Highway crossing control system for railroads utilizing a communications link between the train locomotive and the crossing protection equipment

Claim 2

Apparatus according to claim 1, further characterized by means for retransmitting the first message at least once, and means for preventing operation of said stopping means until the elapse of a period of time for the retransmission of said first message and the acknowledgment thereof.

Claim 3

Apparatus according to claim 2, further characterized by means for generating said first message with information as to the speed of said approaching train and the distance thereof from said crossing, means at said crossing for computing from said information the minimum period of time for said train to reach said crossing, means for operating said retransmitting means within said period of time, and said elapse of period of time being less than said minimum period of time.

Claim 4

Apparatus according to claim 3, further characterized by means for operating said crossing protection equipment to a safe condition where it protects against highway traffic entering said crossing unless said first message is retransmitted with information as to the speed and distance of said train from said crossing indicative of said train not reaching said crossing within said minimum period of time.

Claim 5

Apparatus according to claim 4, further characterized by means for updating said minimum period of time, and means for causing said operating means to place highway crossing equipment in said safe condition unless a subsequent cycle of retransmission of said second message and first message occurs within said updated minimum period of time and said first message upon said subsequent cycle is indicative of said train not reaching said crossing within said updated minimum period of time.

Claim 6

Apparatus according to claim 4, further characterized by means for of transmitting a third message to said equipment from said approaching train whenever it stops or reverses direction, and means for and inhibiting said operating means from placing said crossing equipment in said safe condition upon receipt of said third signal at said equipment.

Claim 7

Apparatus according to claim 1, further characterized by wayside beacon spaced beyond said safe braking distance from said crossing, and means in said first message transmitting means for initiating said first message when a signal is received by said first message transmitting means from said beacon.

Claim 8

Apparatus for controlling the operation of crossing protection equipment guarding a highway crossing for railroad tracks along which trains travel, said equipment having first and second states in which highway traffic across said tracks is allowed and disallowed respectively, characterized by means for establishing a communications link between a train approaching said crossing and the equipment, means for interchanging messages over said link from said approaching train to said equipment and from said equipment to said approaching train, respectively, as to the speed of said approaching train and its distance from said crossing and as to the time when said transmission of a next successive message from said approaching train is required, means for computing a minimum time for said equipment to be disposed in said second state when said link is first established upon receipt of a first of said messages from said approaching train, and means for updating said minimum time upon each interchange of messages from said equipment to said train and from said train back to said equipment.

Claim 9

Apparatus according to claim 8, further characterized by means for communicating first signals to the approaching train when it is at a location sufficiently far from the crossing to enable the train to stop when travelling at maximum allowable speed, means for establishing out said communications link when said approaching train receives said first signals.

Claim 10

Apparatus according to claim 9, characterized in that said first signals communicating means includes means for transmitting said first signals with information as to the identity of the crossing which distinguishes it from other crossings along the tracks, the direction from which the train is approaching the crossing, the identity of which track of multiple tracks on which the train is travelling, and the distance to the crossing, in that said establishing means includes coding said messages from said train to said equipment with said information, said means for coding said messages from said approaching train to said equipment including means for coding said messages from said approaching train with the identity of said approaching train, and said establishing means including means for transmitting said messages from said equipment to said approaching train as acknowledgment messages each coded with the identity of the approaching train so that said acknowledgment massages are addressed exclusively to the approaching train.

Claim 11

Apparatus according to claim 8, further characterized by means for detecting the successive occurrence of occupancy and unoccupancy of said crossing by train, means for operating said equipment to its second state when said minimum time as and when updated expires, and means for operating said equipment back to its first state when said detecting step occurs.

Claim 12

Apparatus according to claim 8, further characterized by means for detecting when the approaching train reaches a minimum distance from the crossing allowing minimum time for the highway crossing protection equipment to assume said second state and means for operating crossing equipment to their second state when it is detected at said minimum distance and said communications link has not been established.

Claim 13

Apparatus according to claim 8, further characterized by wayside signals spaced from said crossing, means for operating wayside signals to allow the approaching train to proceed past said wayside signals toward the crossing when said communications link is established and to disallow the approaching train to proceed when said communications link has not been established, said wayside signal operating means including means for transmitting radio messages addressed to said wayside signals from said crossing equipment when said link is established.