Search Images Maps Play YouTube News Gmail Drive More »
Sign in
Screen reader users: click this link for accessible mode. Accessible mode has the same essential features but works better with your reader.

Patents

  1. Advanced Patent Search
Publication numberUS2347194 A
Publication typeGrant
Publication dateApr 25, 1944
Filing dateAug 31, 1940
Priority dateAug 31, 1940
Publication numberUS 2347194 A, US 2347194A, US-A-2347194, US2347194 A, US2347194A
InventorsHolliday Theodore B
Original AssigneeHolliday Theodore B
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Traffic control device
US 2347194 A
Abstract  available in
Images(2)
Previous page
Next page
Claims  available in
Description  (OCR text may contain errors)

M15125, ,4 T.- B. HOLLIDA'Y 2,347,194

TRAFFIC CONTROL DEVICE Filed Aug. 31, 1940' 2 SheetS-Shet l Fig.1

p i 9 T. B. HOILLIDAYI 2,347,194

TRAFFIC CONTROL DEVICE Filed Aug. 51, 1940 2 Sheets-Sheet 2 H5 KM amount.

It is still another object of this invention to Patented Apr. 25, 1944 UNITED STATES PATENT OFFICE 2,347,194 TRAFFIC common nnvrca Theodore B. Holliday, Dayton, Ohio Application August 31, 1940, Serial No. 354,985

(Cl. 177.33'l) (Granted under the act of March a, 1883, as

amended April 30, 19

6 Claims.

The invention described herein may be manufactured a d used by or for the Government for governmen al purposes, without the payment to me of any royalty thereon.

This invention relates to tramc control ap-.

paratus and in particular to a trafllc control signal operative in response to predetermined excessive speeds of vehicular tramc.

It is an object of the invention to provide means responsive to the passing of a vehicletravelling at a rate in excess of a predetermined value for actuating a signal device for indicating the speed of said vehicle.

It is a further object of the invention to pro videa vehicular speed responsive device, as above described, which is operatively' associated with a traiiic signal so as tocause the traflic signal to consecutively progress from the "green or proceed signal through the amber or cauti8n" signal, to the "red or stop signal, and back again to green."

It is still another object of the invention to provide a device of the above described type having operatively associated therewith means for reporting violations of the stop signal, or, if desired and feasible in operation, the actuasive means for whatever purpose it may be desired to employ same.

With these and incidental other objects in view, the invention includes certain novel features of construction and combinations of parts, the essential elements of which are set forth in appended claims and a preferred form or embodiment of which is hereinafter described 'with reference to the drawings which accompany and form a part of this specification.

In the drawings:

Fig. 1 is a diagrammatic. view showing the general arrangement and plan of functioning of the invention.

Fig. 2 is aschematic circuit drawing of a simplified form of the invention.

A Fig. 3 is a 'schematic circuit drawing of a a preferred embodiment of the invention.

Fig. 4 is a circuit drawing of the oscillatorused in Fig. 3.

Fig. 5 is a diagrammatic view of the arrange ment of the di-pole antennae so as to cause the radio field to beintercepted only by cars.on the tion of more'efiective tra flic control means; such as bars, or gates, in response to violations, by

said vehicle of the stop signal, t i

It is another object of this invention to provide a novel means for determining the passing of two consecutive points. by an object during an interval of timeless than a predetermined provide novel means for actuation of a sequence of trafiic signals in response to a'given stimulus, such as a predetermined excessive speed.

The invention'in general contemplates the provision of two spaced detectors sensitiveto the passing of a vehicle or other object. Associated with the detectors is a timing device for determining the passing of the object between said two points during an interval of time less than a predetermined amountl The timing device includes a condenser associated with the first detector and arranged in a circuit so as to receive a charge, and-employ said charge to hold a relay circuit'closed for a predetermined interval of time.

other object crosses the point at which the second detector is located prior to the expiration of said predetermined interval; there is closed a cir- K cuit which will actuate a signal or other responside-of the road in regulated.

li v ctioni j I .l

Fig. 7 is a schematic circuit. diagram showing an apparatus responsive to aiviolation of a stop signal for photographing the offending vehicle. I

than the length of the automobile but not so far that a second moving vehicle would likely 'comewithin the field of the first detecto'rlbe- In-the event the vehicle or v fore'the first vehicle had entered the field of the second detector. A trafliccontrol light l5 having agreen, amber and red light, or other stop, caution and proceed signalling device: is suitably mounted in the highway in full view of automobile H, but shielded against traflic coming in the opposite direction. Detectors l3 and ii are connected to the timing device It which is connected withthe trafllc control light l5 and operates to tu the light from green, to

which the traflic isbeing Fig. 6 is a schematic circuit diagram showing 1 a modification of the invention wherein the time 'cyclexo'fiiithe lights is regulated by condenser i3 and H, preferably spaced apart slightly more field of detector l4 in less than a predetermined time after entering the field of detector l3, and after "holding the light red for a proper time, to return the light to green.

Similarly, detectors l1 and I8 operate to con trol traflic light is when vehicle l2 travels the distance between detectors I1 and I8 in less than the predetermined time.

As illustrated, detectors I3, I4, l1 and I8 are the di-pole antennae type used with ultra-high frequencyoscillators, as are more specifically hereinafter described in'connection with Figs. 4 and 5. They are adjusted and screened as shown in Fig. 5, so as to generate a radio field (shown in the dotted lines) which is effective for only one-half the width of the roadway.

Referring to Fig. 2, the invention as illustrated therein will be seen to comprise a pair of detectors 22 and 23 of the contact type spaced about four feet apart, or close enough for the front wheels to cross both contacts before the rear wheels reach the first detector. These detectors are connected in a timing circuit so as to actuate a signalling device and circuit when a vehicle intercepts the second detector 23 in less than a predetermined interval of time after intercepting the first detector 22.

A battery 24 supplies energy for both the timing.

circuit and the signalling device. The timing circuit consists of a pair of relays 25 and 26 in parallel connection, a condenser 21 and a variable resistance 28. The relays have spring actuated arms, or other means, for urging them normally open. The condenser and resistance are in parallel connection, and arranged so that the condenser is receiving a charge from the battery during inaction of the device. Upon the closing of the contact at the first detector 22, current flows through the relays 25 and 26, closing the arms 29 and 33. When arm 23 is closed, the circuit from the battery to the condenser is opened and a circuit is made through the arm from the condenser to the relays. In this way the condenser discharges through the relays and thereby causes the arms 23 and 30 to be held closed for a period of time corresponding to the time required for the condenser to discharge the energy stored therein to the point where the current flowing is no longer sufficient to hold the relay arms closed. The length of time which is required for the condenser to discharge can be varied by means of the variable resistance 28 in parallel arrangement with the condenser. By decreasing the resistance the time is decreased, and vice versa. The time is ,set at the value which will be required for an object or vehicle to traverse the distance from detector 22 to detector'23 at the greatest rate of speed considered proper or allowable.

When the vehicle passes contact 23, the circuit is closed from the battery 24 to the motor 32 in the signalling device circuit, provided the relay arm 7 30 is still closed. This means that ii. the vehicle has passed from detector 22 to detector 23 in less time than the time required for the condenser to discharge-which time equals a speed predetermined to be excessivethe signalling device will be put in operation because the arm 30 will still be held closed at the time when the vehicle passes the second detector 23. However, if the vehicle were traveling at a slower speed so that more time would have elapsed than that required for the condenser 21 to discharge, then the arm 30 would have opened and the contact of the second rotary switch arms.

amber, and red light, and a pair of rotary switches 34 and 36 connected to the motor through a reduction gear 31. These rotary switches are of the well-known type having conducting arcuate segments and conducting switch arms. Rotary switch 36 serves to make up the respective circuits for the green, amber and red lights, and rotary switch 34 makes up the circuit for operation of the motor 32 during all but a small arc of the circle in which position the switch 34 is inoperative to supply current to the motor. In this position the motor can be actuated only by the circuit made up through relay arm 30 and the detector The operation of the signalling device circuit is as follows: Normally, and in the position shown, the motor and rotary switches are at rest and the circuit is made up from the battery to the green light through conductor 38 and from the green light back to the battery through conductor 39, switch segment 40, switch arm 42 and conductor 43-45. As above explained, no current is being supplied to the motor for these switches are at rest in the inoperative position of switch 34. When relay arm 30 is closed due to actuation by means of the first detector and then when the contact 23 at the second detector is closed while relay arm 30 still remains closed, a circuit is completed from the battery through the motor 32. This causes the motor to rotate, rotating both switch arms 42' and 46 counterclockwise, as illustrated. The segment 35 of switch 34 is so constructed that the momentary closing of contact 23 will cause the motor to rotate the switch sufficiently that the arm 46 will make contact with the segment 35. Thereafter, even though the circuit through relay arm 30 and contact 23 is opened, a closed circuit for the motor is provided through conductor 38, conductor 48, segment 35, switch arm 46, and conductor 44-45. Since both-rotary switches operate in unison, the switch arms 42 and 46 will be rotated counterclockwise for the portion of the circumference represented by segment 35 of switch 34, at which point the switch arm 46 will again come to the open portion of the circle and open the circuit to the motor. During this same period of revolution, switch arm 42 of switch 36 successively makes contact with segment 50, opening the circuit through the green light and making a circuit through the amber light. Then contact is made with segment 52, opening the circuit through the amber light and making the circuit through the red light'for a large :portion of the revolution. The segments of the switches are so arranged that when the switch arm 46 of the motor controlling switch reaches the open portion, the switch arm 42 of the light cycle switch will come to rest on the extreme end of segment 40 making the circuit for the green light. It will be obvious that the length of time that the amber and red lights are on is governed by the length of the segments and the speed of rotation of the The segment 40 for the green light, as illustrated, is made approximately the size of the segment for the red light, so that in the event it was desired to space the detectors farther apart and they were so spaced that the wheels of one car might rest on one detector while the wheels of a second car were resting on the relay arms 8! and 82 are still closed. This opens the circuit to the amber light and closes the circuit from terminal 83 to the red light through relay arm at, conductor 85, relay arm 82 and conductor 95. When the condenser 80 has discharged to a point where its potential is equal,

to the potential value at which relay l9 dropsout, the circuit to the red light is opened and the circuit to the green light is again completed.

It will be understood that a single source oi current such as a battery might be used to oper= ate the current for all three positive terminals 83, 9!! and 96, and that all the negative terminals could be connected to the negative pole of the battery. In this case, the electrical characteristics of the lights would be the governing factor in the potential of the battery, and the relays and condensers would have to be selected with appropriate values to operate at the potential and l: current required for the lights. on the other hand, separate sources of potential could be supplied for each of the terminals 83, 90 and 96, in which case the values of the lights and relays would be governed withrespect to the source of potential only which was energizingthem.

It will be understood that in lieu of either the electrical contact type detector, or the oscillator antennae type detector, described in the foregoing modifications of the invention, that any satisfactory type of detector can be used, such as photoelectric cells, hydraulic or compressed air tubes, or mechanical means, and that the use of any suitable detector is .to be considered as coming within the scope of this'invention.

It may be desirable under certain conditions of operation and use of-the invention, to associate with the traffic light or other trafiic control indicating means, a further device for more effectively controlling the trafiic, such as a bar or gate, or a device for recording an ofiending vehicle, such as a camera or a recordograph, or a violation reporting signal, which devices will be actuated by the act of the vehicle in violating the "stop signal. This can be accomplish .d by the use of a third detector located adjacent the proper line on the highway at which-the vehicle should stop in response to the stop" 'sig-' The third detector may be any of the types' nal. described or mentioned heretofore, and will be arranged to complete an electrical circuit or other source of energy connection to the device to be operated, just as shown and described in connection with the operation of the traflic signalling devices in the modifications hereinbefore described. Action of the bar; gate, or camera, will be effected by ofiending vehicles only, by means of a contact which is in series connection-between the source of energy and the device to beoperated, and-which contact is associated with the .stop signal so that it may be closed only during energization of the stop signal. This contact functions much in the same manner as I the first detector of Fig. 2, while the third detector used to cause actuation of the bar, gate, or

recording or reportingmeans, functions in the manner of the seconddetector of Fig. 2.

A camera is useful in this arrangement because it can be used to photograph the passin vehicles which "violate the stop signal, in such a position that the license number can be obtained, thereby afiording the authorities information to aid in enforcing the law.

An application of the invention arranged to operate a camera is shown in Fig.7, wherein a detector I00 is illustrated inparallel connection asamos I tached to the trigger mechanism 8 it of an automatic reloading camera H4.

Ii. there is sufiicient power in the red light circult to operate the camera trigger mechanism, it will be obvious thatthe relay arm I06 can be used directly to actuate the trigger and the relay Hit could be eliminated.

It will be understood that any of .he other devices mentioned, or any desired device, may be substitutedior the camera. One particularly useful application ofthis circuit in combination with a traffic signalling device, is that it may be connected to operate bell or othenattention commanding instrument when a red light is violated and thereby call the violation to the attention of a law enforcing ofiicer.

Stillanother application of the invention is the use, in lieu of the traffic signalling device, of a signalling device such as a hell or light operated by the second detector and located at a point where a traiiic ofllcer is waiting. The officer, upon getting the signal that the speed limit is being violated, can note the vehicle which has passed the second detectonand immediately take action to apprehend the violator, being fbrtified with objective evidence of the speed violation.

While the form of mechanism herein shown and described is admirably adapted to fulfill the objects primarily stated, it is to be understood that it is not-intended to confine the invention to the forms or embodiments herein disclosed, for it is susceptible of embodiment in various other forms, all coming within the scope of theclaims which follow.

s What is claimed is: I

l. A signalling device having a plurality of signal indications adapted to. be operated in a predetermined time interval sequence in response to a given stimulus, said device comprising a source of electrica1 energy foroperating said signal indications, a condenser in circuit connection with said source of energy so as to be normally charged thereby, a plurality of relays adapted to be energized by said given stimulus,

said relays having difierent operating current discharge of said condenser will maintain each of said relays closed for the interval of time from the initialenergization thereof to the expiration of the tim e sequence of the indication being controlled by each said relay.

2. In a traflic. control device, a traflic signal comprising a "proceed signal indication, a "caution signal indication, and a "stop signal indication a, source of energy for actuating said signal indications; switchmeans for operatively connecting said energy to said signal indications in a predetermined sequence, said switch means comprising a pair of relays normally open and arranged in series to close a circuit in the open position oi! said relays to energize said proceed 2, cause detector 22 and then proceed on to detector 23-if this action has occurred in less than the predetermined timethe signalling device will be in operation when the rear wheels cross the contacts at detectors 22 and 23, since'the time required for the cycle of operation of the lights is considerably greater than the time required for the complete passing of the vehicle past detectors 23 and 24, and therefore the rear wheels will have no effect on the operation of the device. On the other hand, in the event the front wheels crossed the contact at detector 23; after a greater interval than the predetermined time, they would not be effective to actuate the signalling device, as explained above. For the same reason, the rear wheels would function similarly.

The invention shown in Fig. 8 is similar to that shown in Fig. 2, except that in place of the. concuit from the battery to the condenser 10 during the period of inaction or the device. When a car passes the detector l3, therelay pulls arm F2 in, opening the circuit from the battery to the condenser and closing the circuit from the condenser through'conductor 14 to the plus side of the relay winding 15, thus causing the condenser 70 to discharge through relay 64 for the period of time corresponding to *the period required for the 1 energy stored in the condenser, to fall below the amount required to hold the arm closed.) This? relay is of the double throw'type. having a sec-f nd arm 1.3 which makes up the circuit from the negative pole of the battery to the relay arm I6 during the time that the condenser Ill is discharging. If the vehicle passes the detector. l4

while the relay arm i3 is still closed,.relay arm '16 of relay 66, which is normally spring-urged to the open position, closes in responseto the action. of oscillator 56, .and relay 66 completes the clrcuit from the battery to the motor 32 and back, therebyenergizing the motorand initiating the cycle of operation ofthe lights as described in Fig. 2. A

The modification of the invention shown in Fig 6 is similar to that shown in Fig. 2 with respect tact type of detectors, ultra-high frequency oscillators 54 and 56 with di-pole antennae are used for the detectors l3 and I4. The oscillators are of .the wellknown type for producing a field of radio energy which is radiated through the dipole antennae. These detectors are preferably spaced apartslightly more than the length of a vehicle, as described in connection with Fig. 1. There is no objection, as in the case of the contact type detectors, from the possibility'of two cars coming to rest in a trafiic stop and thus c'ontinuing to actuate the traffic signal, since the oscillator-antennae type detector functions only in response to the initial impulse generated as. the metal object enters the field of radio energy. The circuit of one form of oscillator which-may be'used is shown in Fig. 4. When a metal object, such as a motor vehicle, intercepts a field of radio energy transmitted by the di-pole antennae, the metal'object absorbs the energy and increases the power delivered by the oscillator to the field. This increase in (power delivered causes an increase in plate current of the amplifying tube 58 of sufficient amount to cause a relay connected in shunt with an impedance 60 in the plate circuit of said tube to close, thereby causing the relay arm to function in the same manner as the contact switch 22 in Fig. 2.

In order to be responsive or sensitive to a car on the side of the road adjacent the radiator only, a reflector is placed behind the di-pole antennae in a conventional manner for limiting the field to a segment. of a circle with the lower edge of the field above the usual height of a vehicle at the midpoint of the road. Such an arrangement is diagrammatically shown in Fig. where it is the di-pole' antennae and 62 is the reflector mounted on a stake 63.

The relays 64 and 66 shown connected to the oscillators 54 and 56 in Fig. 3 are connected at the points 61 and 68 of the oscillator circuit shown in Fig. 4. The lead 61 is positive with'respect to'the lead 68 because of the potential drop across the impedance 60. Condenser l0 and variable resistor H are arranged and function in exactly the same manner as shown in Fig. 2. Relay arm '72 is normally urged by a spring, or other means, to the open position, and completes a cirto the timing circuit, except that instead. of. showing the returnelectrical paths, only plus and 1 minus terminals are-shown. This part of the circuit will not be again described because its arrangement and operation is believed .to be obvicue from the previous description. However, the signalling device circuit difiers from that shown in Figs. 2 and 3 in that the light cycle from green to amber to red, and back to green, is governed by relay actuated switches anda condenser instead of by the motor and rotary switches de- "scribed in the foregoing modifications. The signalling device circuit includes the green, amber and red lights, a pair of relays 78 and I9, and a condenser. 80. Relay 18 is a. single arm type and relay 19 is a double throw type having two arms 8i and 82. The relay arms are normally urged to the open position by means of springs. Further description of the circuit will be givenin connection with the operation.

A circuit is normally made to the green light from the potential at terminal 83 through relay arm 8 B, conductor 85, relay arm 82, conductor 86,

the light and conductor 81 to negative terminal 88. When the relay arm 89 is closed as a result of actuation by the first detector 22, the circuit is made from terminal 90 to the contactor 23, constituting the second detector. If this contactis actuated by the passing of the vehicle during the time that the relay arm 89 remainsclosed'.

the circuit is completed from the potential 90 to the negative terminals"9l and 92 through relay windings l8 and 7.9. This causes relay arms 84,

El and 82 to pull in, thereby opening the circuit from the potential 83 to the green light and making up the circuit from potential 83 to the amber light-through arm 84 and conductor 93. The circuit from the terminal Bite the condenser is opened at the same time and the circuit from the condenser through the relay windings is closed by means of relay arm 8| and conductor 94, thereby causing the condenser to discharge through the relay windings, serving to hold the relay arms closed-fora period of. time longer than that which would'-be" n'ormally caused by the temporary closing of-the switch contactor 23. Relay 78 is adjusted to drop out at a higher voltage value than relay'fl9, so that arm 84 will make contact with conductor 85 during the time that potential to a condenser; circuit means responlsive to apredetermined stimulus for momentarily energizing said relays to close same whereby said "proceed signal circuit and said condenser chargmg circuit are opened and a circuit from said potential to the cautionf signal is closed through the relay first in series with the source of potential and a circuit from said condenser through said relays is made up. said first relay being of such constant that its armature opens at a potential value greater than the potential value at which the other relay opens and thereby opens the circuit from said potential to said caution" signal and closes a circuit from said potential to said stop signal, and the other of said relays which makes up the condenser-to-relay circuit opening when said condenser has discharged to the hold-in potential value ofsaid relay to thereby open said condenser-to-rel ay circuit and said potential-to-stop signal indication circuit and to re-establish in the open position of said relays said potential-to-condenser circuit and said potential-to-Fproceed" signal indication circuit.

3. In a trafiic control device, a tramc signal comprising a proceed signal indication, a cantion" signal indication, and a "stop signal indication, a source of energy for actuating said signal indications, switch means for operatively connecting said energy to said indication means in a predetermined sequence, a motor for oper-.- ating said switch means, a source of energy for said motor, a second switch means for connecting said source of energy to said motor during the portion of the cycle of operation of said signal indications corresponding to the cycle of operation for said caution and stop signal indications, and circuit means responsiveto a predetermined stimulus while said ,traflic signal is indicating "proceed to connect said motor with said source of energy through a third switch means for initiating the sequence of operation.

of said first-mentioned switch means.

4. ma highway traiiic control device operative v 5 to provide a "stop" signal in response to predetermined excessiv speeds of a trafiic instrumentality, and being associated with a designated point in said highway beyond which said trailic' instrumentality is forbidden to proceed by said "stop" signal, means responsive to a violation of said stop" signal, comprising a detector arranged to be Sensitive to the passing of said traffic instrumentality beyond the point forbidden by said signal, automatic self-loading camera trained on the view immediately beyond said forbidden point in said highway so as to record the identity of said tra-flic instrumentality, upon actuation thereof, a source of electrical energy. power means adapted to be operatively connected to said source of energy by said detector for actuating said camera, and means associated with said stop," signal for rendering said detector ef fective to energize said power means during operation of said step signal.

5. The combination with a traiiic control device operative to provide a stop signal in response to predetermined excessive speeds of a traflic instrumentality, of a recording instrument for recording violations of said .stop signal; detector means associated with said device responsive to a violation of said stop" such traflic instrumentality; and means actua- Me by the response of said detector means for initiating operation of said recording instrument 6. The combination with a trafiic control device operative to provide a stop signal in re sponse to predetermined excessive speeds of a traflic instrumentality, of a camera trained on the area which will be occupied by such. trailic instrumentalit'y at the point of violation of said stop signal; detector means associated with said device responsive to a violation of said stop signal by such trafiic instrumentality; and means actuable by the-response of said detector means for operating said camera so as to record the identity of said ofiending trainc instrumentality.

THEODORE B. HOLLIDAY.

signal by

Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US2472258 *Jan 9, 1942Jun 7, 1949StairTraffic analyzer
US2521683 *Jun 29, 1944Sep 12, 1950Eastern Ind IncTraffic detection apparatus
US2532231 *May 21, 1949Nov 28, 1950Streeter Amet CoTraffic detector
US2553662 *Aug 15, 1947May 22, 1951Union Carbide & Carbon CorpApparatus for actuating an electromagnetic type camera shutter synchronizer
US2619402 *Oct 3, 1945Nov 25, 1952Mccutcheon John WAutomatically recording the speed and identity of vehicles
US2683071 *Jan 31, 1949Jul 6, 1954Leon PearleTraffic monitoring system
US2769165 *Apr 23, 1954Oct 30, 1956Clyde S BowerAutomatic toll collection system
US2779906 *Mar 26, 1954Jan 29, 1957Cutler Hammer IncBraking systems
US2785395 *Mar 22, 1952Mar 12, 1957Leon PearleSpeed monitor
US2867761 *Nov 29, 1955Jan 6, 1959Bendix Aviat CorpMotor control system
US2871088 *Oct 18, 1952Jan 27, 1959Abell FrankMethod of obtaining evidence of traffic signal violations
US2874367 *Jun 8, 1954Feb 17, 1959De Palma James AHighway signalling system
US2908895 *Mar 22, 1955Oct 13, 1959 Cooper
US2914710 *Sep 4, 1956Nov 24, 1959Cons Electrodynamics CorpRing counter
US2927837 *Jan 11, 1955Mar 8, 1960Paul S MartinTraffic monitoring systems
US3045149 *Jul 15, 1960Jul 17, 1962Willard David SCommand circuit
US3054479 *Oct 4, 1957Sep 18, 1962Stewart Warner CorpSpeed responsive control means for automotive vehicles
US3058109 *Aug 4, 1958Oct 9, 1962Robot Berning Und CoSpeed detecting methods and arrangements
US3060434 *Feb 25, 1959Oct 23, 1962Agfa AgMethod and apparatus for traffic surveillance
US3106259 *Jan 22, 1959Oct 8, 1963United States Steel CorpApparatus for weighing a moving object
US3122740 *Jan 10, 1957Feb 25, 1964Admiral CorpVelocity determining device
US3140485 *Aug 4, 1958Jul 7, 1964Lab For Electronics IncRadar control system responsive to a vehicle moving along a traffic path
US3319222 *Apr 9, 1964May 9, 1967Gentry Jester AllieTraffic control device
US3544958 *Sep 11, 1967Dec 1, 1970Carey Leo JSelective speed signs actuated by vehicle speed sensing
US3613061 *Aug 29, 1968Oct 12, 1971Bryant D LundPressure-responsive, timed, electronic control apparatus and methods
US3634843 *Oct 14, 1968Jan 11, 1972Product Dev Services IncCircuit and method for detecting localized noise level changes and especially electromagnetic noise
US3866165 *Jun 27, 1973Feb 11, 1975Robot Foto Electr KgDevice for monitoring traffic
US3938638 *Dec 17, 1973Feb 17, 1976Franklin Electric Subsidiaries, Inc.Apparatus for receiving and acknowledging the return of a vehicle at a check-in station
US4353054 *Aug 6, 1979Oct 5, 1982King Lawrence JStop sign watcher, a device for monitoring vehicles at full stop sign intersections
US4870267 *Jan 13, 1988Sep 26, 1989The Boeing CompanyAmbient light sensitive activator
US5298738 *Sep 3, 1992Mar 29, 1994Gebert Ruediger HSystem for monitoring vehicles having a start and a stop pair of beams
US5382953 *Apr 14, 1994Jan 17, 1995Hauptli; Wayne L.Device for detecting school bus stop arm violations
US5510764 *Dec 16, 1994Apr 23, 1996Hauptli; Wayne LDevice for detecting school bus stop arm violations
Classifications
U.S. Classification340/937, 346/17, 346/18, 235/98.00A, 342/69, 361/181, 340/936, 318/461, 346/107.2, 318/484, 361/180
International ClassificationG08G1/054, G08G1/052
Cooperative ClassificationG08G1/054
European ClassificationG08G1/054