Safety system for railroad level-crossing

Abstract

 A system detects a foreign object within a protected area of a railroad level-crossing. The system comprises a control unit (3), and at least one sensor (4) arranged on a level-crossing barrier (8), said system being configured to:
detect a specific object (9) during a function test of the system, when the level-crossing barrier (8) is in a first position (P1), and
detect a foreign object within the protected area, when the level-crossing barrier (8) is in a second position (P2).

Description

Technical Field

[0001] The present invention relates to a system, a railroad level-crossing barrier and a method for detecting a foreign object within a protected area of a railroad level-crossing. The system comprises a control unit and at least one sensor.

Background Art

[0002] Railroad level-crossings, or railroad grade crossings, are crossings where a road for vehicles and a railroad track for trains intersect in the same plane. Occasionally accidents occur as a result of vehicles being present on the railroad level-crossing when a train passes. A collision between a train and a vehicle often results in extensive material damage, traffic disturbance as well as in people being fatally injured.

[0003] Several safety systems exist for preventing vehicles from crossing the railroad tracks, such as crossing gates, or crossing barriers, being lowered across the road when a train approaches the crossing. When the crossing barriers are lowered, vehicles are not allowed to pass, and once the train has passed, the crossing barriers are raised to allow road traffic across the tracks. Visual and acoustic signals are commonly combined with crossing barriers.

[0004] Before the train passes the railroad level-crossing, a signal is usually sent to the train driver to indicate whether the crossing is free to pass or not. The signal may be visual, such as a green light if the crossing is clear, and is often arranged at a specific distance before the crossing. If an object is present on the crossing, the signal may be red, allowing the driver of the train to stop the train before it reaches the crossing. In addition, automatic systems are generally arranged for automatically stopping the train, in case the train driver does not respond to a stop signal.

[0005] The signal to the train driver is commonly derived from a system for detecting objects. One example of such a system comprises magnetic detectors buried below ground level in between the railroad tracks at the point of the crossing, sensing a vehicle body made of metal. Another example is laser or infrared detectors, sensing an object interrupting the laser or infrared beam. Both these system are arranged to automatically detect a foreign object on the tracks, and to automatically send a signal to warn the train driver so that the train may be stopped.

[0006] Another system for detecting objects on a level-crossing is based on video surveillance, where the crossing is viewed by a person located in a surveillance central.

[0007] US-6,933,858 discloses yet another system for automatically detecting the presence of a foreign object located within a surveillance area associated with a railroad level-crossing. The system has a transmitter transmitting a signal through the surveillance area and a reflector receiving the transmitted signal. A disturbance or interruption of the signal, e.g. as a result of a foreign object present between the transmitter and the reflector, generates a warning signal for stopping an approaching train.

[0008] A problem with prior art systems for detecting foreign objects present on a railroad level-crossing is that it is difficult, and sometimes impossible, to verify if the system is operable.

[0009] In case of a malfunctioning detection system, foreign objects may not be detected. Moreover, without knowing if the system is operable, it is not possible to know the actual safety status of the railroad crossing.

[0010] To verify if the system is operable, manual function tests are often conducted, resulting in high costs due to a very large number of crossings that frequently must be tested.

Summary of the Invention

[0011] It is an object of the present invention to provide an improvement of the above techniques and prior art.

[0012] These and other objects as well as advantages that will be apparent from the following description of the present invention are achieved by a system, a level-crossing barrier and a method according to the respective independent claims. Preferred embodiments are defined in the dependent claims.

[0013] The system according to the invention is highly advantageous in that the sensor is arranged on the level-crossing barrier, which provides for a dynamic position of the sensor as the crossing barrier switches between two positions for allowing or denying vehicle traffic over the crossing. The dynamic position of the level barrier efficiently allows a specific object to be detected during a selected position of the barrier, for automatically verifying that the system is operable.

[0014] The first position of the level-crossing barrier may be an open position, or may be any position during movement from a closed position to the open position of the level-crossing barrier, for facilitating convenient detection of the specific object.

[0015] The second position of the level-crossing barrier may be a closed position of the level-crossing barrier, which provides for efficient detection of a foreign object within the protected area.

[0016] The system may be configured to provide a signal indicating, in any combination: detection of a foreign object within the protected area, no detection of a foreign object within the protected area, detection of the specific object, and no detection of the specific object. These different indications facilitate efficient communication between the safety system according to the invention and, for example, other railway monitoring systems associated with the railroad level-crossing.

[0017] The system may comprise at least two sensors, and the system may be configured to provide a signal indicating allowed railroad-vehicle passage, if the system provides, from at least one of the two sensors, signals indicating that the specific object was detected during a specific time interval, and no foreign object is detected within the protected area. This prevents the system from denying trains to pass in case one of the sensors is inoperable.

[0018] The system may comprise at least two sensors, and the system may be configured to provide a signal indicating allowed railroad-vehicle passage, if the system provides, from each of the at least two sensors, signals indicating that the specific object was detected during a specific time interval, and no foreign object is detected within the protected area. This provides an increased safety, since information from at least two independent sensors form the basis of denying or allowing a train to pass.

[0019] The specific object may be configured to be detected when the level-crossing barrier is in the first position. This provides for correct detection of the specific object as well as efficient installation of the system on existing railroad level-crossings.

[0020] The specific object may have a predetermined area and be prearranged within the detection area of the at least one sensor, for ensuring proper detection of the specific object.

[0021] The specific object may be a part of the ground, or a part of the railway embankment of the railroad level-crossing, for providing a natural and already present specific object.

[0022] The at least one sensor may be a pulse radar, for providing a sensor efficiently detecting objects under various light and weather conditions.

[0023] The system may be configured to provide a signal indicating detection of a foreign object within the protected area, when no electric power is supplied to the at least one sensor. This ensures that no passage is allowed when, for example, the sensor is broken or when the level-crossing barrier is broken.

[0024] The at least one sensor may be arranged on a pivotable arm of the level-crossing barrier, for conveniently achieving different positions of the level-crossing barrier.

[0025] The method according to the invention has the same advantages as the system according to the invention and may comprise any of the embodiments of the system described above.

[0026] The method according to the invention may comprise the step of providing a signal indicating allowed railroad-vehicle passage of the railroad level-crossing, for convenient integration with existing railroad crossing safety systems.

[0027] The inventive railroad level-crossing barrier comprises a system according to any of the embodiments of the system described above. The railroad level-crossing barrier according to the invention has the same advantages as the system according to the invention.

Brief Description of the Drawings

[0028] Embodiments of the present invention will now be described in detail, by way of example, with reference to the accompanying schematic drawings, in which

Fig. 1 is a top view of a railroad level-crossing and a system according to the invention,

Fig. 2 is a front view of a system according to the invention, with a level-crossing barrier having two different positions,

Fig. 3 is a detailed view of the system, and

Fig. 4 is a detailed view of a second embodiment of the system.

Detailed Description of Preferred Embodiments of the Invention

[0029] Fig. 1 illustrates a railroad level-crossing 2 incorporating double tracks 16, 17 for trains (railroad-vehicles) and a road 20 for road vehicles. The vehicles travel in opposite directions as indicated by the arrows T. Four conventional level-crossing barriers 8, 8', 19, 19' are arranged to prevent vehicles from crossing the tracks 16, 17 when a train approaches and passes the level-crossing 2. The level-crossing barriers 8, 8', 19, 19' per se are arranged and operated in a known manner.

[0030] With reference to Figs 1, 2 and 3, the first level-crossing barrier 8 comprises a pivotable arm 11 and a sensor 4 fixedly arranged on the pivotable arm 11. The sensor 4 is a pulse radar sensor and has a detection area having an extension illustrated by the area D42, for detecting foreign objects within the area D42 when the level-crossing barrier 8 is in its closed position P2 (i.e. the arm 11 is lowered). The extension of the foreign object detection area D42 is defined by the inherent detection area of the sensor 4, and the detection area is moved as the arm 11 is pivoted, since the sensor 4 is fixedly mounted on the arm 11 and since the detection area is fixed in relation to the sensor 4.

[0031] When road vehicle-traffic is allowed to cross the tracks, 16, 17, the level-crossing barrier 8 has an open position indicated by P1 (i.e. the arm 11 is raised). The open position P1 illustrates (see Fig. 2) the arm 11 and the sensor 4 with dashed lines. The open position P1 results in the detection area having an extension illustrated by the area D41.

[0032] It should be noted that the extensions of the detection areas are schematic, and that detection areas for pulse radars generally have "softer" outer boundaries.

[0033] In brief, the detection area of the sensor 4 is fixed to the pivotable arm 11 resulting in the detection area being moved along with the arm 11, as the arm 11 is pivoted.

[0034] A specific object 9, or reference object, is arranged in the detection area D41 of the open position P1 of the level-crossing barrier 8, or in the detection area D41 of the "raised" sensor 4. However, the specific object 9 is arranged outside the detection area D42 of the closed position P2 of the level-crossing barrier 8. Preferably the specific object 9 is a steel plate having a specific area large enough to trigger the sensor 4, and preferably the specific object 9 is arranged above the ground G by means of a post 10 or by any other suitable support.

[0035] The detector 4 is connected to a control unit 3 via a first electric cable 12, and the control unit 3 is connected to a central safety processing unit 14 via a second electric cable 13. The first cable 12 is preferably arranged along the arm 11, the arm 11 is supported by a motor unit 15 for lifting and lowering the arm 11, and the motor unit is mounted on a base 18 which is attached to the ground G.

[0036] The control unit 3 is in a suitable manner arranged between the sensor 4 and the central safety processing unit 14, and in a preferred version the control unit 3 and the sensor are assembled and mounted as one unit on the arm 11.

[0037] The central safety processing unit 14 controls the level-crossing barrier 8 in a known manner and communicates with various railway safety and communication systems.

[0038] In operation, when a train approaches the railroad level-crossing 2, the safety processing unit 14 sends a signal to the level-crossing barrier 8 indicating that that the arm 11 is to be lowered. Before the arm 11 is pivoted from its raised position to its lowered position, the sensor 4 detects the specific object 9 and sends a signal to the control unit 3 indicating whether the specific object 9 is detected or not.

[0039] If the specific object 9 was not detected, the control unit 3 sends to the safety processing unit 14 a signal indicating that the sensor 4 is inoperable. As a result of such a signal, the train is not allowed to pass the crossing 2. Optionally, the train is still allowed to pass, and a signal indicating a need for maintenance of the level-crossing barrier 8 is sent.

[0040] If the specific object 9 was detected, the system is operable, allowing the sensor 4 to detect any foreign object within the detection area D42 of the closed position P2 of level-crossing barrier 8. Such a foreign object may be a vehicle, a person or any other object large enough to be detected. If a foreign object is detected, the control unit 3 sends to the safety processing unit 14 a signal indicating the presence of an object, which results in the safety processing unit 14 indicating to a train driver that his train may not pass the railroad level-crossing 2.

[0041] The communication is automatic between the sensor 4, the control unit 3 and the safety processing unit 14.

[0042] In other words, the safety processing unit 14 provides to the control unit 3 a signal indicating the position, P1 or P2, of the level-crossing barrier 8. When the level-crossing barrier 8 is to be closed, the sensor 4 is controlled by the control unit 3 to send a signal indicating any detection of an object. If the sensor 4 does not detect any object, the control unit 3 indicates an error to the safety processing unit 14. As soon as the level-crossing barrier 8 is closed, the sensor 4 detects any object, and if an object is detected, the control unit 3 sends to the safety processing unit 14 a signal denying an approaching train to pass.

[0043] The second level-crossing barrier 8' corresponds to the first level-crossing barrier 8 and has a corresponding specific object 9', sensor 4' with a detection area 42', arm 11' and control unit (not shown). The third and fourth level-crossing barriers 19, 19' are conventional barriers and are by means of the safety processing unit 14 opened and closed in coordination with the first and second level-crossing barriers 8, 8'.

[0044] Each of the level-crossing barriers 8, 8', 19 and 19' may be correspondingly associated with a respective specific object and consequently fitted with a respective sensor and control unit, resulting in respective detection areas. Preferably the number of crossing barriers incorporating the safety system is governed by the required total detection area, or by the need of overlapping detection areas.

[0045] Of course, a railroad level-crossing having any number of crossing barriers may incorporate the safety system according to this description.

[0046] The cable 12 is arranged to break if a vehicle breaks the arm 11, for allowing the control unit to indicate arm breakage, or for the safety processing unit 14 to detect arm breakage as a result of lost contact with the control unit 3.

[0047] With reference to Fig. 4, a second embodiment of the system comprises two sensors 4, 5 which are connected to the control unit 3, for purpose of providing increased safety. In this case both sensors 4, 5 must detect the specific object 9, and none of the sensors 4, 5 must detect a foreign object, for allowing a train to pass.

[0048] In a version of the second embodiment the two sensors 4, 5 provide increased system reliability since at least one of the sensors 4, 5 must detect the specific object 9 and must not detect a foreign object. This would allow one sensor to break, while the detection/non-detection by the remaining sensor allows or denies passage of a train.

[0049] In yet another embodiment three or more sensors are arranged on a level-crossing barrier for providing increased safety and/or reliability.

[0050] Instead of a pulse radar the sensor may be a video monitoring sensor, a sensor emitting ultra sound, a laser beam or an IR-beam. The specific object may be fitted with a reflector suitable for the selected type of sensor, and different sensor types may be employed in any combination.

[0051] Instead of a level-crossing barrier having a vertically pivotable arm, the level-crossing barrier may have a horizontally pivotable arm, a sliding arm or a foldable arm. The arm may also be vertically lowered or raised. Of course, only a specific part of, or the complete level-crossing barrier, may be moved between the two positions.

[0052] Of course, several variants of sequences of specific object detection and foreign object detection are possible. The detection of the specific object may be done a specific number of times during any predetermined time interval and may be done when the arm is raised or lowered, i.e. when the arm is in motion.

[0053] The sensor and the control unit may be integrated, and each sensor may have a respective control unit. Moreover, in case of more than one sensor, the sensors are arranged not to interfere with each other. It is also possible to provide means for wireless communication between the sensor and the control unit, and/or between the control unit and the safety processing unit.

Claims

1. A system for detecting a foreign object within a protected area (A) of a railroad level-crossing (2), said system comprising a control unit (3) and at least one sensor (4), characterised by the sensor (4) being arranged on a level-crossing barrier (8), said system being configured to:

detect a specific object (9) during a function test of the system, when the level-crossing barrier (8) is in a first position (P1), and

detect a foreign object within the protected area (A), when the level-crossing barrier (8) is in a second position (P2).

2. A system according to claim 1, wherein the first position (P1) of the level-crossing barrier (8) is an open position, or any position during movement from a closed position to the open position of the level-crossing barrier (8).

3. A system according to claim 1 or 2, wherein the second position (P2) of the level-crossing barrier (8) is a closed position of the level-crossing barrier (8).

4. A system according to any one of claims 1-3, wherein the system is configured to provide a signal indicating any of:

detection of a foreign object within the protected area (A),

no detection of a foreign object within the protected area (A),

detection of the specific object (9), and

no detection of the specific object (9).

5. A system according to any one of claims 1-4, comprising at least two sensors (4, 5), wherein the system is configured to provide a signal indicating allowed railroad-vehicle passage, if the system provides, from at least one of the at least two sensors (4, 5), signals indicating that
the specific object was detected during a specific time interval, and
no foreign object is detected within the protected area (A).

6. A system according to any one of claims 1-4, comprising at least two sensors (4, 5), wherein the system is configured to provide a signal indicating allowed railroad-vehicle passage, if the system provides, from each of the at least two sensors (4, 5), signals indicating that
the specific object was detected during a specific time interval, and
no foreign object is detected within the protected area (A).

7. A system according to any one of claims 1-6, wherein the specific object (9) is configured to be detected, when the level-crossing barrier (8) is in the first position (P1).

8. A system according to any one of claims 1-7, wherein the specific object (9) has a predetermined area and is prearranged within the detection area (D41) of the at least one sensor (4).

9. A system according to any one of claims 1-8, wherein the specific object (9) is a part of the ground (G), or a part of the railway embankment of the railroad level-crossing (2).

10. A system according to any one of claims 1-9, wherein the at least one sensor (4) is a pulse radar.

11. A system according to any one of claims 1-10, wherein the system is configured to provide a signal indicating detection of a foreign object within the protected area (A), when no electric power is supplied to the at least one sensor (4).

12. A system according to any one of claims 1-11, wherein the at least one sensor (4) is arranged on a pivotable arm (11) of the level-crossing barrier (8).

13. A method for a railroad level-crossing system, said system arranged to detect a foreign object within a protected area (A) and comprising a control unit (3), and at least one sensor (4) arranged on a level-crossing barrier (8), said method comprising the steps of:

detecting a specific object (9) during a function test of the system, when the level-crossing barrier (8) is in a first position (P1), and

detecting a foreign object within the protected area (A), when the level-crossing barrier (8) is in a second position (P2).

14. A method according to claim 13, further comprising the step of:

providing a signal indicating allowed railroad-vehicle passage of the railroad level-crossing (2).

15. A railroad level-crossing barrier comprising a system according to any one of claims 1-12.

Drawing