US2157236A - Traffic signaling system - Google Patents

Description

May 9, 1939. P. P. HORNI TRAFFIC SIGNALING SYSTEM Filed July 9. 1957 m. in I MW 3 W g 37 DD 6 B mm a m im z y %MW v 7 1 m y .R w W up F. 7 m z W L 0W, 5

INVENTOR wubwmwmo LIGHTS HIGHWAY CROSS ST. 1

Patented May 9, 1 939 UNITED sm rss RATE-NT. OFFIQE Claims.

This invention relates to a trafiic control system of the automatic type the signals of which are subject to control by traific which may be either pedestrian or vehicular.

Sincethe flow of traflic' usually has a greater density on one street than on an intersecting street, it is-necessary to allot'more time to the street having the more dense traffic flow'to expedite vehicular movement and allay congestion. It is well recognized among traific engineers that to unnecessarily change the signal lights by indicating a go'signal to a cross-street to be benefited thereby, and at the same time set up a stop signal to the busy main street, is to aggravate traffic congestion" and invite accident. This undesirable feature may be avoided by providing a. discretionary signal control operable by traffic on the cross street of an intersection. It is particularly desirable to have this traflic control feature on a side-street which has only occasional traflic; In this way, trafiic can flow uninterruptedly until a demand is made by a vehicle on the side-street. Trafiic signals are frequently installed to take care of such oo- 25 casional traffic.

It is likewise desirous under certain conditions to indicate neither a definite Stop nor Go signal on either street unless a side-street "vehicle has demanded the right to cross the intersection by actuating an initiating-device. Theabsence of lights, unlessrequired'for trailic control, is a great saving in power consumption over the continuously operated type of traffic control system, reduces the cost for electric light'bulbs, since fewer replacements are necessary, curtails labor expense for replacement of the burned out bulbs, eliminates much repair work by prolonging the life of the controller, and reduces the percentage of potential accident periods due to an unsupervised interseotion, caused by burned out trafiic signal bulbs.

To supervise an intersection which utilizes a trafiic control system having the signal lights normally extinguished on both the main and the cross-street, it is necessary to provide devices which may be operated by the traffic to control the signals. These devices which are operated by traffic to initiate a signaling cycle with the equipment present in this application, may be operated by a vehicle or a person. It will be noted that means are provided, for cross-street, surface or trolley cars, as well as automobiles, to initiate a signaling cycle. The vehicle actuated initiating means, whether mechanical ormagnetic, are commonly referred to in the art as detectors.

Applicants copending application, Serial No. 484,334 is to be distinguished in part from the instant case which has definite and distinct advantages and improvement thereover.

When traffic is active along a main street, which is controlled by normally extinguished traffic signals, experience shows that it is inadvisable to suddenly present'a Stop signal to the moving traific. To do so, would result in numerous rear end collisions of thevehicles. Consequently, it is expedient to present to moving traific, a warning or caution indication, prior to displaying a Stop signal. This gives the traffic an opportunity to adjust itself to the realization that a traific signal is ahead. While a warning signal is beneficial in the normally extinguished type of traffic signal, it is recognized that the benefits of the warning or caution signal has its limitations, since it attracts the attention of the vehicle driver, but indicates no definite signal.

It is accordingly a primary object of this invention to provide a traific signal control system of the automatic type which has its operation initiated by traffic demand, to cause at least one signal cycle, which indicates Go to the moving traffic and Stop to the cross-street traffic, for a brief interval, then to continue through its normal cycle, part of which cycle indicates G0 to a side street and Stop to the main or intersecting street, then changes to again indicate Go to thehighway and Stop to the cross-street, and shortly thereafter, if no demand is made on the cross-street, to lapse into inactivity, giving no signal light in any direction and thereby permitting the regular uninterrupted flow of traflic on the main street, until a future demand is made by a cross-street vehicle or a pedestrian.

The main street, at the intersection, is frequently of such width that it would require many seconds for a pedestrian to negotiate the distance. This lengthy exposure to moving traffic subjects the pedestrian to a greater danger than if the street were quite narrow. To obviate this hazard, it is provided in this application, and made an object thereof, to allow agreater signalling supervised time for a pedestrian to cross the main highway, than for a vehiclathe shorter vehicle interval, and the longer pedestrian interval, each being initiated by a single independent actuation of the signal initiating means provided.

Another object of this invention is to provide a a system of the type described in which a signal cycle is initiated by a pedestrian or a vehicle approaching the intersection from a cross-street, to control the main street or highway, and the secondary or cross-street, during the signaling cycle, the system having means actuable during the cross-street Go interval to cause deceleration of said interval controlling means by traflic, which controlling means is periodically accelerated and again prepared for deceleration by further actuation of the cross-street trafiic up to the completion of the cross-street green interval.

A further object is to provide a signaling system of the character indicated herein, in which the signaling cycle actuating motor is provided with two windings, one a forward and the other a reversing motor winding, each tending to turn the motor in opposite directions, and being of different torque so that when both windings are energized, the resultant torque on the motor shaft is in a clock-wise direction and when the reversing winding circuit is open, the motor is accelerated, and when the driving winding circuit is open, the shaft motion tends to reverse, in order to properly align the various circuit control cams upon completion of a signal cycle, preparatory to future operations.

A further object of the invention is to provide a traffic actuated signaling system, of the class described wherein the flow of traflic on the crossstreet causes a memory device to become operated during the latter part of a signaling cycle to compel a new signaling cycle to become initiated and thereafter to have the traflic signals lapse into inactivity.

Another object is to provide a signaling system wherein a vehicle passing over a detector initiates a signal cycle, a part of which indicates Go on the street of actuation and Stop on the intersection street, said Go signal being existent for a predetermined interval of time.

While a few of the objects of this invention have been definitely set forth, other and further objects and advantages of the invention will be hereinafter presented and the more novel features thereof defined by the appended claims.

A further object of this novel invention is to provide a signaling system in which a vehicle passing over a detector may initiate a signal cycle a part of which indicates Go on the cross-street, said Go interval being enlargeable up to a practical maximum.

For a better understanding of the invention, reference may be had to the accompanying drawing, in which:

Figure l is a schematic diagram of the circuit and representative mechanical parts utilized in this invention.

Figure 2 discloses a chart to indicate conditions of contact operating cams and signaling lights at several different intervals of a signal cycle.

Figure 3 is a View generally representative of the positions of the cams and their respective cam rider members and associated contacts in a normal position.

The chart in Figure 2 can be better comprehended by associating same with Figure 3. In the latter figure, cams I and 3 are shown with the pivotal cam rider in an inoperated or released position, that is, the cam riders are urged toward the center of the cam. While any means may be used to hold the cam riders against the peripheral surface of the cams, a coil spring 8, is disclosed as representative of the resilient means which may be employed, one spring being used for each of the cam riders. In the chart, the O in each of the squares represents that the cam is in an operated position, that is, the cam rider is urged to its outer extremity from the center of the cam.

In Figure 3, cams 2, 4, 5, E, and l are shown operated. While cam l is indicated as being operated, the chart represents that it is not, in fact, operated, but it may be, without altering the operation or effect of the system. The description of operation will bring out that cam I contacts are ineffective until cam 3 contacts are closed, which permits the cam 'I contact to be operated anytime prior to the closure of cam 3 contact.

Signaling circuits The wiring diagram shown in Figure 1 has two conductors indicated by black heavy lines which are marked with a minus and plus or negative and positive symbol to denote simplyasource of power. The several cams, shown in Figure and numbered from I to I inclusive, have centrally pivoted cam riders which have one end thereof normally urged against the riding surfaces of the various cams.

The opposite ends of the cam riders, have either one or two contacts thereon to engage cooperative contacts the functions of which will be more definitely explained in presenting the operation of the system.

In Figure 1, the cams are numbered as in Figure 3, and are shown schematically as a numbered circle having a movable arm electrically connected thereto. When the switch 9 is moved to engage contact I0, a circuit is traced from negative battery, through conductor I2, contact I0, switch 9, conductors I3 and I4, cam arm 4A, contact I6 and cam arm 2A. The circuit is divided here and one branch goes through contact II, signal light GI (highway green) conductor 30, to positive battery. The other side goes to R2, (cross-street red) conductor 3|, to positive battery. Since cams 2 and 4 are normally shown in an operated position when the signaling apparatus is idle, it will be seen that with switch set 3I0 closed, the lights would indicate a green or Go signal to the highway, or number 1 street, and a red or Stop signal to the cross-street or number 2 street. GI, AI and RI represent the green, amber and red lights respectively on the highway, while G2, A2 and R2 represent green, amber and red lights respectively on the cross-street. In this condition with the 9I0 contacts closed, the system would be said to have a normal highway green.

When the signaling control apparatus is set in operation from an actuation by a cross-street vehicle, the motor M rotates. Suitable gearing is provided between the motor and the cam shaft I8 which has securely fastened thereto, cams I to I inclusive. For purpose of explanation, an arrow pointing in a clockwise direction, is indicated to the left of cam I in Figure 3. After the GI and R2 lights have been energized, subsequent to an initiating actuation, the cam shaft reaches an interval which causes cam arm 2A to restore and engage contact I9 which energizes AI through conductors 20 and 2I. The completion of this circuit causes AI and R2 to be lighted as represented in position 2. A continued rotation of shaft I8 causes cam I to operate, at the latest, just prior to the operation of cam 3. In position 3, cam arm 4A restores to open circuits to AI and R2 and to energize RI through cam arm 3A, contacts 30, conductors 22 and 23, and energize G2 through cam arm. IA, contact 24, conductors 25 and 26, both to connect to positive battery. At this time the cross-street green and highway red. lights are energized. A continued rotation brings the cam to position 4, in which cam arm 1A has restored, which deenergizes G2 and energizes A2 through cam arm IA, contact 21, conductors 28 and 29, to positive battery. In position 5 it will be seen that cam. 3 has restored to break the signaling circuit to R! and A2, substantially simultaneously therewith, cams 2 and 4 operate to again energize GI and G2.

In position 4, cam 2 operates prior to begining of period 5 so that the R2 and GI lights come on together. In the position 2, cam. I operates prior to beginning of position 3 so that RI and G2 lights will also come on together. Cams 2 and I in positions 4 and 2 respectively, show the latest period of operation to prepare the cam contact for simultaneous operation of the red and green light. The earliest time for cam 2 to operate is just after beginning of period 3, as cam 4 is open. The earliest time for cam I to operate is just after beginning of period 5, since at this interval cam 3 is open.

The operation explained immediately above shows the several signaling circuits when the contact set 9-II3 is closed with the lights normally having a highway green and a cross-street red. If the switch 9 engages contact II, it will be noticed the conductor to the negative side of the battery is open. Consequently no current can flow to the lights when the apparatus is idle, yet the lights are prepared for operation through cam arms 2A and 4A, so that the GI and R2 lights will be energized as soon as a Signaling cycle is initiated by traffic. The system would be said, under this condition, to be a normal out, as used in the field, since no lights are energized yet the intersection is protected and highway traffic may move unobstructed. Immediately upon demand, by pedestrian or cross-street traffic, the operation of the system energizes the GI and R2 lights, and. causes the system to move through its cycle, previously explained, permitting cross-street trafiic to control the intersection for a time interval, and then to change the lights in order to restart the highway trafi'lc and stop the cross-street trafic. After the lights have been burning in this position, the signaling system stops its signaling cycle and the lights are extinguished, restoring the system to its normal out condition prepatory for further actuation.

Single vehicle actuation The motor used in the signaling system, has two sets of windings. one set being a driving winding indicated as D which winding rotates the mechanism forwardly, the other winding is for reversing the motor when the driving winding, indicated as R is disconnected, and is used for retarding the forward motion of the motor when both windings are connected. Each set of windings consists of a U shaped group of laminations provided with a main winding and an E shaped group of laminations provided with a phasing winding. These phasing windings are represented in the drawing as P and P. The relation between the main and phasing windings is the same as that employed in the single phase A. C. watt-hour meters. The shaft 32 carries a disc 33 which revolves intermediate the main and phasing windings. In order to obtain a good driving torque, the main winding is connected in series with the phasing winding and said main windings each being bypassed by a condenser which causes the current through the phasing winding to lead the current through the main winding. The reversing winding is connected with the phasing winding in the same relative polarity of the driving winding, but the main winding of the reversing motor is poled oppositely to the main winding of the driving motor and therefore produces a torque tending to drive the disc in the opposite direction. In order to obtain a smaller torque from the reversing motor than from the driving motor, the capacitor 34 of the reversing winding is of a smaller value of capacitance than the capacitor 35 of the driving winding. The phasing windings are assembled in a common mounting with respect to their main winding and moveable about the shaft 32, in axial relation thereto. This permits the simultaneous changing of the motor speed of both the driving and reversing windings. The entire motor is represented by a rectanguiar dotted enclosure indicated as M.

A single vehicle detector which may be of any convenient type, either magnetic or mechanical, is simply represented by two members 36-36, but it is to be understood that this single detector may be paralleled by another detector to take care of trafiic on the opposing side of an intersection of a cross-street. It is apparent that the function of the system will be unchanged by using a plurality of detectors connected in parallel. When switch blades 9 and 31 are moved to the right by means of the connecting insulation strip, 38, shown dotted, contact set 9-I0 would be closed to energize GI and R2. The circuit to the reversing motor would then be broken, by the switch blade 3! having moved oif its contact 66 which associates itself with the reversing winding of the motor. In this condition, there is a light normally green on the highway. When a vehicle moves over the detector to close the contacts 36-36, a circuit may be traced from negative battery through 38, 3636', 39, contact 40, switch 4|, conductor 42, winding of memory relay M, 50, to positive battery. Relay M is energized and draws in its armatures 43 and 44, which armatures now engage 43 and 44 respectively.

After the memory relay is energized, a stick circuit is completed for the relay M, be traced from negative battery, through 45, ar-

and may mature 44, contact 44, conductor 46, armature 47 of relay E, and its associated contact 48, conductors 49, 42, winding of relay M, conductor 50, to positive battery.

When the armature 43 of the memory relay M is energized, the circuit between 43 and 43 is broken which circuit normally energizes the reversing motor over conductor 5|, switch blade 52, contacts II and 53, and the cam arm IA, conductor 54, through the windings of R and P", conductor 55 back to positive battery. The negative battery is normally fed to the armature 43 over conductor 45. The negative battery which is normally on armature 43 of memory relay M is now engaging 43 and a circuit may be traced from negative battery over conductor 45, arm.a

ture 43, contact 43", conductors 56 and 57, to the driving winding D of the motor, coil P, conductor 58 to positive battery.

The motor now having no effect from the reversing winding, can move forward freely and through suitable gearing, causes the cam shaft and its associated cams to be rotated, starting ing operated but it will be noted that this cam the lights which move through the various steps of the signaling cycle. Cam I, according to the chart, may open shortly after the motor starts to rotate, but since contact set 43, 43 is open, a further opening of the cam arm IA can have no effect on the reversing winding of the motor. As No. 1 cam operates, opening the lA-53 contact set, the lB-SB contact set is closed, placing a parallel circuit from. one side of the driving winding of the motor to negative battery. In this case, the circuit may be traced from negative battery, over conductor 60, through contact set IB59, conductors BI, 62, B3, 51, windings D and P, conductor 58 to positive battery. This insures the motor to run as long as this cam I is operated and protects it from stopping, due to opening of the memory relay energizing circuit and the consequent opening of the armature 43 and its associated contact 43".

Cam arm 6A is indicated in the chart as bewhen operated, has its associated contact normally open. The cam arm 5A and its associated contact opens momentarily, that is, the cam 5 isopera'ted periodically. Sometime after the G2 lights have been energized, with the consequent energization of relay E, since G2 and relay E 'arein parallel, the armature 41 of relay E will be drawn in, which opens the memory relay stick circuit fco'ntact set 4'l48 The first of the periodic openings of cam arm 5A from its associated contacts, will positively open the circuit to thememory relay to deenergize same. This is obvious since it is apparent that the cam arm 5A will control the energization of relay M for a short time after the opening of the relay E contact set 4'|-48. A further actuation of the 'detector 36-36f would have no effect upon the signaling circuits since the momentary energizationof the memory relay could not be locked in, sincethe other possible current paths are open at this instant. Furthermore, the 43-43 contact set, which controls the reversing winding of the motor at' certaintimes, is not controllable by this contact set at this instant, since the IA53 contact set is open, due to the operation "of cam I, consequently the motor will run at its normal speed'withoutthe effect of the reversing winding until the end of the cycle, when the cam I releases to breakthe energizing circuit of the driving windings to the motor, through the controlling contacts IB59. When the cam I releases to cause 'deenergization of the driving winding, it causescontact set IA53 to be closed, which now energizes the reversing winding of the motor, since the only other possible controlling contacts 4343', are closed.

The end of the cycle having been reached and the green light returned tothe highway to indicate' a Go signal thereon, said signal will remain there, assumingthe controlling contact set 9l0 is still closed. The reversing winding will contr'ol the motor and start it 'to operate in a reverse direction but'since the ratchet 64 which is suitiably geared to the motor gear train, has a pivotally "mounted pawl 65 associated with said r'atchet'in such, a way that the pawl will engage by the pawl 65 to prevent further rotation. The

purpose of this ratchet and pawl is to insure the cam shaft I8 of a positive stopping position. The

against time.

definiteness of this stopping position, isof prime importance when the signal is operating with the lights normally out, because the starting position of the cams which control the highway green and the cross-street red lights, will determine the duration of the burning of these lights before they change to indicate a difierent signal.

The necessity of this precision of cam positioning at the termination of a cycle with the lights normally deenergized can be 'shown by stating that/in practice,v when utilizing the normally out system, drivers of vehicles become accustomed to the length of time that the stop'indication is presentedto the cross-street before it changes to give them a Go signal. Consequently, the driver familiar with the intersection will adjust the speed of his vehicle so that he may reach the beginning of the intersection just as the light changes, without the necessity. of bringing his vehicle to a full stop, thereby, maintaining the maximum efficiency of speed. If the cam positioning is such that the driver getsthe Go signal on the cross-street before he expects it, there may be no disastrous result, but experience has shown that if he should have the red light stay on the cross-street materially longer than usual, he may,in anticipation of receiving the Go signal, permit his car to run out into the intersection while traflic on the highwaywhich usually travels at a high rate of speed, is attempting to clear the intersection.

It seems needless to say, that many serious accidents have been caused by drivers running into intersections because of this feature of speed While it is true the operator of a vehicle may wrongly estimate his speed, it is nevertheless also true that drivers do depend on this timing of traffic signals and a serious accident might be avoided, or a life preserved, by permitting a driver to have the proper precise timing that he has a right to expect.

Motor retardation during cross street interval When there is a demand on a side street and only one vehiclecrosses the intersection, the

driving winding only controls the forward mo- .been set forth relative to the various circuits necessary for operation by the single vehicle, which single vehicle control was madepossible by the switch 31 being moved to the right and opening the circuit to the reversing motor by disassociating switch 31 with the contact 66 of conductor 54. The starting of the signal'cycle which has been previously explained, is the same for a single vehicle. As soon as the cross-street green, or G2 lights are energized, the relay E is simultaneously energized, which moves the armature 41 against contact 61, which feeds negative battery to the reversing winding of the motor. The circuit may be traced from the nega tive battery over conductor 45, armature 44, contact 44, conductor 46, armature 41, contact 61, conductor 68, contact 31-66, conductor 54, R

and P", conductor 55 to positive battery. Im-

mediately upon energization of the .reversing winding, its consequent effect is to retard the revolutions per minute of the motor. Since the stick: circuit over the controlling contact set ll-48 is broken, the stickcircuit is now only controlled by the cam arm A and its associated contact. As previouslyexplained, the duration of the openingof contacts controlled by cam 5, is periodic, and only open long enough to permit the memory relay M to become deenergized. As soon as the memory relay is deenergized, due to the opening of the 5A cam arm and its associated contact, the contact set 44-44' is open which causesthe current flowing over'the conductor 46, contact set 4'l61-, 68, 31; 66, 54, to the reversing winding, to be interrupted. This permits the motor to move under the influence of the driving winding onlyand to assume its normal speed. Further actuations of c the detector by a vehicle will causethe memory relayto operate, which slows down the motor and causes said memory relayto be released upon the momentary opening of the stick circuit through cam 5A.

In the chart, in position 3, under cam 6, it will be noted that there is an interval for thelatter part of said three position which overlaps into the beginning of position 4, in which cam 6 is not operated. When cam 6 is not operated,- the contactv 6A is in the position shown dotted,- which engages the contactassociated-with said cam arm, and positively closes the stick-circuit of the memoryrelay. When cam arm. 6A is thusassociated with its contact, it will beobserved that further periodic openings of the cam 5 will have absolutely no effect upon the stick circuit. The

memory relay will-be locked in, consequentlmbeyond the control of the periodic openings of the 5A cam arm and its associatedcontact.

In position 3, the latter part of said position finds cam 6 released, which-period isknown as the memory interval, which interval isthat portion of the total memory period: which is included in the. cross-street green period. The .total memory period is that portion of the cycle beginning with the last releasing of thememory relay, and terminating with the end ofthe cycle. In position 4, cam 6 is released during the beginning of the cycle, which release interval indicates the released time allotted for the relay E.

At the beginning of period l, cam 1 releases which opens contact sets 1A--'24 and transfers lights from G2 to A2. The relay E is thereby released, closing-contactset 41-58.- further rendering cam 5 ineffective. After the extension relay has had time to release, the -camIG may again operate which separates cam arm EAfrom its associated contact, thereby permitting the memory relay to be no longer under the control of cam (5, during the remainder of-the cycle.

An actuation during memoryinterval, or ,the total memory period will :cause an additional .revolution of the cam shaft and a corresponding signaling cycle, since the memoryrelay will .be

locked into keepthe contact set 43+43 closed putting negative battery ovcrconductor .5- on" to conductors 56 and 51,.to the driving. motor, causing itto run irrespectiveofthe condition of- Cam I and its associated contact set lB-59.

Continuous operation independent of vehicle actuation this is not necessary since by simply moving a double pole, double throw switch, to another position than that previously described, it is possible to have the system operate continuously and alternatethe Go signal and the corresponding'Stop signal with its intermediate caution periods from one street to the other, in a chain of connected signaling cycles. Two switches, 52 and '4! maybe connected by an insulating member shown dotted as 69, which member may be moved to the right so that the switch blade 42 will be disconnected from contact 40 and the switchblade 52 will be moved from the contact which is associated with 53 and said 52 blade will then be" engaging contact lit. The circuit from all ofthe detectors which leads into conductor-39 can no longer operate the memory relay. The switch 52, and its contact H, now having been broken to open the circuit, to the reversing Winding, and whenswitch 52 is moved to contact 10, battery is fed directly to the driving winding of the motor. In this respect a circuit may betraced from negative battery, over conductor45, armature 43, contact 43', conductor 5|, contact-set 52-40, conductors 62, 53, 5'! to driving winding of the motor, conductor 53 to positive battery. It will thus be seen that since no vehicle actuations can ever affect the signaling apparatus and since the motor is continuously operated forwardly at one speed, the cam shaft will continuously rotate and in turn, cause the lights to be transferred from one positicn to another in their proper sequential relationship, to"enabletrafiic to move orderly.

Operation by surface car .A" pair ofcontactsflZ-JZ are shown in parallel with the-.contact set 3fi--35', both sets of contactswwhen "closed, connecting negative battery to conductor 39, the contact set l2-'i2 is used to control the signaling system by a surface car,-13. In operation, a shoe may be provided abovethe trolley wire, so that a passing surface carwill engage that shoe to operate the signaling system. Theseshoes may be provided on opposite sides of the cross-street so that atrolley car coming from-either:direction, may operate the signal if this. is desirable. .In any case, it will be understood that any pair of 4 contacts which are connected between negative battery and the con- .ductor 39; will, at the proper time, control the signaling system. When a surface car wishes to cross the intersection, the trolley wheel proper, 15, will engagethe shoe 14 which completes the circuit. a When the surface car con-tacts i i-15 areclosed, circuit maybe traced from the source conjunction with the suitable relay T9, the resistor will limit the current flow to permit proper operation of the relay '19, to actuate the armature 12, to initiate a signal cycle.

While a specific arrangement is shown for the operation of the contact set I'd-it, it is to be understood that any arrangement of parts may be used to ultimately cause a pair or" contacts tobe1 operated, which operation causes the initia- .tion of a I signaling cycle.

Pedestrian control A push button shown as P, may be one of several which are placed in parallel and are used to initiate a signaling cycle by a pedestrian desiring to cross the highway. When the button is pressed by the pedestrian, a circuit is closed across the contacts ill-8!, which puts negative battery on the winding of the coil TD and energizes same by getting positive battery over the conductor 82. The energization of the relay TD will attract the armature 83, associated with contact 84. Said contacts being in parallel with the detector 3|36, and trolley contact '|2'!2. It will thus be seen that the attraction of 83 which engages contact 84 will close the circuit from negative battery to conductor 39, thereby initiating a signaling cycle. Relay TD will also attract armature 8B, which en ages contact 85, whereby a stick circuit for the relay TD will be traced from the negative battery over conductor 89, contact set 8'l88, a second contact set 85-86, winding of TD, conductor 82, back to positive battery. This circuit will hold contacts 83--84 closed for a period of time depending on the time required for the relay TD to release, said relay TD being a time delay relay, which has a releasing time required for two operations of the cam 5. Relay Y is a restoring relay which unlocks relay TD, by interrupting the stick circuit due to the opening of the contact set 81-88, the armature 81 being responsive to energization of relay Y, if same is operated at the beginning of the cross street green, or G2 period, and allows relay TD to respond to each impulse caused by closure of contact set 8I8| of push button P. This special pedestrian control circuit is utilized, since it is conventional to provide simply an initiating button parallel to the detector. It has been found in practice, that the time allowed for a vehicle to cross at the intersection, is frequently sufficient for a pedestrian to cross at the intersection, when the initiating contacts for the vehicle and pedestrian control are in parallel. This is permissive because the variation in time between that required by the vehicle and the pedestrian at the intersection, is usually just a few seconds. However, many intersections are so wide that the time discrepancy will vary from 5 to 20 seconds. The time delay relay, therefore, must be able to hold the 83-84 contact set closed for a time greater than that between two impulses of the 5A cam arm.

While specific details of the system have been herein shown and described the invention is not confined thereto as changes and alterations may be and may become apparent to those skilled in the art without departing from the spirit thereof as defined by the appended claims.

Having thus described the invention, what I claim as new and desire to secure by Letters Patent of the United States, is:

1. An automatic signaling system for highway intersections including signal circuits arranged to provide a Go signal for the main highway and a Stop signal for the side street, and circuits arranged to provide a Stop signal for the main highway and a Go signal for the side street, switching means to alternately energize and deenergize the circuits through a cycle in which all signal circuits which are normally deenergized are energized to indicate Go on the main street and later indicate Go on the side street for at least a predetermined minimum period, and then return the Go indication to the main street,

means actuated by trafiic to initiate the said cycle of the switching means, and means associated with the switching means to restore the signal circuits to a normally deenergized condition at the end of a signal cycle.

2. An automatic signaling system for highway intersections including signal circuits arranged to provide a Go signal for the main highway and a Stop signal for the side street, and circuits arranged to provide a Stop signal for the main highway and a Go signal for the side street, switching means normally inactive to deenergize all signal circuits, trailic actuable means associated with said switching means to initiate a signal cycle in which the switching means is activated to alternately energize and deenergize the signal circuits through a cycle in which the Go signal is given to the highway, then to the side street, then back to the highway, and means to restore all the signal circuits to the normally deenergized condition at the end of a signal cycle.

3. In an automatic signaling system for high- Way intersections in which all the signaling circuits are normally deenergized said signaling circuits arranged to provide a Go signal for the main highway and a Stop signal for the side street and circuits arranged to provide a Stop signal for the main highway and a Go signal for the side street, switching means to alternately energize and deenergize the circuits through a signal cycle in which the Go signal is given to the main highway, and later to indicate Go on the side street, and then return the Go indication to the main highway, trafiic actuable means for initiating said signal cycle, and means associated with said switching means to restore all the signaling circuits to a normally deenergized condition at the end of a signal cycle.

4. An automatic signaling system for highway intersections, including signal circuits arranged to provide a Go signal for the main highway and a Stop signal for the side street, and circuits arranged to provide a Stop signal for the main highway and a Go signal for the side street, switching means to alternately energize and deenergize the circuits through a cycle in which all signal circuits which are normally deenergized, are energized to indicate Go on the main highway and later Go on the side street, and then return the Go indication to the main highway, means actuated by traflic to initiate the said cycle of a switching means, and means associated with the switching means to restore the signal circuits to a normally deenergized position at the end of a signal cycle.

5. In an automatic signaling system for highway intersections in which all the signaling circuits are normally deenergized said signaling circuits arranged to provide a Go signal for the main highway and a Stop signal for the side street, and circuits arranged to provide a Stop signal for the main highway and a Go signal for the side street, switching means to alternately energize and deenergize the circuits through a signal cycle in which the G0 signal is sequentially given for a period to the main highway, then to the side street, then again to the main highway, traflic actuable means for initiating said signal cycle, and means associated with said switching means for restoring the signaling circuits to a normally deenergized condition at the completion of a signal cycle.

PAUL P. HORNI.

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