Communications: electrical – Vehicle detectors
Reexamination Certificate
1999-08-06
2001-02-27
Hofsass, Jeffery A. (Department: 2736)
Communications: electrical
Vehicle detectors
C340S933000, C246S125000, C246S126000
Reexamination Certificate
active
06195020
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to railroad crossing safety and control devices. More particularly it relates to a system and method for preventing vehicles from becoming entrapped at a railroad crossing when a train is approaching the crossing.
BACKGROUND OF THE INVENTION
Railroad grade crossings have always posed a danger to vehicles using them. The size and momentum of a train as compared to vehicles which use the crossing, i.e. automobiles, buses and trucks, is so great that a direct collision between a train and a vehicle at a crossing such as an automobile or truck results in not only the total destruction of that vehicle but the death or serious injury of the occupants of the vehicle. The speed and momentum of a train approaching a grade crossing is such that there is little if any chance for the train to stop before reaching the crossing once the engineer of the train knows such a collision is imminent.
Building a viaduct over or under the rail line is generally prohibitive given the cost of construction and subsequent maintenance necessary to maintain it. Thus, the general methods of preventing accidents at a railroad grade crossing rely on providing systems which warn vehicles which use the crossing of the impending approach of a train and lower barriers or gates into place to restrict access to the crossing in the critical seconds before the train arrives at the crossing.
Two systems in wide use today are a standard track circuitry and vital relay network. Most rail lines are sectioned into large long blocks for control and monitoring purposes. The standard track circuitry is a common type of train presence detection circuitry used to detect the presence of a train within a block of track. The vital relay network is a series of relays used to control railroad crossing warning lights and the raising and lowering of primary protective crossing gates. The protective crossing gates generally being gates on the entrance lanes into a crossing. Both of these systems work in conjunction with each other and detect trains by means of electrical conductors across the rails as current flows through rail car wheels. A protected crossing located in the block, ideally at its center, has a vital relay network. Upon receipt of a signal from the standard track circuitry, that a train has entered the block and is approaching the crossing, the vital relay network activates the crossing warning lights and then lowers the crossing gates.
A two gate arrangement as depicted in
FIG. 2A
is a very common arrangement used to restrict access to a railroad crossing. However, the open exit lanes in the two gate arrangement present their own serious problems in that they allow impatient drivers access to the crossing even though the entrance lanes have barriers across them. Such easy circumvention of the safety barriers of a two gate crossing creates significant dangers in any situation and especially on a rail line that has frequent high speed trains using the line every day.
An alternative to the two gate system is the four gate arrangement as depicted in
FIG. 2
which has two additional gates at the exit lanes to the crossing. However, the four gate systems have their own problems. For instance one common problem is the entrapment of a vehicle within the protected area of a four gate crossing because the gates are lowered prior to the vehicle being able to exit from the protected area of the crossing as a train is approaching. Once these vehicles become entrapped between the gates, there is little opportunity for them to escape and avoid being hit by an on coming train. A number of systems currently exist which attempt to deal with the problem of vehicle entrapment; however, these systems are expensive and difficult to install and maintain. A number of them rely on large loops which must be buried in the ground fairly close to the surface of the ground. Additionally, many of these systems lack the capability to respond to wide variety of conditions and circumstances.
Thus, what is need is an inexpensive and easy to install and maintain method and system which allows a vehicle to escape from a four gate protected crossing while retaining all of the advantages of the four gate grade crossing. A system that can also respond to and deal with a wide variety of different conditions and circumstances.
SUMMARY
It is an object of the present invention to provide a system which can detect a vehicle entrapped at a railroad grade crossing and allow it to escape prior to the entry of a train into the crossing. It is another object of the present invention to provide such a system which can adjust to changing conditions so it can continue to successfully serve its purpose.
It is yet another object of the present invention to provide such a system which is cost effective, durable and easily integrated into existing systems with little or no alteration of the current systems.
It is yet another object of the present invention to provide a system which works with and compliments current train warning and grade crossing safety systems.
These and other objects are accomplished by providing a system for determining if a protected area of a railroad crossing is clear of vehicles and providing for the safe escape of any vehicles which may become entrapped in the protected area of a crossing prior to the arrival of a train at the crossing. The system has a plurality of strategically placed sensors located within the protected area of a railroad crossing; a command and control or controller analyzer apparatus to which each of the sensors have a communicative link; and wherein upon receipt of a train approach signal the command and control apparatus periodically takes readings from the sensors, compares those readings with a baseline and generates an all clear signal when it determines no vehicles are present in the protected area of the crossing, and the all clear signal activates an exit gate lowering signal.
In another aspect of this system it has the ability to separately monitor activity on two separate vehicle traffic lanes which traverse the protected area of the crossing and the system can determine which lane or lanes are clear and generate a separate “all clear” signal for each of the lanes individually so that exit gates for only the lane or lanes for which the all clear signals are generated will be lowered.
In a further aspect of the system of this invention, the system continues to take readings from the sensors after generating the all clear signal but before the train arrives at the crossing and, upon obtaining readings form the sensors that a vehicle may be in the protected area during this period of time, ceases generation of the all clear signal which allows the exit gate to be raised until the system determines the vehicle has exited the protected area, whereupon it again generates the all clear signal.
To achieve the objects of this invention it also provides a method for detecting the presence of a vehicle in a protected area of a railroad crossing and providing for the vehicles timely escape from the protected area of the crossing prior to the arrival of a train at the crossing. The method having the following steps: receiving a signal of a train approaching the crossing; commencing sampling of readings from sensors located in the protected area of the crossing; analyzing the readings from the sensors to determine if and when the crossing is clear so that exit gates to the crossing can be lowered; generating an all clear signal when it is determined that the crossing is free of any vehicular traffic; and lowering into place crossing exit gates.
In a further aspect of the method of this invention, it separately analyzes readings from a plurality of sensors to determine which of two lanes for traffic over the crossing is clear, and then it generates a separate all clear signal for each lane of traffic so that an exit gate in the traffic lane, for which the all clear signal is generated, can be lowered.
In another aspect of the method of this invention, it also periodically s
Bader Clifford J.
Brodeur, Sr. Ronald E.
DeRenzi Charles S.
Mullin Eugene
3461513 Canada Inc.
Hofsass Jeffery A.
Previl Daniel
Swabey Ogilvy Renault
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