TRAIN DETECTION SYSTEM FOR RAILROAD GRADE CROSSING

• US 3,725,699 A
• Filed: 01/19/1971
• Issued: 04/03/1973
• Est. Priority Date: 01/19/1971
• Status: Expired due to Term

• Current Assignee: Union Switch & Signal, Inc. (Hitachi, Ltd.)
• Original Assignee: Frank T. Pascoe
• Inventors: Pascoe, Frank T.
• Primary Examiner(s): Forlenza, Gerald M.
• Assistant Examiner(s): Libman, George H.
• Application Number:
  US05/107,656
• Time in Patent Office: 805 Days
• Field of Search: 246/111,112,113,125,130,29R,114,115
• US Class Current: 246/114.00R
• CPC Class Codes: B61L 13/005 optically actuated

Abstract

Laser beam presence detection apparatus is positioned to detect a railroad car occupying any part of the crossing portion of a stretch of track which intersects other tracks in a railroad grade crossing. The laser detector thus checks the occupancy condition of the track portion which is insulated from the adjacent conventional track circuit on each side but is long enough to hold a complete car which does not then shunt the track circuit. The laser detector and the track circuit relay jointly control a stick relay normally held energized solely by the track relay. The laser apparatus is approach energized by the release of the stick relay when a train initially occupies either part of the adjacent track circuit. The stick relay is reenergized only when the track relay and the laser detector each record a nonoccupied condition for the corresponding section of the crossing track. The stick relay controls the entering signal circuits for all possible conflicting routes through the crossing area but simultaneous parallel moves are permitted.

Claims

1. Train detection apparatus, for a stretch of first railroad track intersecting at grade one or more other railroad tracks, the crossing portion of said first track being longer than the wheel span of at least some cars trAversing said track, comprising in combination, a. track circuit means for detecting the occupancy condition of a selected length of said first track adjacent to each end of and insulated from said crossing portion, b. laser beam presence detection apparatus positioned for detecting the presence of a railroad car occupying any part of the crossing portion of said first track, c. a detector relay controlled by said laser beam apparatus to a first and a second position as the presence of a car in said crossing portion is not detected and detected, respectively, and, d. train occupancy recorder means, 1. jointly controlled by said track circuit means and a first position contact of said detector relay for recording and retaining a track occupied indication when any part of a train occupies any part of said first track stretch between the distant ends of said selected lengths, 2. further jointly controlled by said track circuit means and said first position contact of said detector relay for recording a non-occupied track indication when all parts of a train traversing said first track stretch clear all parts of said first track stretch between said distant ends, and, 3. controlled solely by said track circuit means for retaining a non-occupied track indication once recorded until another train enters one of said selected lengths.

2. Train detection apparatus as defined in claim 1 in which, a. said track circuit means includes the rails of said selected track lengths, a source of energy, and a track relay operable between a first and a second position as said selected lengths are non-occupied and occupied, respectively, by a train, b. said train occupancy recorder means is a relay having a stick circuit controlled by a first position contact of said track relay and an energizing circuit jointly controlled by said first position track relay contact and said first position contact of said detector relay.

3. controlled solely by said track circuit means for retaining a non-occupied track indication once recorded until another train enters one of said selected lengths.

4. Train detection apparatus as defined in claim 1 further including, a. a signal control circuit for said stretch of first track and for each said other track for authorizing train movement along the corresponding track, b. each signal control circuit being controlled by said train occupancy recorder means for inhibiting another train movement over said crossing when a train is occupying any part of said first track stretch between the distant ends of said selected lengths.

5. Train detection apparatus as defined in claim 2 further including, a. a signal control circuit for said stretch of first track and for each said other track for authorizing train movement along the corresponding track, b. each signal control circuit being controlled by a contact of said occupancy recorder relay open when that relay is deenergized for interrupting the signal control circuit to inhibit the authorizing of another train movement over said crossing when a train is occupying any part of said first track stretch between the distant ends of said selected lengths.

6. Train detection apparatus, for a railroad grade crossing, in which a first set of one or more tracks crosses a second set of one or more Tracks, each track including a crossing portion in which it intersects all tracks of the other set, each crossing portion being longer than the wheel span of at least some cars which traverse that track, comprising in combination, a. a track circuit means for each track for detecting the occupancy condition of a selected length of the corresponding track adjacent to each end of and insulated from the corresponding crossing portion, b. laser beam presence detection apparatus for each track positioned for detecting the presence of a railroad car occupying only the crossing portion of the associated track, c. a detector relay for each track controlled by the corresponding laser beam apparatus to a first and a second position as the absence and presence, respectively, of a car occupying the corresponding crossing track portion is detected, and d. a track occupancy indication means for each track controlled only by the associated track circuit means for recording the initial occupancy of the selected lengths of the corresponding track by a train, e. each track occupancy indication means jointly controlled by the associated track circuit means and the associated detector relay, after a train occupancy is initially recorded, for recording a subsequent non-occupied condition of said corresponding track only when both said associated track circuit means and the associated laser beam apparatus detect a non-occupied condition for the corresponding selected lengths and crossing portion, respectively.

7. Train detection apparatus as defined in claim 6 in which, a. each track circuit means includes the rails of the corresponding selected track lengths, a source of energy, and a track relay operable between a first and a second position as said corresponding selected track lengths are non-occupied and occupied, respectively, by a train, and b. each track occupancy indication means is a relay having a stick circuit controlled by a first position contact of the associated track relay and an energizing circuit jointly controlled by said first position track relay contact and a first position contact of the associated detector relay.

8. Train detecting apparatus as defined in claim 7, further including, a. a signal control circuit for each track for authorizing a train movement along the corresponding track over its crossing with the other set of tracks, b. each signal control circuit controlled by an energized position contact of the corresponding occupancy indication relay and an energized position contact of each occupancy indication relay for said other set of tracks, for inhibiting the authorization of a train movement along said corresponding track when another train is occupying said corresponding track between the distant ends of its selected lengths or is occupying one of said other set of tracks between the distant ends of its selected lengths.