AU730512B2 - Railroad traffic warning system apparatus and method therefor - Google Patents

Description

i -4 WO 97/25235 PCT/US97/00153 RAILROAD TRAFFIC WARNING SYSTEM APPARATUS AND METHOD THEREFOR TECHNICAL FIELD The present invention relates generally to traffic warning systems and more particularly to a railroad crossing traffic warning system for alerting motorists approaching a railroad grade crossing to the presence of an oncoming railroad train.

Additionally, t he present invention relates generally to railroad warning systems and specifically to a warning system for railroad maintenance-of-way personnel working on or in the vicinity of active railroad tracks.

BACKGROUND OF THE INVENTION There are over 223,000 railroad grade crossings in the United States alone. Most of these crossings, especially those in rural areas, have only warning signs to alert motorists to the danger posed by an approaching train.

Typical of railroad grade crossing warning signs is the familiar X-shaped "RAILROAD CROSSING" sign or "crossbuck." Warning signs, however, only alert motorists to the presence of a railroad crossing and do not alert them to the presence of an oncoming train. Often, a motorist may fail to see an approaching train because he was distracted or because his view of the train was obstructed by environmental conditions or darkness. Consequently, collisions between trains and automobiles at railroad crossings account for thousands of accidents each year, many of which result in extensive property damage and serious injury or death to motorists.

Known to the art are active railroad crossing warning systems utilizing the railroad tracks themselves to detect an approaching train and activate warning signal apparatus such as flashing lights and bells. These systems warn motorists when a train is detected at a predetermined distance from the WO 97/25235 PCT/US97/00153 2 crossing. However, present active warning systems do no take into account the speed of the train and thus make no allowance for the time it will take the train to reach the crossing. For example, a fast moving train may reach the crossing in only a few seconds after it is detected, while a slow moving train may fail to reach the crossing until several minutes have passed. Motorists may become impatient waiting for slow moving trains to reach the crossing.

Consequently, some motorists may begin to ignore the warnings and attempt to cross the tracks possibly causing an accident should a fast moving train be encountered. Further, installation of current active warning systems may require the insulation and resetting of great lengths of track. Additionally, these systems may require the installation of expensive high voltage transformers, relays, and batteries for backup systems. Unfortunately, many rural crossings are not conducive to the installation of active warning systems that requires AC electrical power and extensive grade preparation. Consequently, these crossings usually remain inadequately protected. High speed rail corridors being proposed across the United States will only exacerbate this problem.

These corridors will require improved crossing warning systems to properly secure the safety of both passengers and motorists.

Additionally, railroad crews working on or in the vicinity of active railroad tracks are susceptible to accidents as a result of not being sufficiently warned of an oncoming train entering the work area. The rail work is typically performed in isolated regions away from crossing areas, and therefore the work crews do not have the benefit of standard crossing signals to warn them of approaching trains. Thus, there lies a need for a reliable warning system for warning maintenance-of-way crews which allows the crew to concentrate on the work at hand while providing adequate warning of oncoming train hazards in order to clear the tracks of tools, equipment and workers to avoid an accident.

The railroad crew warning system is further required to be portable and easily set up by the crew in a relatively short period of time. Additionally, the warning system should be of sufficient operational efficiency to activate the warning -3system only upon the detection of a train to thereby mitigate the natural human tendency to ignore the warning system after false activations.

Therefore, it is an object of the present invention to provide an improved railroad crossing warning system for warning a motorist, pedestrian, bystander, or the like to the presence of an approaching railroad train.

SUMMARY OF THE INVENTION According to one aspect of the present invention there is provided a railroad crossing traffic warning system for alerting a motorist approaching a railroad crossing to the presence of an oncoming train, said warning system including: a first sensor positioned adjacent to a railroad track at a first predetermined distance from the railroad crossing operating independently of rails of said railroad track, said first sensor for detecting an oncoming train and for producing a 15 signal in response thereto; a second sensor positioned adjacent to said railroad track at a second *--*predetermined distance from the railroad crossing operating independently of rails of said railroad track, said second sensor for detecting an oncoming train and for 2 producing a signal in response thereto; an alerting device for alerting the motorist to the presence of an oncoming :railroad train such that the motorist may take cautionary or evasive action before the arrival of the train at the railroad crossing; and a controller operatively coupled to said sensor and said alerting device, said controller for receiving the signal from said sensor and controlling operation of said alerting device in response thereto, said controller further including: a processor for processing the signal received from said sensor and controlling said alerting device in response to said processed signal; a sensor signal interface for interfacing said processor with said sensor to provide the signal received from said sensor to said processor; and an alerting device interface for interfacing said processor with said alerting device, wherein said alerting device operates during a failure of said first sensor by detection of an oncoming train by said second sensor to provide fail-safe Sprotection.

-1 P MP W:\marie\GABNODEL\18237c.doc -4- According to a further aspect of the present invention there is provided a railroad crossing traffic warning system for alerting a motorist approaching a railroad crossing to the presence of an oncoming train, said warning system including: means for detecting an oncoming train and producing a signal in response thereto, said detecting means operating independently from rails of a railroad track; means for alerting the motorist to the presence of an oncoming train so that the motorist may take cautionary or evasive action before the arrival of the train at the railroad crossing; and means for receiving the signal from said detecting means and controlling said alerting means in response thereto, said controlling means further including: means for processing the signal received from said detecting means, controlling said alerting device in response to said processed signal and monitoring operation of the system for proper function; :means for interfacing said processing means with said detecting means to S.provide the signal received from said detecting means to said processing means; and means for interfacing said processing means with said alerting means wherein said detecting means includes at least two redundant devices to allow for operation of said alerting means if one of said redundant devices fails to operate correctly.

The present invention may provide an improved railroad crossing warning system suitable for operation at remote or rural railroad grade crossing where a source of AC electrical power may not be available. The railroad crossing warning system of the present invention may be easily installed at existing railroad crossings without removing, replacing or interfering with the existing railroad track.

The invention may provide a railroad crossing warning system having improved warning signal devices, signs and the like. The warning signal devices may be activated at a predetermined interval of time before the train reaches the _railroad crossing.

MP W:madie\GABNODEL\18237c.doc -4a The present invention may provide an improved railroad crossing warning system having means to detect a stopped train at a crossing so that activation of the warning signal device or sign may be continued.

The present invention may provide a means of collecting and recording data regarding the operation of the warning system and information about the trains passing the crossing.

The present invention may provide an improved railroad crossing system including a primary system and redundant backup and fail-safe systems for added reliability and safety. The components are reliable of the warning system preferably are reliable, easily maintained, and protected against vandalism.

The present invention may provide a railroad crossing traffic warning system for alerting a motorist approaching a railroad crossing to the presence of an oncoming train. As used herein, "motorist" is intended to refer not only to operators and passengers of motor vehicles, but also to pedestrians, cyclists, 15 bystander, and the like. Sensors buried adjacent to the train rails at predetermined distances from the railroad crossing may detect the presence of an approaching train. A control unit, processing signals received from these sensors may determine the speed at which the train is travelling and the time required for the train to reach the crossing. At a predetermined time before the train reaches 20 the crossing, the control unit may activate warning apparatus to alert motorists to the presence of the oncoming train. The motorists may then take cautionary or evasive action.

The system may also include improved warning apparatus. The warning apparatus may comprise an X-shaped railroad crossing warning sign or "crossbuck" having reflectors, reflecting paint, or the like for reflecting the headlights of an automobile, a plurality of strobe lights to enhance the motorist's awareness of the approaching train and a train direction indicator. The crossbuck may include a plurality of light emitting diodes or the like mounted on the across the centre of the crossbuck in an X-shape. The train direction indicator may comprise a plurality of lamps placed adjacent to each other in a line. These lamps may be lighted sequentially to indicate the direction in which the oncoming train is travelling. Further, the warning apparatus may further include an audible warning means such as a siren horn or bell to provide an audile output signal.

MP W:.\marie\GABNODEL\18237c.doc -4b- Crossing guard apparatus may also be provided to detect the presence of a stopped train in the railroad crossing so that activation of the warning apparatus may be continued until the train moves from the crossing. The crossing guard may include an infrared transmitter and a receiver mounted diagonally across the crossing. The transmitter may transmit an infrared beam of light across the crossing to the receiver. If a train is present in the crossing the beam is interrupted and a signal is sent to the control unit.

The system may be powered by a rechargeable battery. This battery may be recharged by a solar panel array allowing the system to be deployed at crossings located in rural areas where a source of AC electrical power is not readily available.

Additionally, the present invention may provide a system for warning railroad crews working on or in the vicinity of railroad tracks of oncoming trains. A train detector probe may be placed near the train rails at a predetermined distance from the works crew in either direction along the tracks. Electronic detection, processing and control circuitry may receive and process the detector probe signal which is transmitted via a radio frequency communications link to a Sreceiver in the located vicinity of the crew. The receiver may process the received train detection signal and thereupon may activate a warning system which provides visual and audio warning to the crew of the presence of an *incoming train.

BRIEF DESCRIPTION OF THE DRAWINGS Preferred embodiments of the present invention will now be described with reference to the accompanying figures in which: MP W:marie\GABNODEL\18237c.doc *.20 FIG. 1 is a pictorial view of a typical single track grade crossing employing a railroad crossing warning system according to an exemplary embodiment of the present invention; FIG. 2 is a top plan view of an area surrounding a typical grade crossing, as illustrated in FIG. 1, depicting the placement of the warning system's S. 25 components along the track; FIG. 3A is an elevational view of the embodiment of the invention shown in FIGS. 1 and 2 illustrating the operation thereof before an oncoming railroad train reaches the crossing; FIG. 3B is an elevational view of the embodiment of the invention shown in FIGS. 1 and 2 illustrating the operation thereof after passage of the train; WO 97/25235 PCT/US97/00153 6 FIG. 4 is a perspective view of the basic components of the warning system according to an exemplary embodiment of the present invention; FIG. 5 is a front elevational view depicting a warning signal device according to an exemplary embodiment of the invention; FIG. 6 is a schematic diagram of the warning system illustrating the operational features thereof; FIG. 7 is a front elevational view depicting a warning signal device according to an exemplary embodiment of the present invention employing a crossing gate; FIG. 8 is a front elevational view of a warning signal device mounted on a cantilever assembly according to alternative embodiment of the present invention; FIG. 9 illustrates the use of the present invention in a railroad crossing having multiple railroad tracks, such as in an industrial area or near a freight yard; FIG. 10 is a top plan view of a typical application of the present invention; FIG. 11 is a perspective view of the basic components of a preferred embodiment of the present invention; FIG. 12 is an elevation view of the present invention showing typical operation thereof; FIG. 13 is an elevation view of the present invention further showing typical activation thereof; FIG. 14 is an elevation view of the present invention further showing typical deactivation thereof; and FIG. 15 is a schematic diagram of the present invention showing the operational features thereof.

DETAILED DESCRIPTION OF AN EXEMPLARY EMBODIMENT A. DESCRIPTION OF FIGS. 1 TO 9 FIG. 1 depicts a typical single track grade crossing employing a railroad WO 97/25235 PCT/US97/00153 7 crossing warning system 10 according to an exemplary embodiment of the present invention. The warning system 10 preferably comprises several components which' operate separately of the railroad's track, equipment, or systems to provide means of actively warning a motorist, pedestrian, or the like ("motorist") approaching the crossing of the presence of an oncoming train.

Warning signal devices 12 may be erected adjacent to a road or highway 14 on either side of the crossing 16. These devices 12 are preferably positioned facing oncoming traffic so as to be clearly visible to a motorist approaching the crossing on the road or highway 14. Preferably, each device 12 comprises a standard X-shaped railroad crossing warning sign or "crossbuck" 18 having reflectors, reflective paint, or the like for reflecting the lights of an approaching automobile. The crossbuck 18 may be mounted on a post, pole, mast or like' supporting means 20 which is anchored in the ground next to the crossing.

Visibility of the crossbuck 18 may be further enhanced by a plurality of light emitting diodes ("LED"s) 22 mounted across the center of the crossbuck 18 such that they form an X-shape. These LEDs 22 may be animated, i.e. made to flash so as to attract the motorists attention. A strobe light/train direction advisory sign 24 may be mounted above the crossbuck 18 on the mast This sign 24 may include a plurality of strobe lights 26 which function to alert inattentive motorists to the presence of the approaching train. A train direction indicator 28 may also be provided comprising a plurality of lamps 30 placed adjacent to each other in a straight line. Upon detection of the presence of an approaching train by the system, these lamps 30 may be lighted sequentially in a repetitious manner to indicate the direction in which the oncoming train is traveling. Embodiments of the warning signal device 12 may further include an audible warning means such as a siren horn or bell (not shown) to provide an audible warning to the motorist.

A control unit 32 may activate the warning signal devices 12 when an approaching train is detected. The control unit 32 may be housed in a waterproof underground vault 34 located near the railroad grade crossing. The WO 97/25235 PCT/US97/00153 8 vault 34 may include a steel access door 36 secured by a locking device 38 such as a hasp to receive a padlock or the like. The buried vault 34 may provide physical security for the control unit 32 protect the control unit's electronics from the extreme temperature changes that could be experienced were the control unit 32 to be located in an above ground enclosure which had no heating and air conditioning. Preferably, the vault 34 may be grounded to provide electrostatic shielding to the electronic components contained therein.

The system 10 is preferably powered by rechargeable batteries (not shown). The batteries may be housed within the vault 34 with the control unit 32. Recharging of the batteries may be accomplished by means of a solar panel array 40 mounted on a pole, or post 42 near the crossing. Use of solar panels 40 to recharge the system batteries is desirable when the system 10 is to be deployed at crossings located in rural areas where a source of electrical power is not readily available. The crossbuck 12, strobe light/train direction advisory sign 24, and solar panels 40 may have transparent coverings comprising 1/2 inch thick LEXAN or the like to prevent damage due to the environment or vandalism.

As illustrated in FIG. 2, the system 10 preferably includes a series of remote sensors probes 50 which are capable of detecting the presence of a train 52. The sensor probes 50 may be positioned adjacent to the train rails 54 at predetermined distances from the railroad crossing 56. Preferably, each sensor 50 comprises a magnetometer enclosed in a sealed housing assembly which may be buried in the right-of-way to the railroad tracks to prevent vandalism. The magnetometers produce a signal in response to local disturbances of an electromagnetic field, such as the disturbance of the magnetic field of the earth caused by the passing of a large metallic object such as a train. The sensor probes 50 may be interconnected with electronic circuitry in the control unit 32 which produces a binary (on or off) signal when the presence of a train is detected. Shielded, rodent proof, multi-conductor sealed cables 58, which may also be buried in the right-of way, may WO 97/25235 PCT/US97/00153 9 interconnect the remote sensor probes 50 to the control unit 32. These cables 58 may be further protected by electronic circuitry within the control unit 32 which monitor the integrity of a closed loop circuit in the buried cable. In the event that a cable 58 is cut or damaged, the control unit 32 will sense a break in the closed loop circuit and place the system in a fail safe mode of operation which automatically activates the warning signal devices 12.

FIGS. 3A and 3B illustrate operation of the system 10 to detect an approaching train 52 and activate warning signal devices 12 located at the crossing 56. The railroad crossing warning system 10 preferably comprises a primary train detection subsystem and a secondary or backup train detection subsystem. The primary train detection subsystem may include two speed traps 60 each comprising two sensor probes 50a 50b positioned on either side of the grade crossing 56 along the track 62 at a predetermined distance from each other. The sensor probes 50a 50b are preferably located at a sufficient distance from the grade crossing 56 to permit the system 10 to activate the warning signal devices 12 at a predetermined interval of time before the arrival of the train 52 regardless of the train's speed. The sensor probes 50a 50b may be buried in the earth in the right-of-way adjacent to the track 62 to prevent damage or vandalism. As a train 52 approaches the crossing 56, it passes a first primary sensor probe 50a positioned at a first predetermined distance from the crossing 56 and is detected. The first primary sensor probe 50a provides a train detection signal to the control unit 32 which is preferably located in the underground vault near the crossing 56. As the train 52 continues toward the crossing 56, it reaches a second primary sensor probe 50b positioned at a second predetermined distance from the crossing 56 such that its distance from the first primary sensor probe 50a is known. The second primary sensor probe 50b also detects the presence of the train 52 and sends a second train detection signal to the control unit 32. Electronic circuitry, preferably including a microprocessor, in the control unit 32 measures the time interval between receipt of the first train detection signal and receipt of the WO 97/25235 PCT/US97/00153 second train detection signal and using the known distance between the first and second primary sensor probes 50a 50b calculates the speed of the train 52 and the time it will take the train 52 to reach the crossing 56.

A secondary or backup subsystem may also be provided should the primary system fail to properly detect the approaching train. Like the primary subsystem, the backup subsystem may include magnetometer sensor probes buried in the earth in the right-of-way on either side of the grade crossing 56. Each backup sensor probe 50c is preferably positioned at a predetermined distance from the crossing 56 along the track 62. The backup sensor probes 50c, however, are placed between the second primary subsystem sensor probe and the grade crossing 56 at a sufficient distance from the crossing to permit activation of the warning signal devices 12 before the train 52 reaches the crossing. During normal operation, the primary subsystem, upon proper detection of a train 52 by both the first and second primary sensor probes 50b, disables operation of the backup system. If, however, the primary subsystem malfunctions or the train 52 is not detected by both of the primary sensor probes 50a 50b, the backup subsystem provides means of activating the warning signal devices 12 before the train 52 reaches the crossing 56. For example, the approaching train 52 is detected by the first primary sensor probe 50a. However, due to malfunction, the second primary sensor probe 50b fails to detect the train 52. The primary subsystem cannot determine the speed of the approaching train 52 in order to determine the appropriate time in which to activate the warning signal devices 12. Electronic circuitry, preferably including a microprocessor, within the control unit 32 does not disable the backup subsystem. As the train 52 continues toward the crossing 56, it reaches the first of the backup sensor probes 50c and is detected. The backup sensor probe 50c provides a signal to the control unit 32 which may immediately activate the warning signal devices 12.

A crossing guard subsystem may be provided comprising apparatus capable of detecting the presence of a train 52 either moving or stopped across WO 97/25235 PCT/US97/00153 11 the grade crossing 56. The crossing guard subsystem preferably allows the warning system to continue activation of the warning signal devices 12 until the train 52 clears the crossing. The crossing guard subsystem is preferably enabled when either the primary or backup subsystems detect the presence of a train 52 approaching the crossing 56. An infrared transmitter 64 and receiver 66 may be mounted on posts 68 located near the crossing 56 on either side of the track 62. Preferably, these posts 68 are positioned so that the transmitter 64 may transmit an infrared beam of light diagonally across the crossing 56 to the receiver 66. If a train 52 is present in the crossing 56 the infrared beam is interrupted and does not reach the receiver 66. The receiver 66 then may provide a signal to the control unit 32 indicating the presence of a train 52 in the crossing 56. After the train 52 has passed the crossing, the receiver 66 may provide a signal to the control unit 32 indicating that the end of the train 52 has cleared the crossing 56. The control unit 32 may then deactivate the warning signal devices 12 immediately or after a predetermined interval of time, for example 10 seconds. When no train has been detected by the warning system's primary or backup subsystems, the crossing guard subsystem is preferably disabled by the control unit 32 to avoid false activation of the warning signal devices 12 by an automobile or truck passing through the crossing.

As illustrated in FIG. 4, the warning system 10 may include several standard components which may be easily assembled together when deployed at a remote site such as a grade crossing located in a rural area. The control unit 32 may be mounted in an above-ground enclosure 70. This enclosure may be made of steel and have a locking mechanism 78 to prevent vandalism.

The enclosure 70 may be mounted to a mast or like support 42 which may also provide means for supporting the solar panel array 40. Cables 58 may be provided to interconnect the warning signal device 12, sensor probes 50, and control unit 32. These cables 58 may be buried in the earth adjacent to the tracks during installation of the warning system 10. Conduits 72, preferably WO 97/25235 PCT/US97/00153 12 made of steel or the like, may be provided to protect cable not buried.

FIG. 5 depicts a railroad crossing warning signal device 12 according to an exemplary embodiment of the present invention. The warning signal device 12 preferably comprises a standard X-shaped railroad crossing warning sign or "crossbuck" 18 mounted on a post or mast 20. The surface of the crossbuck 18 preferably includes a plurality of reflectors, reflecting paint or the like for reflecting the lights of an automobile. A plurality of high intensity light emitting diodes 22 or the like may be mounted across the center of the crossbuck 18 in an X-shape. These LEDs 22 may be animated, i.e. made to repeatedly flash on and off to attract the attention of motorists and enhance visibility of the sign at night or in poor weather conditions. Further, a shroud 74 may be mounted on the mast 20 behind the crossbuck 18 to improve the contrast between the crossbuck 18 and its background. Preferably, this shroud 74 is black. A strobe light/train direction advisory sign 24 may be mounted above the crossbuck 18 on the mast 20. Like the crossbuck 18 this sign 24 may also have a black shroud 76 to improve the contrast between it and its background. The upper half of the sign 24 may comprise an array of strobe lights 26 which when activated function to alert the motorist of an approaching train. Preferably the array comprises four strobe lights which may have an intensity of approximately 4.5 million candlepower each. The strobe lights 26 are preferably red in color and may strobe or flash at a rate of approximately 440 flashes per minute to indicate to the motorist that he must stop. The lower half of the strobe light/train direction advisory sign 24 may comprise a train direction indicator 28 which provides a means of indicating to the motorist the direction the approaching train is traveling. The train direction indicator 28 may comprise a plurality of amber colored lamps 30 placed adjacent to each other so that they form a straight line. Upon detection of the presence of an approaching train by the system, these lamps 30 may be lighted sequentially to indicate the direction in which the train is traveling. For example, if a train is approaching the crossing from the left, the left-most lamp 30a is lighted first, WO 97/25235 PCT/US97/00153 13 then extinguished. Immediately thereafter, the next lamp in line 30b is lighted and extinguished, then the next 30c, and so on in quick succession until the right-most lamp 30d is lighted then extinguished so that to a motorist viewing the sign 24, a single light appears to move from left to right. This sequence is then repeated until the train clears the crossing and the warning signal device 12 is deactivated. If a train approaches the crossing from the right, the sequence is reversed so that it would appear to a motorist viewing the sign 24 that a single light moves from right to left. Embodiments of the warning signal device 12 may further include an audible warning means such as a siren horn or bell to provide an audible output signal (not shown).

FIG. 6 is a block diagram illustrating the interconnection of the various subsystems and components of the warning system. A sensor subsystem may comprise a primary sensor probe array 82 and a backup sensor probe array 84 each including several magnetometer sensor probes and corresponding electronic circuitry to determine when a probe has detected the presence of a train. The sensor probes of the primary sensor probe array 82 are preferably arranged to form speed traps on either side of the grade crossing. Each speed trap may comprise two sensor probes placed at a predetermined distance from each other. The backup sensor probe array 84 may comprise two backup sensor probes placed on either side of the crossing between the crossing intersection and the innermost primary sensor probe.

The sensor probes are preferably sealed assemblies which may be buried in earth for their useful life. Each sensor probe may be interconnected with electronic monitoring circuitry which produces a binary (on or off) signal when the presence of a train is detected by that probe. The primary sensor probe array 82 is monitored by electronic circuitry of the primary control subsystem 86 while the backup sensor probe array 84 is monitored by electronic circuitry of the backup control subsystem 88. Both the primary and backup sensor probe array monitoring circuitry is preferably located in the control unit which may be housed an environmentally sealed equipment enclosure 70 (FIG. 4) or WO 97/25235 PCTIUS97/00153 14 vault 34 (FIG. The sensor subsystem 80 may comprise eight Cartel CT-6 magnetometer probe assemblies 50 (FIG 4) which terminate into five each CT- 2N circuit board subassemblies (not shown). The CT-2B control board may be modified to include the addition of a voltage spike protection zener diode across its probe input connectors (not shown). This modification may substantially reduce the vulnerability of the assembly to damage should lightning strike the immediate vicinity of a sensor probe. The CT-6 probe construction features a sheath containing an epoxy encapsulated coil of wire terminated to a shielded cable.

Interconnecting cable 58 (FIG. 4) may be provided between the sensor probes and the control unit. This cable may be a foam/skin insulated filled cable meeting REA Specification PE-89, such as CASPIC FSF manufactured by Essex Groups, Inc. of Decatur, Illinois. The interconnecting cable may be buried in the earth and preferably features sheathing to provide protection against water penetration, and mechanical or rodent damage. The cable may also be shielded to reduce susceptibility to natural or manmade electromagnetic interference. Preferably, the cable is capable of supporting sensor probes located at distances of 2 or more miles from the associated control unit. However, the present invention would seldom require cable lengths longer than a half mile. (A speed trap located mile from a grade crossing would allow 25 seconds of warning time for a train traveling at 72 miles per hour.) A cable monitoring or cable guard subsystem 100 (FIG. 6) may monitor the integrity of a closed loop circuit in the buried cable. In the event that the cable is cut or damaged, the cable guard subsystem 100 preferably forces the warning system 10 into a fail safe condition 90 mode of operation resulting in illumination of the warning signal device's displays 92, which include the crossbuck LEDs 22 (FIG. strobe lights 26 (FIG. and train direction indicator 28 (FIG. 5) and audible warning means.

The control unit preferably comprises four additional subsystems: the primary control subsystem 86, the backup control subsystem 88, the WO 97/25235 PCT/US97/00153 data recording or data logger subsystem 94, and the warning signal device control subsystem 96. The primary control subsystem 86 may include the speed trap sensor probe monitoring circuits and a dedicated microprocessor assembly. This subsystem monitors the speed trap sensor probes and upon detection of an approaching train, determines parameters such as the train's speed, length, and the like in order to initiate activation of the warning signal device displays 92 located at the grade crossing. Preferably, the warning signal device displays 92 are activated at a predetermined time interval before the train reaches the crossing, regardless of the train speed. The primary control subsystem 86 may also initiate deactivation of the warning signal device displays 92 when the sensor probe arrays 82 84 and/or crossing guard subsystem 98 sense that the end of the train has passed the grade crossing.

The primary control subsystem 86 may then reset the system in preparation for another train.

The backup control subsystem 88 preferably comprises a micro controller assembly which monitors the backup sensor probe array 84. If not disabled by the primary control subsystem 86, the backup control subsystem 88 may initiate activation of the warning signal device displays 92 whenever one or more of the backup sensor probes detects a train. Preferably, this subsystem is automatically operational in the event of a failure of the primary control subsystem 86.

The data recording or data logger subsystem 94 may comprise a micro controller subassembly including a microprocessor, date/time clock, and battery protected random access memory. This subsystem may monitor the primary control subsystem 86 and record various parameters including the speed and length of each passing train as well as the function of the system during each train passing. In addition, the data logger subsystem 94 may periodically perform diagnostic tests of the backup control subsystem 88 and backup sensor probe array 84. If the backup subsystem 88 is found faulty, the data logger subsystem 94 may place the warning system 10 into the fail-safe WO 97/25235 PCT/US97/00153 16 condition 90 mode of operation. The microprocessor assembly (not shown) may include a lithium battery or the like to maintain the date/time clock and to maintain information stored in volatile memory.

The primary control subsystem and data logger micro controller assemblies may employ 8-bit microprocessors or the like. For example, the primary control subsystem 86 may utilize an RTC 31/52 computer board assembly, manufactured by Micromint Inc. of Vernon, Connecticut. Similarly, the data logger subsystem 94 may utilize a NanoLink micro controller board assembly, manufactured by Dison Technologies of Santa Barbara, California.

Software may be employed to control the microprocessor's operation and to set operation variables. Thus, the warning system may be configured to meet the operational requirements of an individual site operational without modification to the system's hardware or physical installation.

The crossing guard subsystem 98 including the crossing guard transmitter 64 (FIGS. 3A, 38) and receiver 66 (FIGS. 3A, 3B) may provide a signal to the control unit indicating the presence of a train in the crossing. The control unit may use this signal to continue activation of the warning signal displays 92 when a train has stopped in the crossing and thus would not otherwise be detected by the backup sensor probe array 84. The control unit may utilize this signal to verify when a train has cleared the crossing.

The warning signal device control subsystem 96 may comprise relay logic circuits switched on and off by the control unit's subsystems to provide fail safe operation of the warning signal device displays 92. All relays in the subsystem are preferably maintained in the actuated (contacts open) state at all times. All relays are preferably industrial quality electro mechanical or solid state relays.

A power supply subsystem 102 may be provided comprising one or more rechargeable batteries and recharging circuitry. This recharging circuitry may operate using conventional 120/240 VAC electrical power from a public utility or other external source. In more remote areas, a solar panel array may WO 97/25235 PCT/US97/00153 17 provide electrical power to recharge the batteries so that the system may be operated independently from outside power sources. The power supply's batteries and recharging circuitry may be mounted in the same waterproof underground equipment vault which houses the control unit.

The railroad crossing warning system 10 may provide redundant means to activate the warning device displays 92 located at the railroad grade crossing. The system preferably comprises two basic layers of protection: (1) the control subsystems and the fail safe condition. The control subsystems may include two separate subsystems having electronic circuitry used to control the warning signal device displays 92: the primary control subsystem 86 and its associated primary sensor probe array 82, and the backup control subsystem 88 and its associated backup sensor probe array 84. The primary control subsystem 86 monitors the primary sensor probe array's speed traps and activates the warning signal device displays 92 whenever a sensed event the detection of a train) is deemed a normal train passing event the train passes through a speed trap within a defined time window). If the sensed event does not fall within "normal" train passing event criteria, control of system preferably reverts to the backup control subsystem 88. If the sensed event falls within "normal" train passing event criteria, the primary control subsystem 86 may disable the backup control subsystem 88 and take control of the system.

During the time that the backup control subsystem 88 is disabled, the primary control subsystem 86 may analyze the backup control subsystem 88 for proper operation. If the backup control subsystem 88 is found faulty, the primary control subsystem 86 may place the entire warning system into the fail safe mode of operation. Conversely, the purpose of the backup control subsystem 88 is to activate the warning signal device displays 92 in the event that the primary control subsystem 86 is unable to do so. Thus, redundancy is achieved by virtue of the backup subsystem's capability to protect a grade crossing should the primary control subsystem fail. Additionally, the backup control subsystem 88 may offer protection whenever unusual events (i.e.

WO 97/25235 PCT/US97/00153 18 events which do not fall within "normal" train passing event criteria) are in process. Examples of unusual events include: 1. A short train passes slowly through a primary sensor probe array 82 speed trap and stops. When the train again moves, it may be detected by the backup sensor array 84 allowing the backup control subsystem 88 to activate the warning signal device displays 92.

2. A train comes to a stop while spanning the crossing. The crossing guard subsystem 98 may continue activation of the warning signal device displays 92. When the train again moves, the backup control subsystem 88 may continue activation of the warning signal device displays 92 since the primary sensor probe array 82 would not have detected the train.

3. A high railer passes through a primary sensor array speed trap in the reverse direction it is detected by the innermost sensor probe before being detected by the outermost sensor probe). When the outermost sensor probe detects the high railer, the primary control subsystem's micro controller is alerted that an event may be in progress.

The micro controller finds that the innermost sensor probe has already detected the train. Since the micro controller may require about .32 seconds to become fully active after being alerted that the outermost sensor probe is tripped, it determines that something has passed through the speed trap in about 0.32 seconds (in excess of 200 mph), rejects the event as being outside normal train passing event criteria, and does not disarm the backup control subsystem 88.

The second level of redundancy is provided by the fail safe condition The fail safe condition 90 is the condition where a vital relay is no longer energized. Upon loss of power to the vital relay the relay contacts may close thus providing power to the warning signal device displays 92. The warning signal device displays 92 may remain illuminated until maintenance is performed on the system and the control unit circuitry is manually reset. The WO 97/25235 PCT/US97/00153 19 fail safe condition mode of operation is the final level of redundancy regarding protection of the grade crossing. The fail-safe condition may be achieved by maintaining a display relay in a contacts-open position whenever the warning signal device displays 92 are not to be illuminated. In the event of a failure of the control unit circuitry the vital relay would be de-energized and would revert to it's normally closed state. Closure of the relay connects the warning signal device displays 92 directly to battery power and the displays remain illuminated until the fault is repaired and the system is reset by maintenance personnel.

FIGS. 7 and 8 depict alternative embodiments of the present invention wherein the warning signal device may be modified for use at grade crossings experiencing a high volume of automobile traffic. As shown in FIG. 7, the warning signal device 12 may comprise a standard crossing gate 110 to prevent motorists from entering the grade crossing when an approaching train is detected. Upon detection of an approaching train and activation of the warning signal device by the system, a cantilevered arm 112 may be lowered across the roadway at the entrance to the crossing to block automobiles from entering the crossing. After the train has cleared the crossing, the arm 112 may be raised to allow traffic to pass through the crossing. The gate 110 be mounted directly to the mast 20 of the warning signal device 12 or may itself be free standing. A plurality of lights such as LEDs 114 may be mounted along the center of the arm 112. These LEDs 114 improve the motorists ability to see the closed gate at night or in poor weather. Although a standard railroad crossing gate 110 is shown, the present invention anticipates the use of four quadrant gates and the like. FIG. 8 illustrates an alternative arrangement of the warning signs. A cantilever support structure 120 may have a cantilevered arm, truss assembly, or the like 122 which may extend over a multilane roadway. One or more animated crossbucks 18 may be mounted on this structure as required to adequately warn motorists in all lanes of traffic.

Likewise, multiple strobe light/train directional indicator signs 24 may be mounted on the cantilevered arm 122 of the support structure 120 to warn the WO 97/25235 PCT/US97/00153 motorists in all lanes of traffic.

FIG. 9 illustrates the use of the present invention in a crossing 128 having multiple railroad tracks such as in an industrial area or near a freight yard. Sensor probes 50 may be placed at various positions on along of the tracks 130 to detect the presence of oncoming trains 132. Preferably the sensor probes 50 are buried in the right of way along the outermost train rails 134 and are capable of detecting a train moving along any of the tracks 130.

In view of the above detailed description of a preferred embodiment and modifications thereof, various other modifications will now become apparent to those skilled in the art. The claims below encompass the disclosed embodiments and all reasonable modifications and variations without departing from the spirit and scope of the invention.

B. Description of FIGS. 10 to FIG. 10 illustrates a typical application of a second embodiment of the present invention. A maintenance-of-way crew 100 is required to work on a length of active railroad track 120 in an area defining a construction zone 140.

The maintenance-way-crew 100 provides necessary upkeep and maintenance of the railroad tracks 120 which may be active, meaning that the tracks 120 are in use by trains while construction is being performed. The possibility of an oncoming train 160 poses a serious safety hazard to the crew 100 working on the track 120 who must concentrate on the construction work to be performed while constantly being alert to the possible oncoming train 160. Often the topography of the land and nearby flora and fauna prevent the workers 100 from becoming aware of the oncoming train hazard 160 to sufficiently move themselves and their equipment to a position of safety before the arrival of the train 160. Thus, the combination of the terrain, flora and fauna, such as a clustering of trees 180, and the layout of the track 120, such as bend 200, may combine to block the view and sounds of an oncoming thereby increasing the safety hazard to the maintenance-of-way crew 100. The present invention provides a system to detect an oncoming train 160 to provide adequate warning WO 97/25235 PCT/US97/00153 21 of the railroad construction crew 100 to maneuver to a position of safety in time to avoid an accident.

As can be seen from FIG. 10, a remote sensor unit 220 is placed at a predetermined distance, preferably approximately one mile, in either or both directions along tracks 120. Each sensor unit 220 preferably includes two sensor probes 240 which are capable of detecting the presence of a train 160.

The sensor probes 240 are preferably responsive to local disturbances of an electromagnetic field, such as the disturbance of the magnetic field of the earth caused by the passing of the train 160, a large metallic object.

In response to the passing train 160, the sensors 240 send a detection signal to the sensor unit 220 which contains the necessary processing electronics to process the detection signal of the sensors probes 240. The sensor unit 220 includes signal transmission means which is preferably a radio frequency transmitter with an antenna 260 to transmit the train detection signal to a receiver unit 280. The receiver unit 280 is located in the vicinity of the construction zone 140 and the workers 100, and includes signal receiving means which preferably includes an antenna 380 and a radio frequency receiver. The receiver unit 280 includes processing electronics necessary to receive and process train detection signals received from the sensor unit 220.

A crew warning means 400 is coupled to the receiver unit 280 to visually and audibly alert and warn the crew 100 that an oncoming train 160 has been detected. Upon being alerted by the crew warning means 400, the construction crew 100 may move to a safe position until the train 160 has passed, whereupon the crew 100 may resume working. The sensitivity of the sensor probes 240 may be optimally adjusted such that only the mass of a train 160 will trigger the warning system and that other vehicles such as a truck 420 will not cause false alarms which degrade the confidence of the workers 100 in the integrity of the warning system.

FIG. 11 illustrates the main components of the present invention.

Sensor unit 220 preferably comprises a light weight and durable plastic, WO 97/25235 PCT/US97/00153 22 fiberglass or steel weatherproof housing which contains sensing, processing and control electronics. The sensor unit 220 preferably includes a solar panel array 440 which provides power to the electronic sensing circuitry contained within the sensor unit 220 and is used primarily to maintain a charge on a power supply battery contained within the sensor unit 220. The sensor unit 220 includes receiving jacks 460 for receiving a plug 480 at the end of sensor probe 240. The sensor probe plug 480 connects to a receiving jack 460 of the sensor unit 220 via a length of probe cabling 500. The length of the probe cabling 500 is sufficiently long to allow the positioning of the sensor probe 240 near the railroad track 120 while allowing for the positioning the sensor unit 220 in an optimal position to receive maximum solar energy incident upon the solar panel array 440.

The crew warning means 400 includes a portable light standard 520 which may be erected near the construction zone 140. The light standard 520 preferably includes telescopic legs 560 which extend from and are hinged at a spring resistance hinge 580 making the light standard 520 readily collapsible and capable of being placed upon uneven terrain while remaining sturdily in place. The light standard 520 preferably includes four legs but may alternatively use three legs as well. Erected vertically from spring hinge 580 is a mounting shaft 600 upon which are mounted visual warning means 620 and audio warning means 640. The visual warning means is preferably two L.O.S.

beacons mounted on the mounting shaft such that the light emitted therefrom sweeps horizontally in order to cover a maximum area which includes the construction zone 140. The beacons may be Commander Strobe Beacons, Model 5200 manufactured by Whelen Engineering Co. of Chester, Connecticut, the beacons using a xenon flash bulb. The audio warning means 640 preferably includes two warning siren horns capable of emitting a high decibel warning sound that can be heard over the noise of construction activity. The beacons 620 and horns 640 are mounted to a mounting unit 660 which is in turn mounted to the mounting shaft 600. Two safety flags 680 of bright safety WO 97/25235 PCT/US97/00153 23 orange color are mounted at the top end of the mounting shaft 600 to generally alert others that construction activity is occurring in the vicinity. An omindirectional antenna 380 is mounted on the shaft 520 and connected to the receiver unit 280.

The antenna 380, beacons 620 and horns 640 are connected to the receiver unit 280 via a receiver cable 700 which connects to a jack 460 with a plug 480 at the end of the cable 700. The receiver unit 280 is generally of the same or similar construction as the sensor unit 220 in that it is constructed of a light weight plastic, fiberglass or steel material and is weatherproof. The receiver unit 280 is constructed having a hinged lid 720 which is opened during operation. A solar panel array 440 is mounted in the lid 720 of the receiver unit 280 which may receive energy when the lid 720 is in an open position. The receiver unit 280 also includes a control panel (not shown) having basic operational controls on-off switch, reset switch, etc.). The receiver unit may also include a handle 740 for ease of portability.

FIG. 12 depicts the operation of the present invention in detecting the presence of an oncoming train. The receiver unit 220 is placed up the tracks 120 from the construction zone 140 at a predetermined distance therefrom. In a preferred embodiment of the present invention the receiver unit 220 is placed approximately one mile from the construction zone 140 which provides approximately one minute warning time to the crew 100 for average train speeds of sixty miles per hour.

The sensor probes 240 are placed alongside the train tracks 120 parallel thereto. Only one probe 240 is required to sense a train 160, but preferably two probes 240 are utilized for redundancy in case of failure of one of the probes. Further, the utilization of two probes provides both information as to the direction and speed of the oncoming train. In an alternative embodiment of the present invention, two sensor probes 240 may be utilized to detect the direction and speed of an oncoming train 160. Further, it has been found that the sensor probes 240 are directionally sensitive in that the probes 240 exhibit WO 97/25235 PCT/US97/00153 24 greater sensitivity at the end of the probe 240 connected to the probe cable 500. Preferably, the probes 240 are laid alongside the tracks 120 with the end of the probe 240 connected to the cabling 240 pointing toward the direction from which the oncoming train 160 will approach and the free end of the probe 240 pointing toward the construction zone 140.

A moving incoming train 160 induces current in the sensor probe 240 upon the train passing by the probe 240. The induced signal from the train 240 is detected by the electronic circuitry of the receiver unit 220 and transmitted to the receiver unit 280 which is located at the construction zone 140. The sensor unit 220 and the receiver unit 280 are couple via a radio frequency communications link 760. The receiver unit 280 receives the transmitted detection signal from the sensor unit 220 and thereupon activates the crew warning means 400 which is placed in the vicinity of the construction zone 120. The beacon and the horns are thereby activated, visually and audibly alerting the crew 100 to the presence of the oncoming train 160.

FIGS. 13 and 14 illustrate the operation of an embodiment of the present invention in which two sensor units are utilized. A first sensor unit 220A and a second sensor unit 220B each placed in either direction down the tracks 120 form the construction zone 140. As shown in FIG. 13, an incoming train 160 passing by sensor unit 220A activates the crew warning means 400 whereupon the crew 100 may take precautionary action.

As shown in FIG. 14, sensor unit 22B will be activated as the train 160 exits the construction zone 140 and passes sensor unit 220B further long down the tracks 120. When the train 16 has completely passed by sensor unit 220A, sensor unit 220A stops transmitting the train detection signal to the receiver unit. The sensor unit 220B will send a detection signal to the receiver unit 280 upon the passing of the train 160. The receiving of a detection signal from down track receiver unit 220B indicates and verifies the passing of the train whereupon the receiver unit may initiate automatic deactivation of the crew warning means 400.

WO 97/25235 PCTIUS97/00153 The warning system is thereby automatically reset and ready to detectthe next incoming train. Logic processors included with the electronic circuitry of the receiver unit are capable of processing the presence, absence, sequence and timing of the detection signals from sensor unites 220A and 220B, activating the crew warning means 400 when a train 160 is incoming and deactivating the crew warning means 400 when the train 160 has passed and then resetting the system.

A manual reset means is also provided.

FIG. 15 illustrates schematically the electronic components of the present invention. The sensor probes ("SENSOR") 240 connect to sensor unit 220 and are coupled to sensor processor cards ("SP CARD") 780. The sensor processor cards 780 interface with electronic processing means ("PROCESSOR") 800 and include circuitry electronic circuitry to act as a buffer between the sensors probes 240 and the processing means 800.

In a preferred embodiment of the present invention, the sensors probes 240 comprise an inductor coil winding having a powdered iron core or other similar paramagnetic material. The sensors probes detect variations in the magnetic field of the earth when a train passes nearby by detecting the resulting change of permeability of the space surrounding the inductor coil. A moving train passing by the sensor probe 240 alters the magnetic flux lines of the earth's magnetic field through the inductor coil of the probes 240 thereby inducing a current in the inductor coil of the sensors 240 which is detected, received and amplified by the sensor processor cards 780. Thus, sensor probes 240 provide an electrical output signal in response to local variance in the magnetic field of the earth caused by a passing train. The sensors function similarly to musical instrument pickups with the magnetic field of the earth acting as the permanent magnet and the train acting as the vibrating strings.

The sensors probes 240 are preferably Cartel CT-6 magnetometer probes available from Preferred Technology Group of Lancaster, Pennsylvania or similar thereto. The sensor processor cards 780 include magnetometer control circuits also manufactured by Preferred Technology Group available as CT-2B circuit .4 WO 97/25235 PCT/US97/00153 26 board subassemblies. The sensor processor cards 780 preferably include a voltage spike protector clamp across the probe input terminals 460 to protect the circuitry from environmental voltage spikes caused by lightning, for example. The sensitivity of sensor probes 240 may be adjusted with the sensor processor cards 780. The sensitivity of the sensor probes 240 is preferably optimally adjusted to detect trains without being triggered by other types of vehicles cars, trucks, etc.).

The processor means 800 connects with a detector processor and transmitter ("DETECTOR(S) PROCESSOR TRANSMITTER") 820 which includes communications means for communicating with the receiving unit 280 including an internal antenna ("ANTENNA") 260. The sensor unit 220 preferably receives operational power from a battery ("BATTERY") 840 and solar panel array ("SOLAR") 440. The battery 840 is preferably a rechargeable lead acid type battery designed to operate in extreme environmental conditions. Alternatively, the rechargeable battery 840 may comprise other various types of rechargeable electrochemical cells such as alkaline, nickel-cadmium, nickel-metal hydride, sealed lead-acid, zinc-air or lithium ion cells or the like, for example.

The solar panel array 440 may be utilized to provide electrical energy converted from solar energy to charge the battery 840 and to provide a trickle charge thereto to keep the battery 840 topped off. Additionally, the solar panel array 440 may be utilized to provide supplemental operational power to the detector unit 120 in case of depletion of the battery charge or battery failure, for example.

A similar battery ("BATTERY") 880 and solar panel array ("SOLAR") 440 are also included with the receiver unit 28 for providing operational power thereto. The battery 880 is preferably a sealed, rechargeable lead-acid type battery manufactured by GNB Industrial Battery Company of Saint Louis, Missouri as the "ABSOLYTE" product which is designed for solar service and railroad equipment applications. The battery 840 preferably includes a battery charging regulator model ASC 12/2 available from Siemens Solar Inc. of Camarillo, California. The solar panel 440 is a model M75 available also available form Siemens.

WO 97/25235 PCT/US97/00153 27 Upon the detection of an oncoming train 160, the transmitter 820 transmits a signal via a radio frequency communications link ("RADIO LINK") 760 to a receiver ("RECEIVER PROCESSOR") 860 contained within the receiver unit 280.

Antennas ("ANTENNA") 260 and 820 are provided for the transmitter processor 820 and the receiver processor 860 respectively to increase the signal gain of the radio communications link 760. The radio communications link 760 preferably utilizes a band of 8 spread spectrum channels at a frequency licensed by the Federal Communications Commission for such type of radio frequency communications. The radio frequency communications between the sensor unit 220 and the receiver unit 280 is preferably dual-tone multiple frequency (DTMF) encoded, spread spectrum modulated transmission to avoid unintended jamming or interference from other radio frequency sources operating in the vicinity thereby preventing loss of communication or false alarms. The processors (800, 820, 860) of the present invention are preferably implemented in RTC31/52 computer board assemblies as manufactured by Micromint Inc. of Vernon, Connecticut.

In the event that a train encroaches the vicinity of the sensor unit 220, the sensor probes 240 detect the presence of the train and send a detection signal received by the sensor probe cards 780 of the receiver unit 220. The sensor probe cards 780 send a signal to the processor 800 in response to the detection signal received from the sensor probes 240. The processor 800 activates the detector transmitter 820 to commence transmission of a coded warning signal to the receiver 860 of the receiver unit 280. The receiver 860 receives and decodes the transmitted warning signal whereupon a latch relay ("LATCH RELAY") 900 is triggered to activate visual warning means ("WARNING LIGHT") 620. Further, a switch and relay ("SWITCH RELAY") 920 is triggered thereby activating audible warning means ("HORN") 640. The visual and audible warning means (620, 640) alert the workers of the approaching train so that they may take the necessary evasive actions to stop work and to move themselves and any equipment to safety.

After the train 160 has passed, a manual reset switch ("RESET") 940 may be engaged by the workers to reset the latch relay 900 and the switch and relay WO 97/25235 PCT/US97/00153 28 920, thereby turning off the visual and audible warning means (620, 640) warning and resetting the warning system for the next train detection event. Alternatively, the warning system may be programmed to automatically rest upon passing of the train as it is sensed passing a second sensor unit 220.

An important feature of the present invention is a handshaking communications protocol between the sensor unit 220 and the receiver unit 280.

The sensor unit 220 preferably transmits an "all clear" call signal at periodic intervals every five seconds) to the receiver unit. The successful transmission and reception of the call signal verifies the proper functioning of the crew warning system. If the all clear call signal is not received, the receiver unit 280 immediately enters into an alarm mode. In the alarm mode, a system fail warning light located on the control panel of the receiver unit or other alarm may be activated to alert the workers that protection is no longer provided by the warning system The failure to receive the call signal may be caused by battery failure, component failure, unforeseen damage to the sensor unit 220, or loss of integrity of the radio frequency communication link 760, for example.

In an alternative embodiment of the present invention, multiple sensor units 220 may be utilized in areas having multiple railroad tracks. Each sensor unit 220 is preferably capable of operating in conjunction with up to four sensor probes 220 simultaneously. Further, the receiver unit 280 is preferably designed to receive and process up to eight different transmission codes from eight individual sensor units 220 simultaneously. Utilization of multiple probes 240 and sensor units 220 is of particular utility in areas having several railroad track such as wyes, spurs, or switchyards, for example.

Additional embodiments of the present invention contemplate implementation of an event recorder for monitoring and recording train activity. The recorded event data may be utilized in analysis of accidents or close calls to determine event causation and to learn how the system may be improved if necessary. The event recorder may be implemented by additional programming of the microprocessors (800, 820, 860) of the present invention in conjunction with WO 97/25235 PCT/US97/00153 29 non-volatile electronic memory NVRAM, EEPROM, FLASH RAM) or battery refreshed electronic memory SRAM, DRAM) or other means for saving the event data magnetic tape). The electronic memory is preferably a 64 kilobyte static random access memory chip (SRAM) backed by a lithium type battery. Other types of data may also be monitored and recorded such as battery charge condition, train speed, train length, direction of approach, etc.

In view of the above detailed description of a preferred embodiment and modifications thereof, various other modifications will now become apparent to those skilled in the art. The claims below encompass the disclosed embodiments and all reasonable modifications and variations without departing from the spirit and scope of the invention.

Claims (19)

1. A railroad crossing traffic warning system for alerting a motorist approaching a railroad crossing to the presence of an oncoming train, said warning system including: a first sensor positioned adjacent to a railroad track at a first predetermined distance from the railroad crossing operating independently of rails of said railroad track, said first sensor for detecting an oncoming train and for producing a signal in response thereto; a second sensor positioned adjacent to said railroad track at a second predetermined distance from the railroad crossing operating independently of rails of said railroad track, said second sensor for detecting an oncoming train and for producing a signal in response thereto; an alerting device for alerting the motorist to the presence of an oncoming railroad train such that the motorist may take cautionary or evasive action before S 15 the arrival of the train at the railroad crossing; and a controller operatively coupled to said sensor and said alerting device, said controller for receiving the signal from said sensor and controlling operation of said alerting device in response thereto, said controller further including: a processor for processing the signal received from said sensor and controlling said alerting device in response to said processed signal; a sensor signal interface for interfacing said processor with said sensor to provide the signal received from said sensor to said processor; and an alerting device interface for interfacing said processor with said alerting device, wherein said alerting device operates during a failure of said first sensor by detection of an oncoming train by said second sensor to provide fail-safe protection.

2. The railroad crossing traffic warning system of claim 1, wherein said first sensor and said second sensor comprises a magnetometer.

3. The railroad crossing traffic warning system of claim 1, wherein said controller comprises a rechargeable battery.

4. The railroad crossing traffic warning system of claim 1, wherein said alerting device comprises: -1 a support placed at an entrance to the railroad crossing; and MP W:narie\GABNODEL\18237c.doc -31 a visual warning assembly mounted on said support for providing a visual output signal, said visual warning assembly being responsive to said controller.

The railroad crossing traffic warning system of claim 4, wherein said visual warning assembly comprises an X-shaped railroad crossing warning sign, said warning sign having a reflector for reflecting the lights of an oncoming automobile and a plurality of lighting devices forming an X-shape.

6. The railroad crossing traffic warning system of claim 5, wherein said lighting device comprises a light emitting diode.

7. The railroad crossing traffic warning system of claim 4, wherein said visual warning assembly comprises a strobe light.

8. The railroad crossing traffic warning system of claim 4, wherein said visual warning assembly comprises a train direction indicator, said train direction indicator including a plurality of lamps arranged adjacent to each other in a line wherein said lamps may be lighted sequentially to indicate the direction in which 15 an oncoming train is travelling.

9. The railroad crossing traffic warning system of claim 1, wherein said alerting device comprises audible warning device.

The railroad crossing traffic warning system of claim 9, wherein said audible warning device comprises a siren horn.

11. The railroad crossing traffic warning system of claim 9, wherein said audible warning device comprises a bell.

12. A railroad crossing traffic warning system for alerting a motorist approaching a railroad crossing to the presence of an oncoming train, said warning system including: means for detecting an oncoming train and producing a signal in response thereto, said detecting means operating independently from rails of a railroad track; means for alerting the motorist to the presence of an oncoming train so that the motorist may take cautionary or evasive action before the arrival of the train at the railroad crossing; and means for receiving the signal from said detecting means and controlling said alerting means in response thereto, said controlling means further including: MP W:nmade\GABNODELt8237c.doc 32 means for processing the signal received from said detecting means, controlling said alerting device in response to said processed signal and monitoring operation of the system for proper function; means for interfacing said processing means with said detecting means to provide the signal received from said detecting means to said processing means; and means for interfacing said processing means with said alerting means wherein said detecting means includes at least two redundant devices to allow for operation of said alerting means if one of said redundant devices fails to operate correctly.

13. The railroad crossing traffic warning system of claim 12, wherein said detecting means comprises a magnetometer.

14. The railroad crossing traffic warning system of claim 12, further comprises means for supplying power to the system. S 15

15. The railroad crossing traffic warning system of claim 12, wherein said alerting means comprises: S--means for providing a visual warning to a motorist; and means, placed at an entrance to the railroad crossing, for supporting said visual warning providing means. 20

16. The railroad crossing traffic warning system of claim 15, wherein said alerting means further comprises means for indicating the direction in which the oncoming train is travelling.

17. The railroad crossing traffic warning system of claim 12, wherein said alerting means comprises means for providing an audible warning.

18. The railroad crossing traffic warning system of claim 1, wherein said processor is a microprocessor.

19. The railroad crossing traffic warning system of claim 1, wherein said processor further performs diagnostics to monitor operation of the system for proper function. MP W:'narie\GABNODEL\18237c.doc -33- A railroad crossing traffic warning system substantially as herein described with reference to the accompanying drawings. DATED: 6 December, 2000 PHILLIPS ORMONDE FITZPATRICK Attorneys for: EVA SIGNAL CORPORATION a o MP W:\marie\GABNODEL\18237c.doc