CA2270066A1 - Railway rail acoustic rockfall detector - Google Patents
Railway rail acoustic rockfall detector Download PDFInfo
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- CA2270066A1 CA2270066A1 CA 2270066 CA2270066A CA2270066A1 CA 2270066 A1 CA2270066 A1 CA 2270066A1 CA 2270066 CA2270066 CA 2270066 CA 2270066 A CA2270066 A CA 2270066A CA 2270066 A1 CA2270066 A1 CA 2270066A1
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- acoustic
- physical event
- metal guideway
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B61—RAILWAYS
- B61L—GUIDING RAILWAY TRAFFIC; ENSURING THE SAFETY OF RAILWAY TRAFFIC
- B61L23/00—Control, warning or like safety means along the route or between vehicles or trains
- B61L23/04—Control, warning or like safety means along the route or between vehicles or trains for monitoring the mechanical state of the route
- B61L23/041—Obstacle detection
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B61—RAILWAYS
- B61L—GUIDING RAILWAY TRAFFIC; ENSURING THE SAFETY OF RAILWAY TRAFFIC
- B61L1/00—Devices along the route controlled by interaction with the vehicle or train
- B61L1/02—Electric devices associated with track, e.g. rail contacts
- B61L1/06—Electric devices associated with track, e.g. rail contacts actuated by deformation of rail; actuated by vibration in rail
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
- G01V1/00—Seismology; Seismic or acoustic prospecting or detecting
- G01V1/001—Acoustic presence detection
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- Physics & Mathematics (AREA)
- Life Sciences & Earth Sciences (AREA)
- Mechanical Engineering (AREA)
- Acoustics & Sound (AREA)
- Environmental & Geological Engineering (AREA)
- Automation & Control Theory (AREA)
- Geology (AREA)
- Remote Sensing (AREA)
- General Life Sciences & Earth Sciences (AREA)
- General Physics & Mathematics (AREA)
- Geophysics (AREA)
- Train Traffic Observation, Control, And Security (AREA)
Abstract
A highly reliable early warning system is disclosed. The warning system provides immediate detection of railway activity and early warning of dangerous railway conditions such as rockfall, to train crews and to Rail Traffic Control offices.
The warning system has acoustic sensors coupled to one of the rails of a railway for detecting sound or vibration induced by physical events. The detected acoustic signals are analyzed and if above a threshold, compared to neighboring acoustic detections. If a suspect condition is identified, an alarm is generated. The alarm signal may be transmitted over any communication system to the Rail Traffic Control office and to the trains traveling toward the suspect track location. When desired, the alarm may employ wireless transmissions to stop the trains remotely. When more than one acoustic sensor detects the same event, the exact location can be determined. Physical events that are detected may be stored in a sound file.
These may be catalogued as to location, time and suspected cause for retrieval and analysis later.
The warning system has acoustic sensors coupled to one of the rails of a railway for detecting sound or vibration induced by physical events. The detected acoustic signals are analyzed and if above a threshold, compared to neighboring acoustic detections. If a suspect condition is identified, an alarm is generated. The alarm signal may be transmitted over any communication system to the Rail Traffic Control office and to the trains traveling toward the suspect track location. When desired, the alarm may employ wireless transmissions to stop the trains remotely. When more than one acoustic sensor detects the same event, the exact location can be determined. Physical events that are detected may be stored in a sound file.
These may be catalogued as to location, time and suspected cause for retrieval and analysis later.
Description
RAILWAY RAIL ACOUSTIC ROCKFALL DETECTOR
FIELD OF THE INVENTION
This invention is a device to sense, locate, and signal rockfalls onto, and subsidence and rising water beneath, railway tracks that may present a danger to the safe movement of trains.
BACKGROUND OF THE INVENTION
The prior art in railway right-of-way safety, with regards to hazards, has advanced little in decades. The prior art safety measures consist of Slide Detector Fences, Wash Out Detectors (WOD), monitoring electrical continuity through the rails, fibre-optic cable break warning systems, and direct observation of the railway right-of-way. Only the WOD and the cable break warning systems have been recently developed. These decades-old safety measures continue to be installed.
A Slide Detector Fence (SDF) consists of a number of horizontal wires strung about 30 centimeters apart on a series of vertical wood poles typically spaced five to twenty meters apart. The poles are placed parallel to the railway track on the side that is 2o susceptible to rockfalls. A rockfall or slide is detected by loss of electrical continuity when a single fragile wire is broken. This detection causes a visual signal to be given to approaching train crews.
There are several problems with SDF. First, SDF coverage is only part of potential rockfall areas. The wires can be broken by something as insignificant to safety as an animal or a tree branch. The SDF cannot discriminate between a small rock and a large boulder.
The SDF must be repaired after each break or detection. Until repaired, all trains passing the SDF are required to pass the entire length of the SDF at a speed that will allow stopping within the range of vision, for example; short of a blockage or other hazard.
This slowing of rail traffic causes a slowdown of opposing rail traffic in single track territory, backing up 3o traffic in both directions. Sometimes additional relief train crews are required to complete the train's trip. Additionally, slowly traveling trains expend extra resources and fuel to brake and reaccelerate. Repairs are sometimes delayed due to the threat of continued rockfalls injuring the repair crews. Locating and repairing the break can be time consuming due to the remoteness of the areas where these fences are typically found, and the length of a single circuit of fence which can extend to upwards of one kilometer in length. SDF are not suitable for areas of slope near the natural angle of repose. In this type of region, there are boulders that may be loosened by a freeze-thaw cycle or rain; however, too many animals can break the SDF in such a region, so that the number of false alarms prohibits the use of SDF. SDF are primarily deployed between the tracks and near-vertical cliffs.
The WOD are installed to stop catastrophic accidents such as the Canadian National Rail (CN) accident at Conrad, B.C., Canada on March 26, 1997. In that accident, two locomotives and eight rail cars derailed into a large depression that was created by a landslide. The two CN crew members on board the lead locomotive were killed.
The diesel fuel caught fire and ignited the derailed equipment. More details are available in the Transport Safety Board of Canada (TSB) report No. R97V0063. The TSB Internet site is at to "http:llbst-tsb.gc.ca!"
A WOD has two forms. The original form, installed on CN's main line, consists of a wire, fabricated from material similar to the SDF, with weights attached. The wire and weights assembly is buried beneath the right of way, in an area of suspect earth stability.
Should the earth wash out or otherwise subside, one of the weights will break the wire causing a loss of electrical continuity which, in turn, activates a signal to warn approaching trains. There has never been a detection of subsidence on this system due to the very limited number of installations. An advance in WOD technology was made in late 1997. It involved the use of mercury tilt switches installed on posts positioned along the railway right-of-way. If the ground washes out or shifts to cause a change in attitude of the post, or 2o the post itself is struck, the mercury switch will tilt sufficiently to cause a loss of electrical continuity. Similarly, if the connecting wire is broken there will be a loss of electrical continuity. The loss of electrical continuity will trigger an alarm causing trackside signals to give a warning and a radio message to be broadcast to the trains nearby, informing their crew members that there is a suspected washout.
WOD are very limited in use. They are difficult to repair and expensive to install.
During construction the original WOD disturbs the track bed they are meant to protect. If they are installed too close to the tracks, they may be disturbed by the normal subgrade movements caused by the trains. If installed too far away, they may miss a small washout.
Another method of monitoring rail lines currently in use involves detecting a problem 3o by sensing a loss of electrical continuity through the rail. A break may occur because of service stresses of trains and equipment, because of thermal contraction on the coldest of winter days, because the road bed subsides under the track, or because a rock strikes one of the rails with sufficient force. If either of the rails break, the loss of electrical continuity changes the block, interlocking or Centralized Traffic Control (CTC) trackside signals to their most restrictive indication. These signals are similar to an intersection traffic light. The signals do not, by themselves, stop any train; they must be acted on by the train crew, who must witness such a signal prior to rolling over the location of the break.
Crews whose train has already traveled past the last one of these signals when a break occurs in the train's present block receive no indication of a broken rail.
The electrical continuity of the track can remain even if there is a sizable chasm created by a washout beneath the track. The CN Conrad accident had a chasm of about 60 meters (200 feet) of unsupported track that did not break until a train came upon it.
Similarly, on September 22, 1993, a barge, being shoved by the towboat Mauvilla, in dense fog, struck a span over Big Bayou Canot in Alabama, USA. The bridge was knocked several feet out of alignment. Eight minutes later an Amtrak train derailed off the bridge at 116 kmlh. (72 m.p.h.), killing 47 people. The rails, although bent and unable to support and guide a train, continued to be electrically continuous and therefore did not give any warning through the trackside signal system. More details are available in National Transportation Safety Board report adopted September 19, 1994, Notation 6167B. In addition, rocks as large as automobiles can roll onto the track without breaking the sturdy rails.
The SDF, original WOD, and the rail electrical continuity detection systems all depend on receiving a detection before the train crew observes the last signal on approach to the hazard. In many areas, the trackside signals are several kilometers apart. Thus, there is time for a hazard to occur without the crew receiving information through the trackside signal system.
2o Another system that has recently been developed is a fibre-optic cable break warning system. This was developed subsequent to the CN Conrad accident.
Should the fibre-optic cable break, a warning is received in the fibre-optic network office and relayed to the RTC office. The RTC staff must cause all the signals to turn to their most restrictive indication and make an emergency radio message broadcast to warn train crews.
In the Conrad accident the fibre-optic cable did not break during the washout, but was broken by the moving train during the fatal accident. This system has had success at detecting rockfalls immediately adjacent to the track that did not break either rail.
Most rockfalls do not have the impact and placement to trigger this system.
Another method of track hazard detection depends on observation. A hazard may be seen by a member of the train crew during their tour of duty, during routine or random track patrols, or while investigating reports from the public.
Many of the areas that rockfalls and washouts occur are remote and are not frequented by the public. As well, these rights-of-way are private property and most railway companies discourage the public's presence. The trains run 24 hours a day. The public would be unlikely to see hazards except by daylight. The natural hazards that cause these accidents are most frequently caused by severe weather such as higher than normal rainfall. This weather is frequently accompanied by diminished visibility, as was the situation in the September, 1993 Amtrak accident. These two conditions make the public less likely to be present or to observe hazards in remote areas.
People traveling the roadways that parallel the tracks offer a good chance of spotting a dangerous situation. Even if a dangerous condition was sighted, the public may not be inclined or able to report it. These typically remote areas are not normally served by cellular phone companies, the correct railway company's track may be difficult to identify, and the railway's phone number may be difficult to obtain. Relying on the public to report hazards has proven to not be a dependable solution in the North American railway environment.
Routine or random track patrols can spot a hazard that has occurred. They can give, if conscientious enough, some insight into the possibility of emerging dangerous areas some of the time. In many cases, however, a hazard such as a rockfall occurs suddenly.
The history of the area would indicate, with more accuracy, the likelihood of rockfalls. This is the type of area where SDF are installed. The two drawbacks of the patrols are the cost involved in manual observation and, in CTC, the delay to trains. A track patrol is typically a highway-railway (hi-rail) vehicle; a pickup truck with an extra set of wheels attached that fit the rails, but of much smaller diameter and weight than standard rolling stock wheels.
Rolling stock includes locomotives and standard rail cars, also referred to as "equipment" in 2o the Canadian Rail Operating Rules (CROR). A hydraulic system to raise and lower the extra set of wheels is provided. The patrols are used to precede a train along the track. The small diameter of wheels and need to stop short of a hazard may not permit the hi-rail vehicle to travel at speed over 40 km/h. The braking distance required increases greatly on wet, frosty or icy rail as substantiated by the testing by the TSB on the collision of two hi-rail vehicles. It tested and measured braking distances from 30 m.p.h. (48 kmlh) on dry pavement, dry rail and wet rail. The respective distances were 44, 94, and 880 feet. This TSB
report number R96T0008 is available on the TSB website. Thus on 60 kmlh (35 m.p.h.) track, the patrol must wait for trains to pass, then get on the track, patrol, then get clear of the track and report to the Rail Traffic Control (RTC) staff typically 15 minutes minimum prior to the 3o expected arrival of the next train. To be any closer than 15 minutes or 10 kilometers would not allow the following train to continue at full track speed because of the workings of the CTC signal system. Consequently, even if every train could be preceded by a patrol, conditions may change in the 15 minute period required between the safety inspection vehicle and the train.
Generally, when a train is the first to encounter a hazard on the track, it cannot stop short of the hazard. Trains take a long distance to stop. Stopping distance is a function of, amongst other things: speed, track grade, brake set up, total weight of the train, steel-on-steel friction, and the length of the train. Steel-on-steel friction is, in most cases, less than half of that of rubber-on-pavement experienced by cars. Train length is significant because the change in air pressure that causes the air brake application can only propagate through 5 the train at the rate of the speed of sound through the train's air brake pipe. The air brake pipe is built into all equipment with connecting hoses at each end of the equipment. This allows for control of the brakes on a series of rail cars from a locomotive, when the hoses are joined. This continuous air brake pipe propagates the changing air pressure required to actuate the brakes. It will take about 6 seconds for a change in pressure to propagate to through an 1800 meter (6000 foot) long train. Significant retarding force on the wheels takes additional seconds. In other cases there may be little opportunity to see the hazard because of darkness, curved track, or snowfall. One hazard that is not easily seen is a change in the gauge of the track, sometimes caused by a rolling rock striking a rail. Gauge is the standard distance between the inside of the pair of rails.
Several types of remote-controlled companion or pilot railway cars have been proposed. They explore the track in front of the locomotive or train at a distance that allows the train to stop if a dangerous condition is detected. Examples of such systems can be found in U.S. patents 5,627,508 and 5,623,244 to Cooper et al. (1997), and 5,429,329 to Wallace et al. (1995). These inventions have not enjoyed commercial success because 2o they require modifications to the CTC signal system or operating rules.
Furthermore, they are expensive to build and maintain and they occupy track that could be used for revenue generating rolling stock, most noticeably when train and companion car are in a siding. Less noticeably, but more significantly, these inventions would cause a greater spacing of trains proceeding in either direction, much like the track patrols. On some systems no method of pilot car removal from the tracks has been proposed once past the trackage of greatest need; on other systems the pilot car couples onto the front of the train until needed again.
Communication could be interrupted in tunnels. These pilot vehicles do not detect a dangerous event that occurs between the time at which it inspects the track and the time at which the train arrives. If notice could be given to the train crew, an emergency train brake 3o application may reduce the negative consequences. For example, a rock slide may derail less rail cars if any advance notice can be given. As yet, no pilot vehicle communicates with the RTC office.
One prior art system, U.S. patent 5,713,540 (1998) to Gerszberg et al, uses detected sound to indicate railway activity. The Gerszberg system monitors the rails in pairs and identifies a dangerous condition by noting the difference in detections between the rails. If a rock struck the track it would be heard louder on one rail when compared to the other rail. Also, the Gerszberg system generates an alarm when there is a very large sound detected on both rails. Such a system however, is unable to distinguish between a small acoustic event occurring near an acoustic sensor from a large event occurring at a distance.
Also, some tracks have metal bars or metal or concrete ties that tie the rails together. These may act as sound conductors and eliminate or substantially reduce the measurable difference between the sounds on each rail making it significantly less likely to detect the anticipated difference in sounds. The Gerszberg system has no locating feature. The physical event that was acoustically sensed cannot be located with any accuracy. It employs only microphones and has a lower limit of sound detection of 30 hertz.
Rockfalls 1o may be more easily detected by sensing vibrations of much lower frequencies. It has a digital signal processor to provide audio signature analysis but has no attenuation calculation to ascertain the original acoustic energy of the railway activity.
To have the capacity to calculate, this the system would need to know the distance between the sensor and the detected event. The Gerszberg system cannot be used near a public crossing or other noise-generating safe situation or the initial filtered signals may require a higher threshold before generating an alarm. Comparing the pairs of detections between rails might generate a false alarm in cases of thermal expansion and accompanying rail creep. It has no feature that would stop an endangered train without the locomotive driver's actions.
Lastly, the Gerszberg system cannot detect mud slides, snow and rock avalanches, 2o washouts, track subsidence, high water and other low acoustic energy events that may be hazardous.
Another prior art system, U.S. patent 5,743,495 (1998) to Kenneth Brakeley Welles II et al uses detected movements of the rail to determine flat wheels on a train and the location of broken rails. The Welles system contemplates detecting only in the presence of vibration induced by trains; train movements are a required element of detection. It consists of a single sensor at each location so oriented so as to detect vibration in the vertical and horizontal axis. Horizontal is defined to be along the rail length. Welles uses a central processor to detect redundancies of events, but assumes or knows the travel time of the waves created by the event to the sensor is instantaneous or insignificant in this 3o configuration.
Yet another prior art system is proposed in Canadian application 2,242,723 to Stephens. This acoustic system proposes detection and recognition of sound and vibration transmitted by the rail or metal guideway. The Stephens system recognizes an event by the acoustic signature, locates the event by detecting it and signal arrival time, in each direction 3s along the rail, making an estimate of the original acoustic energy by factoring in the attenuation of the rail. In addition an acoustic signal may be added to the rail to detect low acoustic energy events. This would not require a train noise to detect broken rails as in the Welles system. The Stephens system does not account for all the waves introduced into a rail by an event such as a rockfall. As the rail is usually struck from the side and the rock may not stay in contact with the rail, the rail resonates with its own frequency, masking other frequencies peculiar to the rockfall or other event. This resonating wave may travel slower than the other waves of sound.
Before the 1980's, the conventional method of stopping a train was by opening an anglecock on the brake pipe and releasing some or all of the pressurized air.
That was done from the locomotive, for controlled stops, or from the caboose, for emergency stops.
to The locomotives are equipped with a special slow-reduction valve. During the 1980's, the art of remote train braking advanced somewhat with the development of an end of train device or the Sensing and Braking Unit (SBU). The SBU is a wireless transmitting and receiving box that is secured to the last car of a train, and replaces some functions of a caboose. The SBU is attached to the air brake pipe. One function of the SBU is to initiate ~5 an emergency brake application on the train when it receives a wireless communication signal. This gives the locomotive engineer the capacity to stop the train from the locomotive in emergency situations via an SBU attached to the last car. Should there be a pinched air hose or otherwise blocked brake pipe, the train could still be stopped. This system was meant for the exclusive use of the crew of that train only.
OBJECTS AND ADVANTAGES
An object of the present invention is to provide an early warning system for trains which has the following advantages:
(a) continuous monitoring of the track even after a train passes the last signal on approach to a hazard;
(b) instant RTC, crew and train notification of a hazard so the train can be stopped at any time;
(c) low operational costs, namely the price of electricity to operate acoustic sensing and alarm equipment;
(d) low maintenance costs with no need for repairs after a detection of a fallen rock;
(e) post hazard notification allowing trains to resume normal track speed after the first train has passed the location of the suspected hazard;
(f) a method of deducing the location of the suspected hazard, so a train need only be restricting its speed on approach to that location;
(g) an alarm system where the train need not slow down if a track patrol can inspect the suspected hazard site prior to the train's arrival;
(h) accurate and automatic compilation of the location, and time of the suspected event that caused the alarms;
(i) an ability to deduce the size and therefore the danger of a rockfall or physical event;
(j) an ability to sense vibration from physical events below 30 hertz;
(k) minimal use of fossil fuels and therefore environmentally friendly.
Further objects and advantages will become apparent from considering the ensuing description and drawings.
SUMMARY OF THE INVENTION
In accordance with the present invention, this is a system to detect, locate, and classify the source of acoustic waves transmitted by the rails of a railway.
These waves are induced by a rockfall or physical event, and excite natural frequencies of the rail, of which there are many. One detectable vibration is of the rail head about the longitudinal axis of the rail. These acoustic waves, comprising sound and vibration, will be detected by acoustic 2o sensors, and analyzed to identify the type and size of the phenomena that caused them.
When detected between and by at least two sensors, the location can be determined. If a dangerous situation is suspected from the information collected, the relevant train and the RTC staff can be notified to assist in the protection of the train, its crew, the right of way, and the public.
Additionally an event-triggered sound inducer (AI) may be installed on the rail to be activated upon detection of rising water or a track subsidence, when additional wiring would be costly.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram of one embodiment of the railway warning system according to the present invention.
FIG. 2 is a diagram of one embodiment of the alarm system to notify and stop an endangered train.
FIG. 3 is a series of diagrams of acoustic inducers representing different configurations.
FIG. 4 is a diagram of a rail section showing the preferred locations of a geophone.
to FIG. 5 is a diagram of a rail section with an acoustic transmitting attachment.
FIG. 6 is a diagram of an event-triggered acoustic inducer.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
15 A typical embodiment of this system starts at a microphone, geophone, listening device, or acoustic sensor (AS) attached to one rail. There is an acoustic coupling between the rail and the AS. This coupling can be a sound bar, or simply a direct or indirect mechanical connection between the rail and AS. If the AS is a geophone and rockfall detection is the main purpose, it should be installed as far up and to the outside of the rail 2o as practical. Also it should be oriented to read vibration in the gauge-field axis, that is, perpendicular to the rail length. The dynamic sensitivity range of the AS
should be as wide as required to ensure complete detection of all relevant acoustic sources.
Seismic survey equipment such as geophones are manufactured to respond in the range of 2 to 250 hertz but detect outside that range. The dynamic range of frequencies generated by hazards may 25 dictate the AS is a combination of transducers such as a contact microphone and geophone to detect an upper limit of 30 kilohertz when this would be advisable. The AS
must be electrically isolated to avoid interference with existing track circuit operation. Other AS's are placed along the rail at a distance. The distance is determined by first determining the acoustic energy generated in the rail of a rockfall or physical event that would be 3o hazardous. The AS's are then spaced so that event can be detected by at least two AS's attached to the same rail, when attenuation is factored in under conditions such as snowfall.
Groups of AS's are wired to a single location so that the acoustic signal from neighboring AS's may be compared. The signals are fed into an analog-to-digital converter or other signal conditioning device and then brought together at a location that has an acoustic 35 analyzer, or acoustic signal processing unit, typically a sound and vibration analyzing computer. This computer, comprising a digital signal processor (DSP) and timing and logic circuitry has information on acoustic signatures (AcSig's) generated by physical events upon the rail. This device has logic circuitry that can compare the AcSig from each AS, then aided by artificial intelligence interpretation, identify a matched signal occurring in a short period of time, its location and its energy at that location. The acoustic signal processing 5 unit has circuitry to determine the acoustic energy of an AcSig and to compare the time of arrival of each AcSig at each AS. The acoustic signal processing unit can detect the strongest AcSig and ascertain the location of the source by comparing the relative time of arrival of the AcSig's from other proximate AS's.
The computer has the ability to record the time, location, intensity, and suspected to type of hazard. This data is stored in an AcSig storage device.
The computer has circuitry to send out a warning when an AcSig of predetermined energy and duration, as calculated at the source, is received. This warning may be fibre-optically transmitted to the RTC office and the block or CTC trackside signal system. The train crew would be notified by radio. Also, if dictated by a lack of response time, a wireless communication frequency may be sent to the SBU, activating the emergency braking feature.
Additionally, a sound or vibration inducer may be installed on the rail. It imparts an acoustic signature onto or into the rail. This consistent or alternately, event-triggered acoustic signature need only be detected by one AS. The event-triggered device for 2o detecting rising water could use the mercury float switch of U.S. patent No. 5175402 to complete an electrical circuit. The connection wires would run to the easiest accessible acoustically monitored rail of the railway. Groups of switches may be wired in parallel to one AI.
DETAILED DESCRIPTION OF THE DRAWINGS
Referring now to FIG. 1, there is shown one embodiment of a warning system according to the present invention hereinafter referred to as warning system 10. As shown, warning system 10 has a pair of acoustic sensors 20 and 22 coupled to one rail, an analog-3o to-digital converter 23 and 24 coupled to each acoustic sensor with outputs which are fed into an acoustic signal processing unit 12. The acoustic signal processing unit 12 contains a digital signal processor 26 and a timing and logic circuit 28. The acoustic signal processing unit 12 is coupled to an acoustic signature storage device 18, a wireless communication signaling device 14 and the Rail Traffic Control (RTC) office 30. The RTC
office 30 staff have the use of a wireless radio 16 to talk to the train crews.
In operation, acoustic sensors 20 and 22 detect sound or vibration on the same rail and output analog signals to their respective analog-to-digital converters 23 and 24. The digital signals are input to the acoustic signal processing unit 12. The digital signal processor 26 compares and identifies signals that were from the same physical event.
These matched signals are then passed to the timing and logic circuit 28. It will compare the acoustic signatures to known vibrational patterns of the rail induced by physical events. If the AcSig is in the safe category, no further action is taken. If in the unsafe category, the location is deduced, the initial acoustic energy is determined, and if a minimum threshold is exceeded, a suspect condition is identified. The acoustic signal processing unit 12 outputs to to an acoustic signature storage device 18 and the RTC office 30. Should the timing and logic circuit 28 locate a train that is approaching the detected suspect location from the RTC
office 30, information, between sensors 20 and 22, the acoustic signal processing unit 12 will broadcast a signal from the wireless communication signaling device 14 that will initiate a brake pipe pressure reduction on any approaching train. When there is input to the t5 acoustic signature storage device 18, it will assure the trackside signal 32 is at its most restrictive indication. All suspected hazardous condition information will be transmitted to the RTC office 30 so the staff can request a track patrol of the suspect track, make a broadcast by wireless radio 16 to the trains and reset the trackside signal 32.
Referring now to FIG. 2, there is shown one embodiment of a remote braking system 2o according to the present invention hereinafter referred to as emergency remote braking system 40. Should there be a suspected hazardous physical event 86 sensed between acoustic sensor 88 and acoustic sensor 89 which is received by the acoustic signal processing unit, locator and logic unit 90 and should the system determine a train 80 is closely approaching, then an emergency broadcast is made of an emergency braking 25 frequency through antenna 94 to be received by SBU 84. Information regarding the proximity of the train may be obtained from the RTC office 92. Triggering the SBU causes application of the emergency brakes on the railway equipment 80 and 82. Should the acoustic signal processing unit, locator and logic unit 90 determine there is no immediate danger to trains from the suspected hazard then a message is sent to the RTC
office 92 3o and there a decision can be made to take one of the following courses of action: talk by radio 96 to a Track Patrol (not shown), talk by radio 96 to the train crew through radio 100, or if required a wireless signal may be communicated on an emergency braking frequency broadcast through antenna 98 to SBU 84.
FIG. 3 shows an array of events and that can be sensed by a low-acoustic-energy 35 event system. FIG. 3A shows the placement of an acoustic inducer (AI), 102 on rail 106 and such signal being read for consistence by acoustic sensor (AS) 104. FIG.
3B illustrates a mud slide 112 muffling the acoustic energy of AI 102 as read by AS 104. FIG.
3C shows the rail 106 suspended in the air by a track subsidence, thus increasing the energy of the acoustic inducer 102 read by the AS 104. FIG. 3D shows a triggered acoustic inducer, 120 caught in a washout or subsidence 120, thus producing a waveform to be detected by AS
122.
FIG. 4 is a description of one vibrational mode of the rail. It shows rail section 140 once struck or induced with vibration, as caused by a rock hitting the subgrade close to the track, vibrating in the most easily detectable mode defined by arrows 142 and 144.
FIG. 5 shows a continuous tube or fin intermittently attached to the rail to capture l0 and conduct acoustic information from hazards. Rail section 160 has a continuous tube 162 intermittently attached by acoustic couples 164. The continuous tube is acoustically monitored by microphone, not shown, at locations along its length.
FIG. 6 shows an event-triggered acoustic inducer. An acoustic inducer will be installed on an acoustically monitored section of the rail 180. A blasting cap 182 is set and attached below the rail, 180 and wired in series with a battery 188 and a mercury tilt switch 194. The tilt switch 194 is secured in orientation to a post 200. The battery and blasting cap are contained within a container 186 that is secured to the underside of the rail 180. Should the post 200 tilt then the mercury 198 will contact a metal conductive strip 196 and the electrical circuit will be completed through wires 190 and 192 to cause detonation of 2o blasting cap 182. This causes a vibration to be detected by an acoustic sensor, not shown.
Accordingly, the reader will see that the railway acoustic sensing and location assembly can be used to tremendously improve safety. It will save on environmental and equipment damage and will locate, with reasonable accuracy, the location of natural hazard events. It can sense and respond to the natural hazard that has just occurred.
It will reduce costs. It will save lives.
OPERATION
The early warning system is used in the following manner. First, the trackage that is 3o susceptible to rockfalls is identified. Then frequency measurements of are made of typical or representative vibrations transmitted by the rail when struck by, or a rock falls near, the track. Thermal expansion and the accompanying rail creep atop the ties caused by solar heating of the rail will cause a movement of the rail. This will need to be accounted for in determining a hazardous event occurrence, such as readings of horizontal movement along the rail length, with little movement in the other horizontal axis.
The AcSig's of events that are potentially hazardous to train movements may be recorded so as to be analyzed. These potentially hazardous AcSig's include:
rocks falling near the track or striking the rails and ties, running water or mud hitting the rails and ties, sun kinks occurring (an extreme form of thermal expansion which causes the rail to go out of alignment taking on an 'S' shape and usually carry the ties and some ballast along with the rails), washouts that leave the rail suspended over a chasm, and vandalism. Vandalism most often takes the form of items dropped or set on the track.
Finally, a distinct sound must be identified. The sound must be capable of being economically reproduced by a manufactured sound inducer. It may be electrical or 1o mechanical or other in origin. An electromagnetic exciter similar to USA
patent 4402210 (expired) may be used for a mechanical sound inducer.
The collected AcSig's are now classified into safe or unsafe AcSig's. The safe AcSig's include the vibration associated with the normal running sounds of the train. A key to classifying this AcSig is the duration of the vibrations detected and also its building, is steady intensity, and tapering effect as a train approaches, rolls over, and moves away from an AS. The unsafe AcSig's include the natural phenomena that are in the washout and rockfall category or vandalism. These will usually be shorter in duration. An acoustic energy threshold must be determined for the naturally occurring unsafe AcSig; most easily programmed threshold would be when sensed by two AS.
2o The system is then activated. Any detections are sent to a location near the site or transmitted to a remote location that contains the means for analysis. These detections are compared to the collected AcSig and comparison is aided by artificial intelligence interpretation. Typical transmission modes are by wire or fiber optic cable that run beside the rail bed. The cable is used for information transmission and to activate the rail signal 25 system. Another method may be to analyze the information at the site and transmit a dangerous condition warning by radio or satellite.
With a series of AS's attached to the same rail, the location of the wave origin can be deduced when detected between and by at least two AS's. The time delay can be sensed by timing the of arrival of the AcSig at the first AS in each direction to detect the 3o AcSig. The rail, when hit by a rock, produces a plurality of wave motions and depending on the size, weight and method of securement to the ties, will have a variety of detectable waveforms. The easiest to detect, when the rail is struck from the side is a horizontal movement of the rail head. The speed of this wave depends on the stiffness of the rail and its mass and will change as conditions change such as when the rail head wears. Therefore 35 a test must be conducted on a sample section of the railway and the distance must be determined between AS's, by survey methods. Using real time for when AcSig are received, the distance from the midpoint between the two AS's is d. Then d=X[AS1-AS2]
where AS1 is the time of receiving the AcSig at the first AS, AS2 is the time at the second AS. This will give the location from the midpoint assuming the AcSig is between the two AS's. If the physical event was outside the pair of AS's the time delay between the two AS's will be a maximum and the calculation will erroneously conclude the event occurred at one AS. In this case, the string of acoustic sensors will need to be extended to properly locate the event. The "X" represents one half the speed of the wave propagating along the rail.
Acoustic energy at the source of the physical event can then be deduced by comparing the acoustic energy received at the two strongest AS's attached to the same rail and by to calculating the location by the relative time of arrival of the wave and the acoustic decay or attenuation of the rail for the distance traveled by the wave. This will yield two calculations from the same event, for comparison of accuracy.
In some cases, snow or mud slides may not produce a great deal of acoustic energy. This may be more prevalent after a snowfall covers the rail reducing the acoustic transmission properties of the rail. To detect these slides, consistent wave inducers may be installed on the rail and this predetermined waveform relayed to the AS can be analyzed for consistency. Sound anomalies or a change in attenuation would indicate some physical change has occurred between the acoustic inducer and an AS. For a use such as this, only one AS is required to receive the induced waveform and to indicate a dangerous situation.
2o The location will not be known exactly but may be between the source and receiver points.
As there is insufficient acoustic energy from the event itself to determine an event has occurred, this method offers a practical way to detect a dangerous event. This technique may also be used to detect snowfall and then start operation of the CTC switch point heaters that melt snow thus allowing the rail switch points to move and line the route for an approaching train.
Also an event-triggered acoustic inducer (AI) can be installed to indicate an event.
With a series of AS in place, an AI may be installed in a suspect location to detect rising water or subsidence without the delay, cost, and disturbance of laying additional wire along the track. This device would have sufficient stored energy to be transmitted to the rail and 3o then be sensed by an AS. The stored energy may be by battery power, spring and hammer mechanical striker, explosive charge or other chime. Groups of gravity tilt switches or float switches may be wired to one AI.
When a perceived dangerous vibration is detected, there will be an alarm initiated.
The alarm may include storing information regarding time, location, and intensity of the suspected event in a sound file or acoustic signature storage device. The alarm can be registered at the RTC office and may be directed to trains. If in signalized territory, the alarm can trigger the trackside signals, changing them to their most restrictive indication as seen by a train crew on approach to the detected dangerous event location. The alarm may also trigger a radio broadcast to warn the crew by voice, specifying the location of the detection.
There are three levels of alarms that can be initiated. Firstly, if no train is closely 5 approaching, that is, if the signals are not set to allow passage of any train, the RTC staff can request a patrol of that track location. Secondly, if a train is somewhat close, the RTC
staff can make an emergency broadcast to the train crew to stop. The RTC staff may then allow the train to proceed but prepare to stop short of the suspect location.
There the train crew would do a visual inspection. Thirdly, if too close for verbal instructions to the crew and to the train was equipped with SBU or other wireless communication controlled brake pipe air pressure reducing device, then the RTC office or field logic circuitry can apply the emergency brakes to the train. The train locations and directions can be ascertained by the CTC block signal system, the RTC office, by satellite, or through this invention. The SBU
unit numbers would be kept updated by the RTC office through a trackside Automatic 15 Equipment Inventory (AEI) tag reader or an additional Universal Emergency Braking Frequency (UEBF) would be installed on each SBU for the specific use of the RTC staff.
AEI tags are installed on most North American railway equipment and SBU's.
All detections of significance can be compiled to aid in producing rockfall mileage frequency graphs or correlated manually with information reported from track patrols. This 2o will aid in identifying areas for rock scaling scheduling and other remedial work.
CONCLUSIONS, RAMIFICATIONS, AND SCOPE
Although the description above contains many specificities, these should not be construed as limiting the scope of the invention but merely providing illustrations of some of the presently preferred embodiments of this invention. Many others are possible. For example, the system can be simplified in analysis of AcSig's by turning off the system when rolling stock approaches, sound filters may be employed or substituted to detect only specific waveforms, both rails could be monitored and compared, as in the Gerszberg 3o system. The duration of a high energy sound is most important in determining the possible cause. Orientation of the AS's sensing direction is a consideration, if installed on a bridge, vertical waves may be more important and could be used to aid in determining a dangerous condition. All AcSig's could be sent by radio frequency to a remote location for comparison and analysis, analog-to-digital conversions, or signal conditioning can be made at any convenient location in the system, accelerometers or sonar devices could be used for the acoustic sensors, a field location feedback system could be developed for maintenance personnel by which a location could be determined by striking the rail with any solid object, to ascertain if the location just struck was the exact location of a recorded rockfall that may have occurred months earlier. This system could be used for erecting signs and flags that are required by railway operating rules.
Also, the description should not limit the industrial applications. Any mode of transportation that has a substantially continuous metal guideway or frame could propagate the acoustic waves with a predictable velocity. Even dissimilar metals or materials can be accounted for. Therefore, any guided transportation system can adapt this device for use.
Some examples follow.
l0 This invention can be applied to a subway or light rail passenger transport system to detect rare, but potentially dangerous or fatal hazards. Acts of vandalism, such as rocks dropped on the track, are more likely than natural rockfalls. It can be adapted to monorail systems or magnetic levitation guideways. It can be applied to other modes of transport. A
mine ore transport system may have analogous problems. Conveyor belt systems are sometimes jammed with the commodity they convey thus destroying rollers or a length of belt until detected. Increased vibrational activity from these destructive processes could be employed to locate and stop the machinery. Also amusement rides that are guided by steel guideways can be monitored for hazards. All of the above can be categorized as metal guideway transportation systems even if acoustic sensors are not attached to any metal part.
The above description includes exemplary embodiments and methods of implementing the present invention. References to specific examples and embodiments in the description should not be construed to limit the present invention in any manner, and is merely provided for the purpose of describing the general principles of the present invention. Accordingly, the scope of this invention should be determined not by the embodiments presented here, but by the appended claims and their legal equivalents.
FIELD OF THE INVENTION
This invention is a device to sense, locate, and signal rockfalls onto, and subsidence and rising water beneath, railway tracks that may present a danger to the safe movement of trains.
BACKGROUND OF THE INVENTION
The prior art in railway right-of-way safety, with regards to hazards, has advanced little in decades. The prior art safety measures consist of Slide Detector Fences, Wash Out Detectors (WOD), monitoring electrical continuity through the rails, fibre-optic cable break warning systems, and direct observation of the railway right-of-way. Only the WOD and the cable break warning systems have been recently developed. These decades-old safety measures continue to be installed.
A Slide Detector Fence (SDF) consists of a number of horizontal wires strung about 30 centimeters apart on a series of vertical wood poles typically spaced five to twenty meters apart. The poles are placed parallel to the railway track on the side that is 2o susceptible to rockfalls. A rockfall or slide is detected by loss of electrical continuity when a single fragile wire is broken. This detection causes a visual signal to be given to approaching train crews.
There are several problems with SDF. First, SDF coverage is only part of potential rockfall areas. The wires can be broken by something as insignificant to safety as an animal or a tree branch. The SDF cannot discriminate between a small rock and a large boulder.
The SDF must be repaired after each break or detection. Until repaired, all trains passing the SDF are required to pass the entire length of the SDF at a speed that will allow stopping within the range of vision, for example; short of a blockage or other hazard.
This slowing of rail traffic causes a slowdown of opposing rail traffic in single track territory, backing up 3o traffic in both directions. Sometimes additional relief train crews are required to complete the train's trip. Additionally, slowly traveling trains expend extra resources and fuel to brake and reaccelerate. Repairs are sometimes delayed due to the threat of continued rockfalls injuring the repair crews. Locating and repairing the break can be time consuming due to the remoteness of the areas where these fences are typically found, and the length of a single circuit of fence which can extend to upwards of one kilometer in length. SDF are not suitable for areas of slope near the natural angle of repose. In this type of region, there are boulders that may be loosened by a freeze-thaw cycle or rain; however, too many animals can break the SDF in such a region, so that the number of false alarms prohibits the use of SDF. SDF are primarily deployed between the tracks and near-vertical cliffs.
The WOD are installed to stop catastrophic accidents such as the Canadian National Rail (CN) accident at Conrad, B.C., Canada on March 26, 1997. In that accident, two locomotives and eight rail cars derailed into a large depression that was created by a landslide. The two CN crew members on board the lead locomotive were killed.
The diesel fuel caught fire and ignited the derailed equipment. More details are available in the Transport Safety Board of Canada (TSB) report No. R97V0063. The TSB Internet site is at to "http:llbst-tsb.gc.ca!"
A WOD has two forms. The original form, installed on CN's main line, consists of a wire, fabricated from material similar to the SDF, with weights attached. The wire and weights assembly is buried beneath the right of way, in an area of suspect earth stability.
Should the earth wash out or otherwise subside, one of the weights will break the wire causing a loss of electrical continuity which, in turn, activates a signal to warn approaching trains. There has never been a detection of subsidence on this system due to the very limited number of installations. An advance in WOD technology was made in late 1997. It involved the use of mercury tilt switches installed on posts positioned along the railway right-of-way. If the ground washes out or shifts to cause a change in attitude of the post, or 2o the post itself is struck, the mercury switch will tilt sufficiently to cause a loss of electrical continuity. Similarly, if the connecting wire is broken there will be a loss of electrical continuity. The loss of electrical continuity will trigger an alarm causing trackside signals to give a warning and a radio message to be broadcast to the trains nearby, informing their crew members that there is a suspected washout.
WOD are very limited in use. They are difficult to repair and expensive to install.
During construction the original WOD disturbs the track bed they are meant to protect. If they are installed too close to the tracks, they may be disturbed by the normal subgrade movements caused by the trains. If installed too far away, they may miss a small washout.
Another method of monitoring rail lines currently in use involves detecting a problem 3o by sensing a loss of electrical continuity through the rail. A break may occur because of service stresses of trains and equipment, because of thermal contraction on the coldest of winter days, because the road bed subsides under the track, or because a rock strikes one of the rails with sufficient force. If either of the rails break, the loss of electrical continuity changes the block, interlocking or Centralized Traffic Control (CTC) trackside signals to their most restrictive indication. These signals are similar to an intersection traffic light. The signals do not, by themselves, stop any train; they must be acted on by the train crew, who must witness such a signal prior to rolling over the location of the break.
Crews whose train has already traveled past the last one of these signals when a break occurs in the train's present block receive no indication of a broken rail.
The electrical continuity of the track can remain even if there is a sizable chasm created by a washout beneath the track. The CN Conrad accident had a chasm of about 60 meters (200 feet) of unsupported track that did not break until a train came upon it.
Similarly, on September 22, 1993, a barge, being shoved by the towboat Mauvilla, in dense fog, struck a span over Big Bayou Canot in Alabama, USA. The bridge was knocked several feet out of alignment. Eight minutes later an Amtrak train derailed off the bridge at 116 kmlh. (72 m.p.h.), killing 47 people. The rails, although bent and unable to support and guide a train, continued to be electrically continuous and therefore did not give any warning through the trackside signal system. More details are available in National Transportation Safety Board report adopted September 19, 1994, Notation 6167B. In addition, rocks as large as automobiles can roll onto the track without breaking the sturdy rails.
The SDF, original WOD, and the rail electrical continuity detection systems all depend on receiving a detection before the train crew observes the last signal on approach to the hazard. In many areas, the trackside signals are several kilometers apart. Thus, there is time for a hazard to occur without the crew receiving information through the trackside signal system.
2o Another system that has recently been developed is a fibre-optic cable break warning system. This was developed subsequent to the CN Conrad accident.
Should the fibre-optic cable break, a warning is received in the fibre-optic network office and relayed to the RTC office. The RTC staff must cause all the signals to turn to their most restrictive indication and make an emergency radio message broadcast to warn train crews.
In the Conrad accident the fibre-optic cable did not break during the washout, but was broken by the moving train during the fatal accident. This system has had success at detecting rockfalls immediately adjacent to the track that did not break either rail.
Most rockfalls do not have the impact and placement to trigger this system.
Another method of track hazard detection depends on observation. A hazard may be seen by a member of the train crew during their tour of duty, during routine or random track patrols, or while investigating reports from the public.
Many of the areas that rockfalls and washouts occur are remote and are not frequented by the public. As well, these rights-of-way are private property and most railway companies discourage the public's presence. The trains run 24 hours a day. The public would be unlikely to see hazards except by daylight. The natural hazards that cause these accidents are most frequently caused by severe weather such as higher than normal rainfall. This weather is frequently accompanied by diminished visibility, as was the situation in the September, 1993 Amtrak accident. These two conditions make the public less likely to be present or to observe hazards in remote areas.
People traveling the roadways that parallel the tracks offer a good chance of spotting a dangerous situation. Even if a dangerous condition was sighted, the public may not be inclined or able to report it. These typically remote areas are not normally served by cellular phone companies, the correct railway company's track may be difficult to identify, and the railway's phone number may be difficult to obtain. Relying on the public to report hazards has proven to not be a dependable solution in the North American railway environment.
Routine or random track patrols can spot a hazard that has occurred. They can give, if conscientious enough, some insight into the possibility of emerging dangerous areas some of the time. In many cases, however, a hazard such as a rockfall occurs suddenly.
The history of the area would indicate, with more accuracy, the likelihood of rockfalls. This is the type of area where SDF are installed. The two drawbacks of the patrols are the cost involved in manual observation and, in CTC, the delay to trains. A track patrol is typically a highway-railway (hi-rail) vehicle; a pickup truck with an extra set of wheels attached that fit the rails, but of much smaller diameter and weight than standard rolling stock wheels.
Rolling stock includes locomotives and standard rail cars, also referred to as "equipment" in 2o the Canadian Rail Operating Rules (CROR). A hydraulic system to raise and lower the extra set of wheels is provided. The patrols are used to precede a train along the track. The small diameter of wheels and need to stop short of a hazard may not permit the hi-rail vehicle to travel at speed over 40 km/h. The braking distance required increases greatly on wet, frosty or icy rail as substantiated by the testing by the TSB on the collision of two hi-rail vehicles. It tested and measured braking distances from 30 m.p.h. (48 kmlh) on dry pavement, dry rail and wet rail. The respective distances were 44, 94, and 880 feet. This TSB
report number R96T0008 is available on the TSB website. Thus on 60 kmlh (35 m.p.h.) track, the patrol must wait for trains to pass, then get on the track, patrol, then get clear of the track and report to the Rail Traffic Control (RTC) staff typically 15 minutes minimum prior to the 3o expected arrival of the next train. To be any closer than 15 minutes or 10 kilometers would not allow the following train to continue at full track speed because of the workings of the CTC signal system. Consequently, even if every train could be preceded by a patrol, conditions may change in the 15 minute period required between the safety inspection vehicle and the train.
Generally, when a train is the first to encounter a hazard on the track, it cannot stop short of the hazard. Trains take a long distance to stop. Stopping distance is a function of, amongst other things: speed, track grade, brake set up, total weight of the train, steel-on-steel friction, and the length of the train. Steel-on-steel friction is, in most cases, less than half of that of rubber-on-pavement experienced by cars. Train length is significant because the change in air pressure that causes the air brake application can only propagate through 5 the train at the rate of the speed of sound through the train's air brake pipe. The air brake pipe is built into all equipment with connecting hoses at each end of the equipment. This allows for control of the brakes on a series of rail cars from a locomotive, when the hoses are joined. This continuous air brake pipe propagates the changing air pressure required to actuate the brakes. It will take about 6 seconds for a change in pressure to propagate to through an 1800 meter (6000 foot) long train. Significant retarding force on the wheels takes additional seconds. In other cases there may be little opportunity to see the hazard because of darkness, curved track, or snowfall. One hazard that is not easily seen is a change in the gauge of the track, sometimes caused by a rolling rock striking a rail. Gauge is the standard distance between the inside of the pair of rails.
Several types of remote-controlled companion or pilot railway cars have been proposed. They explore the track in front of the locomotive or train at a distance that allows the train to stop if a dangerous condition is detected. Examples of such systems can be found in U.S. patents 5,627,508 and 5,623,244 to Cooper et al. (1997), and 5,429,329 to Wallace et al. (1995). These inventions have not enjoyed commercial success because 2o they require modifications to the CTC signal system or operating rules.
Furthermore, they are expensive to build and maintain and they occupy track that could be used for revenue generating rolling stock, most noticeably when train and companion car are in a siding. Less noticeably, but more significantly, these inventions would cause a greater spacing of trains proceeding in either direction, much like the track patrols. On some systems no method of pilot car removal from the tracks has been proposed once past the trackage of greatest need; on other systems the pilot car couples onto the front of the train until needed again.
Communication could be interrupted in tunnels. These pilot vehicles do not detect a dangerous event that occurs between the time at which it inspects the track and the time at which the train arrives. If notice could be given to the train crew, an emergency train brake 3o application may reduce the negative consequences. For example, a rock slide may derail less rail cars if any advance notice can be given. As yet, no pilot vehicle communicates with the RTC office.
One prior art system, U.S. patent 5,713,540 (1998) to Gerszberg et al, uses detected sound to indicate railway activity. The Gerszberg system monitors the rails in pairs and identifies a dangerous condition by noting the difference in detections between the rails. If a rock struck the track it would be heard louder on one rail when compared to the other rail. Also, the Gerszberg system generates an alarm when there is a very large sound detected on both rails. Such a system however, is unable to distinguish between a small acoustic event occurring near an acoustic sensor from a large event occurring at a distance.
Also, some tracks have metal bars or metal or concrete ties that tie the rails together. These may act as sound conductors and eliminate or substantially reduce the measurable difference between the sounds on each rail making it significantly less likely to detect the anticipated difference in sounds. The Gerszberg system has no locating feature. The physical event that was acoustically sensed cannot be located with any accuracy. It employs only microphones and has a lower limit of sound detection of 30 hertz.
Rockfalls 1o may be more easily detected by sensing vibrations of much lower frequencies. It has a digital signal processor to provide audio signature analysis but has no attenuation calculation to ascertain the original acoustic energy of the railway activity.
To have the capacity to calculate, this the system would need to know the distance between the sensor and the detected event. The Gerszberg system cannot be used near a public crossing or other noise-generating safe situation or the initial filtered signals may require a higher threshold before generating an alarm. Comparing the pairs of detections between rails might generate a false alarm in cases of thermal expansion and accompanying rail creep. It has no feature that would stop an endangered train without the locomotive driver's actions.
Lastly, the Gerszberg system cannot detect mud slides, snow and rock avalanches, 2o washouts, track subsidence, high water and other low acoustic energy events that may be hazardous.
Another prior art system, U.S. patent 5,743,495 (1998) to Kenneth Brakeley Welles II et al uses detected movements of the rail to determine flat wheels on a train and the location of broken rails. The Welles system contemplates detecting only in the presence of vibration induced by trains; train movements are a required element of detection. It consists of a single sensor at each location so oriented so as to detect vibration in the vertical and horizontal axis. Horizontal is defined to be along the rail length. Welles uses a central processor to detect redundancies of events, but assumes or knows the travel time of the waves created by the event to the sensor is instantaneous or insignificant in this 3o configuration.
Yet another prior art system is proposed in Canadian application 2,242,723 to Stephens. This acoustic system proposes detection and recognition of sound and vibration transmitted by the rail or metal guideway. The Stephens system recognizes an event by the acoustic signature, locates the event by detecting it and signal arrival time, in each direction 3s along the rail, making an estimate of the original acoustic energy by factoring in the attenuation of the rail. In addition an acoustic signal may be added to the rail to detect low acoustic energy events. This would not require a train noise to detect broken rails as in the Welles system. The Stephens system does not account for all the waves introduced into a rail by an event such as a rockfall. As the rail is usually struck from the side and the rock may not stay in contact with the rail, the rail resonates with its own frequency, masking other frequencies peculiar to the rockfall or other event. This resonating wave may travel slower than the other waves of sound.
Before the 1980's, the conventional method of stopping a train was by opening an anglecock on the brake pipe and releasing some or all of the pressurized air.
That was done from the locomotive, for controlled stops, or from the caboose, for emergency stops.
to The locomotives are equipped with a special slow-reduction valve. During the 1980's, the art of remote train braking advanced somewhat with the development of an end of train device or the Sensing and Braking Unit (SBU). The SBU is a wireless transmitting and receiving box that is secured to the last car of a train, and replaces some functions of a caboose. The SBU is attached to the air brake pipe. One function of the SBU is to initiate ~5 an emergency brake application on the train when it receives a wireless communication signal. This gives the locomotive engineer the capacity to stop the train from the locomotive in emergency situations via an SBU attached to the last car. Should there be a pinched air hose or otherwise blocked brake pipe, the train could still be stopped. This system was meant for the exclusive use of the crew of that train only.
OBJECTS AND ADVANTAGES
An object of the present invention is to provide an early warning system for trains which has the following advantages:
(a) continuous monitoring of the track even after a train passes the last signal on approach to a hazard;
(b) instant RTC, crew and train notification of a hazard so the train can be stopped at any time;
(c) low operational costs, namely the price of electricity to operate acoustic sensing and alarm equipment;
(d) low maintenance costs with no need for repairs after a detection of a fallen rock;
(e) post hazard notification allowing trains to resume normal track speed after the first train has passed the location of the suspected hazard;
(f) a method of deducing the location of the suspected hazard, so a train need only be restricting its speed on approach to that location;
(g) an alarm system where the train need not slow down if a track patrol can inspect the suspected hazard site prior to the train's arrival;
(h) accurate and automatic compilation of the location, and time of the suspected event that caused the alarms;
(i) an ability to deduce the size and therefore the danger of a rockfall or physical event;
(j) an ability to sense vibration from physical events below 30 hertz;
(k) minimal use of fossil fuels and therefore environmentally friendly.
Further objects and advantages will become apparent from considering the ensuing description and drawings.
SUMMARY OF THE INVENTION
In accordance with the present invention, this is a system to detect, locate, and classify the source of acoustic waves transmitted by the rails of a railway.
These waves are induced by a rockfall or physical event, and excite natural frequencies of the rail, of which there are many. One detectable vibration is of the rail head about the longitudinal axis of the rail. These acoustic waves, comprising sound and vibration, will be detected by acoustic 2o sensors, and analyzed to identify the type and size of the phenomena that caused them.
When detected between and by at least two sensors, the location can be determined. If a dangerous situation is suspected from the information collected, the relevant train and the RTC staff can be notified to assist in the protection of the train, its crew, the right of way, and the public.
Additionally an event-triggered sound inducer (AI) may be installed on the rail to be activated upon detection of rising water or a track subsidence, when additional wiring would be costly.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram of one embodiment of the railway warning system according to the present invention.
FIG. 2 is a diagram of one embodiment of the alarm system to notify and stop an endangered train.
FIG. 3 is a series of diagrams of acoustic inducers representing different configurations.
FIG. 4 is a diagram of a rail section showing the preferred locations of a geophone.
to FIG. 5 is a diagram of a rail section with an acoustic transmitting attachment.
FIG. 6 is a diagram of an event-triggered acoustic inducer.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
15 A typical embodiment of this system starts at a microphone, geophone, listening device, or acoustic sensor (AS) attached to one rail. There is an acoustic coupling between the rail and the AS. This coupling can be a sound bar, or simply a direct or indirect mechanical connection between the rail and AS. If the AS is a geophone and rockfall detection is the main purpose, it should be installed as far up and to the outside of the rail 2o as practical. Also it should be oriented to read vibration in the gauge-field axis, that is, perpendicular to the rail length. The dynamic sensitivity range of the AS
should be as wide as required to ensure complete detection of all relevant acoustic sources.
Seismic survey equipment such as geophones are manufactured to respond in the range of 2 to 250 hertz but detect outside that range. The dynamic range of frequencies generated by hazards may 25 dictate the AS is a combination of transducers such as a contact microphone and geophone to detect an upper limit of 30 kilohertz when this would be advisable. The AS
must be electrically isolated to avoid interference with existing track circuit operation. Other AS's are placed along the rail at a distance. The distance is determined by first determining the acoustic energy generated in the rail of a rockfall or physical event that would be 3o hazardous. The AS's are then spaced so that event can be detected by at least two AS's attached to the same rail, when attenuation is factored in under conditions such as snowfall.
Groups of AS's are wired to a single location so that the acoustic signal from neighboring AS's may be compared. The signals are fed into an analog-to-digital converter or other signal conditioning device and then brought together at a location that has an acoustic 35 analyzer, or acoustic signal processing unit, typically a sound and vibration analyzing computer. This computer, comprising a digital signal processor (DSP) and timing and logic circuitry has information on acoustic signatures (AcSig's) generated by physical events upon the rail. This device has logic circuitry that can compare the AcSig from each AS, then aided by artificial intelligence interpretation, identify a matched signal occurring in a short period of time, its location and its energy at that location. The acoustic signal processing 5 unit has circuitry to determine the acoustic energy of an AcSig and to compare the time of arrival of each AcSig at each AS. The acoustic signal processing unit can detect the strongest AcSig and ascertain the location of the source by comparing the relative time of arrival of the AcSig's from other proximate AS's.
The computer has the ability to record the time, location, intensity, and suspected to type of hazard. This data is stored in an AcSig storage device.
The computer has circuitry to send out a warning when an AcSig of predetermined energy and duration, as calculated at the source, is received. This warning may be fibre-optically transmitted to the RTC office and the block or CTC trackside signal system. The train crew would be notified by radio. Also, if dictated by a lack of response time, a wireless communication frequency may be sent to the SBU, activating the emergency braking feature.
Additionally, a sound or vibration inducer may be installed on the rail. It imparts an acoustic signature onto or into the rail. This consistent or alternately, event-triggered acoustic signature need only be detected by one AS. The event-triggered device for 2o detecting rising water could use the mercury float switch of U.S. patent No. 5175402 to complete an electrical circuit. The connection wires would run to the easiest accessible acoustically monitored rail of the railway. Groups of switches may be wired in parallel to one AI.
DETAILED DESCRIPTION OF THE DRAWINGS
Referring now to FIG. 1, there is shown one embodiment of a warning system according to the present invention hereinafter referred to as warning system 10. As shown, warning system 10 has a pair of acoustic sensors 20 and 22 coupled to one rail, an analog-3o to-digital converter 23 and 24 coupled to each acoustic sensor with outputs which are fed into an acoustic signal processing unit 12. The acoustic signal processing unit 12 contains a digital signal processor 26 and a timing and logic circuit 28. The acoustic signal processing unit 12 is coupled to an acoustic signature storage device 18, a wireless communication signaling device 14 and the Rail Traffic Control (RTC) office 30. The RTC
office 30 staff have the use of a wireless radio 16 to talk to the train crews.
In operation, acoustic sensors 20 and 22 detect sound or vibration on the same rail and output analog signals to their respective analog-to-digital converters 23 and 24. The digital signals are input to the acoustic signal processing unit 12. The digital signal processor 26 compares and identifies signals that were from the same physical event.
These matched signals are then passed to the timing and logic circuit 28. It will compare the acoustic signatures to known vibrational patterns of the rail induced by physical events. If the AcSig is in the safe category, no further action is taken. If in the unsafe category, the location is deduced, the initial acoustic energy is determined, and if a minimum threshold is exceeded, a suspect condition is identified. The acoustic signal processing unit 12 outputs to to an acoustic signature storage device 18 and the RTC office 30. Should the timing and logic circuit 28 locate a train that is approaching the detected suspect location from the RTC
office 30, information, between sensors 20 and 22, the acoustic signal processing unit 12 will broadcast a signal from the wireless communication signaling device 14 that will initiate a brake pipe pressure reduction on any approaching train. When there is input to the t5 acoustic signature storage device 18, it will assure the trackside signal 32 is at its most restrictive indication. All suspected hazardous condition information will be transmitted to the RTC office 30 so the staff can request a track patrol of the suspect track, make a broadcast by wireless radio 16 to the trains and reset the trackside signal 32.
Referring now to FIG. 2, there is shown one embodiment of a remote braking system 2o according to the present invention hereinafter referred to as emergency remote braking system 40. Should there be a suspected hazardous physical event 86 sensed between acoustic sensor 88 and acoustic sensor 89 which is received by the acoustic signal processing unit, locator and logic unit 90 and should the system determine a train 80 is closely approaching, then an emergency broadcast is made of an emergency braking 25 frequency through antenna 94 to be received by SBU 84. Information regarding the proximity of the train may be obtained from the RTC office 92. Triggering the SBU causes application of the emergency brakes on the railway equipment 80 and 82. Should the acoustic signal processing unit, locator and logic unit 90 determine there is no immediate danger to trains from the suspected hazard then a message is sent to the RTC
office 92 3o and there a decision can be made to take one of the following courses of action: talk by radio 96 to a Track Patrol (not shown), talk by radio 96 to the train crew through radio 100, or if required a wireless signal may be communicated on an emergency braking frequency broadcast through antenna 98 to SBU 84.
FIG. 3 shows an array of events and that can be sensed by a low-acoustic-energy 35 event system. FIG. 3A shows the placement of an acoustic inducer (AI), 102 on rail 106 and such signal being read for consistence by acoustic sensor (AS) 104. FIG.
3B illustrates a mud slide 112 muffling the acoustic energy of AI 102 as read by AS 104. FIG.
3C shows the rail 106 suspended in the air by a track subsidence, thus increasing the energy of the acoustic inducer 102 read by the AS 104. FIG. 3D shows a triggered acoustic inducer, 120 caught in a washout or subsidence 120, thus producing a waveform to be detected by AS
122.
FIG. 4 is a description of one vibrational mode of the rail. It shows rail section 140 once struck or induced with vibration, as caused by a rock hitting the subgrade close to the track, vibrating in the most easily detectable mode defined by arrows 142 and 144.
FIG. 5 shows a continuous tube or fin intermittently attached to the rail to capture l0 and conduct acoustic information from hazards. Rail section 160 has a continuous tube 162 intermittently attached by acoustic couples 164. The continuous tube is acoustically monitored by microphone, not shown, at locations along its length.
FIG. 6 shows an event-triggered acoustic inducer. An acoustic inducer will be installed on an acoustically monitored section of the rail 180. A blasting cap 182 is set and attached below the rail, 180 and wired in series with a battery 188 and a mercury tilt switch 194. The tilt switch 194 is secured in orientation to a post 200. The battery and blasting cap are contained within a container 186 that is secured to the underside of the rail 180. Should the post 200 tilt then the mercury 198 will contact a metal conductive strip 196 and the electrical circuit will be completed through wires 190 and 192 to cause detonation of 2o blasting cap 182. This causes a vibration to be detected by an acoustic sensor, not shown.
Accordingly, the reader will see that the railway acoustic sensing and location assembly can be used to tremendously improve safety. It will save on environmental and equipment damage and will locate, with reasonable accuracy, the location of natural hazard events. It can sense and respond to the natural hazard that has just occurred.
It will reduce costs. It will save lives.
OPERATION
The early warning system is used in the following manner. First, the trackage that is 3o susceptible to rockfalls is identified. Then frequency measurements of are made of typical or representative vibrations transmitted by the rail when struck by, or a rock falls near, the track. Thermal expansion and the accompanying rail creep atop the ties caused by solar heating of the rail will cause a movement of the rail. This will need to be accounted for in determining a hazardous event occurrence, such as readings of horizontal movement along the rail length, with little movement in the other horizontal axis.
The AcSig's of events that are potentially hazardous to train movements may be recorded so as to be analyzed. These potentially hazardous AcSig's include:
rocks falling near the track or striking the rails and ties, running water or mud hitting the rails and ties, sun kinks occurring (an extreme form of thermal expansion which causes the rail to go out of alignment taking on an 'S' shape and usually carry the ties and some ballast along with the rails), washouts that leave the rail suspended over a chasm, and vandalism. Vandalism most often takes the form of items dropped or set on the track.
Finally, a distinct sound must be identified. The sound must be capable of being economically reproduced by a manufactured sound inducer. It may be electrical or 1o mechanical or other in origin. An electromagnetic exciter similar to USA
patent 4402210 (expired) may be used for a mechanical sound inducer.
The collected AcSig's are now classified into safe or unsafe AcSig's. The safe AcSig's include the vibration associated with the normal running sounds of the train. A key to classifying this AcSig is the duration of the vibrations detected and also its building, is steady intensity, and tapering effect as a train approaches, rolls over, and moves away from an AS. The unsafe AcSig's include the natural phenomena that are in the washout and rockfall category or vandalism. These will usually be shorter in duration. An acoustic energy threshold must be determined for the naturally occurring unsafe AcSig; most easily programmed threshold would be when sensed by two AS.
2o The system is then activated. Any detections are sent to a location near the site or transmitted to a remote location that contains the means for analysis. These detections are compared to the collected AcSig and comparison is aided by artificial intelligence interpretation. Typical transmission modes are by wire or fiber optic cable that run beside the rail bed. The cable is used for information transmission and to activate the rail signal 25 system. Another method may be to analyze the information at the site and transmit a dangerous condition warning by radio or satellite.
With a series of AS's attached to the same rail, the location of the wave origin can be deduced when detected between and by at least two AS's. The time delay can be sensed by timing the of arrival of the AcSig at the first AS in each direction to detect the 3o AcSig. The rail, when hit by a rock, produces a plurality of wave motions and depending on the size, weight and method of securement to the ties, will have a variety of detectable waveforms. The easiest to detect, when the rail is struck from the side is a horizontal movement of the rail head. The speed of this wave depends on the stiffness of the rail and its mass and will change as conditions change such as when the rail head wears. Therefore 35 a test must be conducted on a sample section of the railway and the distance must be determined between AS's, by survey methods. Using real time for when AcSig are received, the distance from the midpoint between the two AS's is d. Then d=X[AS1-AS2]
where AS1 is the time of receiving the AcSig at the first AS, AS2 is the time at the second AS. This will give the location from the midpoint assuming the AcSig is between the two AS's. If the physical event was outside the pair of AS's the time delay between the two AS's will be a maximum and the calculation will erroneously conclude the event occurred at one AS. In this case, the string of acoustic sensors will need to be extended to properly locate the event. The "X" represents one half the speed of the wave propagating along the rail.
Acoustic energy at the source of the physical event can then be deduced by comparing the acoustic energy received at the two strongest AS's attached to the same rail and by to calculating the location by the relative time of arrival of the wave and the acoustic decay or attenuation of the rail for the distance traveled by the wave. This will yield two calculations from the same event, for comparison of accuracy.
In some cases, snow or mud slides may not produce a great deal of acoustic energy. This may be more prevalent after a snowfall covers the rail reducing the acoustic transmission properties of the rail. To detect these slides, consistent wave inducers may be installed on the rail and this predetermined waveform relayed to the AS can be analyzed for consistency. Sound anomalies or a change in attenuation would indicate some physical change has occurred between the acoustic inducer and an AS. For a use such as this, only one AS is required to receive the induced waveform and to indicate a dangerous situation.
2o The location will not be known exactly but may be between the source and receiver points.
As there is insufficient acoustic energy from the event itself to determine an event has occurred, this method offers a practical way to detect a dangerous event. This technique may also be used to detect snowfall and then start operation of the CTC switch point heaters that melt snow thus allowing the rail switch points to move and line the route for an approaching train.
Also an event-triggered acoustic inducer (AI) can be installed to indicate an event.
With a series of AS in place, an AI may be installed in a suspect location to detect rising water or subsidence without the delay, cost, and disturbance of laying additional wire along the track. This device would have sufficient stored energy to be transmitted to the rail and 3o then be sensed by an AS. The stored energy may be by battery power, spring and hammer mechanical striker, explosive charge or other chime. Groups of gravity tilt switches or float switches may be wired to one AI.
When a perceived dangerous vibration is detected, there will be an alarm initiated.
The alarm may include storing information regarding time, location, and intensity of the suspected event in a sound file or acoustic signature storage device. The alarm can be registered at the RTC office and may be directed to trains. If in signalized territory, the alarm can trigger the trackside signals, changing them to their most restrictive indication as seen by a train crew on approach to the detected dangerous event location. The alarm may also trigger a radio broadcast to warn the crew by voice, specifying the location of the detection.
There are three levels of alarms that can be initiated. Firstly, if no train is closely 5 approaching, that is, if the signals are not set to allow passage of any train, the RTC staff can request a patrol of that track location. Secondly, if a train is somewhat close, the RTC
staff can make an emergency broadcast to the train crew to stop. The RTC staff may then allow the train to proceed but prepare to stop short of the suspect location.
There the train crew would do a visual inspection. Thirdly, if too close for verbal instructions to the crew and to the train was equipped with SBU or other wireless communication controlled brake pipe air pressure reducing device, then the RTC office or field logic circuitry can apply the emergency brakes to the train. The train locations and directions can be ascertained by the CTC block signal system, the RTC office, by satellite, or through this invention. The SBU
unit numbers would be kept updated by the RTC office through a trackside Automatic 15 Equipment Inventory (AEI) tag reader or an additional Universal Emergency Braking Frequency (UEBF) would be installed on each SBU for the specific use of the RTC staff.
AEI tags are installed on most North American railway equipment and SBU's.
All detections of significance can be compiled to aid in producing rockfall mileage frequency graphs or correlated manually with information reported from track patrols. This 2o will aid in identifying areas for rock scaling scheduling and other remedial work.
CONCLUSIONS, RAMIFICATIONS, AND SCOPE
Although the description above contains many specificities, these should not be construed as limiting the scope of the invention but merely providing illustrations of some of the presently preferred embodiments of this invention. Many others are possible. For example, the system can be simplified in analysis of AcSig's by turning off the system when rolling stock approaches, sound filters may be employed or substituted to detect only specific waveforms, both rails could be monitored and compared, as in the Gerszberg 3o system. The duration of a high energy sound is most important in determining the possible cause. Orientation of the AS's sensing direction is a consideration, if installed on a bridge, vertical waves may be more important and could be used to aid in determining a dangerous condition. All AcSig's could be sent by radio frequency to a remote location for comparison and analysis, analog-to-digital conversions, or signal conditioning can be made at any convenient location in the system, accelerometers or sonar devices could be used for the acoustic sensors, a field location feedback system could be developed for maintenance personnel by which a location could be determined by striking the rail with any solid object, to ascertain if the location just struck was the exact location of a recorded rockfall that may have occurred months earlier. This system could be used for erecting signs and flags that are required by railway operating rules.
Also, the description should not limit the industrial applications. Any mode of transportation that has a substantially continuous metal guideway or frame could propagate the acoustic waves with a predictable velocity. Even dissimilar metals or materials can be accounted for. Therefore, any guided transportation system can adapt this device for use.
Some examples follow.
l0 This invention can be applied to a subway or light rail passenger transport system to detect rare, but potentially dangerous or fatal hazards. Acts of vandalism, such as rocks dropped on the track, are more likely than natural rockfalls. It can be adapted to monorail systems or magnetic levitation guideways. It can be applied to other modes of transport. A
mine ore transport system may have analogous problems. Conveyor belt systems are sometimes jammed with the commodity they convey thus destroying rollers or a length of belt until detected. Increased vibrational activity from these destructive processes could be employed to locate and stop the machinery. Also amusement rides that are guided by steel guideways can be monitored for hazards. All of the above can be categorized as metal guideway transportation systems even if acoustic sensors are not attached to any metal part.
The above description includes exemplary embodiments and methods of implementing the present invention. References to specific examples and embodiments in the description should not be construed to limit the present invention in any manner, and is merely provided for the purpose of describing the general principles of the present invention. Accordingly, the scope of this invention should be determined not by the embodiments presented here, but by the appended claims and their legal equivalents.
Claims (23)
1. A method for detecting and locating a physical event which affects a metal guideway transportation system comprising the steps of:
(a) monitoring a metal guideway of said metal guideway transportation system at a pair of disposed apart monitoring locations to detect acoustic waves produced by said physical event, said physical event occurring substantially between said disposed apart monitoring locations, and said acoustic waves propagating through said metal guideway;
and (b) locating said physical event by comparing a relative time of arrival of said acoustic waves at said pair of disposed apart monitoring locations.
(a) monitoring a metal guideway of said metal guideway transportation system at a pair of disposed apart monitoring locations to detect acoustic waves produced by said physical event, said physical event occurring substantially between said disposed apart monitoring locations, and said acoustic waves propagating through said metal guideway;
and (b) locating said physical event by comparing a relative time of arrival of said acoustic waves at said pair of disposed apart monitoring locations.
2. A method according to claim 1, further comprising the steps of:
(a) storing the intensity of said acoustic waves to form a library of acoustic signatures; and (b) storing the location of said physical event, whereby areas of said metal guideway transportation system which are prone to a type of physical event may be identified.
(a) storing the intensity of said acoustic waves to form a library of acoustic signatures; and (b) storing the location of said physical event, whereby areas of said metal guideway transportation system which are prone to a type of physical event may be identified.
3. A method according to claim 1, further comprising at least one of the steps of:
(a) classifying said physical event;
(b) evaluating the severity of said physical event and whether said physical event poses a threat to safe operation of said metal guideway transportation system; and (c) responding to said physical event in a manner whereby safe operation of said metal guideway transportation system may be maintained.
(a) classifying said physical event;
(b) evaluating the severity of said physical event and whether said physical event poses a threat to safe operation of said metal guideway transportation system; and (c) responding to said physical event in a manner whereby safe operation of said metal guideway transportation system may be maintained.
4. A method according to claim 3, wherein said classifying step is accomplished by at least one of:
(a) filtering said acoustic waves; and (b) timing said acoustic waves, thereby assisting to detect a condition on said metal guideway transportation system.
(a) filtering said acoustic waves; and (b) timing said acoustic waves, thereby assisting to detect a condition on said metal guideway transportation system.
5. A method according to claim 3, wherein said evaluating step is accomplished by measuring the acoustic energy of the detected acoustic waves and calculating the acoustic energy at its source.
6. A method for detecting a physical event which affects a metal guideway transportation system comprising the steps of:
(a) introducing predetermined acoustic waves onto a metal guideway of said metal guideway transportation system at a first location, said predetermined acoustic waves propagating through said metal guideway;
(b) acoustically monitoring said metal guideway at a second location; and (c) detecting a change in said predetermined acoustic waves, said change indicates a physical event has occurred between said first location and said second location.
(a) introducing predetermined acoustic waves onto a metal guideway of said metal guideway transportation system at a first location, said predetermined acoustic waves propagating through said metal guideway;
(b) acoustically monitoring said metal guideway at a second location; and (c) detecting a change in said predetermined acoustic waves, said change indicates a physical event has occurred between said first location and said second location.
7. A method according to claim 6, further comprising at least one of the steps of:
(a) evaluating the severity of said physical event and whether said physical event poses a threat to safe operation of said metal guideway transportation system; and (b) responding to said physical event in a manner whereby safe operation of said metal guideway transportation system may be maintained.
(a) evaluating the severity of said physical event and whether said physical event poses a threat to safe operation of said metal guideway transportation system; and (b) responding to said physical event in a manner whereby safe operation of said metal guideway transportation system may be maintained.
8. A method according to claim 7, wherein said evaluating step is accomplished by measuring the change of the acoustic energy in said predetermined acoustic waves.
9. A system for detecting and locating a physical event which affects a metal guideway transportation system comprising:
(a) a pair of acoustic sensors acoustically coupled to a metal guideway of said metal guideway transportation system at disposed apart locations and each of said pair of acoustic sensors operative to detect acoustic waves produced by said physical event, said physical event occurring substantially between said disposed apart locations, and said acoustic waves propagating through said metal guideway and producing corresponding analog electrical signals;
(b) a pair of signal conditioners electrically coupled to respective outputs of said pair of acoustic sensors, each of said pair of signal conditioners operative to convert said analog electrical signals to conditioned signals representative of said acoustic waves of said physical event;
(c) an acoustic signal processing unit coupled to said pair of signal conditioners, said acoustic signal processing unit is operative to process said conditioned signals to locate said physical event.
(a) a pair of acoustic sensors acoustically coupled to a metal guideway of said metal guideway transportation system at disposed apart locations and each of said pair of acoustic sensors operative to detect acoustic waves produced by said physical event, said physical event occurring substantially between said disposed apart locations, and said acoustic waves propagating through said metal guideway and producing corresponding analog electrical signals;
(b) a pair of signal conditioners electrically coupled to respective outputs of said pair of acoustic sensors, each of said pair of signal conditioners operative to convert said analog electrical signals to conditioned signals representative of said acoustic waves of said physical event;
(c) an acoustic signal processing unit coupled to said pair of signal conditioners, said acoustic signal processing unit is operative to process said conditioned signals to locate said physical event.
10. A system according to claim 9, further comprising an acoustic signal storage device operative to store said conditioned signals of said physical event, building a library of acoustic signatures, and to store the location of said physical event, whereby areas of said metal guideway transportation system prone to a type of physical event may be identified.
11. A system according to claim 9, wherein said acoustic signal processing unit is further programmed to classify and to evaluate the severity of said physical event and whether said physical event poses a threat to safe operation of said metal guideway transportation system and to respond to said physical event in a predetermined manner whereby safe operation of said metal guideway transportation system may be maintained.
12. A system according to claim 9, wherein said metal guideway is a rail and said vehicle is a train.
13. A system for detecting a physical event which affects a metal guideway transportation system comprising:
(a) an acoustic inducer operative to introduce predetermined acoustic waves onto a metal guideway of said metal guideway transportation system at a first location;
(b) an acoustic sensor acoustically coupled to said metal guideway of said metal guideway transportation system at a second location, said acoustic sensor operative to monitor said metal guideway and to sense acoustic phenomena including said predetermined acoustic waves as they are propagating through said metal guideway and to produce a corresponding analog electrical signal;
(c) an signal conditioner electrically coupled to an output of said acoustic sensor and operative to convert said analog electrical signal to a conditioned signal representative of said acoustic phenomena including said predetermined acoustic waves; and (d) an acoustic signal processing unit coupled to said signal conditioner, said acoustic signal processing unit is operative to classify said conditioned signal, including a change in the predetermined signal, said change indicates said physical event has occurred between said first location and said second location.
(a) an acoustic inducer operative to introduce predetermined acoustic waves onto a metal guideway of said metal guideway transportation system at a first location;
(b) an acoustic sensor acoustically coupled to said metal guideway of said metal guideway transportation system at a second location, said acoustic sensor operative to monitor said metal guideway and to sense acoustic phenomena including said predetermined acoustic waves as they are propagating through said metal guideway and to produce a corresponding analog electrical signal;
(c) an signal conditioner electrically coupled to an output of said acoustic sensor and operative to convert said analog electrical signal to a conditioned signal representative of said acoustic phenomena including said predetermined acoustic waves; and (d) an acoustic signal processing unit coupled to said signal conditioner, said acoustic signal processing unit is operative to classify said conditioned signal, including a change in the predetermined signal, said change indicates said physical event has occurred between said first location and said second location.
14. A system according to claim 13, wherein said acoustic signal processing unit is further programmed to evaluate the severity of said physical event and whether said physical event poses a threat to safe operation of said metal guideway transportation system and to respond to said physical event in a predetermined manner thereby maintaining safe operation of said metal guideway transportation system.
15. A system according to claim 13, wherein said metal guideway is a rail and said vehicle is a train.
16. A method for detecting a physical event producing an acoustic signature propagating through a metal guideway of a metal guideway transportation system comprising the steps of:
(a) monitoring said metal guideway of said metal guideway transportation system to detect said acoustic signature; and (b) analyzing said acoustic signature to classify said physical event.
(a) monitoring said metal guideway of said metal guideway transportation system to detect said acoustic signature; and (b) analyzing said acoustic signature to classify said physical event.
17. The method of claim 16, wherein said analyzing step is accomplished by at least one of the steps of:
(a) filtering said acoustic signature; and (b) comparing said acoustic signature to acoustic signatures of known physical events.
(a) filtering said acoustic signature; and (b) comparing said acoustic signature to acoustic signatures of known physical events.
18. The method of claim 16, wherein said metal guideway is a rail and said metal guideway transportation system is a railway.
19. A method of ascertaining the location of a physical event that produces an acoustic signature propagating through a metal guideway of a metal guideway transportation system comprising the steps of:
(a) detecting said acoustic signature in each direction along said metal guideway;
(b) locating the pair of detections;
(c) sensing a time delay between said pair of detections; and (d) calculating said location of said physical event.
(a) detecting said acoustic signature in each direction along said metal guideway;
(b) locating the pair of detections;
(c) sensing a time delay between said pair of detections; and (d) calculating said location of said physical event.
20. The method of claim 19 further including ascertaining the original acoustic energy of said physical event by substantially knowing:
(a) the distance traveled by said acoustic signature until being detected;
(b) the acoustic energy detected; and (c) an attenuation of acoustic energy along said metal guideway whereby the severity of said physical event may be ascertained.
(a) the distance traveled by said acoustic signature until being detected;
(b) the acoustic energy detected; and (c) an attenuation of acoustic energy along said metal guideway whereby the severity of said physical event may be ascertained.
21. An acoustic sensor acoustically coupled to a rail and means for recognizing a rockfall from acoustic vibrations sensed.
22. An acoustic signal producing trigger device that automatically produces an acoustic signal onto a rail when a physical event occurs, thereby producing a high energy acoustic signal from a low acoustic energy event.
23. A physical event detection device comprising at least two disposed apart geophones acoustically coupled a same rail to sense said physical event.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2270066 CA2270066A1 (en) | 1999-04-19 | 1999-04-19 | Railway rail acoustic rockfall detector |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2270066 CA2270066A1 (en) | 1999-04-19 | 1999-04-19 | Railway rail acoustic rockfall detector |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2270066A1 true CA2270066A1 (en) | 2000-10-19 |
Family
ID=29588859
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2270066 Abandoned CA2270066A1 (en) | 1999-04-19 | 1999-04-19 | Railway rail acoustic rockfall detector |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2270066A1 (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2005005223A1 (en) * | 2003-06-27 | 2005-01-20 | General Electric Company | Rail and train monitoring system and method |
| WO2010003220A1 (en) * | 2008-06-17 | 2010-01-14 | Weir - Jones Engineering Consultants Ltd. | System and method for detecting rock fall |
| WO2012059108A1 (en) | 2010-11-05 | 2012-05-10 | Nkt Cables Group A/S | An integrity monitoring system and a method of monitoring integrity of a stationary structure |
| CN106161607A (en) * | 2016-06-30 | 2016-11-23 | 重庆尚渝网络科技有限公司 | Equipment network system on tunnel and locomotive |
| EP3473518A1 (en) * | 2017-10-17 | 2019-04-24 | Next Generation Rail Technologies S.L. | System for detecting events or situations having associated patterns of acoustic vibrations in a train rail and vibration detector unit for this system |
-
1999
- 1999-04-19 CA CA 2270066 patent/CA2270066A1/en not_active Abandoned
Cited By (17)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6951132B2 (en) | 2003-06-27 | 2005-10-04 | General Electric Company | Rail and train monitoring system and method |
| WO2005005223A1 (en) * | 2003-06-27 | 2005-01-20 | General Electric Company | Rail and train monitoring system and method |
| AU2009267754B2 (en) * | 2008-06-17 | 2013-08-29 | Weir - Jones Engineering Consultants Ltd. | System and method for detecting rock fall |
| WO2010003220A1 (en) * | 2008-06-17 | 2010-01-14 | Weir - Jones Engineering Consultants Ltd. | System and method for detecting rock fall |
| CN102123899A (en) * | 2008-06-17 | 2011-07-13 | 韦尔-琼斯工程顾问有限公司 | System and method for detecting rock fall |
| CN102123899B (en) * | 2008-06-17 | 2013-09-25 | 韦尔-琼斯工程顾问有限公司 | System and method for detecting rock fall |
| EP2635875A4 (en) * | 2010-11-05 | 2013-11-20 | Nkt Cables Group As | INTEGRITY CONTROL SYSTEM AND INTEGRITY CONTROL METHOD OF STATIONARY STRUCTURE |
| CN103201592A (en) * | 2010-11-05 | 2013-07-10 | Nkt电缆集团公司 | An integrity monitoring system and a method of monitoring integrity of a stationary structure |
| WO2012059108A1 (en) | 2010-11-05 | 2012-05-10 | Nkt Cables Group A/S | An integrity monitoring system and a method of monitoring integrity of a stationary structure |
| JP2014502345A (en) * | 2010-11-05 | 2014-01-30 | エヌコーテー ケーブルス グループ アクティーゼルスカブ | Stationary structure integrity monitoring system and integrity monitoring method |
| US9612189B2 (en) | 2010-11-05 | 2017-04-04 | Nkt Cables Group A/S | Integrity monitoring system and a method of monitoring integrity of a stationary structure |
| KR101916004B1 (en) | 2010-11-05 | 2018-11-09 | 엔케이티 케이블스 그룹 에이/에스 | An integrity monitoring system and a method of monitoring integrity of a stationary structure |
| CN106161607A (en) * | 2016-06-30 | 2016-11-23 | 重庆尚渝网络科技有限公司 | Equipment network system on tunnel and locomotive |
| CN106161607B (en) * | 2016-06-30 | 2019-05-10 | 重庆尚渝网络科技有限公司 | Network system of the equipment on tunnel and locomotive |
| EP3473518A1 (en) * | 2017-10-17 | 2019-04-24 | Next Generation Rail Technologies S.L. | System for detecting events or situations having associated patterns of acoustic vibrations in a train rail and vibration detector unit for this system |
| WO2019076993A1 (en) | 2017-10-17 | 2019-04-25 | Next Generation Rail Technologies S.L. | System for detecting events or situations having associated patterns of acoustic vibrations in a train rail and vibration detector unit for this system |
| US11623672B2 (en) | 2017-10-17 | 2023-04-11 | Next Generation Rail Technologies S.L. | System for detecting events or situations having associated patterns of acoustic vibrations in a train rail and vibration detector unit for this system |
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