Control arrangement for a railroad level crossing

A control arrangement for a railroad level crossing is disclosed. The control arrangement comprises monitoring sensors for monitoring the level crossing, the monitoring sensors arranged to detect an obstruction within a restricted area at or near to the level crossing, and a processing unit associated with the monitoring sensors and arranged to generate an alarm warning when an obstruction is detected. The alarm warning is used to adjust a Movement Authority issued to a train approaching the level crossing.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a U.S. National Phase filing of International Application No. PCT/AU2016/050533, filed on Jun. 23, 2016, and claiming priority to Australian Patent Application No. 2015902470 filed Jun. 25, 2015. The present application claims priority to and the benefit of all the above-identified applications, which are all incorporated by reference herein in their entireties.

FIELD OF THE INVENTION

The present invention relates to a control arrangement for a railroad level crossing.

BACKGROUND OF THE INVENTION

A railroad level crossing is an intersection between a railroad and a road or path where the railroad traverses the road at the same level, i.e. instead of crossing over it using a bridge or under it using a tunnel.

A problem implicit in level crossings is the increased danger to users of the road due to a collision between a train and a person or vehicle that is traversing the railroad track. As it is not easy to quickly stop a train due to its momentum, the emphasis at level crossings is to clear the track of people and vehicles in advance when a train is approaching so that the train has a clear right of way through the level crossing. This is achieved in most cases by emitting a warning signal when a train approaches the level crossing to instruct users to clear the railroad track and subsequently blocking off the road by boom gates until the train has passed through the level crossing.

The applicant is aware of railroad safety systems to warn a train driver if a railroad track at a level crossing is not free, e.g. if it is occupied by a stalled vehicle or other obstruction. For example, such safety systems are discussed in EP 1849679. If the railroad track is obstructed, then an alarm warning is passed to the train driver to indicate to the driver to slow down or stop the train before it reaches the level crossing. There can also be automatic systems also exist that stop the train if the train driver does not react to the alarm warning.

A disadvantage of existing railroad safety systems is that they are primarily designed for regular passenger or goods trains, which have a much shorter length than heavy haul trains carrying mine ore that may be up to 1.8 km in length. As such the existing safety systems tend to be reactive to the detection of an obstruction at a level crossing and are therefore normally issued only a short period before the train reaches the level crossing. A normal reaction to an alarm warning being raised is thus to stop the train by applying its emergency brakes.

Heavy haul trains used for transporting mine ore normally travel vast distances in very remote areas. Due to increased labour costs and to improve operation efficiency, some of these heavy haul trains have been modified to be autonomous so that they operate without train drivers and are controlled remotely from a central operating office. The autonomous trains are fitted with additional radar and sensory equipment and mapping technology as well as having further trackside sensors installed along the railroad track to govern the movement of the train. In one embodiment utilised by the Applicant, the operation of such autonomous trains is regulated by issuing the train with a Movement Authority to cause the train to autonomously move at an authorised preselected speed to a predetermined location. A number of discrete Movement Authorities may be issued to a train during its transit from its origin to its endpoint destination, whereby each Movement Authority directs the train to move to a desired location.

The generation of each Movement Authority can be a manual process or it can itself be at least partially automated. In either case, a central operating office receives several input variables used to determine the desired Movement Authority. These variables may include, for example, the specific railroad track to use, the number and location of trains running on the track, the overall length of the respective trains, and the speed of travel of the respective trains. Using these variables, the central operating office ensures that the train is able to move without hindrance or possibility of collision with other trains.

As it is desirable to avoid unnecessarily stopping the trains, each Movement Authority is preferably calculated and issued prior to the expiration of an earlier Movement Authority.

SUMMARY OF THE INVENTION

According to one aspect of the present invention, there is provided a control arrangement for a railroad level crossing, the control arrangement comprising:

monitoring sensors for monitoring the level crossing, the monitoring sensors arranged to detect an obstruction within a restricted area at or near to the level crossing;

a processing unit associated with the monitoring sensors and arranged to generate an alarm warning when an obstruction is detected;

wherein the alarm warning is used to adjust a Movement Authority issued to a train approaching the level crossing.

The monitoring sensors may be provided on opposed sides of a railroad track passing through the level crossing.

The monitoring sensors may be provided diagonally across the level crossing.

The monitoring sensors may comprise laser scanner equipment.

The restricted area may comprise a plurality of zones, each zone associated with at least one of the monitoring sensors.

The restricted area may extend outwardly on opposed sides of the level crossing up to boom gates associated with the level crossing.

The monitoring sensors may be adapted to detect an obstruction previously present within the restricted area or an obstruction entering the restricted area.

The processing unit may comprise at least one timer associated with the monitoring sensors to determine a length of time that an obstruction has been detected within the restricted area.

The processing unit may comprise a first timer arranged to be continuously operable irrespective of whether or not a train is approaching the level crossing.

The first timer may be arranged to determine if the obstruction has remained in the restricted area for longer than thirty seconds.

The processing unit may comprise a second timer arranged to be operable only when a train is approaching the level crossing.

The second timer may be arranged to determine if the obstruction has remained in the restricted area for longer than ten seconds.

The processing unit may be operatively associated with an island track of the level crossing, whereby the processing unit may be arranged to determine whether or not an obstruction detected with in the restricted area is another train.

The processing unit may be arranged to prohibit generation of the alarm warning if the obstruction is detected in another train.

The alarm warning may be transmitted to a central operating office for the attention of an operator at the central operating office and wherein the alarm warning may be stored on a vital signalling server.

The alarm warning may be transmitted to a driver of the train.

The train may be an autonomous train with the alarm warning being transmitted to an automated train control system of the train.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring toFIG. 1of the drawings, there is shown a single railroad level crossing10showing a single railroad track12traversing a road14. Boom gates16are provided on opposed sides of the track12and, in use, are adapted to stop people or vehicles traversing a restricted area18over and/or near to the level crossing10when a train is approaching.

The level crossing10further includes a conventional short island track19which covers the width of the level crossing10. This island track19is adapted to determine if a train is traversing the level crossing10and to raise the boom gates16once the train has cleared the level crossing10.

The level crossing10is provided with a control arrangement20shown more particularly inFIG. 3.

The control arrangement20includes monitoring sensors in the form of laser scanner equipment, wherein two sensors are provided on opposed sides of the track12and are arranged diagonally across the level crossing10. InFIG. 1the first sensor is indicated as ODS1and the second sensor is indicated as ODS2. The first sensor ODS1is arranged to scan area zones of the restricted area18indicated by ODS11and ODS12, where ODS11is an area zone covering the track12near to the sensor ODS1and where ODS12is an area zone between the track12and its opposed boom gate16b. Similarly, the second sensor ODS2is adapted to scan area zones of the restricted area18indicated by ODS21and ODS22, where ODS21is an area zone covering the track12near to the sensor ODS2and where ODS22is an area zone between the track12and its opposed boom gate16a. The monitoring sensors ODS1and ODS2are arranged to detect any obstructions present within their respective area zones of the restricted area18.

As shown inFIG. 2, the control arrangement20can be similarly applied to a dual railroad level crossing22having a first (or eastbound) railroad track EML and a second (or westbound) railroad track WML traversing a road14. Due to the similarities between the single and dual railroad level crossings10and22, the same reference numerals are used to indicate like features.

Referring toFIG. 3, the control arrangement20includes a processing unit24adapted to generate one or more Movement Authorities26for a train (referred to hereinafter as the primary train) travelling along the track12. The processing unit24is adapted to receive input from the monitoring sensors ODS1and ODS2and to generate a Movement Authority for the primary train. If any obstruction is detected within the restricted area18then the processing unit24is adapted to adjust a subsequent Movement Authority issued to the primary train.

The processing unit24applies a logic process, generally indicated by reference numeral28, by which the processing unit24is able to determine if an obstruction is present at the level crossing10,22. The processing unit24has a first timer30associated with the sensors ODS1and ODS2. The processing unit24further has a second timer32associated with the sensors ODS1and ODS2, the second timer32also associated with a track relay34that is located along the track12in advance of the level crossing10,22. The track relay34is adapted to be activated (dropped) when a primary train approaches the level crossing10,22and passes beyond the track relay34.

The level crossing10,22is normally deemed to be in an inactive state when no primary train is approaching the level crossing10,22. However, if a primary train approaches the level crossing10,22and passes beyond (drops) the track relay34then the level crossing10,22is deemed to be in an active state. The level crossing10,22remains in the active state until the island track19indicates that the primary train has passed beyond and cleared the level crossing10,22, whereafter the level crossing10,22is again deemed to be in an inactive state.

The first timer30is associated with the sensors ODS1and ODS2by logic “OR” gates, whereas the second timer32is associated with the sensors ODS1and ODS2by a logic “AND” gate. The first timer30is adapted to be used in conducting a first stage analysis in determining if the level crossing10,22is obstructed. The second timer32is adapted to be used in conducting a second stage analysis in determining if the level crossing10,22is obstructed. Both the first stage analysis and the second stage analysis run concurrently. Nominally, in this example, the first timer30is programmed to reset at thirty second intervals, while the second timer32is programmed to reset at ten second intervals. Accordingly, the first stage analysis is repeated at thirty second intervals, while the second stage analysis is repeated at ten second intervals. However, it should be apparent that both these reset intervals can be adjusted as needed and can be independently configured for shorter or longer periods as desired.

During the first stage analysis, if either monitoring sensor ODS1or ODS2detects that an obstruction is present within any one of the area zones ODS11, ODS12, ODS21or ODS22of the restricted area18and the obstruction remains within the restricted area18for a period exceeding the nominal reset interval of the first timer30(e.g. thirty seconds) then, applying the steps of the logic process28, the processing unit24will reach a result determination36that the track12, EML or WML is obstructed at the level crossing10,22. This first stage analysis is performed continuously both while the level crossing10,22is in its active state and in its inactive state, i.e. irrespective of whether or not a primary train is approaching the level crossing10,22.

During the second stage analysis, if a primary train approaches the level crossing10,22and passes the track relay34, then the second timer32will be initiated and the level crossing10,22will be in an active state. If the presence of an obstruction is detected by either monitoring sensor ODS1or ODS2within any one of the area zones ODS11, ODS12, ODS21or ODS22of the restricted area18and the obstruction remains within the restricted area18for a period exceeding the nominal reset interval of the second timer32(e.g. ten seconds) then, applying the steps of the logic process28, the processing unit24will reach a result determination36that the track12, EML or WML is obstructed at the level crossing10,22. This second stage analysis is performed only while the level crossing10,22is in an active state, i.e. only if a primary train is approaching the level crossing10,22and has dropped the track relay34.

The logic process28further makes provision for an override switch38, which can be toggled to force the processing unit24to make an obstructed result determination36at the level crossing10,22irrespective of whether or not the presence of an actual obstruction is detected by either of the monitoring sensors ODS1or ODS2. Such an override switch38can be used, for example, if one or more of the sensors ODS1, ODS2becomes faulty or if the level crossing10,22requires maintenance work and the maintenance workers wish to ensure that no primary train will traverse the level crossing10,22.

Referring now toFIG. 4, there is shown an operational flow diagram400for the control arrangement20when used in relation to the level crossing10ofFIG. 1. After initialisation402, the level crossing10is initially in its inactive state404.

As explained above, the restricted area18is continuously monitored by the monitoring sensors ODS1or ODS2, even while the level crossing10is in the inactive state404. Thus should an obstruction406enter or be present in the restricted area18and remain in the restricted area18for a period exceeding the (thirty second) nominal period of the first timer30, then a result determination36is made that the level crossing10is obstructed. Should the obstruction be cleared408, then the level crossing10returns to its cleared inactive state404.

In the scenario where a primary train approaches the level crossing10and passes the track relay34thereby causing a relay drop410, the level crossing10is put into its active state412and the restricted area18will be monitored for the presence of obstructions by the monitoring sensors ODS1or ODS2in relation to the second timer32. If an apparent obstruction is detected, a further analysis thereof is made to determine if the apparent obstruction is an actual obstruction at the level crossing10.

It should be borne in mind that two trains can follow each other along the track12without forming an obstacle to each other provided they are moving in the same direction and at roughly the same speeds. Accordingly, if the two trains are relatively closely following each other, then a secondary train may still be traversing the level crossing10while the primary train is approaching the level crossing10. Thus the control arrangement20determines if the apparent obstruction is merely such a secondary train. This analysis is made by inspecting the island track19present in the level crossing10. If the island track19indicates that it is occupied414, the control arrangement20will identify that a secondary train is currently traversing416the level crossing10. Accordingly, the control arrangement20will take no further action but merely waits until the island track19is cleared418after the secondary train has passed out of the restricted area18so that the level crossing10can return to its active state412.

However, if the analysis of the island track19indicates that it is not occupied, then the control arrangement20will identify that the apparent obstruction is an actual obstruction420and a result determination36is made that the level crossing10is obstructed. For clarity, it is emphasised that the control arrangement20will reach an obstructed result determination36if the presence of any vehicle, any person or any other object is detected within in the restricted area18after the track relay34is dropped, apart from the presence of a secondary train which will not be considered to be an obstruction. The underlying reasoning therefore is that the location and direction and speed of movement of any secondary train will be known to the central operating office and thus will be taken into account when issuing Movement Authorities to the primary train.

Any result determination36reached that the level crossing10is obstructed results in the control arrangement20raising an alarm that serves to warn operators to prohibit the primary train from moving through the level crossing10. The alarm warning is transmitted to an automated train control system422present on the primary train and the alarm warning is concurrently transmitted to a vital signalling server424at the central operating office for reviewing by an operator at the central operating office.

Referring now toFIG. 5, there is shown an operational flow diagram500for the control arrangement20when used in relation to the level crossing22ofFIG. 2. After initialisation502, the level crossing22is initially in its inactive state504.

Similar to above, the restricted area18is continuously monitored by the monitoring sensors ODS1or ODS2, even while the level crossing22is in the inactive state504. Thus should an obstruction506enter or be present in the restricted area18and remain in the restricted area18for a period exceeding the (thirty second) nominal period of the first timer30, then a result determination36is made that the level crossing22is obstructed. Should the obstruction be cleared508, then the level crossing22returns to its cleared inactive state504.

In a scenario wherein a primary train approaches the level crossing22and passes the track relay34thereby causing a relay drop510, the level crossing22is put into its active state512and the restricted area18will be monitored for the presence if obstructions by the monitoring sensors ODS1or ODS2in relation to the second timer32. If an apparent obstruction is detected, a further analysis thereof is made to determine if the apparent obstruction is an actual obstruction at the level crossing22.

Again, it should be borne in mind that two trains can follow each other along either of the a tracks EML or WML without forming an obstacle to each other provided they are moving in the same direction and at roughly the same speeds. If the two trains are relatively closely following each other, then the secondary train may still be traversing the level crossing22while the primary train is approaching the level crossing22. This analysis is made by inspecting the island track514on the eastbound track EML and by inspecting the island track516on the westbound track WML. If the EML island track indicates that it is occupied514, the control arrangement20will determine that a secondary train is currently traversing518the level crossing22on the eastbound track EML. Similarly, when the WML island track indicates that it is occupied516, the control arrangement20will determine that a secondary train is currently traversing520the level crossing22on the westbound track WML. If both the EML and WML island tracks indicate that they are occupied514,516, either simultaneously or shortly after each other, then it indicates that secondary trains are traversing the level crossing22in both the eastbound and westbound directions522. Accordingly, the control arrangement20will take no further action but merely waits until both the EML and WML island tracks are cleared so that the level crossing22can return to its active state512.

However, if the analysis of the island track in the eastbound track EML indicates that it is not occupied, then it is known that the apparent obstruction detected within the area zones ODS22and ODS12is an actual obstruction524of the eastbound track EML. Also, if the analysis of the island track in the westbound track WML indicates that it is not occupied, then it is known that the apparent obstruction detected within area zones ODS11and ODS21is an actual obstruction526of the westbound track WML. Again, for clarity, it is emphasised that the control arrangement20will consider the level crossing22obstructed if the presence of any vehicle, any person or any other object is detected within the relevant area zones ODS11, ODS12, ODS21or ODS22after the track relay34is dropped, apart from the presence of a secondary train which will not be considered to be an obstruction.

Any determination reached that either or both of the tracks EML or WML is obstructed results in the control arrangement20raising an alarm that serves to warn an operator to prohibit the primary train from moving through the level crossing22on the related EML or WML track. The alarm warning is transmitted to the automated train control system528on the primary train and the alarm warning is concurrently transmitted to a vital signalling server530at the central operating office.

Any alarm warning424,530transmitted to the central operating office, results in the issuing of a new or an adjustment to the Movement Authority26issued to the primary train. Such an adjustment may be to initially slow down the speed of the primary train, and subsequently to limit the Movement Authority to a position located before the level crossing10,22so that the primary train will come to a halt before entering the level crossing10,22. If the primary train is already too close to the level crossing10,22to come to a complete halt before traversing the level crossing10,22, for example if a person suddenly enters the restricted area18after the boom gates16have been lowered, then the control arrangement will cause the Movement Authority26to be varied such that the emergency breaks of the primary train will be applied thereby to mitigate any damage that may be caused.