GB2569452A

GB2569452A - System and method for rail vehicle detection and alert

Info

Publication number: GB2569452A
Application number: GB1818628.8A
Authority: GB
Inventors: Wing Chan Ho; Sum Fai Lor Ricko; Fei LEE Tsz; Hon Lun So Ken
Original assignee: MTR Corp Ltd
Current assignee: MTR Corp Ltd
Priority date: 2017-11-17
Filing date: 2018-11-15
Publication date: 2019-06-19
Anticipated expiration: 2038-11-15
Also published as: GB201818628D0; GB2569452B

Abstract

The system comprises a first radio-frequency identification (RFID) reader 15 for detecting the presence of a RFID tag mounted to a rail vehicle 7 travelling along a rail track. The first RFID reader 15 is arrangeable in advance of an intersection (for example, level crossing) 1 along the rail track to detect the RFID tag 31 of the rail vehicle approaching the intersection. The system further comprises a second RFID reader 17 for detecting the presence of the RFID tag of the rail vehicle, the second RFID reader 17 being arrangeable after the intersection for detecting the RFID tag of the rail vehicle after the intersection. The system is configured to trigger an event upon detection of the RFID tag by the first RFID reader. The event may be to provide a visual and audible alert to vehicle drivers 11 and pedestrians 13 at the level crossing 1. The system further comprises a first proximity sensor 39 arrangeable in advance of the intersection at a position for detecting the presence of a wheel of the rail vehicle, and a second proximity sensor 39 arrangeable after the intersection at a position for detecting the presence of a wheel of the rail vehicle. The proximity sensor counts wheels entering and leaving an intersection, and enables the number of cars and length of the rail vehicle 7 to be determined (number of wheels per car will be known).

Description

SYSTEM AND METHOD FOR RAIL VEHICLE DETECTION AND ALERT

FIELD OF THE INVENTION

The present invention relates to a system and method for rail vehicle detection and alert.

BACKGROUND OF THE INVENTION

Major urban areas have large transport networks for the mass transit of large numbers of people, as well as high volumes of goods. Such mass transit networks typically comprise several different transit types including heavy rail, high-speed rail, light rail, buses, and cars. Since mass transit networks extend across relatively high density urban areas, inevitably, there is some overlap or intersection of the underlying mass transit network infrastructure. For example, rail lines of a mass transit network may intersect at various points with roads of the mass transit network. Such points of intersection or junctions are commonly referred to as level crossings.

Level crossings present a potential safety hazard, particularly since rail vehicles are heavy relative to other vehicle types and usually require greater braking distances. Many measures are taken to mitigate the risk of accidents at level crossings including the use of barriers that are movable between a first position in which road vehicles, cyclists, and pedestrians are prevented from crossing the rail line and a second position in which road vehicles, pedestrians and cyclists may cross the rail line. Through manual or automatic control of barriers and/or warning signals at level crossings, the flow of traffic by rail vehicles, and road vehicles and pedestrians may be controlled in an efficient manner with low risk of accident or collision. In the case of some level crossings, no traffic control or warning system is in place at all, instead requiring all parties approaching the level crossing to do so with caution and also relying on the rail vehicle driver to sound a horn to warn road users and pedestrians that the rail vehicle is approaching. Despite these measures, though, the risk of accidents at level crossings has not been eliminated.

Light rail networks tend to carry a greater risk of accident at level crossings than other types of transit in a mass transit network. This is because light rail networks are typically open, aboveground railway systems in which rail vehicles, road vehicles and pedestrians share relatively large numbers of junctions or intersections and, hence, points at which an accident can occur. Tn Hong Kong, for example, the light rail system in certain territories shares more than one hundred points of intersection with the road network. Light rail vehicle drivers on the light rail network are required to drive using line of sight and are also required to obey the Road Traffic Ordinance in the same way as other road users such as bus and car drivers, which includes adhering to certain speed limits and stop signals. Due to increases in population density and, hence, road and rail traffic at junctions, the likelihood of injury and fatal accidents at junctions is increasing.

With reference to Fig. 1, there is shown a level crossing 1 comprising an intersection between a railway track 3 and a road 5, with a rail vehicle 7 approaching the level crossing 1. Control of rail vehicle traffic through the level crossing is facilitated by a two aspect signalling system which includes an automatic point control and a route setting mechanism that is operated by local point controllers across junctions. The signalling system adopts a signal display scheme provided on a fixed signal 9 adjacent the track to indicate to rail vehicle drivers whether to stop or proceed. Referring to Figs. 2a to 2c, the signal display scheme comprises a two aspect, two colour scheme with three states, namely, ‘proceed’ corresponding to a white chevron symbol in steady state, ‘proceed but about to change’ corresponding to a flashing white chevron symbol, and ‘stop’ corresponding to a red ‘T’ shape signal in steady state.

In the example depicted, a braking marker showing the maximum allowable speed of 45km/h and a stop line are arranged in advance of the level crossing to indicate to the rail vehicle driver to reduce speed to the limit from the braking marker onwards until drawing to a halt at the stop line, assuming the stop signal is displayed. The braking marker is located at an adequate distance from the stop line to ensure the rail vehicle can stop by the stop line without excessive or emergency braking. The stop line is spaced from the road junction to provide a small safety margin in the event the rail vehicle is unable to stop by the stop line due to, for example, adverse weather conditions or slow driver reaction time. The maximum junction speed is set as 35km/h to keep the rail vehicle 7 within a speed considered to be sufficiently low to reduce the risk of accident as the rail vehicle moves through the junction.

A “request” loop antenna is arranged along the track before the braking marker so that, when a rail vehicle passes through the request loop antenna, sending of a “request to proceed” signal to a wayside electronic controller is triggered requesting that the fixed signal be changed to proceed. Although in the embodiment depicted no warning or barrier control system is provided for road users and pedestrians, if a traffic signalling system is present, the request to proceed signal may also trigger sending of a “request stop” signal by the wayside controller to a remote terminal unit (RTU) and road traffic controller adjacent the road junction. In response to the request to proceed transmission, the fixed signal changes to the proceed signal (Fig. 2c). Where a road traffic control signal is in place, the stop signal causes the roadside signalling system to change to a stop sign to alert pedestrians and road users to the oncoming rail vehicle.

A “cancel” loop antenna is arranged along the track on the side of the intersection opposite the request loop antenna. The cancel loop antenna is configured to transmit a signal cancelling the request to proceed signal upon passing of the rail vehicle through the cancel loop antenna section of track, thereby switching the fixed signal back to the stop sign (Fig. 2b) and, where a roadside traffic signal is present, changing the traffic sign for road users and pedestrians to proceed. Upon passing through the level crossing and the subsequent cancel loop antenna, the rail vehicle may continue to run at the maximum permitted track speed until the next braking marker, fixed signal or level crossing.

Although such light rail systems make use of automatic fixed signalling mechanisms at junctions to control the flow of traffic and give priority to rail vehicles, whether pedestrians and road users follow and adhere to stop signals can neither be predicted nor controlled, especially where no warning system or barrier control system is in place at the level crossing. Furthermore, since light rail vehicles have a much longer braking distance than road vehicles when travelling at the same speed, the consequences of a light rail vehicle hitting a pedestrian or other vehicle are usually much higher than that of a road vehicle. Even though light rail vehicle drivers are particularly cautious when approaching level crossings or other types of junctions, accidents involving rail vehicles, and pedestrians and road vehicles, still persist. Such accidents, even if minor, can have a significant impact on operation of the rail network.

The risk of accident involving a rail vehicle is not only limited to level crossings. There is also a risk of accident in rail vehicle depots where rail vehicles are stored and serviced. The risk of accident is especially high during relatively hectic, peak hours when a high volume of rail vehicle traffic is transiting between the depot and the outside rail network.

Depot vehicle traffic control is usually handled by Depot Operation Controllers (DOC). The control of rail vehicles entering a depot to be stabled involves the DOC moving point machines manually and remotely, with the aid of CCTV and radio communication systems, and then communicating to the driver of the rail vehicle via radio to move to a designated track. Observing through depot cameras of the CCTV system, the DOC must then ensure the vehicle has completely passed through the point machine and is stabling at the designated track before any further point machine movement. Due to the human factor in depot traffic control, though, the risk of accident, which includes danger to depot workers and rail vehicle derailment, is relatively high.

It is an object of the present invention to provide an improved system and method for detecting a rail vehicle and raising an alert to the presence of the rail vehicle so that flow of rail vehicle traffic through an intersection along a rail line can be controlled more safely and efficiently

SUMMARY OF THE INVENTION

In accordance with a first aspect of the present invention, there is provided a system for rail vehicle detection and alert comprising a first radio-frequency identification (RFID) reader for detecting the presence of a RFID tag mounted to a rail vehicle travelling along a rail track, the first RFID reader arrangeable in advance of an intersection along the rail track to detect the RFID tag of the rail vehicle approaching the intersection, and a second RFID reader for detecting the presence of the RFID tag of the rail vehicle, the second RFID reader arrangeable after the intersection for detecting the RFID tag of the rail vehicle after the intersection, wherein the system is configured to trigger an event upon detection of the RFID tag by the first RFID reader, and wherein the system further comprises a first proximity sensor arrangeable in advance of the intersection at a position for detecting the presence of a wheel of the rail vehicle, and a second proximity sensor arrangeable after the intersection at a position for detecting the presence of a wheel of the rail vehicle.

Advantageously, the system may be used to determine track occupancy at different sections of track either side of a junction or intersection along a rail track so that the flow of traffic through the junction or intersection can be efficiently and accurately controlled. By determining track occupancy to control traffic flow through the junction or intersection, the risk of accident at or around a junction or intersection can be reduced.

The system may further comprise one or more additional RFID readers arrangeable before and/or after the intersection. The intersection may be a junction between a rail track and a road or a place at which a rail track diverges or two or more rail tracks converge.

The first and second proximity sensors may be arrangeable to detect the wheels of at least one side of the rail vehicle so that the total number of wheels of the rail vehicle can be determined.

The system may be configured to count up the wheels of the rail vehicle detected by the first proximity sensor so as to record a cumulative total of wheels detected by the first proximity sensor and further configured to compare the number of wheels of the rail vehicle detected by the second proximity sensor with the cumulative total of wheels. The system may be configured to trigger an event if the number of wheels counted by the first proximity sensor do not match the number of wheels counted by the second proximity sensor. The system may be configured to determine the number of rail cars of the rail vehicle dependent on the number of wheels detected.

The event may comprise one or more of an electronic communication, audible alert, visual alert, blocking of a part of the intersection by a barrier, point change, change in visual signal, or cancellation of one or more of the aforesaid.

The system may further comprise a display operable to display an event triggered by one or more RFID readers of the system. The system may further comprise one or more audible or visual indicators arrangeable at an intersection for alerting pedestrians or road users that a rail vehicle is approaching the intersection upon detection of an RFID tag of a rail vehicle by the first RFID reader.

The system may be configured to activate or deactivate the audible or visual indicators in response to detection by the first or second RFID readers of an RFID tag of a rail vehicle.

The system may be configured to detect the presence of a plurality of RFID tags mounted to a rail vehicle comprising a plurality of rail cars, each rail car comprising at least one RFID tag of the plurality of RFID tags.

According to a second aspect, there is provided a system installed in a railway network comprising an intersection, the system comprising a first RFID reader for detecting the presence of a RFID tag mounted to a rail vehicle travelling along a rail track toward the intersection, the first RFID reader installed along the rail track in advance of the intersection to detect the RFID tag of the rail vehicle approaching the intersection;

a second RFID reader for detecting the presence of the RFID tag of the rail vehicle, the second RFID reader installed after the intersection for detecting the RFID tag of the rail vehicle after the intersection;

wherein the system is configured to trigger an event upon detection of an RFID tag by the first RFID reader;

and wherein the system further comprises a first proximity sensor installed in advance of the intersection at a position for detecting the presence of a wheel of the rail vehicle, and a second proximity sensor installed after the intersection at a position for detecting the presence of a wheel of the rail vehicle.

The system may further comprise a visual or audio indicator operable in response to detection of an RFID tag by the first or second RFID readers, wherein the visual or audio indicators are arranged to alert one or more third parties to the presence of a rail vehicle.

According to a third aspect, there is provided a method of controlling movement of traffic through an intersection in a railway network comprising the steps of:

detecting the presence of a radio-frequency identification (RFID) tag mounted to a rail vehicle travelling towards the intersection by a first RFID reader positioned at a location along a rail track in advance of the intersection;

counting the number of wheels of at least one side of the rail vehicle detected by a first proximity sensor positioned along the rail track;

in response to the detection of the RFID tag by the first RFID reader, triggering an event associated with the intersection;

detecting the presence of the RFID tag of the rail vehicle by a second RFID reader positioned at a location along a rail track after the intersection after the rail vehicle has passed through the intersection; and counting the number of wheels of at least one side of the rail vehicle detected by a second proximity sensor positioned along the rail track after the intersection.

The method may further comprise the step of comparing the number of wheels counted by the first proximity sensor with the number of wheels counted by the second sensor to determine whether or not the total number of wheels match.

The method may further comprise the step of triggering an event when the second RFID reader detects the presence of the RFID tag of the rail vehicle.

The method may further comprise the step of comparing information read from the RFID tag by the first RFID reader with information read from the RFID tag by the second RFID reader to check that the same RFID tag has passed through the intersection.

The method may further comprise the step of detecting the presence of a RFID tag mounted to the or a different rail vehicle by a third RFID reader positioned at a location along a rail track after the intersection.

The second and third RFID readers may be arranged along the same length of rail track and spaced apart by a distance sufficient for an RFID tag of one rail vehicle to be arranged in proximity to and read by the second RFID reader and for an RFID tag of a second rail vehicle to be arranged in proximity to and read by the third RFID reader.

According to a fourth aspect, there is provided a method of installing a system for detecting a rail vehicle comprising the steps of:

installing a first RFID reader for detecting the presence of a RFID tag mounted to a rail vehicle at a location along a rail track in advance of an intersection along the rail track;

installing a first proximity sensor along the rail track in advance of the intersection at a position at which the first proximity sensor can detect a wheel of a rail vehicle traveling along the rail track, the system configured to trigger an event upon detection of an RFID tag by the first RFID reader;

installing a second RFID reader for detecting the presence of a RFID tag mounted to a rail vehicle at a location along a rail track after the intersection; and installing a second proximity sensor along the rail track after the intersection at a position at which the second proximity sensor can detect a wheel of a rail vehicle traveling along the rail track.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the present invention will be explained in further detail below by way of examples and with reference to the accompanying drawings, in which:7

Fig. 1 shows a conventional signalling system and a corresponding chart showing the speed profile of the rail vehicle as it travels along the depicted section of railway track;

Fig. 2a shows a schematic representation of symbols of a signalling system used to control movement of a rail vehicle;

Fig. 2b shows the ‘stop’ signal shown in Fig. 2a;

Fig. 2c shows the ‘proceed’ signal shown in Fig. 2a;

Fig. 3 shows a schematic plan view of a level crossing including a system according to an embodiment of the present invention;

Fig. 4 shows a cross section front view of a rail vehicle on rails and includes part of the system shown in Fig. 3;

Fig. 5 shows an enlarged side view of part of a rail vehicle including part of the system shown in Fig. 3;

Fig. 6 shows a schematic plan view of a section of railway track including part of the system shown in Fig. 3;

Fig. 7 shows an enlarged cross section view of a rail supporting a wheel of a rail vehicle, and a proximity sensor part of the system shown in Fig. 3 adjacent the rail;

Fig. 8a shows a speed profile of a light rail vehicle as it approaches a safety distance region before an intersection;

Fig. 8b shows the relationship between braking distance and gradient;

Fig. 8c shows how rail line gradient may change over distance;

Fig. 9 shows a schematic representation of a depot including a plurality of railway tracks for stabling of rail vehicles and a plurality of intersections or points via which rail vehicles may enter a stabling section of railway track in the depot; and

Fig. 10 is a schematic representation of a display operable to provide a visual indication of track occupancy at stabling positions of the depot shown in Fig. 9.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to Fig. 3, there is shown a level crossing 1 comprising a rail vehicle detection and alert system to automatically determine the presence of a rail vehicle 7 before and after the level crossing 1 and alert drivers of road vehicles 11 and pedestrians 13 to the presence of the rail vehicle 7 approaching or leaving the level crossing 1. By automatically determining the presence of a rail vehicle 3 approaching or leaving the level crossing 1, barriers, audio and visual alerts and other elements arranged in proximity to the level crossing 1 may be quickly activated and deactivated, thereby improving the efficiency of traffic control through the level crossing and reducing the risk of accident.

The rail vehicle detection and alert system comprises a first detector 15 arranged along the railway track 3 in advance of the level crossing 1 and a second detector 17 arranged along the railway track 3 after the level crossing 1. In the embodiment depicted, the first 15 and second 17 detectors comprise radio-frequency identification (RFID) readers operable to read RFID microchips or tags in the 2.4GHz frequency band. The RFID readers 15, 17 are active identification tags that are designed for outdoor environments, capable of reading and interrogating RFID tags over a range of up to 8 metres, and operable over a wide range of temperatures from 0°C to 60°C.

As shown most clearly in Fig. 6, the detectors 15, 17 are affixed to a support 19 which is attached to a pair of sleepers 21 and arranged such that the detectors 15, 17 are positioned within the track gauge around midway between the railway lines of the track 3. Power is provided to the detectors 15, 17 by electrical cabling 23 which is routed through and protected by plastic tubing 25 arranged along one side of a sleeper 21 and beneath the rails of the track 3. Each detector 15, 17 is connected to a local railway communication system via an RS-485 network which assigns a unique ID to each detector 15, 17 for network communication to enable location specific detection signals to be generated and transmitted by the detectors 15, 17 upon detection of a rail vehicle 7.

A rail vehicle 7 may comprise one or more rail cars that are attached together end to end. Typically, in light rail networks, the rail vehicle 7 comprises either one or two cars. With particular reference to Figs. 4 and 5, detection of rail vehicles 7 by the detectors 15, 17 is facilitated by a RFID tag 31 arranged on each car of the rail vehicle 7. Each RFID tag 31 interacts with, and is read by, the detectors 15, 17 upon passing the respective detectors as the rail vehicle 7 travels along the track 3. In the embodiment depicted, the RFID tag 31 comprises a passive RFID tag and is therefore powered by electromagnetic energy transmitted from the detectors 15, 17. It will be appreciated by a person skilled in the art that active RFID tags could alternatively be used. Like the detectors 15, 17, the RFID tags 31 are configured to operate in the 2.4GHz frequency band so that they may be interrogated and read by the detectors 15, 17. It will be appreciated that the RFID tags 31 of the system may be existing RFID tags that are already mounted to and associated with each rail car of a rail vehicle 7 for detection by the detectors 15, 17. Thus, the detectors 15, 17 may be chosen and configured to interrogate existing RFID tags of the rail vehicle 7.

The RFID tags 31 are attached to a junction box 33 on the underside of the front of each rail car of the rail vehicle 7 via a stainless steel bracket 35 which is affixed to the junction box 33. The bracket 35 is configured to hold the RFID tag 31 at or around the middle of the rail vehicle undercarriage at a position at which the RFID tag 31 can be energised and read by the detectors 15, 17 upon passing of the rail vehicle 7 and, hence, the RFID tag 31 directly over the detectors 15, 17. In the embodiment depicted, the RFID tags 31 are held in a position at which the distance of separation is approximately 220mm above the horizontal plane of the running surface of the rail head when passing directly overhead. Whilst the detectors 15, 17 have a range of several metres, a distance of separation of 220mm is chosen to ensure reliable and accurate interrogation of the RFID tags 31 as the rail vehicle 7 travels along the track 3. The RFID tags 31 store identification information specific to the rail car to which the RFID tag 31 is attached so that each rail car can be identified by the system upon interrogation.

Turning to Fig. 3, the rail vehicle detection and alert system further comprises lights 27 and loudspeakers 29 which are arrangeable at the level crossing 1 to provide visual and audible alerts to drivers of road vehicles 11 and pedestrians 13 when the presence of a rail vehicle 7 approaching or leaving the level crossing 1 is detected. The lights 27 and/or loudspeakers 29 may be supported by corresponding bollards (not shown) which extend upwardly from the ground and which are located at the mouth of the level crossing 1 to provide clear and immediate visual and/or audio alerts to pedestrians and road users. Barriers (not shown) may also be provided at the level crossing 1 which are operable between a first position in which road vehicles 11 and pedestrians 13 are prevented by the barriers from traversing the level crossing 1, and a second position in which the barriers do not block the road 5 so that road vehicles 11 and pedestrians 13 may traverse the railway track 3.

Communication between the detectors 15, 17, and lights 27 and loudspeakers 29 is enabled by a local network to which each component of the system is electrically connected. The local network comprises a trackside control unit 37 which is operable to receive a detection signal from the detectors 15, 17 and to transmit a control signal to the lights 27 and loudspeakers 29 at the level crossing 1. Through appropriate control of the warning lights 27 and loudspeakers 29, road vehicle drivers 11 and pedestrians 13 are alerted to the presence of an oncoming rail vehicle 7 so that they can stop and allow the rail vehicle 7 to safely pass before traversing the level crossing 1.

The system further comprises at least one proximity sensor 39 arranged adjacent a rail 40 of the track 3 and located at the same section of track as a corresponding detector 15, 17. With particular reference to Fig. 7, the proximity sensor 39 is affixed to a stainless steel bracket 41 comprising a housing 43 to at least partially shield the proximity sensor 39 from external forces and contaminants. The bracket 41 further comprises a base section 45 which supports the proximity sensor 39 and housing 43 and extends beneath the rail 40 from one side to the other, and a pair of clamps 47a, 47b bolted to the base section 45 and arranged to clamp either side of the base 49 of the rail 40 to fix the bracket 41 and proximity sensor 39 relative to the rail 40. The proximity sensor 39 is positioned according to its specifications and capabilities so as to be able to detect a wheel 51 of the rail vehicle 7 passing by the proximity sensor 39 as the rail vehicle 7 travels along the track 3. In the embodiment depicted, the proximity sensor is angled toward the region through which the flange 53 of the wheel 47 transits upon passing of the rail vehicle 13, and within a distance of approximately 200mm but outside the structure gauge (S.G.) so as not to physically interfere with wheel movement.

The proximity sensor 39 is configured to detect the presence of a wheel 51 passing through the detection zone of the proximity sensor 39 such that the number of wheels 51 of the vehicle 7 and, hence, the length of the rail vehicle 7 and number of rail cars can be determined. For example, in a light rail network in which a rail car has four axles and two wheels per axle, the rail car has a total of eight wheels. Since the proximity sensor 39 is located adjacent one rail 40 of the track 3, the proximity sensor 39 will count four wheels of a rail vehicle 7 comprising a single rail car or eight wheels if the rail vehicle 7 comprises two rail cars. Thus, the proximity sensor 39 enables the number of cars and length of the rail vehicle 7 to be determined.

As shown in Fig. 6, electrical power is provided to the proximity sensor 39 from the same power cables that provide electrical power to the detectors 15, 17. The proximity sensors 39 are also connected to the local area network so as to transmit detection signals to the trackside control unit 37 each time a wheel 51 passes, and is detected by, the sensor 39. Thus, the proximity sensor 39 provides an additional means for detecting the presence of a rail vehicle 7 and, importantly, works alongside the detectors 15, 17 to not only confirm the presence of a rail vehicle 7 but also to ensure that the number of wheels 51 of the rail vehicle 7 counted as the rail vehicle 7 approaches a level crossing 1 matches the number of wheels 51 of the rail vehicle 7 counted by a proximity sensor 39 located after the level crossing 1. This enables the system to verify that the entire rail vehicle 7 has passed through the level crossing 1 or other point along a track 3.

The section of railway track 3 within which the first 15 and second 17 detectors and the associated proximity sensors 39 are contained may be designated as a ‘detection zone’ 55 inside which the presence of the rail vehicle 7 can be detected and tracked. The location of the detectors 15, 17 and sensors 39 and, hence, size of the detection zone 55 may be chosen so as to coincide with the location and position of the loop antennas and signalling system of an existing traffic control system, thereby further enhancing the reliability of the system. To ensure pedestrians 13 and road vehicle 11 drivers are alerted in a timely manner to the presence of an oncoming rail vehicle 7, the position of the first detector 15 and corresponding proximity sensor 39 must be appropriately determined based upon permitted rail vehicle 7 speed through the level crossing 1, the braking distance of the rail vehicle 7, and also the gradient of the track 3 approaching the level crossing 1.

The braking distance (S) of a rail vehicle 7 depends on the following factors:

• speed of train (u) when brakes are applied;

• the deceleration rate (a) available with a full-service brake application, which varies according to the coefficient of friction between a train wheel and the rail;

• brake delay time (ta), the delay from when the brakes are applied by the train driver to when they actually become effective;

• the state of the wear of the brake pads and the air pressure available in the brake cylinders;

• the geography of the track, in particular the track gradient (G) the train travels over from when the brakes are commanded to where the front of the train stops; and • the mass distribution (m) of the train .

By considering the above factors and the energy transfer during deceleration with external work (i.e. braking), the braking distance can be expressed as below:

Braking Work + Kinetic Energy + Potential Energy = 0 m * (a) * S + - *m*u² + m*g* (h^ — h₂) = 0 (1) where g is the acceleration due to gravity.

With reference to Figs. 8a to 8c, since the change in height Ah = h₂ - hi relates to the gradient

G = — and A h = S * sina a for small a, S ~ d and sina ~ tana. Therefore,

A h = S * tana (2)

Substituting (2) into (1) gives, —U²

S = —-------------, for deceleration, a < 0 (3)

2(a-g* tana) ^{J v J}

From formula (3), it would be an uphill gradient when h₂> hi, i.e. A h > 0, thereby resulting in a smaller braking distance.

With reference to Fig. 8c, it should be noted that the gradient varies along the railway line.

Therefore, the average gradient is expressed as below:

Σ”=ι di

Average gradient G =-----rΣΠ ttj ⁱ⁼¹Gi

Thus, the detection zone 55 is configured to start at an appropriate distance from the level crossing 1 as determined by the required rail vehicle braking distance and rail vehicle speed when approaching and passing through the level crossing 1 to ensure that sufficient warning is given to pedestrians 13 and road vehicles 11 in the vicinity of the level crossing 1 to enable them to take appropriate measures to avoid collision with the rail vehicle 7. Arranging the detectors according to the required braking distance for the rail vehicle as dependent on speed when approaching the level crossing 1 additionally allows the rail vehicle driver sufficient time to stop the rail vehicle 7 before the level crossing 1, if necessary or required.

In use, a rail vehicle 7 comprising a RFID tag 31 storing vehicle specific information, and travelling toward a level crossing 1, enters a detection zone 55 and passes over the first detector

15. The first detector 15 interrogates the RFID tag 31 to obtain the stored data which is then transmitted to the wayside control unit 37 for further processing. Upon receipt of the detection signal, the control unit 37 transmits an activation signal to the warning lights 27 and loudspeakers 29 thereby triggering a visual and audible alert to warn road vehicles 11 and pedestrians 13 that a rail vehicle 7 is approaching the level crossing 1. The system is configured to act within one second of interrogating the RFID tag 31 so that road vehicle 11 and pedestrians 13 are almost immediately alerted and have sufficient time to take appropriate precautions.

As the rail vehicle 7 passes the proximity sensor 39 associated with the first detector 15, the proximity sensor 39 detects each passing wheel 51 of the rail vehicle 7 and transmits each wheel detection event to the control unit 37. The control unit 37 incrementally counts each wheel detection event and stores a cumulative total so that it has a record of the total number of wheels 51 of the rail vehicle 7 approaching the level crossing 1.

When the rail vehicle 7 passes through the level crossing 1 and over the second detector 17 such that the RFID tag is interrogated by the second detector 17, a detection signal is transmitted to the control unit 37 to indicate that the rail vehicle 7 is exiting the detection zone 55 and, hence, level crossing 1. The proximity sensor 39 associated with the second detector 17 detects each wheel 51 of the rail vehicle 7 and transmits each wheel detection event to the control unit 37.

The control unit subtracts each detection event from the stored cumulative total until the total is determined to be zero, thereby indicating that every wheel 51 of the rail vehicle 7 has passed through the level crossing 1 and confirming that no part of the rail vehicle 7 remains in the level crossing 1 area. Upon detection of the rail vehicle 7 and confirmation that all wheels 51 have passed through the level crossing 1, the control unit 37 transmits a deactivation signal to the lights 27 and loudspeakers 29 to cancel the warning signs and, thereby, signal to pedestrians 13 and road vehicles 11 that it is safe to traverse the level crossing 1.

It will be appreciated that the system is not restricted for use only at level crossings 1 and that the system may be arranged anywhere within a railway network where it is desired to determine track occupancy by a rail vehicle 7 and to alert individuals to the presence of a rail vehicle 7 at particular areas of track.

For example, with reference to Figs. 9 and 10, the system may be of particular use at rail depots where rail vehicles 7 are stabled and serviced when not in use. As can be seen from Fig. 9, rail depots 101 comprise a high density of points that enable rail vehicles 7 to be directed to specific stabling tracks SI - S16 which each can accommodate a pair of rail cars either as separate rail vehicles or a pair of interconnected rail cars forming a single rail vehicle. In the embodiment depicted, a RFID detector 115 and a proximity sensor 139 are arranged at the entrance to the plurality of points leading to each stabling track position. The detector 115 is an RFID reader configured to interrogate and read information stored on an RFID tag arranged on a rail car of a rail vehicle entering the stabling area. The proximity sensor 139 is arranged alongside a rail of the track so as to detect each passing wheel of a rail vehicle as it enters the stabling area.

A pair of RFID readers 117a, 117b is arranged along each stabling track position so as to detect the presence of an RFID tag on a rail car of a rail vehicle. Providing a pair of detectors 117a, 117b enables the system to detect the presence of an RFID tag and, hence, a rail car on a stabling track so as to determine whether one or both rail car stabling positions of a stabling track are occupied. The distance between the two detectors 117a, 117b is chosen to be greater than the length of a rail car to ensure that two rail cars can occupy a position on the stabling track at which a corresponding detector 117, 117b can interrogate the RFID tag of the adjacent rail car and determine its occupancy of a stabling position. Each stabling track SI to S16 also comprises a proximity sensor arranged adjacent a rail of the stabling track so as to count the number of wheels of a rail vehicle entering the stabling track.

The system further comprises a local area network to which each detector 115, 117a, 117b and proximity sensor 139 is connected so that detection signals can be transmitted to a central control unit (not shown). The system used in a depot environment additionally comprises a display 160 connected to the network and configured to provide a visual indication to the Depot Operation Controllers (DOC) as to which track stabling positions are occupied. The display 160 may be a computer monitor of a computer system configured to generate an image of a series of virtual lights, each of which corresponds to a stabling position. Alternatively, the display may comprise a board of LEDs, each of which corresponds to a stabling position. In either case, the virtual light or LED may be illuminated to indicate occupancy of a stabling position. Referring to Fig. 10, the display 160 may include sixteen rows of two lights each associated with a track stabling designation from SI to SI6. A first light 162 of each pair may be designated with a letter ‘A’ corresponding to the first position of a stabling track, and a second light 164 of each pair may be designated with a letter ‘B’ corresponding to the second position of a stabling track.

In use, a rail vehicle may enter the stabling area and, in so doing, pass through the initial detection area at the entrance to the stabling area. The first detector 115 interrogates the RFID of each rail car of the rail vehicle thereby determining the passing of a rail vehicle, the rail vehicle identity and the number of cars. The initial proximity sensor 139 counts the number of wheels of the rail vehicle to record a cumulative total of wheels and, hence, confirm the number of rail cars of the rail vehicle. The detection signals of both the first detector 115 and proximity sensor 139 are transmitted over the local area network to the central control unit. Based on the detected information about the rail vehicle, through appropriate control of the points, the DOC can redirect the rail vehicle to a stabling track with sufficient space to accommodate the rail vehicle. Thus, for a two car rail vehicle, the DOC will redirect the rail vehicle to a stabling track position comprising two spaces, and for a single car rail vehicle, the DOC may optionally redirect the rail vehicle to a stabling track with an available single space.

When the rail vehicle enters an assigned stabling track e.g. SI, the RFID tag of the or each rail car is interrogated by a second detector 117a and a third detector 117b. As will be apparent, where the stabling track is empty, the rail vehicle will trigger both detectors 117a, 117b. In the case of a single car rail vehicle entering an empty stabling track, the rail vehicle will eventually come to rest in proximity to stabling position SI A and will only trigger each detector of the pair 117a, 117b once. Thus, based on received detection events, the system can determine that track position SI A is occupied by a single car vehicle and that track position SIB is empty. Therefore, the system causes only the light associated with SI A to be illuminated on the display 160. Accordingly, the DOC has a simple reference guide for determining track occupancy in the stabling positions. On the other hand, if a two car rail vehicle enters a stabling track e.g. S6, the detector 117a associated with the first stabling position S6A is triggered once by the RFID tag of the front car of the rail vehicle and the detector 117b associated with the second stabling position S6B is triggered twice i.e. once by the RFID tag of the front car passing through to the next stabling position and a second time by the RFID tag of the rear car. Based on the transmitted detection events, the system determines that both track stabling positions are occupied and illuminates both lights on the display 160 that are associated with S6 to provide a visual guide for the DOC.

Additionally, the proximity sensor 139 associated with each stabling track counts the number of wheels of the rail vehicle entering the stabling track. As in the first described embodiment, each wheel detection event transmitted to the central control system is subtracted from the cumulative total recorded by the initial proximity sensor until the cumulative total hits zero. At this point, the system determines that all of the rail vehicle has passed through a particular point and has entered a stabling track. Thus, the DOC is notified by the system that the point can be changed to permit a new rail vehicle to be safely redirected into a stabling track position. Accordingly, the system advantageously minimises the risk of derailment of a rail vehicle due to, for example, 5 premature point switching whilst a rail vehicle is still transiting through a point. By providing a quick visual reference, the system improves the efficiency of the DOC whilst reducing the risk of human error and, hence, the risk of accident or injury in the depot.

The above embodiments are described by way of example only. Many variations are possible without departing from the scope of the invention as defined in the appended claims.

Claims

1. A system for rail vehicle detection and alert comprising a first radio-frequency identification (RFID) reader for detecting the presence of a RFID tag mounted to a rail vehicle travelling along a rail track, the first RFID reader arrangeable in advance of an intersection along the rail track to detect the RFID tag of the rail vehicle approaching the intersection, and a second RFID reader for detecting the presence of the RFID tag of the rail vehicle, the second RFID reader arrangeable after the intersection for detecting the RFID tag of the rail vehicle after the intersection, wherein the system is configured to trigger an event upon detection of the RFID tag by the first RFID reader, and wherein the system further comprises a first proximity sensor arrangeable in advance of the intersection at a position for detecting the presence of a wheel of the rail vehicle, and a second proximity sensor arrangeable after the intersection at a position for detecting the presence of a wheel of the rail vehicle.

2. The system as claimed in claim 1, further comprising one or more additional RFID readers arrangeable before and/or after the intersection.

3. The system as claimed in any preceding claim, wherein the intersection is a junction between a rail track and a road or a place at which a rail track diverges or two or more rail tracks converge.

4. The system as claimed in any preceding claim, wherein the first and second proximity sensors are arrangeable to detect the wheels of at least one side of the rail vehicle so that the total number of wheels of the rail vehicle can be determined.

5. The system as claimed in claim 4, configured to count up the wheels of the rail vehicle detected by the first proximity sensor so as to record a cumulative total of wheels detected by the first proximity sensor and further configured to compare the number of wheels of the rail vehicle detected by the second proximity sensor with the cumulative total of wheels.

6. The system as claimed in claim 5, configured to trigger an event if the number of wheels counted by the first proximity sensor do not match the number of wheels counted by the second proximity sensor.

7. The system as claimed in any one of claims 4 to 6, wherein the system is configured to determine the number of rail cars of the rail vehicle dependent on the number of wheels detected.

8. The system as claimed in any preceding claim, wherein the event comprises one or more of an electronic communication, audible alert, visual alert, blocking of a part of the intersection by a barrier, point change, change in visual signal, or cancellation of one or more of the aforesaid.

9. The system as claimed in any preceding claim, further comprising a display operable to display an event triggered by one or more RFID readers of the system.

10. The system as claimed in any preceding claim, further comprising one or more audible or visual indicators arrangeable at an intersection for alerting pedestrians or road users that a rail vehicle is approaching the intersection upon detection of an RFID tag of a rail vehicle by the first RFID reader.

11. The system as claimed in claim 10, wherein the system is configured to activate or deactivate the audible or visual indicators in response to detection by the first or second RFID readers of an RFID tag of a rail vehicle.

12. The system as claimed in any preceding claim configured to detect the presence of a plurality of RFID tags mounted to a rail vehicle comprising a plurality of rail cars, each rail car comprising at least one RFID tag of the plurality of RFID tags.

13. A system installed in a railway network comprising an intersection, the system comprising a first RFID reader for detecting the presence of a RFID tag mounted to a rail vehicle travelling along a rail track toward the intersection, the first RFID reader installed along the rail track in advance of the intersection to detect the RFID tag of the rail vehicle approaching the intersection;

14. The system as claimed in claim 13, further comprising a visual or audio indicator operable in response to detection of an RFID tag by the first or second RFID readers, wherein the visual or audio indicators are arranged to alert one or more third parties to the presence of a rail vehicle.

15. A method of controlling movement of traffic through an intersection in a railway network comprising the steps of:

16. The method as claimed in claim 15, further comprising the step of comparing the number of wheels counted by the first proximity sensor with the number of wheels counted by the second sensor to determine whether or not the total number of wheels match.

17. The method as claimed in claim 15 or claim 16, further comprising the step of triggering an event when the second RFID reader detects the presence of the RFID tag of the rail vehicle.

18. The method as claimed in any one of claims 15 to 17, further comprising the step of comparing information read from the RFID tag by the first RFID reader with information read from the RFID tag by the second RFID reader to check that the same RFID tag has passed through the intersection.

19. The method as claimed in any one of claims 15 to 18, further comprising the step of detecting the presence of a RFID tag mounted to the or a different rail vehicle by a third RFID reader positioned at a location along a rail track after the intersection.

20. The method as claimed in claim 19, wherein the second and third RFID readers are arranged along the same length of rail track and spaced apart by a distance sufficient for an RFID tag of one rail vehicle to be arranged in proximity to and read by the second RFID reader and for an RFID tag of a second rail vehicle to be arranged in proximity to and read by the third RFID reader.

21. A method of installing a system for detecting a rail vehicle comprising the steps of:

installing a first proximity sensor along the rail track in advance of the intersection at a position at which the first proximity sensor can detect a wheel of a rail vehicle traveling along the rail track, the system configured to trigger an event upon detection of an RFID tag by the first RFID reader; installing a second RFID reader for detecting the presence of a RFID tag mounted to a rail vehicle at a location along a rail track after the intersection; and installing a second proximity sensor along the rail track after the intersection at a position at which the second proximity sensor can detect a wheel of a rail vehicle 5 traveling along the rail track.