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Publication numberUS2664499 A
Publication typeGrant
Publication dateDec 29, 1953
Filing dateJun 19, 1948
Priority dateJun 19, 1948
Publication numberUS 2664499 A, US 2664499A, US-A-2664499, US2664499 A, US2664499A
InventorsMuse Kenneth L
Original AssigneeWestinghouse Air Brake Co
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Apparatus for controlling highway crossing signals
US 2664499 A
Abstract  available in
Images(1)
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Claims  available in
Description  (OCR text may contain errors)

K. L. MUSE Dec. 29, 1953 APPARATUS FOR CONTROLLING HIGHWAY CROSSING SIGNALS Filed June 19, 1948 a B m u H B M M W Z 1 Z #04 E? I 5 fil 9 H7 N 9, G T w W aw r Z r ww T L Maw. Q

HIS ATTORNEY Patented Dec. 29, 1953 UNITED srArr ATENT QEFICE APPARATUS FOR CONTROLLING HIGHWAY CROSSING SIGNALS Kenneth L. Muse, Hagerstown, Md., assignor to Westinghouse Air Brake Company, a corporation of Pennsylvania My invention relates to apparatus for controlling highway crossing signals, and particularly to apparatus for interrupting the operation of a highway crossing signal when a train stops on a control track section for the highway crossing signal, and for then again starting operation of the signal when the train resumes its movement toward the highway crossing.

In order to avoid unnecessarily delaying the users of a highway at the intersection of a railway with the highway, it is important that the operation of a highway crossing signal shall be interrupted if a train stops on a control track section for the highway crossing signal. It is also very desirable to prevent useless operation of a highway crossing signal in order to maintain the respect of users of a highway for the indication given by a highway crossing signal. If a highway crossing signal is operated when it should. not be operated, users of a highway may become accustomed to disregarding its indication, and may then sometimes be mistaken and disregard its indication when such action is dangerous.

One feature of my invention is the provision of means for interrupting the operation of a highway crossing signal if a train approaching a highway crossing stops on a control track section for the signal.

Another feature of my invention is the provision of means for again starting the operation of a highway crossing signal when a train resumes its movement toward a highway crossing after having stopped on a control track section for the highway crossing'signal.

I shall describe one form of apparatus embodying my invention, and shall then point out the novel features thereof in claims.

The accompanying drawing is a diagrammatic view showing one form of apparatus embodying my invention, in which a railway track which intersects a highway is divided to form a crossing section at the highway, and two approach control sections one adjacent each end of the crossing section; in which one rail of an intermediate portion of a given one of the approach sections is divided to form an intermediate section; in which operation of a highway crossing signal is started when a train approaches the intersection over either of the approach control sections; in which operation of the crossing sigha! is interrupted if a train approaching the intersection stops on the given approach control section; and in which operation of the highway crossing signal is then resumed when the train moves over the intermediate section.

Similar reference characters refer to similar parts in the drawing.

, .In the drawing, the contacts operated by the various relays are identified by numbers, each such number having a distinguishing prefix from which it is separated by a dash when the associated contact is shown apart from the relay by which it is operated. The prefix for each of these contact numbers comprises the reference character for the respective relay by which the associated contact is operated. For example, contact IR-ZO, shown in the lower right-hand portion of the drawing in the circuits for relay ZS, is identified by the number 26 separated by a dash from the prefix IR which is the reference character for relay IR by which this contact is operated.

Referring further to the drawing, a stretch of railway track is shown intersected by a highway H. A highway crossing signal, which may be of the flashing light type or of any other suitable design, but which, in order to simplify the drawing, is shown as a bell G, is located adjacent the intersection of the railway track and the highway H.

Rails I and Ia of the railway track are divided by insulated joints 2 to form a crossing section 2T and two approach control sections, one adjacent each end of the crossing section. A given one of the approach control sections has two portions, one of which is designated AIT and the other of which is designated BIT. The other approach control section is designated 3T An intermediate portion of the given approach r control section is divided by insulated joints 3 to form an intermediate section ZT, which is shorter than the distance between the trucks of a car, between portions AIT and BIT. The intermediate section ZT has one rail in common with portions AIT and BIT of the given approach section. Portions AIT and BIT are connected with each other around section ZT by a jumper 5.

Each of the track sections is provided with a track circuit including a relay, designated by the reference character R with a distinguishing prefix, connected across the rails adjacent one end of the section, and a suitable source of current, such as a battery 4, connected across the rails adjacent the opposite end of the section.

A repeater relay, designated by the reference character ZP, is controlled, by pole changing contacts 6 and l of relay ZR for the intermediate section, to be energized by current of nori II An eastbound control stick relay ET has a pickup and a stick circuit, both of which are controlled by a front contact 3 of relay iR, and the pickup circuit also controlled by a front contact t of relay 2R. A westbound control stick relay WT is similarly controlled byrelays BR. and 2R.

An eastbound direction stick relay, designated by the reference character ES, is controlled by relays ET and ER to become energized when an eastbound train enters section ET, and is then controlled to remain energized while the train moves through section 3T. ,A westbound direction stick relay, designated by the reference character WS, is similarly controlled by relays WT and ER to become energized when a westbound train enters section 2T, and is controlled to remain energized while the westbound train moves through the g ven track section comprising portions Al? and BIT.

A timing stick relay, designatedby thereference character ZS, is controlled to'become energized when a train enters the ,given control section comprising portions AiT and'BlT. A't'ime element device TE is controlled by a front contact 2 1 of relay ZS.

A signal control relay, designated by the reference character XR, is normally energized by a circuit which includes front contacts lR-lZ and iiR-i'i of the track relays "for the two approach control sections and contactifi of the track relay for the crossing section. Relay has also a second energizing circu t including front contact ZS-Hi of relay ZS, and contact (5 of time element device TE which'becomes closed when time element device TE has been energized a measured period of time. RelayXR is also controlled .by front contacts L8 and [.3 of relays ES and WS, respectively, to .be energized when a train is receding from the intersection ,of the railway and the highway through the given approach control section or through section .3-1. Highway crossing signal G is controlled by a hack contact is of relay XR.

Having described, in generaLthe arrangement andthe control of the-apparatus shown by the accompanying drawing, I shallnow describe in detail its operation.

As shown in the drawing, all parts of the apparatus are in the normal condition thatis, each of the track sections is unoccupied and, therefore, track relays ZR, IR, 2R, and iiRrare ener gized; relay ZP is energized by current of normal polarity; relays ET, WT, and KR are energized; and relays ES, WS,and ZS,'time element device TE, and crossing'signal Gjare deenergized.

The track circuit for the .given approach control section, including relay IR, passes from a batter through rail 1 of port on AIT of the given approach control section, jumper wire 5 connected around the intermediate section ZT, rail 5 of portion Bi-T, winding of relay iE,-and rail is of portions 381T and A'lT,back to battery ii. Relay Z? is energized by current of normal relay ET is also closed which is the same as the pickup circuit just traced except that it includes contact in of relay ET instead of contact 9 of relay 2R. Relay WT is energized by a pickup and .a stick circuit which are similar to the pickup and'stick circuits just traced for relay ET.

Relay XR is energized by a circuit passing from term nal B, through contact lR-IZ, contact [6 of relay 2R, contact ER-i'i, and the winding of relay XE to terminal N.

'I-shall assume that, with apparatus embodying .my invention, :a train moving from left to right shown in the accompanying drawing, which I shall assume isthe eastbound d rection, enters portion AIT of the given approach control section, causing relay IE to become deenergized. Relay ET, therefore, in turn becomes deenergized because contact 8 of relay HR becomes opened. Also, with relay lR deenergized, the circuit previously tracedifor relay 'XR is open at contact lR-JZ, causing relay XR 'to become .deenerg zed. 'RelayXR, upon becoming deenergized, starts the operation of crossing signal G by a circuit passing "from terminal B, through contact 19 of relay XR, and crossing signal G to terminal N.

With relay IR deenergized, a pickup circuit is completed for relay ZS, this circuit passing from terminal B, through'contacts lR-Zii 'and 'ZP-El, contact 22 of time element device 'IE, and the winding of relay ZS to terminal N. Relay ZS, upon becoming energized by its pickup circuit, "completes its stick circuit which is the same as 'thepic'kup circuit just traced except thatit includes contact 23 of relay ZS instead of contact oftime element device TE.

Relay ZS, upon becom ng energized, completes a circuit for energizing time element device TE, this circuit passing from terminal B, through contact '24 of relay Z5, and the control element of time element device TE to terminal ,N. Time element "device TE, after becoming energized, opens its contact 22 .in the pickup circuit traced for relayZS which, however, then remains energized by its stick circuit previously described. Time element device TE does not close its contact it until the lapse of a measured period of time after time element device TE has become energized.

,I shall assume further that the eastbound train, afterenteringportionnIT of the givenapproach control section, proceeds at a speed such that time element device TE does not close its contact (5 before the train enters section ZT, deenergizing relay ZR. When relay ZR becomes deenergized, relay ZP is deenergized for a brief period between the opening of contacts 5 and of relay ZR at their front points, and the closing of these contacts at their back points. When contacts e and i become closed at their back points, relay ZP becomesenergized by current of reverse polar ,ity in a circuit which is the same as the circuit previously traced for this relay except that it includes the back points of contacts 6 and 1 instead of the front points of these contacts. On account of relay ZP being deenergized, and then being energized in the reverse direction, contact ZP-2l of relay 2? in the circuit for relay ZS becomes momentarily opened, causing relay .ZS to become .deenergized. Time element device TB .is therefore also deenergized because of the opening of contact 24 of relay ZS. Relay ZS cannot become energized again until contact 22 of time element device TE becomes closed. .Relay ZS,

upon again becoming energized, completes the circuit previously traced for time element device TE for starting the operation of time element device TE again.

Since section ZT is shorter than the distance between trucks of a car, relay ZR Will again become energized while section ZT is between the front trucks of the car and the rear trucks of the car. It follows that while a train is moving over section ZT, relay ZP is repeatedly energized alternately by current of normal and reverse polarity.

I shall also assume further that the train enters section 2T before time element device TE closes its front contact l5 after the train leaves section ZT. Relay XR, therefore, remains deenergized while the eastbound train is moving through the given approach control section comprising portions AI'I and BIT. Relay XE remains deenergized while the train occupies section 2T, because contact [6 of relay 2R is then open in the control circuits for relay XR.

When the train enters section 2T, relay ES becomes energized by its pickup circuit passing from terminal B, through the back point of contact 25 of relay ET, contact 26 of relay 2R, front point of contact 27 of relay WT, contact WS-23, and the winding of relay ES to terminal N. Relay ES, upon becoming energized, completes its stick circuit passing from terminal B, through the back point of contact 25 of relay ET, contact 26 of relay 2R, contact 29 of relay ES, and the winding of relay ES to terminal N.

When the train enters section 3T, relay 35,

becomes deenergized, and its contact 8 opens the circuits previously described for relay WT, causing relay WT to become deenergized. A second stick circuit for relay ES is thereby completed, passing from terminal B, through the back point of contact 21 of relay WT, contact 29 of relay ES, and the winding of relay ES to terminal N. Although the pickup circuit previously traced for relay ES is opened at the front point of contact 2! of relay WT, relay ES remains energized by its first stick circuit while contact 2'! of relay WT is open between its front and back points.

When the train leaves portion BIT of the given approach section, relay IR becomes energized, and opens the pickup and stick circuits for relay ZS, causing relay ZS to become deenergized. Time element device TE in turn be comes deenergized because of the opening of contact 24 of relay ZS.

When the train leaves section 2T, relay ET again becomes energized by its pickup circuit previously traced. Relay ES, however, remains energized by its second stick circuit traced through the back point of contact 21 of relay WT. Relay XR now becomes energized by a second cir cuit, passing from terminal B, through contact lR-IZ, contact it of relay 23, contact 18 of relay ES, and the winding of relay XR to terminal N. Relay .XR, upon becoming energized, opens its contact l9, thereby deenergizing signal G.

When the train leaves section 3T, the circuit first traced for relay XR again becomes closed. Also, when the train leaves section 3T, relay WT again becomes energized by its pickup circuit previously described. Relay WT, upon becoming energized, opens its contact 2'! at the back point, thereby deenergizing relay ES.

,1 shall nextassume that, with all parts of the apparatus again in the normal condition, an eastbound train enters portion AIT of the given approach control section and stops on portion AIT, deenergizing relay XR, which, in turn, causes operation of signal G to be started. Relay ZS becomes energized, as previously described, causing time element device TE also to be energized. Upon the lapse of a measured period of time, device TE closes its front contact 55, thereby completing a third circuit for energizing rela XR, this circuit passing from terminal B, through contact ZS-ie, contact l5 of time element device TE, contact is of relay 2R, contact 3R-ll, and the winding of relay XR, to terminal N. Relay XR, upon thus becoming energized, opens its contact is, and thereby interrupts the operation of signal G.

When the train resumes its movement toward highway H, relay ZP becomes repeatedly energized alternately by current of normal and reverse polarity, while the train moves over section ZT, as previously described, causing relay ZS to become deenergized, which, in turn, deenergizes time element device TE. Relay XR is thus deenergized because of the opening of contact l5 of time element device TE, and therefore the operation of signal G is started again by the closing of contact it of relay Kit. The operation of the apparatus as the train now proceeds over portion BiT of the given approach control section, and over sections 2T and ST is as previously described.

If, instead of stopping on approach section portion AIT, the train proceeds onto section ZT, relay ZS will become deenergized, causing time element device TE to be deenergized, as previously described. If the train stops with a pair of wheels on section ZT, relay ZP will be constantly energized by current of reverse polarity, so that, when back contact 22 of time element device TE becomes closed, relay ZS will become energized by its pickup and stick circuits previously traced. Time element device TE will then become energized because of the closing of contact 2 of relay ZS. Upon the lapse of a measured period of time, device TE will close its contact l5, causing relay XR to be energized, as previously described, which in turn interrupts the operation of signal G, as also previously described.

I shall now assume that all parts of the apparatus are again in the normal condition, and that a we tbound train enters section 3T. Contact 8 of relay 3R, therefore, becomes opened, causing relay WT to become deenergized. With relay 3R. deenergized, contact BR-I'l opens the circuit first traced for relay XR, causing relay XR to become deenergized. With relay deenergized, the operation of signal G is begun because of the 0105- ing of contact IQ of relay XR.

When the train enters section 2T, relay W S becomes energized by its pickup circuit passing from terminal B, through the back point of contact 21 of relay WT, contact 26 of relay 2R, front point of contact 25 of relay ET, contact ES-ZS, and the winding of relay WS to terminal N. Relay WS, upon becoming energized, completes a stick circuit which is the same as the pickup circuit just traced except that it includes contact 29 of relay WS instead of contact ns-za and the front point of contact 25 of relay ET. I

When the train leaves section 3T, contact 312 becomes closed, but relay XR is now deenergized because contact N5 of relay ER is open.

When the train leaves section 2T, relay XR becomes energized by a third circuit, passing from terminal B, through contact I3 of relay WS, contact I6 of relay 2R, contact t'iR-ll, and the winding of relay XR to terminal N. The operation of crossing track sec 1i --si'gnal G is then stopped because of the opening foregoing description, it is believed that the operation of the apparatus for any other possible train movement can be readily traced by referring to the accompanying drawing.

Although I have herein shown and described only one form of apparatus embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. In a control system for a highway crossing signal adjacent the intersection of a railway track with a highway, in which the railway track is divided into a crossing track section at the inter 'secti'on'and two approach control sections one ad- ,iacent each end of said crossing track section, and in which a direction stick relay for each direction of trafiic movements is controlled to be come energized when a train moves in the corresponding'direction from an approach control section onto said crossing track section, the combination comprising, a timing stick relay, a time element device, means controlled by a train upon occupying one of said app oach control sections for energizing said timing stick relay, means controlled by a front contact of timing stick relay for energizing said tine element device, means controlled by a train upon entering said one appreach control sectnn for starting operation of said crossing signal, means controlled by front contacts of said timing stick relay and said time element device for interruptin operation of said crossing signal, means controlled by further movement of said train toward said intersection for again starting operation of highway crossing signal before said train enters said crossing trac section, and means controlled by each of said direction sck ays for stopping operation of'said crossing s nal when a leaves onin a corresponding direction.

12. In a control system for a highway crossing signal adjacent the in ersection of a railway track with a highway, in which the railway track is divided to form a crossing track section at the intersection, and in which a direction stick relay for each direction of movements is controlled to become energized when a train moving in the co responding direction enters said crossing track section, the combination comprising, a timing stick relay, a time element device, means controlled by a train approaching said intersection in a given direction for energizing said timing stick relay, controlled by a front contact of said timing stick relay for energizing said time element device, means controlled by a train approaching said intersection in either direction for starting operation of said highway crossing signal, means controlled by said time element device and by said timing stick relay for interrupting operation of crossing signal if a train stops when approaching said intersection in said given direction, means controlled by further movement of said train toward said intersection for again starting operation of said crossing sigh :n'al before said train enters said crossing track section, and means controlled by each of said direction sti'ckrelays for stopping operation of said crossing signal when a train recedes from said intersection.

3. In a control system for a highway crossing signal adjacent the intersection of a railway track with a highway, in which a direction stick relay for each direction of trafiic movements is controlled to become energized when a train moving .in the corresponding direction arrives adjacent the intersection, the combination comprising, a time element device, means controlled by a train approaching said intersection in a given direcition ior energizing said time element device, means controlled by a train approaching said intersection in either direction for starting operation of :said highway crossing signal, means controlled by said time element device after it has been energized ameasured period of time for stopping operation of said crossing signal if a train moving-in said given direction is 'in any location before 'arriving'at a given point adjacent said intersection, means controlled by further movement or" said train toward said intersection for again starting operation of said crossing signal before said train arrives at said given point adjacent said intersection, and means controlled by each of said direction stick relays for stoppin: operation of said crossing signal when a train recedes in the corresponding direction from said intersection.

4. In a control system for a highway crossing signal adjacent the intersection of a railway track with a highway, in which the railway track is divided into a crossing track section at the intersection and an approach control section adjacent an end of said crossing track section, the combination comprising, a time element device, means controlled by 'a train approaching said intersection in 'a given direction for starting operation of said highway crossing si nal and energizing said time element device, means controlled by said time element device for inter rupting operation of said crossing signal if said train stops on said approach control section be- .fore entering said crossing track section, means controlled by said train upon resuming its movement for again starting operation of said crossin"; signal before said train enters said crossing track section, and means controlled by said train for continuing operation of said crossing signal while said train occupiessaid crossing track section.

5. Ina control system for a highway crossing signal adjacent the intersection of a railway track with a highway, in which said railway track is divided to form a crossing section at the highway and an approach section adjacent said crossin; section, and in which each of said track sections is provided with a track circuit including a track relay, the combination comprising, an intermediate portion of said approach section divided to form an intermediate section which is shorter than the distance between the trucks of a railway car, a track circuit including a track relay for said intermediate section, a repeater relay for said track relay for said intermediate section controlled by pole-changing contacts of the track relay to be energized by current of n 1- mal or reverse polarity according as the track relay is energized or deenergized, a time element device. a'timing stick relay, a pickup and a stick circuit for said timing stick relay each of which is controlled by a back contact of the track'relay for said approach section and by a front contact of said repeater relay and said pickup circuit also controlled by a back contact of said time element device, a circuit controlled by a front contact or" said timing stick relay for energizing said time element device, a signal relay, a circuit controlled by front contacts of the track relays for said approach and crossing sections for controlling said signal relay, a second circuit controlled by front contacts of said timing stick relay and of said time element device and also of the track relay for said crossing section for controlling said signal relay, and means controlled by said signal relay for controlling said crossing signal.

6. In a control system for a highway crossing signal adjacent the intersection of a railway track with a highway, in which said railway track is divided to form a control section ad acent said intersection, the combination comprising, an intermediate portion of said control section divided to form an intermediate section which is shorter than the distance between the trucks of a railway car, a track circuit for said intermediate section including a track relay, a repeater relay controlled by pole-changing contacts of said track relay to be energized by current of normal or reverse polarity according as said track relay is energized or deenergized, a front contact of said repeater relay which becomes opened for a brief period of time when the polarity of energization of said repeater relay is chan ed by said pole-changing contacts, a time element device, a timing stick relay, a pickup and a stick circuit for said timing stick relay each of which is controlled to be closed when said approach section is occupied by a train while said front contact of said repeater relay is closed and said pickup circuit also controlled by a back contact of said time element device, means controlled by a front contact of said timing stick relay for energizing said time element device, a si nal relay, a control circuit for said si nal relay which is normally energized but which is deenergized when said control section is occupied, a second control circuit for said si nal relay controlled by front contacts of said timing stick relay and said time element device, and means controlled by said signal relay for controlling said crossing signal.

7. In a control system for a hi hway crossing signal adjacent the intersection of a railway track with a highway, in which said railway track is divided to form a control section adjacent said intersection, the combination comprisin an intermediate portion of said control section divided to form an intermediate section which is shorter than the distance between the trucks of a railway car, a time element device, means controlled by a train upon entering said control section for starting operation of said highway crossing signal and for energizing said time element device, means controlled by said time element device after being energized a measured period of time for interrupting operation of said crossing si nal, means controlled by movement of said train over said intermediate section for again starting operation of said crossing signal, and other means controlled by said train upon arriving adjacent said intersection for at times starting operation of said highway crossing signal.

8. In a control system for a highway crossing signal adjacent the intersection of a railway track with a highway, in which said railway track is divided to form a control section and a crossing track section adjacent said intersection, the combination comprising, means controlled by a train upon entering said control. section for starting operation of said highway crossing signal, means controlled by a train it it stops on said control section for stopping operation of said highway crossing signal, means within said control section effective when said train resumes movement for again starting operation of said highway crossing signal before said train enters said crossing track section, and means controlled by said train on said crossing track section for continuing operation of said signal.

9. In a control system for a highway crossing signal adjacent the intersection of a railway track with a highway, in which said railway track is divided to form a control section and a crossing track section adjacent said intersection, the combination comprising, means controlled by a train upon entering said control section in a given direction for starting operation of said highway crossing signal, means controlled by a train if it stops on said control section for interrupting operation of said crossing signal, means controlled by said train upon resuming its movement toward said intersection for again starting operation of said crossing signal before said train enters said crossing track section, and. means controlled by said train for continuing operation of said crossing signal while said train occupies said crossing track section.

10. In a control system for a hi hway crossing signal ad acent the intersection of a railway track with a highway, in which the railway track divided to form a crossing track section at the intersection, and including means controlled by a train approaching said intersection in a given direction for starting operation of said highway crossing signal, the combination comprising, time element means controlled by said train for interrupting operation of said highway crossing signal if said train stops approaching said intersection after it has started operation of said highway crossing signal, means controlled by said train upon again resuming its movement toward said intersection for again startin operation of said highway crossing signal before said train enters said crossing track section, and means controlled by said train for continuing operation of said crossing signal while said train occupies said crossing track section,

KENNETH L. REUSE,

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,698,459 Spray Jan. 8, 1929 1,998,175 Thompson Apr. 16, 1935 2,346,518 Tizzard Apr. 11, 1944 2,370,704 Allen Mar. 6, 1945 2,379,209 Allen June 26, 1945 2,452,868 Quinlan Nov. 2, 1948 2,628,306 McMahon Feb. 10, 1953

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
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US2628306 *May 29, 1948Feb 10, 1953Westinghouse Air Brake CoApparatus for controlling highway crossing signals
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US2740887 *Nov 28, 1951Apr 3, 1956Westinghouse Air Brake CoControl apparatus for highway crossing signals
US2850623 *Apr 16, 1954Sep 2, 1958Westinghouse Air Brake CoControl apparatus for highway crossing signal
US2852666 *Dec 31, 1952Sep 16, 1958Westinghouse Air Brake CoHighway crossing protection control apparatus
US2887571 *Jun 18, 1954May 19, 1959Bettison David CApparatus for controlling highway crossing signals
US2905810 *Oct 17, 1955Sep 22, 1959Gen Railway Signal CoMotor car protection system for railroads
US8028961Dec 26, 2007Oct 4, 2011Central Signal, LlcVital solid state controller
US8157219Jan 15, 2008Apr 17, 2012Central Signal, LlcVehicle detection system
US8469320Sep 30, 2011Jun 25, 2013Central Signal, LlcVital solid state controller
US8517316Mar 27, 2012Aug 27, 2013Central Signal, LlcVehicle detection system
US8888052Aug 20, 2013Nov 18, 2014Central Signal, LlcVehicle detection system
US9026283May 30, 2011May 5, 2015Central Signal, LlcTrain detection
US9067609Jun 19, 2013Jun 30, 2015Central Signal, LlcVital solid state controller
US20080169385 *Jan 15, 2008Jul 17, 2008Ashraf AhtashamVehicle detection system
US20080183306 *Dec 26, 2007Jul 31, 2008Central Signal, LlcVital solid state controller
Classifications
U.S. Classification246/130, 246/161
International ClassificationB61L29/00, B61L29/28
Cooperative ClassificationB61L29/286
European ClassificationB61L29/28C