Communications: electrical – External condition vehicle-mounted indicator or alarm – Transmitter in another vehicle
Reexamination Certificate
1998-02-20
2001-04-17
Wu, Daniel J. (Department: 2736)
Communications: electrical
External condition vehicle-mounted indicator or alarm
Transmitter in another vehicle
C340S566000, C340S902000, C340S905000, C340S988000, C246S003000, C246S12200A, C246S126000, C246S166100
Reexamination Certificate
active
06218961
ABSTRACT:
BACKGROUND OF THE INVENTION
The present application is related generally to systems and methods for preventing collisions between vehicles on railway systems and, in particular, to systems and methods for determining accurate locations of railway vehicles and/or for providing proximity warnings or brake applications when a collision threat is detected.
A long standing problem in the railway industry has been the competing interests of maximizing throughput on the railway system while maintaining sufficient separation of the vehicles to prevent collisions. Significant time and resources have been expended towards developing proximity detecting systems which alert vehicle operators to potential collision threats. The typical proximity detection system includes the capability of the system to take automatic action to stop the vehicle should the operator not take the required action in response to a proximity warning.
Generally, in such prior art systems the location, speed, direction of travel and identification number of each vehicle is collected. This information may then be analyzed to determine which vehicles present a collision threat to one another. Once a vehicle is determined to be a collision threat, the proximity detecting systems will issue a proximity warning once the trains come within a predetermined threshold distance to each other. For example, if a train is travelling northbound on a track towards point A and a second train is travelling southbound on the same track to point A, a prior art proximity detecting system would issue a proximity warning to each train as the trains got within a certain distance of one another. Similarly, if two trains were travelling on the same track in the same direction and the trailing train was travelling at a faster speed than the lead train, a proximity warning would be issued when the distance between the two trains decreased to a certain predetermined threshold distance.
A common characteristic of the prior art proximity detection systems is the automatic enforcement braking if the proximity warning is not acknowledged by the operator. For example, many prior art collision avoidance systems require that the operator acknowledge the receipt of the proximity warning within a certain amount of time or the proximity detection system initiates enforcement braking to cause the train to come to a complete stop.
Some prior art proximity detection systems require more than mere acknowledgement of the proximity warning. For example, one such prior art system requires the operator of the train receiving the proximity warning to establish voice communications with the identified collision threat train in order to satisfy the warning acknowledgement and prevent automatic braking of the train. See, for example, the Hsu U.S. Pat. No. 5,574,469 issued Nov. 12, 1996.
Another general characteristic of many of the prior art proximity detection systems is that there may be more than one predetermined threshold distance. For example, when two vehicles are determined to be a collision threat and come within some predetermined threshold distance, a proximity warning is issued to each vehicle. If the distance between the trains should subsequently decrease to a second predetermined threshold distance, a second proximity warning may be given. This second proximity warning may have associated with it some additional required action of the operator. For example, an operator of a train may receive a proximity warning when it is determined that his train and another train pose a potential collision threat to each other and the distance between the two trains has decreased to eight miles. The operator may be required to acknowledge the alarm by depressing an acknowledgement button. If the acknowledgement button is not depressed within a set amount of time of receiving the alarm, the train may initiate proximity enforcement braking commands automatically. If the operator acknowledges the proximity alarm but the distance between the two trains decreases to five miles, a second proximity warning may be issued. This second warning may have associated with it, required action from the operator in addition to acknowledging the alarm, such as reducing the speed of the train. In a similar manner, there may be multiple predetermined threshold distances each with an associated required operator action in order to prevent the proximity detecting system from initiating enforcement braking commands to slow the train.
In order to prevent continuous unwanted alarms and enforcement actions in an area where trains are commonly within the proximity warning threshold (i.e., railyards) it is common for the prior art systems to offer a method of allowing the operator to manually disable the proximity detection system. However, the ability to disable the proximity detection system may lead to the inadvertent disablement of the system when the train leaves an area of congestion. Additionally, because of the severity of the resulting action if a proximity alarm is not acknowledged, there may also be situations when the vehicle operator would prefer to receive a proximity warning but would want to prevent an enforcement action.
A significant decrease in the net worth of a proximity detection system occurs if the system can not minimize false alarms. This is particularly true if the false alarm leads to an enforcement action which may have ramifications to the schedules of the entire railway system. For example, a vehicle that is following another vehicle at approximately the same speed and at a distance approximately equal to one of the predetermined threshold distances may cause a proximity alarm if the vehicle closes to less than the threshold distance. The alarm may clear if the trailing vehicle falls beyond the threshold distance. If the trailing vehicle subsequently closes within the threshold distance again a second proximity alarm would then be received. Without some method of screening out those situations where a continuous alarm may be expected, the operator may become desensitized to the importance of the proximity alarm. As a result, the operator may not acknowledge the “expected” alarm, inadvertently resulting in an enforcement action and unscheduled stopping of the vehicle.
Inherent in the operation of railed vehicles is conflict with not only other vehicles on the railway system but also non-railway system vehicles whose path may cross the path of a vehicle system on a railway (i.e., a railway crossing which allows automobiles to cross over the train tracks). Various systems have been developed which will warn the non-railway vehicle of the impending approach of the railway system vehicle.
Generally, in such prior art systems, a wayside centric approach is taken to warn vehicles of an approaching train. For example, a train may continuously transmit a signal at a predetermined signal strength along the direction of movement of the train. Wayside receivers located at the railway crossing will receive the signal as the train approaches the crossing. When the signal is received, the wayside unit may cause warning bells to ring, or warning lights to activate or crossing gates to close (or any combination of the three). Upon seeing and/or hearing the warning signals, an operator of a non-railway vehicle will know a train is approaching the crossing. While this warning system has proven effective at rail crossings, it is not an effective method of preventing collisions between vehicles where both vehicles are travelling on the same track. For instance, one characteristic of the prior art warning systems of this type, is that the actual location of the train is not determined nor utilized. Rather the relative location of the train with respect to the crossing is instrumental in activating the warning system. The warning signal transmitted by the train is usually a fixed signal of sufficient range to take into account expected propagation losses such that even in a worst case propagation loss environment, the warning signals will be activated in sufficient time to warn and/
Easterling Scott
Gottfried Michael S.
Gross Eric
Guarino Anthony J.
Peek Ernest
G.E. Harris Railway Electronics, L.L.C.
Goins Davetta W.
Rogers & Killeen
Wu Daniel J.
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