to a railway vehicle passage on said segment, said at least two changes ofcurrent value being respectively representative of the inbound and of the outbound of said railway vehicle on said segment,- detect a fall on said segment of foreign materials from the railway vehicle during said time period, by: - determining an after occupancy current value of said transmitted current and / or of said received current after expiration of said time period,- determining the absolute value of the difference between said after occupancy current value and said reference current value,- if the absolute value of the difference value is higher than a predetermined threshold, identifying a fall on said segment of foreign materials from the railway vehicle during said time period,- alert about the presence on said segment of foreign materials.

Images