US2214199A - Traffic signaling system - Google Patents

Description

Sept. l0, 1940. c, E, LoMAx TRAFFIC SIGNALING SYSTEM 5 sheets-sheet 1 Filed Nov. 26, 193'7 Sept. l0, 1940. Q E, LOMAX 2,214,199

TRAFFIC SIGNALING SYSTEM Filed Nov. 26, 1957 5 Sheets-Sheet 2 EEG. NIGHT SERVICE RELAY INVENTOR. CLARENCE E; LOMAX ATTORNEYS.

Septn 10, 1940. Q E LOMAX TRAFFIC SIGNALING SYSTEM Filed Nov. 26. 1937 5 Sheets-Sheet 3 .EDUU m2] N mS w m INVENTOR. CLARENCE E. LOMAx ATTORNEYS.

M M, M

Sept- 10, 1940. c. E. LOMAX TRAFFIC SIGNALING SYSTEM Filed Nov. 26, 1937 5 Sheets-Sheet 4 .EDUEU m23 CLARENCE E. LOMAX BYfemym/VM@ www t z: WEEE@ Sept. l0, 1940. c. E. LOMAX TRAFFIC SIGNALING SYSTEM Filed NOV. 26, 1937 FIG. 5

` (g l m REDUCTION GEAR BOX

5 Sheets-Sheet 5 INVENTOR,

CLARENCE E. LOMAX BYMI- 'g a ATTORNEYS,

Patented Sept. l0, 1940 UNITED STATES 'PATENT OFFICE TRAFFIC SIGNALING SYSTEM Application Novembei 26, 1937, Serial No. 176,502

29 Claims.

The present invention relates to signaling i: systems and more particularly to improvements or a street are controlled from a master control station over lines interconnecting the master control station and signaling device switching units or control boxes located at the respective trame intersections.

In signaling systems of the character noted the plurality of signaling devices located at each traffic intersection conventionally comprise a plurality of groups of lamps, each group including red, green, and amber signal lamps positioned to face in one traflic approach direction, thereby to give universally recognized indications to approaching motor vehicle operators. In a four-way intersection four such groups of lamps 0 are usually provided for properly signaling in each of the four traic approach directions. The lamps at each intersection are arranged automatically to be controlled by the apparatus embodied in an associated control box or switch- 5 ing unit, which apparatus functions repeatedly to energize the lamps in a denite cyclic order. Thus on a north-south-east-west intersection the Anorth-south right of way signals are energized for a portion of each operating cycle simultaneously with the east-west stop signals. During another portion of each operating cycle the north-south stop signals are energized simultaneously with the east-west right of way signals. Between the respective portions of each operating cycle allotted to traffic right of way to the respective intersecting trac lanes are periods conventionally known as change-over intervals during which the amber or caution signals are alone energized or are energized in con- .10 junction with the right of way or stop signals. A complete operating cycle for the group of lamps at any intersection includes, therefore, the two periods respectively giving right of way. to the two intersecting traffic lanes, and two change- L15 over periods.

In any system of the form described which involves a plurality of intersections to be controlled it is desirable that the operating cycles of the signal devices located atthe various in- .50 tersections be related in a particular mannersuch that the most expeditious movement of heavy trailic-may be obtained. As an example cf related control of the trailic signal operating cycles there may be cited those systems which are provided for controllingA the traic along (o1. liv-asv) main thoroughfares and wherein the so-called progressive type of traffic control is employed. In this, as in other similar modes of traffic control, the proper relation between the operating cycles of the signal lamps at the various traflic intersections is attained through the expedient of synchronizing the operating cycles of the switching units controlling the lamps at the respective intersections. Obviously, if a nonsynchronous relation develops between the operating cycles of the switching units it is followed by an alteration of the desired relation between the operating cycles of the signaling devices. Another desirable feature usually incorporated in such a system relates to the provision of means whereby the percentage of a signal operating cycle allotted to trame right of way in a particular direction may be changed at will, thereby to adapt the signaling to changing traflc conditions. Still another feature to be found in modern systems of the character described relates to the provision of means for interrupting the normal operation of the signaling apparatus in case of fire or other emergencies and for displaying a characteristic signal indicating the emergency condition in all ofthe approach directions at each intersection, and Imeans for displayingthe caution signal only during periods of light traic. While all of the above noted features are to be found in prior arrangements, the apparatus involved is quite complicated in character and expensive to manufacture and install. Moreover, in the prior systems having incorporated therein all of the features outlined above, a complicated line circuit including an unduly large number of relatively heavy gauge line conductors is required for interconnecting each of the switching units or control boxes with the master control station.

It is an object of the present invention, therefore, to provide animproved signaling system oi."y the general character briefly described above which is of simple and economic construction, which operates in a thoroughly reliable manner to provide all of the above-mentioned control features, and which requires an inexpensive line circuit including a very small number of line conductors.

It is an additional object of the invention to provide in a system of the form described, an improved line circuit interconnecting the various control boxes or switching units and the master control station, 'which circuit is so connected and arranged that the possibility of any Yswitching unit being rendered inoperative, due to a fault in the line circuit, is practically eliminated.

It is a further and more specific object of the invention to provide a signaling system of the character described wherein improved and exceedingly simple circuit arrangements are employed for maintaining synchronized the operating cycles of a plurality of interconnected switching units.

The invention.as described in detail hereinafter is illustrated in its application to a traffic control signaling system wherein a single line circuit interconnects the control apparatus located at the master control station with the control apparatus embodied in each of the plurality of switching units. 'I'he objects as set forth above are in part attained in accordance with the present invention by providing in each switching unit a cyclically operating rotary switch for controlling the energization of the various associated signaling devices. In one embodiment of the invention the actuating means incorporated in each unit for driving the wipers of the associated switch over its associated bank contacts comprises a motor magnet which is connected and arranged to be energized in accordance with spaced pulses applied to the line circuit at the master control station. In a modification of the switching unit the switch wipers are arranged to be driven by a motor which is operated through one cycle, to advance the associated wipers, during each pulse applied to the line circuit. In each modification there is provided in the master control station pulse generating means, and means comprising a relay operative in accordance with the pulse output of the pulse generator for applying to the line circuit voltage pulses, corresponding to the generated pulses.V These voltage pulses are utilized to energize means embodied in each switching unit for controlling th en-ergization of the switch wiper driving means. Also located at the master control station is a cyclically operating rotary switch arranged to be driven in accordance with the generated pulses so that the operating cycles thereof are synchronized with the operating cycles of each of the rotary switches respectively embodied in the various switching units connected to be controlled over the line circuit. In other words, with the system operating properly, the operating position of the rotary switch located at the master control station corresponds at al1 times with the operating positions of each of the rotary switches embodied in the respective'switching units. At a predetermined point in each operating cycle of the switch located at the master control station, means controlled by this switch are caused to operate to impress on the line circuit a control voltage which causes synchronizing means embodied in the respective switching units to operate and correct any non-synchronous relation` between the operating cycles of the units.

In accordance with a further feature of the invention the pulse generating means located at the master control station is arranged to produce pulses at two different rates and, in order that the percentage of each signaling cycle allotted to tramo right of way in a given direction may be altered to conform to changing traffic conditions, the rotary switch located at the control station is arranged to change the pulse transmission over the line circuit from one rate to the other at a predetermined point in each cycle of its operation. As an adjunct to this feature, manually loperable means are provided at the master control station whereby the selective and continuous transmission of pulses over thc line circuit at either of the two rates may be achieved.

In one embodiment of the invention the fire alarm or emergency signaling consists in the continuous energization of the stop signals in all directions and the intermittent energization of the caution signals in all directions, this mode of energizating the signaling lamps being achieved through the provision of a manually operable switch at the master control station which, when operated to its off-normal position, functions to cause the interruption of the normal operation of the switching units. With this switch operated to its off-normal position the various switching units are conditioned to cause the energization of the signaling devices noted, the flashing of the caution or amber lamps being achieved through the continuous transmission of pulses at one rate from the master control station and over the line circuit to each of the switching units; In the other embodiment of the invention the normal operation of the switching units is also interrupted through the actuation of a manually controlled switch provided at the master control station, but in this embodiment a distinct signaling device is provided at each intersection which is continuously energized following the operation of the re or emergency switch to discontinue the normal operation of the associated switching unit. In order to adapt the system to conditions of extremely light traic such as ordinarily occur in the early morning hours, an additional `manually operable switch is provided at the master control station which, when operated, functions to cause the normal operation of the switching units to be discontinued and the caution signals at the various intersections to be intermittently or continuously energized, as desired.

Various additional features of the invention pertain to the specific arrangement of the circuit elements, whereby the above referred to and additional operating features not specifically mentioned are attained.

The novel features believed to be characteristic of the invention are set forth with particularity in the appended claims. 'Ihe invention both as to its organization and method of operation together with further objects and advantages thereof will best be understood by reference to the specification taken in connection with the accompanying drawings in which Figs. 1 and 2 illustrate a traffic signaling system having embodied therein certain features of the present invention; Figs. 3 and 4 illustrate a second embodiment of the invention; and Fig. 5 illustrates the details of certain of the elements embodied in the arrangement of Figs. 3 and 4.

Referring now more particularly tov Figs. 1 and 2 of the drawings the system there illustrated comprises a plurality of switching units, as shown in Fig. 2, a master control station, as shown in Fig. 1, and a three-conductor line circuit interconnecting the control station with each of the switching units. Only one of the switching units, namely, that located in proximity to and arranged to control the signaling devices at the trailic lane intersection 56, is illustrated in detail, but it will be understood that each of the other switching units, including the unit 65 associated with the signaling devices serving the traic lane intersection 6|,are identical in character with that illustrated. As shown, the signaling devices at the intersection 56 of the east and west highway 50 and. the northand south highway 55 comprise a red or stop signal lamp 224, a green orright of way signal lamp 223, and an amber or caution signal lamp 222, arranged to give indications to the tramo traveling east and west along the highway 50. Also included in the plurality of signaling devices at the intersection 56 are the red, green, and amber signal lamps 221, 228 and 229, respectively, which are arranged to govern tramo traveling in the north and south directions along the intersecting highway 55.

These signaling devices have operating circuits traced hereinafter, all of which include the bus conductors 243 and 244, and which are arranged selectively to be completed in the manner pointed out in detailhereinafter through the operation of the relays included in the group comprising R220, R225, R230, R235, R240, and R245. Voltage is impressed across the bus conductors 243 and 244 from the secondary winding 248 of a transformer 241 having its primary winding 249 connected to any suitable source of commercial frequency current at its terminals 242. In this embodiment ofthe invention it is contemplated that the direct current required for energizing the above enumerated relays shall be obtained through the provision of a full wave rectifying unit, not shown, connected between the commercial frequency current source and the direct current bus conductors commonly included in the operating circuits of the relays. In order to simplify the description of these circuits the direct current source is individually indicated for each of the relays ascomprising a battery having its positive terminal grounded, but it will be understood that a single current 4source of the form described will, in practice, be used.

For the purpose of energizing the enumerated signaling devices or lamps in a definite cyclic order there is provided `a cyclically operating switch in the form of a rotary stepping switch 280. This switch, which may be of any standard commercial construction, includes a plurality of I sets of bank contacts 285, 286, 281, and 288,

wipers 28|, 282, 283, and 284, respectively associated with the contact sets in the order of their enumeration, and means comprising a motor magnet M289 and a ratchet and pawl mechanism, not shown, for driving the wipers over the contacts of the respective associated sets. Specifically, the operating circuits for the various relays referred to above have embodied therein the contacts and wipers of the switch 280 and are arranged so that the circuit connections for energizing the signaling devices are controlled/ by the movement of the wipers noted over their associated contacts. 1

'I'he magnet M289 is arranged to be energized from the full wave rectifying unit mentioned above and for the purpose of controlling the energization of this magnet in its operation to step the enumerated wipers of the switch 280 over the contacts of the respective vassociated contact sets, there is provided a polarized relay R250 havingl its winding connected in series with an oppositely poled polarized relay R255 across two conductors C46 and C41 of the three-conductor line circuit 45. This relay R250 is so poled that it operates only when voltage of one polarity is impressed across the two line conductors noted. Similarly, R255, which is provided for the purpose of maintaining a synchronous relation between the operating .cycle of the rotary switch 280 and the operating cycles of the corresponding rotary switches embodied in the various other switching units, operates only in response to voltage applied between the two line conductors noted'of a polarity oppositethat of the voltage to which R250 responds. Specifically, R250 is energized when negative potential is applied to C46 and the opposite positive terminal of the 'A potential source is connected to the grounded or common conductor C41, and R250 operates when the polarity of the voltage applied to the conductors noted is reversed.

' As pointed out previously, there is provided in each of the switching units meanscontrollable from the master control station for interrupting the normal operation of the apparatus in cases of emergency and for displaying in each direction of traiiic iiow along an intersection, signals indicating the emergency condition. In the present embodiment of the invention this means comprises the polarized relay R210 and the relay R2I0 having its operating circuit arranged to be controlled by R210. The winding of R210 is connected in series with the winding of R215 across a different pair cf conductors of the line circuit, namely, C41 and C48. The emergency condition is indicated through the continuous display of the red or stop signals in all directions supplemented by the intermittent or ilashing display of the caution or amber signals in all directions. This mode of operation is achieved through the continuous energization of R2|0 to hold operated the two relays R230 and R240 thereby to maintain the red signal lamps energized and through the intermittent operation of the polarized relay R250 inresponse to voltage pulses applied to the conductors C46 and C41, thereby repeatedly to operate R260. 'Ihis repeated operation of R260 results in the intermittent energization of R220 and R235 which relays control, respectively, the amber or caution signal lamps 222 and 229.

In order to modify the circuit arrangement of the apparatus to make the operation of the signaling devices at the intersection 50 conform to the requirements of light trailc, as for example that which occurs in the early morning hours, there is provided means comprising the polarized relay R215 for interrupting the normal operation of the unit and for causing all of the amber lamps located at the intersection to be energized. As noted above, these amber lamps are indicated at 222 and 229 and the operating circuits therefor are under the control of R220 and R235, respectively. These two relays in turn are arranged to be energized in response to the operation of R265 which latter relay includes an obvious operating circuit controlled by the above noted polarized relay R215. The polarized relays R250, R255, R210 and R215 are arranged to be energized by way of the line circuit from current sources located in the master control station in the manner described with greater particularity hereinafter.

Referring now more particularly to the details of the master control station illustrated in Fig. 1, the apparatus located at this station comprises a cyclically operating rotary stepping switch I which is arranged to be operated in ,different rates.

which comprises two sets oi bank contacts I9 and 20 of twenty-tive points each, wipers I1 and I8 respectively associated with the contact sets I9 and 20, and means comprising a motor magnet erates to produce spaced control pulses at two 'I'his generator, which is only diagrammatically shown, may, if desired, take the form or a circuit breaker driven by a synchronous motor through a gear reduction box and arranged intermittently to apply ground potential to CII5 at one rate and to CIIB at a diiIerent rate. In the arrangement illustrated it is contemplated that the fast pulses shall be applied to CI I5 and the slow pulses to the conductor CIIB. These pulses control the energization of RI20 which relay includes contact lsprings embodied in the operating circuits for MI5 and RI10. As indicated, the relay RI10 is provided with a set of amature springs for impressing voltage across the line conductor C46 and C41 of the correct polarity to cause the operation of all of the polarized relays, corresponding to R250, individually included in the respective switching units. v

In order to control the elapsed time interval required for a complete operating cycle of each of the switching units and of the associated plurality of signaling devices, thereby to adapt the traffic control to changing traffic conditions, there ls provided means comprising the relay RI I0 for selectively connecting RI20 to be energized in accordance with the pulses applied to CI I5 or CI I6, whereby RI10 is energized at the selected pulse rate to repeat the pulses, through the application of voltage across C46 and C41, to the above noted polarized relays embodied in the respective switching units. During the normal operation of the controller, the relay RI II) is arranged to be energized for a portion of each operating cycle of the switch III and to be deenergized during the remaining portion of each operating cycle, so that unequal time intervals are required for the display of the right of way sig- 'nais along the respective intersecting highways. Alternatively, the change over from fast pulsing to slow pulsing may be attained through the provision of a time clock or time controlled switch for controlling the relay RI I0 in lieu of the switch I0. Such automatic control of the pulse rate selecting relay RI I0 may be interrupted through the operation of the key switch 23 to one or the other of its two oiI-normalpositions, thereby to cause this relay to be continuously deenergized or continuously energized in the manner described more particularly hereinafter.

For the purpose of maintaining the operating cycles of the various rotary switches corresponding to and including switch 280 synchronized with each other and with the operating cycles of the rotary switch I0 the lastmentionedswitchis arranged to control RI 30 which latter relay functions to control the operation of RI 60. The relay RISU, when operated, applies voltageV across C46 and C41.of a polarity opposite that applied to these conductors throughthe operation of RI10, thereby to cause the energization and operation of the polarized relays, corresponding to and including R255, which relays, as was pointed out above, functionto cause any non-synchronous condition between the operating cycles of the various switches to be corrected.

Fire alarm control is achieved through the provision of the manually operable key switch 36 which normally occupies the position indicated in the drawings and, when operated to its oiI-normal position, completes circuits for energizing RIIlII and RIBII, thereby to interrupt the normal operation of the switch III and the various rotary switches embodiedin the several switching units controlled by way of the line circuit 45. With this key switch operated a circuit is also completed for energizing RI1II in accordance with the fast pulses applied to CI I5 by the pulse generator 30, whereby the amber or caution signal devices located at the respective controlled intersections are energized.

Control of the switching units to interrupt the normal mode of operation thereof and to render the same effective continuously to energize the amber or caution signal devices located in the controlled intersections during the hours when light traillc persists is attained by providing a second manually operable key switch 3| which is arranged to control the energization of the cycle interrupting relay RI 00 and the relay RI90. The last mentioned relay when energized applies voltage between C41 and C48 of the correct polarity to cause energization of all of the polarized relays corresponding to and includng R215 associated with the line circuit 45. As pointed out above, these polarized relays, when energized, cause the continuous energization of all of the amber signal devices loca-ted at the associated traffic intersection. In addition to the elements in the master control station briefly referred to above there are provided signal lamps 2l, 22, 21, 28 and 29 which function in the manner pointed out in detail hereinafter visually to indicate to an attendant or operator the particular operating condition of the system' at any given time. Current for energizing the various relays, indicating lamps and the operating magnet of the switch l0 is preferably supplied from a common bus, not shown, to which is applied the output voltage of a full wave rectifying unit having its input terminals connected to the usual source of commercial frequency alternating current. For convenience in describing the circuits, however, the source of current for energizing each element of the apparatus has been individually indicated, in accordance with conventional practice, as comprising an isolated battery. As regards the current source for applying voltage to the line circuit 45, it is pointed out that two electrically independent batteries are employed. The positive terminal of one of the two batteries is connected to the grounded common return conductor C41 and the negative terminal is arranged to be connected to the conductor C46 through the operation of either of the two relays Rl1il and RI8ll. The negative terminal of the other of the two batteries is connected to the common conductor C41 and the positive terminal thereof is arranged to be connected to the conductor C48 through the operation of RI 60 or RI90. It will be understood that a single source or battery may be used providing the four relays noted are suitably arranged to prevent short circuiting of the source when the terminals thereof are switched from one side of the line circuit to the other.

Referring now more particularly to the operation of the apparatus illustrated in Figs. 1 and 2 and assuming that the elements of the master control station occupy the positions illustrated in the drawings, ground pulses applied to CI I5 by the pulse generator 30 are eiective to cause the intermittent energization oi RI20 over a circuit extending from ground on the conductor noted by way of RCII2, RAIII, RAIOI, and through the winding of R|20 to battery. This relay, upon operating, completes at RAIZI a circuit for energizing the motor magnet MI5, thereby to prepare this magnet to step the wipers I1 and I8 from engagement with the respective ilrst contacts of the sets I9 and 20 and into engagement with the respective second contacts of these contact sets. The circuit noted extends from ground at RAI02 by way of RAI2I, RAI3I, RCI32, and through the winding of MI5 to battery. 'I'he stepping operation of the switch I occurs when the magnet MI is deenergized at the end of the ground pulse on CI I5. Simultaneously with the completion of the above traced circuit for MI5 a. circuit is completed at RAI22 for energizing RI'IIJ, this circuit extending from ground at RAI02 by way of RAI22, RAI34, RCI36, RCI05, RAI03, and through the winding of RI to battery. The relay RI10 upon operating applies negative battery potential, as indicated, to C48, the opposite terminal of the potential source being connected to C41 through the ground connections indicated. Thus, voltage oi one polarity is impressed across the line conductors C46 and C41 for the duration of the ground pulse applied to CII5 and during the interval when the relays RI and RI1IJ are held energized. 'Ihis voltage pulse results in the energization and operation of R250 and the corresponding relays embodied in the Various other switching units associated with the line circuit 45. Due to the polarity of this voltage, however, the polarized relay R255 is not energized and remains inactive.

The relay R250, upon operating, completes, at RAI, a circuit for energizing M289, which circuit extends from ground at the armature noted by way of RA2I6, RC2I I, and-through the winding of M289 to battery. When energized over the above traced circuit M289 prepares the switch 280 to step the enumerated wipers thereof one step. When the magnet M289 is subsequently deenergized at the end of the ground pulse applied to CII5 these wipers are moved into engagement with their respective associated second contacts. It is to be observed that with the wipers of the switch 280 standing in engagement with any of their respective associated contacts numbered from 1 to 12 and with R2I8 deenergized, circuits are completed for energizing R230 and R245'. The operating circuit for R230 extends from ground at RA2 I3 by way of the switch wiper 282, any one of the rst twelve contacts of the set 288 and through the winding of R230 to battery. With this relay in its operated position an obvious circuit is completed at RA23I for energizing the stop signal device 224 controlling traflic traveling in an east-west direction. The circuit for energizing R245 extends from ground at RA2 I5 by way of the switch wiper 284, any one of the rst twelve contacts of the "set 288, and through the winding of R245 to battery. With this relay energized, an obvious circuit is completed at RA24B for energizing the green or trainc right of way signal 228 controlling tramo proceeding in the north and south directions.

It will be apparent from the preceding description that the above described operations of RI20, the switch I0, R250, and the switch 280, occur each time a ground pulse is applied to CI I5, thus causing the two switches I0 and 280,v together with the other switches similar to the switch 280 and embodied in the other switching units, to be stepped in synchronism, thereby to measure the time interval during which right'oi' way is given to the traillc traveling in the north and south directions. no eifect upon the energized condition of the relays R230 and R245 since therespective wipers of the switch 280 are of suillcient width to bridge two contacts during the transition interval when the wipers are being stepped from one position to another.

As noted above, the ilrst portion oi' the operating cycles of the respective rotary switches embodied in the various switching units controlled over the line circuit steps of the wipers respectively embodied therein. During the interval required for the last four of the rst twelve steps, however, a circuit is completed for energizing R235 thereby to energize the amber or caution signal device 229 so that an overlapping energization of this signal and the trailic. right of way signal 228 occurs. The circuit noted extends from ground at RA2I4 by wayof switch wiper 283, any oi the contacts numbered from nine to twelve of the set 281 and.l through the winding of R235 to battery. Obviously with R235 energized a circuit is completed at RA238 for energizing the signal device 229. When the wipers of the switch 280 are stepped into engagement with their respective associated thirteenth contacts, the i-lrst change-over period of the operating cycle is completed. Thus, when this occurs, the above traced operating circuits for R230, R235, and R245 are interrupted at the switch Wipers 282, 283, and 284, respectively, and circuits are completed for energizing R225 and R240. The circuit for energizing R225 extends from ground at RA2 I 3 by way of the switch wiper 282, the multipled thirteenth to twenty-fifth contacts of the set 286, and through the winding of R225 to battery. 'I'he operating circuit for R240 extends from ground at RA2I5 by way of the switch wiper 284, the multipled thirteenth to twenty-lifth contacts of the set 288, and through the winding of R240 to battery. With R225 energized an obvious circuit is completed at RA226 for energizing the green or rightV of way signaling device 223 controlling trailic in an east-west direction. Concurrently with the energization of the device 223 the red or stop signaling device 221, governing trailic proceeding in the north-south directions, is energized through the operation of R240 to complete, at RA24I, the operating circuit for this device. Hence the trafc right of way is transferred from the northsouth highway 55 to the east-west highway 50. Assuming that the bank contact wiring of each oi' the other ,switching units corresponds to that of the unit shown, the trac right of way is simultaneously transferred to the east and west highway 50 at each of the other intersections having signaling devices controlled by the other switching units.

Since the switch I0 embodied in the master control station is operated in synchronism with the switch 280 and the other switches corresponding thereto, the wipers thereof will be stepped into engagement with their respective associated thirteenth contacts substantially simultaneously with the transfer of tramo right of way in the manner described above. When this occurs the operating circuit for RI I0 is interrupted at the switch wiper I8 causing this relay to restore its armature RAI II so that the ground pulses applied to CI I8 control the operation oi RI20, Since these pulses occur at a much 75 The stepping operations noted have 5 45 corresponds to twelve l5 newer me than the pulses Aapplica to cl ns it will be apparent that a considerably longer time interval willl berequired for the wipers of the' switch III and the wipers of the other synchro- -nously operating switches embodied'in the respective switching units, to be stepped over the remaining contacts of their respective associated sets. Hence, tramo right of way is given to the traiilc traveling along the highway Il! for a time interval which is considerably longer than the ,interval during which traiilc right of way is allotted to the trai'iic traveling on the intersecting highways. The-modepf operation of the apparatus is, however, exactly the same as that describedabove irrespective of the rate of the control pulses.

During the continued operation of the switch 280 and when the wipers of the switch 280 are stepped into engagement with their respective associated twenty-third contacts a circuit is completed for energizing R220, this circuit extending from ground on RAZ I4 by way ofthe switch wiper.

' 283, the twenty-third contact of the set 281, and

through the winding o f R220 to battery.l This relay upon operating completes, at RA22I, -an obvious circuit for energizing the amber or caution signal device 222 governing traiiic proceeding along the highway lSII. Since the above traced units. To this end and when the Wiper I8 of the switch I0 is stepped into engagement with its twenty-fifth contact a circuit is completed for energizing RISO, which circuit extends from ground at RAI|I2 by way of the switch wiper I8, RAISI, and through the winding ofRIIU to battery. The relay RISU, upon operating, interrupts,'at RAISI and RCI32, the pulsing circuit extending toMIi and prepares, at RAIII and RCI, a circuit for energizing RI4IL The relay RISII also interrupts, at RAIN and RCI I6, the above-traced operating circuit for RI 'III and prepares,.at RAI 34 and RCI, a circuit, tracedhereinafter, for energizing RI 80. When Rl2lloperates following the operation of RISO, both of the prepared circuits referred to above are completed, that for energizing Rl4llextending from ground at RAI02 by way of RAI2I, RAISI, RCI, and through the winding` of R to battery, and that for RI6Il extending from-sground at RAIM by way of RAI22, RAI, RCI, and through the winding of RIS!! to battery. 'I'he relay RI40, upon operating, prepares, at RAMI, a circuit for energizing itself in series with RIEII, this circuit extending from ground at RAI02 by way of MAIS,

the winding of RIM, RAMI, and through the.

winding of RI4II tobattery. The above-traced circuit is completed shortly following the operation of RI40 and when R120 restores to remove, at RAI2I, the short circuit placed across the winding of RIM through the operation of RI4II.

The relay RIIII, upon operating, interrupts at RAIN the above-traced operating circuit for Rllli. -When RIM restores, it reprepares, at

RAMI and REI, the above-traced pulsing circuit for MIIl and interrupts the operating circuit for RMI.

, 'I'he relay RI, upon operating` shortly following the operation'of RI 3l, applies. at RAI 6 I positive battery potential to C46. Hence, voltage of a polarity opposite that applied between C46 and C41 through the operation of RIN is now impressed across the two line conductors noted.V

'I'his voltage is not effective to cause the energization and operation of R2ll,but is eifective- -to energize the polarized relay R255, which relay now operates to complete, at RA256, acircuit for causing the s witch 280 to operate to a position corresponding'to-that of the switch I0, in the event the first-named switch has failed to operate in synchronism with the cycle control switch I0. To clarify this point, let it be assumed that the wipers of the switch 2M -have fallen two steps behind the wipers'of the switch Il! so that when the last-mentioned switch has completed its operating cycle the wipers of the switch 280- stand 'in engagement with their respective associated twenty-third contacts. When R255 operates and with the wipers of .switch 2" standing in the position noted, a circuit is completed for energiz-l ing M289, this circuit extending fromground at RANG by way of the multipled contacts of the contact set 285, theswitch wiper 28`I, MA289", and' through the winding of M289 to battery. By virtue of the self-interrupting contacts associated with MANS', the magnet M289 operates buzzer fashion to drive the associated wipers 28| to 284, inclusive, instantly to restore these wipers to a position corresponding to that occupied by the wipers of the switch Il, or into engagement with their respective associated twentyiifth contacts. When the wiper`28l is stepped from engagement with its associated twentyfourth contact and into engagement with its associated twenty-fifth contact, the above-traced operating circuit for M289 is permanently interrupted so that no further operation of the switch 280 occurs until the next operating cycle is initiated. It will be understood that'if any of the switches corresponding to the switch 280 and embodied in the other switching units are out of synchronism with the switch I Il similar operations will occur to restore these switches to positions such that the desired synchronous relation prevails.

Shortly following the restoration of RI30 in sponds to the beginning of a new operating cycle for the switch I0 and the various synchronously operating switches embodied'in the respective switching units. When RI40 restores it interrupts, at RAI4I, a further point in the circuit for energizing RI 50 and RI4I in series and, hence, the apparatus is restored to the condition which prevailed at the beginning of the operating cycle just described. The operation of the apparatus during succeeding cycles is exactly the same as that described above and is continuous for so long as the various manually operable key switches 23, Il, and 38 are maintained in the positions shown in the drawings. An indication that this :node of operation persists is' given by the alternate energization of the signal lamps 2| and 22 during the operation of the switch Il). Thus, with the wiper I'I standing in engagement with any odd numbered contact of the contact set I 9, a circuit is completed for energizing the lamp 2|, this circuit extending from ground at RAI 02 by way of the switch wiper I1 and the filament of the lamp 2l to battery. Similarly, with the switch wiper I1 standing in engagement with any even numbered contact of the contact set I9, a circuit substantially similar with that traced above is completed for energizing the signal lamp 22.

As pointed out above, the key switch 23 is provided for the purpose of changing the time interval required for each operating cycle of the signaling devices located at the various intersections and for the additional purpose of changing the percentage or portion of each operating cycle which is allotted to trac right of way in the two traflic approach directions. It hasalso been pointed out that with the switch 23 standing in its normal position preference is given to traflic traveling along the highway 50 in that the right of way signals governing traflc along this highway are maintained energized for a longer period than are the right of way signals governing traffic on the intersecting highways. If the prevailing traiic is such that equal right of way periods should be assigned to traffic in the two intersecting directions of trafiic movement, the switch 23 may be operated to either of its two off-normal positions so that RI I0 is either continuously energized or continuously deenergized. Thus, with the actuating element of this switch operated to its right olf-normal position, the above-traced operating circuit extending by way of the switch wiper I8 is interrupted at the switch spring 25 and a new operating circuit extending from ground at the spring 26 is completed. Hence, RI I0 is maintained energized so long as the actuating element of the switch 23 is restrained in the ofi-normal position noted and the fast ground pulses applied to CI I5 are utilized exclusively in controlling the apparatus at the master control station as well as the apparatus embodied in the various switching units. When, on the other hand, the actuating member of the switch 23 is moved to its left oli-normal position, the operating circuit for RI I0 is opened at the switch spring 24, so that this relay is restored to place the apparatus in the master control station and the various switching units under the control of the slow ground pulses applied to CI I6. Obviously, this condition prevails until such time as the actuating element of the switch 23 is restored to its normal position.

VThe control of traic in cases of emergency, such, for example, as in instances where it is desired to give right of way to a re truck or an ambulance, is achieved through the operation of the switch 36 to its off-normal position, thereby to interrupt the normal operation of the cycle control switch I0 and each of the switches, corresponding to and including the switch 280 individually embodied in the respective switching units. Thus, when the key switch 36 is operated to its off-normal position, a circuit is completed for energizing RI00, this circuit extending from. ground at the switch spring 42 by way of the spring 4l and through the winding RI00 to battery. At the switch springs 31 and 38, an obvious circuit is completed for energizing the indicating lamp 28 and RI80 in parallel, and, at the springs 39 and 40, a circuit is prepared for energizing RI10 and the indicating lamp 21 in accordance with the pulses applied to the conductor CI I5. The relay RI 00, upon operating, functions to interrupt, at RAIUI, the pulsing circuit for RI20; to interrupt, at RAI02, a point in the common portion of the above-traced circuits for energizing MI5, RIIO, RI30,.RI40, and RI50;. and to interrupt, at RAI03 and RCI05, a point in the first-traced pulsing circuit for RI10. The circuit for energizing RI10 and the lamp 21 is completed upon the operation of RI00 and extends from CIIE by way of the spring 39 to the spring 40 where it divides, one branch extending through the lamp 21 to battery and the other branch extending by Way of RCI04, RAI03, and the winding of RI10 to battery.

When RI operates it impresses, at RAI8I, battery potential across the pair of line conductors C4 1 and C48, the negative terminal of the voltage source being connected to C48 and the opposite positive terminal being connected to C41. yThrough the operation of RI10 in accordance with the ground pulses applied to CI I6, voltage pulses corresponding to the ground pulses are also impressed across the conductors C46 and C41, it being pointed out that the negative terminal of the voltage source associated with these conductors is connected to C46 at RAI1I during each interval when RI10 is operated.

Turning now to the operations which occur in each of the switching units in response to the operation of the switch 36 to its off-normal position and considering only the unit illustrated in detail in Fig. 2, it is pointed out that the voltage impressed across C41 and C48 through the operation of RI80 is of the correct polarity to cause the energization and operation of R210. This relay, upon operating, completes, at RA21I, an obvious circuit for energizing R2I0, which latter relay, upon operating, interrupts, at RA2I6 andk RC2 II, a point in the above-traced circuit for energizing M288. At RA2 I3, RA2I4, and RA2 I 5, the relay R2I0 interrupts points in the above-traced operating circuits for R220, R225, R230, R235, R240, and R245, thus causing any energized ones of the signal devices to be deenergized. Substantially simultaneously, alternate circuits are completed for energizing R230 and R240, these circuits both starting from ground at RA268 and one thereof extending by way of RA2I6' and through the winding of R240 to battery, and the other thereof extending by way of RA2 I1 and the winding of R230 to battery. The resulting operation of these two relays causes the two red or stop signal devices 224 and 221 to be energized, which condition prevails until such time as the key switch 36 is restored to its normal position.

During the period when R210 is energized, the polarized relay R250 responds to the voltage pulses impressed between the line conductors C46 and C41 by the relay RI10. Each time R250 operates it completes,at RA25I, a circuit extending by way of RA2 I6 and RC2 I2 for energizing R260. Hence, the relay R260 is caused to operate in accordance with the voltage pulses impressed across C46 and C41. Each time this relay operates it completes at RA26I and RA26I obvious circuits for respectively energizing the relays R235 and R220. This last-mentioned pair of relays control, in the manner pointed out above, the energization of the caution or amber signal devices 222 and 229. Thus, it will be understood that ashing amber signals are exhibited to the traiiic on each of the highways 50 and 55 for so long as the switch 36 is maintained in its oiT- normal position. 'I'he fact that the red or stop signal devices located in the various intersecting points along the highway 50 are energized is indicated by the illuminated condition of the indieating lamp 28 and the further fact that flashing amber is also being exhibited to'the traillc on these highways is indicated by the intermittent hashing of thev indicating lamp 21, this latter lamp being energized each time a ground pulse is applied to Cl I5.

When the switch 36 is restored to its normal position, the above-traced operating circuits'for RI88 and RI88 are obviously interrupted, as are also the circuits for energizing the indicating lamps 21 and 28. When RI88 restores it disconnects, at RAI8 I, battery from the line conductors C41 and C48, thereby to cause the deenergization of all the relays corresponding to and including the polarized relay R218 in the switching unit illustrated. As a result, R2 I 8 is caused to restore so that the switch 288 is again conditioned to respond to impulses transmitted by way of the line conductors C46 and C41. When RI88 restores, the above-traced circuit for transmitting pulses to RI18 is opened at RAI83 and RCI84, thereby to stop the transmission of voltage pulses by way of the conductors C46 and C41 to R258. With R2I8 and R25lldeenergized, it is apparent that the operating circuitsfor-R238, R248, and R268 are interrupted. Hence, the red and amber signal' lamps at the intersection 56 are deenergized.

When R I88 restores it also functions to reprepare the circuit for energizing RI28 in accordance with the pulses generated by the pulsegenerator 38 andthe circuit for energizing RI18 Thus,

in accordance with the operation of RI28. the apparatus is restored to normal and the cyclic operation of the various rotary switches is continued from the point at which it was interrupted when the switch 36 was operated to its oir-normal position. Y

As pointed out above, the manually operable key switch 3| is provided for the purpose of interrupting the normal operation of the switching units controlled over the line circuit 45 and for causing these units to function to energize the caution signaling devices located at the respective intersections. When this switch is operated to its ofi-normal position, there is completed at the contact springs 32 and 33 an obvious circuit for energizing RI88, which relay functions in the manner described above to interrupt the operation of the rotary switch I8 and each of the synchronously operated rotary switches individually embodied in the various switching units. Briefly summarized, the relay RI 88 functions to interrupt the operating circuit of RI28 in accordance with the pulses applied to either CII5 or CI I6, and with RI28 inactive the relays RI68 and RI18 are maintained deenergized so that no voltage pulses are applied across the line conductors C46 and C41. With RI28 deenergized, the operating circuit for MI5 is held open at RAIZI. application of voltage pulses to C46 and C41 is discontinued the operation of rotary switches corresponding to and including the switch 288 is stopped. Hence, the cyclic energization of the various signaling devices controlled by the switches is discontinued.

With the key switch 3l standing in its oi-normal position a circuit is completed for energizing RISO and the indicating lamp 28 in parallel, this circuit extendingk from ground at the switch spring 34 to the spring 35 where it divides, one branch extending through the lamp 28 to battery and the other branch extending through the winding of RI98 to battery. With RI88 energized, voltage is impressed between the line conductors C41 and C48 of the line circuit '45, it be ing observed that the polarity of this voltage is such that positive potential is applied to the conductor C48. 'Ihis voltage is correctly poled to cause the operation o! the polarized relay R215 andthe relays corresponding thereto lin the re'- spective other switching units controlled over the line circuit 45. Only the operations which occur in the switchingunit illustrated in detail in'llg. 2 and resulting from theoperation oi R215 will be considered in detail, it being understood that identical operations occur in .each of the other switching units controlled by way of the line circult shown. With R215 energized, an obvioul` circuit is completed at RA218 for energizing R285. The last-mentioned relay, upon operating, com pletes, at RA268, an obvious circuit for energizing R2I8. 'I'he relay R2I8.in turn interrupts, in the manner pointed out previously, the operating circuits for any energized ones of the relays R228, R225, R238, R285, R248 and R245, so that the circuits extending by way of the wipers and bank contacts of the switch 288 are rendered ineffective to energize any one of the group of enumerated relays. vAt its armatures RA2I6 and RA2I1, the relay R2 I 8 prepares the previously-traced circuits for energizing R288 and R248, these circuits being held open, however, due to the operated condition of R265. 'At RA2I6, the relay R2I8 interrupts a point in the above-traced operating circuit for M289 and prepares a point in the circuit for energizing R268.

The relay R265, upon operating, further functions to complete circuits for energizing R228 and R235, these circuits extending from ground at RA268 and RA261, respectively, and extending over obvious paths, including the respective windings oi the relays noted to battery. With this pair of relays energized, the operating circuits for the caution or amber signaling devices 222 and 228 are completed at the armatures RA22I and RA236, respectively. Thus, caution signals are continuously displayed at each of the controlled intersections for so long as the key switch SI is restrained to its of! -normal position. This energized condition. of the amber signaling devices is indicated at the master control station through the energization of the indicating lamp 28 upon the operation of the switch 8| in its off-normal position.

When the key switch 3l is restored to its normal position the above-traced operating circuits for RI88 and RI88 are interrupted, causing these relays to restore. The relay RI88, upon restoring, reconditions, in the manner pointed out in detail above, the apparatus at the master control station to respond to the impulses applied to CI I5 or CI I6, depending upon the position of the switch I8, whereby the normal operation of the system is again resumed. When the relay RI88 falls back, the operating circuit for R215 is interrupted, causing the last-mentioned relay to restore and open the operating circuit for R265. When R265 falls back, the operating circuits for R2I8, R228, and R235 are opened in an obvious manner. Following the deenergization of these three relays the apparatus embodied in the switching unit illustrated in Fig. 2 is recondi tioned to operate in the normal manner as described above. In a similar manner each of the other switching units associated with the line circuit 45 is reconditioned for normaloperation.

As pointed out previously, the system of Figs. 1 and 2 requires that a separate full wave rectifier be provided in each switching unit for the purpose of energizing the various relays included inY the unit/In the system illustrated lin Figs. 3, 4 and 5, on the other hand, no rectifying apparatus is required at any of the switching units for the reason that the wipers of the rotary switches embodied in the respective units are arranged to be driven by alternating current motors and the only relays required are those controlled directly by way ci' the line circuit interconnecting the master control station and each of the switching units. Here again only one switching unit is illustrated in detail, namely, that for controlling the tramc signaling devices governing traiiic proceeding through the intersection 460 of the eastwest highway 450. 0f the signaling devices indicated, the red, green, and amber lamps 454, 452 and 453. respectively, are suitably arranged to govern traic proceeding along the highway 450 while the red, green, and amber lamps 454, 456, and 456, respectively, are suitably arrangedto govern traffic proceeding Aalong the north-south intersecting highway. It will be understood that similar signaling devices are provided at each of the other intersections, such, for example, as the intersection 465, which devices are controlled -by switching units identical in arrangement to that illustrated in detail in Fig. 4. The unit for controlling the signaling devices governing trame through the intersection 465 is diagrammatically illustrated at 410. The above-enumerated sig'- naling devices at the intersection 460 are arranged to be energized in a predetermined cyclic manner in accordance withthe operation of a cyclically operating rotary 'switch indicated generally at 440. This switch comprises four sets of bank contacts, 44|, 442, 443, and 444, and wipers 446, 441, 448V, and .449, respectively, associated with the contact sets in the order of their enumeration. The enumerated wipers are arranged to be driven by the alternating current motor schematically indicated at 402 through the driving mechanism depicted with particularity in Fig.

s 5 and described in detail hereinafter. Thismotor includes anv operating circuit having three I branches arranged respectively to be completed by way of theA cam actuated switch springs 423 and 424, and the wiper 446 of the switch 440. Also included in the branch of the operating circuit controlled by the springs 423 are the armature springs of a polarized relay R400 having its winding connected in series with that of an opposite polarized relay R4i0 across the line conductors C363 and C364 of the line circuit 362. In a similar manner the' second branch of the operating circuit for the motor 402 includes armature springs under the control of the polarized relay R4i0, and the third branch of the operating circuit for the motor 402 includes armature springs under the control of a polarized relay R420. As will be notedfrom the detailed description of the operation of the switching unit following hereinafter, the polarized relay R400 comprises means responsive to-impulses of one polarity applied between the line conductors C363 and C364 for causing the motor 402 to drive the wipers of the switch 440 in accordance with these pulses. Similarly, the oppositely poled polarized relay R4|0 comprises means responsive to voltage pulses of -opposite polarity applied between the line conductors noted for causingA the motor 402 to drive the enumerated switch wipers of the rotary switch 440 in accordance with the pulses of opposite polarity. The polarized relay R420 comprises a portion of means for maintaining the switch 440 operating in synchronism with the other similar switches embodied in the various other switching umts and the cycle control switch included in the apparatus at the master control station, and includes a winding connected in sevries with the winding of a fourth polarized relay R430 across the two line conductors C364 and C365'of the line circuits 362. This last-mentioned relay, which is responsiveonly to voltage of a particular polarity impressed between the line conductors noted, is provided for the purpose of energizing predeterminedones of the signaling devices located at the intersection 460 when volt` -highway 450 and the intersecting highways.

Such emergency traffic signaling is attained through the energization of the special lamp 434 which is provided at the intersection 460 and is located in a strategic position such that its illu mination may be observed from any one of the four directionsof approach. I'he circuit for energizing this lamp npt only includes the armature springs controlled by the polarized relay R430 but also armature springs controlled by the polarized relay R4 I 0.

All of the signaling devices or lamps are energized from a standard commercial frequency alternating current source, one side of the current source being connected to the terminal 426 and the opposite side of the source being connected to the switch wiper 448 and the armature RA43I of R430. The same source is included in the operating circuit for the motor 402, this source being connected 'between the terminal 403 and the armature RA43I of the relay R430. For the purpose of energizing the special lamp 434 from the same source, one side of this source is connected to the armature RA4I i of the polarized relay R4I0 and the opposite side of the source is connected to the lower terminal of the lamp as indicated. Since the four relays R400, R4i 0, R420 and R430 are controlled directly through the application of voltagey between the line conductors of the line circuit 362, it will be apparent ing unit is obviated.

Before describing the details of the apparatus located at the master control station, attention is directed to the mechanism diagrammatically illustrated in Fig. 5, which mechanism functions to drive the wipers of the switch 440 from the motor 402 and to control the switch springs 423 and 424. As indicated, the two sets of springs, namely, the spring sets 423 and 424, are'arranged to be controlled by camming elements 50| and 502, respectively, these elements being mounted to rotate with a shaft 503 which is driven by the motor 402 through a gear reduction mechanism 500. Thel springs making up the spring assemblies 423 and 424 are insulated from each other and are mounted on a frame member which may comprise a portion of the housing for the apparatus illustrated in Fig. 4. 'I'he lower spring of the assembly 423 is provided at its free extremity with a cam follower projection 505 which is arranged to drop in either of the two camming depressions 506 and 501 cut at diametrically opposite points along the periphery of the camming element III. similarly, the lower spring of the assembly 424 is provided at its free extremity with a camming projection 522 which -isarrangedtodropineitherofthetwocamming depressions 522 and III provided at diametrically opposite points around the circumference of the camming element 542. It will be imderstood from the description which follows that the lower springs of each of the assemblies 422 and 424 are biased away from the respective associated upper springs so that there is a tendency for the -oppositeiy disposed contacts carried by the respective springs of each set to assume an open circuit position. Considering the spring assembly 422, this position is only attained, however, when the position of the shaft 402 is such that the projection 505 nests in one of the depressions 524 or 521. Similarly, the cooperating contacts carried by the springs of the assembly 424 are only disengaged when the `projection 5,22 is dropped into one of the two depressions 502 and 5I0. In this connection it is pointed out that the elements 50i and 502 are so mounted on the shaft 502 that the depressions 525 and 502 are not in angular coincidence, but are displaced with respect to each other about the axis of the shaft by a right angle. Itis evident, therefore, that the springs 422 and the springs 424 cannot occupy open circulated positions at the same time.

The wipers 444 to 442, inclusive, of the rotary switch 440 are mounted for rotation on a'shaft 5Ii which carries a ratchet wheel 5I2 at one end thereof. Rotary movement is imparted to the shaft 5I I during rotation of the shaft 502 through the operation of a pawl mechanism comprising a pawl 5I3 pivotally mounted at 5I4 on a rocker arm 5I5 and biased into engagement with the ratchet wheel 5I2 by means of a coilspring 5I4. The arm 5I5 is, in turn, pivotally mounted at lil and includes a free end biased, by means of a coil spring 5I9, into engagement ,with the pe- A riphery of a camming element 5I! carried by the shaft 502. The element 5I0 is provided at points displaced by ninety degrees around the periphery thereof with camming projections 520, 520', 52| and 52| which serve to rock the arm 5I5 about its pivot point 5 I 1, thereby to condition the ratchet and pawl mechanism to step the enumerated wipers one step during each quarter tively, whereby the ratchet and pawl mechanism is prepared to step the wipers of the switch 440 at the end of each period during which the motor 402 is energized. During the portions of each revolution of the shaft 502 when the ratchet and pawl mechanism is being rocked by the camming element 5I8, the ratchet wheel 5I2 is restrained against backward movement through the provision of a locking pawl 522 pivotally mounted at 522 and biased into engagement with the teeth of the ratchet wheel -by a coil spring 524. It will readily be apparent that when the projection 520, for example, rides against the left extremity of the arm SI5, this arm is rocked in a clockwise direction regressively to step the pawl from one tooth of the ratchet wheel 5I2 to the preceding tooth. Thereafter, and when the projection 520 rides from beneath the left extremity of the arm SI5, the bias exerted on this arm by the spring 5I9 rocks the arm in a counterclockwise direction to rotate the shaft 5II and the wipers $811' asians' ried thereby through an angle required to step the wipers from engagement with one set of ba-nk contacts and into engagement with the next succeeding' set of bank contacts. Returning now to a consideration of the a paratus located at theY master control station and illustrated in detail in Fig. 3, it.will be noted that there is a marked resemblance between this apparatus and that shown in Fig. l. Thus, it will be recognised that the pulse generator 214 corresponds to the similar device 22 embodied in the system of Fig. l, and that the switches 204, 24|, and 24|, correspond respectively to the similar switches 22, 2i, and 22 of the Fig. 1 arrangement. The relay network comprising the relays R2I2, R222, R220, R242, R242, R222,v and R212 is somewhat different from that shown in Fig. 1, both as regards the functions performed thereby and the mode of interconnecting the operating circuits thereof with the cycle control switch indicated generally at 224. This last-mentioned .switch is of conventional construction and is in `The relays aan, aan, and am, which control the application of voltage across the conductors of the line circuit 242, have their operating circuits arranged to be controlled directly by the switch 240. rather than by certain o'thers of the relays embodied in the master control station. Current for energizing the various relays, indicating lamps and the motor magnet of the switch 22| is supplied .from a common direct current bus, not shown, which may be energized either from a battery or by connecting the same to the output terminals of a full wave rectifier. Here. as in Fig. l, individual current sources for each of the circuit elements are shown, however, in order to facilitate a description of the many circuits involved. voltages of opposite polarity are applied-to the conductors of the line circuit 202 through the provision of two independent bat' teries in the exact manner set forth above in the g'scrliption pertaining to the arrangement of Before describing the detailed operation of the system illustrated in Figs. 3 and 4 attention is directed to the arrangement of the line circuit interconnecting the master control station with each of the several switching units. This circuit is connected to form a continuous loop as indicated by the dash lines appearing in the lower right-hand portion of Fig. 4, so that control current from the master control station is fedto each of the switching units over two branches in parallel. Since a common grounded return conductor C264 is used in conjunction with each of the conductors C252 and C285, it is unnecessary to complete the loop of the common conductor for, by grounding the common conductor at each end thereof, the eect of a complete loop is simulated. It will be observed that by providing a line circuit in the form of a continuous loop or ring, none of the switching units can be rendered inoperative' through the occurrence of an open-circuit line fault in the line circuit. 'I'his is true for the reason pointed out above, namely, that control current is fed to each of the switching units through two branches of the line circuit in parallel.

- Referring now in greater detail to the operation of the apparatus illustrated in Figs. 3, 4, and 5, and assuming that the elements of the master control station occupy the positions illustrated in the drawings, a circuit` is completed for energizing R300 to maintain this relay in its operated position. This circuit extends from ground at RA3I2 by way of the switch wiper 385, the multipled bank contacts of the contact set 382, the switch springs 305, 306, 301, and 308 and through the winding of R300 to battery. With this relay operated, the pulse responsive relay R320 is connected to be energized in accordance with ground pulses applied to C304 by the pulse generator 315. When a ground pulse is applied to C304 the operating circuit for R320 is completed, this circuit extending by way of RC302, RA30I, RA3l I, and through the winding of R320 to battery. The relay R320, upon operating, completes, at RA32I, an obvious circuit for energizing the slow-to-release relay R330. This last-mentioned relay, upon operating, opens, at RA33I and RA332, points in the circuits, traced hereinafter, for energizing the relays R350 and R310, respectively. l

At RA322, the relay R320 completes a circuit for energizing R350, this circuit extending from ground at RA3I2 by way of RA322, the switch wiper 386, the multipled odd contacts of the contact set 383, and through the winding of R350 to battery. The relay R350, upon operating, completes, at RA35I, a circuit for impressing direct voltage between the line conductors C363 and C364. As indicated in the drawings the polarity of this voltage is such that a positive potential is applied to C363, the negative terminal of the source beingconnected to the grounded return s conductor C364 as indicated.

Simultaneously with the operation of R350 a circuit is completed, at RA32I, for energizing the motor magnet M381, this circuit extending from ground at RA3|2 by way of RA32I and 'through the winding of M381 to battery. The magnet M381 upon being energized conditions its associated ratchet and pawl mechanism to step the wipers 384, 385 and 386 of the switch 380 from engagement with their respective associated first contacts and into engagement with their respective associated second contacts. Thereafterand when the ground pulse responsible for the operation of R320 is terminated to cause this relay to restore, the circuit for energizing M381 is interrupted at RA32I. With this magnet deenergized, the ratchet and pawl mechanism noted operates to step the wipers of the switch 380 one step. When R320 'restores at the end of the ground pulse applied to C304, the operating circuit for R350 is interrupted at RA322, causing the last-mentioned relay to restore to disconnect the direct current voltage source from across the line conductors C363 and C364. It is believed obvious that the above described operations occur each time a ground pulse is applied to C304 by the pulse generator 315, and, further, that the wipers of the switch 380 are stepped at the rate of one step for each ground pulse impressed on C304. It is pointed out, however, that R350 does not operate each time R320 operates. Thus, when the wipers of the switch 380 are stepped into engagement with their respective associated second contacts the operating circuit for R350 is opened at the switch wiper 386 and a circuit is prepared at this same wiper for energizing R340. This last-mentioned circuit is completed upon the subsequent operation of R320 when the next succeeding ground pulse is applied to C304 and extends from ground at RA3I2 by way of RA322, the switch wiper 386, the multipled even contacts of the set 383, and through the winding of R340 to battery. The relay R340, upon operating, applies direct current voltage between the line conductors C363 and C364, which is of a polarity opposite that of the voltage applied between these conductors through the operation of R350."

Thus, when R340 operates it connects at RA34I the negative terminal of the direct current source to C363, the positive terminal being connected to the grounded return conductor C364 as indicated.

From the above it will be apparent that R350 and R340 are alternately energized in response to alternate operations of R320 and function to apply voltage pulses of alternate opposite polarity between the line conductors C363 and C364. These pulses are applied to the line conductors noted for so long as the rotary switch 380 operates.

It will be observed that when the rotary switch 380 is operated to a position such that the switch wiper 335 no longer stands in engagement with any one of the first nine conductors of. the set 382, the operating circuit for R300 is interrupted. When this relay falls back the pulse responsive relay R320 is connected by way of RA30I and RC303 to be energized in accordance with the ground pulses applied to C305 rather than the pulses applied to C304. The purpose of this arrangement is exactly the same as that set forth vabove with reference to the similar arrange- .ment illustrated in Fig. l, and hence need not be further described. y

'I'he response of each of the switching units to the voltage pulses of alternate opposite polarity impressed between the line conductors C363 and C364 of the line circuit 362 is. identical, and ac cordingly a consideration of the operation of the apparatus illustrated in detail in Fig. 4 will sufce to render clear an understanding of the operation of the system as a whole. With the wipers of the switch 440 standing in their respective home positions as illustrated in the drawings, a circuit is prepared at the switch springs of the assembly 424 for energizing the motor 402 from the alternating current source connected to thel terminal 403. When, therefore, a positive potential pulse is impressed on C363 by the relay R350, the polarized relay R4I0 operates to complete the branch of the operating circuit for the motor 402 which extends from one side of the alternating current source at the armature RA43I and by way of RC432, RA4I2, the springs of the assembly 424 and through the motor 402 to the opposite side of the source at the terminal 403.- The motor 402 is now energized and drives the shaft 503 through one-quarter of a revolution, at which time the cam projection 508 on the lower spring of the assembly 424 drops into the cam depression 5|0 of the element 502 to open the above-traced branch of the motor operating circuit. During of the element 55|. Hence. the second branch of the operating circuit for the motor 452 is prepared at the springs of the assembly 423.

This last-mentioned `circuit is completed upon the subsequent operation of R345 to apply a voltage pulse across C353 and C354 of the correct polarity to cause the operation of the polarized relay R430 and extends from: oneside of the source by way of RAMI, the springs of the assembly 423, and through the'motor 452 to the opposite side of the source. With the motor again energized the shaft 553 is driven through another quarter of a revolution, at which time the projection 505 extending from the lower. spring of the assembly 423 drops into` the cam depression 501 to interrupt the above-traced second branch of the operating circuit for the motor 452. During this rotation of the shaft 503, the ratchet and pawl mechanism functions to rotate the shaft II to step the wipers of the switch 440 a second step, or into engagement with their respective associated third contacts. Obviously with the shaft 503 standing in a position such that the springs of the assembly 423 are disengaged, the projection 505 carried by the lower spring of the assembly 424 rests on the A outer peripheral surface of the camming element 502. Hence, the contacts carried by the springs of the assembly 424 are brought into engagement to prepare the first-mentioned branch of the operating circuit for the motor 402. Since voltage pulses of alternate opposite polarity are impressed across C353 and C364 for so long as the apparatus in the master control station is functioning in the manner just described, the motor 402 is alternately energized over the two branches of its operating circuit traced above and the wipers of the switch 440 are stepped successively into engagement with their respective associated contacts. In this connection it is pointed out that the duration of the voltage pulses applied to the line circuit must be sumcient to permitthe motor 402 to drive the shaft 503 through a complete operating cycle each time the motor is energized. With the arrangement shown it is contemplated that approximately one second shall be required for the motor 402 to drive the shaft 503 the one-quarter revolution representing each operating cycle. This means. of course, that each ground pulse applied to C304 or C305 by the pulse generator 315 must endure for a time interval slightly greater than one second. The difference in the pulse rates of the pulses applied to C304 and C305 is attained through changing the spacingv interval between successive pulses.

Assuming that the switch 440 is started in operation from its home position as illustrated in the drawings, the stop or red signaling device 45| governing trailic proceeding along the highway 450 and the trailic right oi' way signaling device 455 governing traiiic on the intersecting highway are maintained energized during the interval when the wipers of the .switch 440 are being advanced over the first nine of their respective associated contacts. The path of the current for energizing the signaling device 45| extends from one terminal of the current source as indicated at 426 by Way of the signaling device noted, the multiplied rst nine contacts of the set 442, the switch wiper 441, RC432, and RAA43I to the opposite side of the current source. 'I'he circuit for energizing the signaling device 455 extends from o ne l 555 extending from the lower spring of the assembly 423 rid on the outer peripheral surface side of the current source at the terminal 425 by way of the device 455, the multipled iirst nine contacts of the set 444, the switch wiper` 445, RC432. and RA43I to the opposite side of the current source. During the period Just preceding transfer of trame right of way from the northsouth highway to the east-west highway 453, the north-south amber or caution signaling device is energized. Thus, when the switch wiper 443 isdriven into engagement with the eighth contact of the set 443, a circuit is completed for energizing the device 455. This circuit extends from one side of'the source at the terminal 425, through the device 455 and by way of the switch wiper 445 to the opposite side oi' the source. Since the eighth and ninth contacts of the set 443 are multipled together the device 455 is maintained energized until vthe wipers of the switch 440 are stepped into engagement with their respective associated tenth contacts, at which time the above-traced operating circuit for this device is interrupted at the wiper 445. Simultaneously with the deenergization of the north-south caution signal the operating circuits for the signaling devices 45| and 455 are interrupted at the wipers 441 and 443, respectively, and circuits are completed for energizing the signaling device 452 and 454, therebyto givetrafllc right of way to the traffic proceeding along the highway 450. These lastmentioned signaling devices are continuously energized over obvious circuits until the wipers of the switch 440 are stepped from engagement with their respective associated eighteenth contacts and into engagement with their respective associated first contacts to initiate another oper- 'ating cycle of the switching unit. During the interval just preceding the retransfer of traillc right of way to the north-south intersecting highway a caution signal is displayed to the traffic proceeding along the highway 450 through the energization of the signaling device 453. The circuit for energizing this device extends from one side of the source at the terminal 426 through the device noted by way of the multipled seventeenth and eighteenth contacts of the set 443 and the switch wiper 440 to the opposite side of the source.

From the preceding description it will be apparent that the switch 440 is synchronously operated with the cycle control switch 330 located at the master control station. Specifically each time the wipers of the switch 330 are stepped one step the wipers of the switch 440 are also stepped one step. It is possible that the synchronous relation between the operating cycles of the two switches noted may be disturbed and, in order to correct any such non-synchronous relation, provisions are made for bringing the operating positionsl of the wipers embodied in the respective switches into'coincidence at the end of each operating cycle of therswitch 350. To this end a circuit is provided for energizing R360 at the end oi' each operating cycle of the switch 300 and when the switch wiper 336 is driven into engagement with the eighteenth contact of the set 333. This circuit extends from ground at RA3I2 by way of RA322, the switch wiper 335, the eighteenth contact of the contact set 353 and through the winding of R350 to battery. 'I'he relay R360, upon operating, impresses a control voltage betwen the line conductors C364 and C365, the polarity of this voltage being such that negative potential isV impressed on C365. 'I'his control voltage is of the proper polarity to cause the operation of the polarized relay.R420, which relay, upon operating. completes a circuit for energizing the motor 402, this circuit .extending .from one side of the source at RA43I by way of RC432, RA422, the wiper 440, the multipled contacts oi' the contact set 44| and through the motor 402 to the opposite side oi the source at the terminal 403. As a result, the motor 402 drives the wipers of the switch 440 until they reach their respective home positions as indicated in the drawings, at which time the above-traced operating circuit for the motor 402 is interrupted at the wiper 440. Obviously, if the switch 440 vis operating in synchronism with the switch 380 the only eiiect produced by the operation of R420 is that of completing a multiple branch circuit for energizing the motor 402, it being understood from the previous description that the other branch circuit extends by way of the springs included in the assembly 423.

The method by which the normal operation of the various switching units connected to the line circuit 302 is interrupted in cases requiring emergency trailic indications along the highway 450 is somewhat similar to that described above with reference to the apparatus illustrated in Figs. l and 2. Thus, when the key switch 355 is operated from its normal position as indicated in the drawings to its ofi-normal position, a circuit is completed for energizing the relay R3I0, this circuit extending from ground at the switch spring 350 by way of the spring 351 and through the winding of R3I0 to battery. The relay R3l0, upon operating, interrupts, at RA3I2, a point in the common portion of the circuits for energizing R300, R330, M381 and the two indicating lamps 383 and 389. At RA3II, the relay R3I0 opens a point in the pulsing circuit for R320, thereby to interrupt the operation of the switch 380 and to stop the alternate operation of therelays R340 and R350. With the switch 355 operated to its oi-normal position an alternate circuit is prepared for energizing R350, 'this circuit extending from ground at the switch spring 358 by way of the springs 358 and 342, RA33I RA312, and through the winding of R350 to battery. This relay, which only operates following the operation of the slow-to-release relay R310 as described hereinafter, functions to impress a direct voltage across C363 and C304 in a manner such that the positive terminal of the voltage source is connected to C303. At the switch springs 350 and 358, a circuit is completed for energizing R310, which circuit extends from ground at the spring 350 and by way of the spring 358, RA332 and the winding of R310 to battery. This relay, upon operating, applies at RA31I direct voltage between the line conductors C304 and C305, this voltage being so poled that positive potential is applied to C305, and completes the abovetraced circuit for energizing R350. At the springs 343 and 344 an obvious circuit is completed for energizing the indicating lamp 3l3, thereby to indicate the emergency condition which prevails.

When voltage of the polarity described is applied between C304 and C385 through the operation of R310, the polarized relay R430 is caused to operate to prepare, at RA435. the previouslymentioned circuit for energizing the emergency signaling device 434.

Similarly and when voltage of the polarity noted is impressed between C303 and C304 through the operation of R350, the polarized relay R4I0 is caused to operate, and, upon operating, completes, at RA4II, the above-mentioned circuit for energizing the emergency signaling device 434 located at the intersection 400. The operation of R4I0 further results in the preparation of one branch of the operating circuit for the motor 402, but, dueto the operation of R430 before the operation of R4I0, this branch circuit is now open at RA43I and RC432. The energization of the device 434 indicates to trame traveling in all directions the emergency condition which exists. When R430 operates it interrupts, at RA43I and RC432, a point in the common portion of the operating circuits for all o1' the red and green signaling devices located at the intersection 460, and completes, at RA43I, RC433 and RC430, `obvious circuits for energizing the caution or amber lamps v453 and 450 located at this intersection. Hence, the indication occasioned by the energization of the lamp 434 is supplemented by the indication given by the illuminated caution lamps.

The restoration of the apparatus to its normal operating condition following the above-described sequence o! operations is achieved by returning the switch 355 to its normal position at which time the operating circuits i'or R3I0, R350. R310, and the indicating lamp 3 I3 are opened in an obvious manner. When R3I0 restores, it prepares, at RA3I2, the operating circuits for R300, R330, the indicating lamps 308 and 389, M381,` and the two relays R340 and R350, and, at RA3II,- the pulsing circuit extending to the pulse responsive relay R320. When R350 and R310 restore to disconnect the above-mentioned control voltages from the conductors of the line circuit, the polarized relays R4I0 and R430 restore. When the two polarized relays restore, the operating circuits for the signaling devices 434, 453 and 450 are interrupted and the apparatus of the switching unit resumes its normal operationas described above.

It is noted that when the switch 355 is restored to its normal position the operating circuits for R350 and R310 are simultaneously opened. Due to the slow-to-release. characteristic of R310, however, R350 is the first of these two relays to restore. Hence, R4I0 is caused to restore, to open, at RA4I2, the prepared point in the operating circuit for the motor 402, before R430 is deenergized to prepare, at RA43I and RC432, another point in this circuit. The described order in which R4I0 and R430 are caused to operate and restore is important since it eliminates any possibility of the motor 402 being falsely energized to drive the wipers of the switch 440 to a position ahead of the position occupied by the wipers of the cycle control switch 380 in response to the operation of the key switch 355 between its normal and off-normal positions.

The normal operation of the apparatus may not only be discontinued through the operation of the switch 355 to its oil-normal position, but also through the operation of the night switch 345 to its off-normal position. 'I'his latter switch is provided for the purpose of conditioning the apparatus to energize only those signaling devices located at the various intersections which function to give caution indications during periods when light trailic conditionsv exist. Specically, when this switch is actuated to its oinormal position an obvious circuit is completed at the springs 340 and 341 for energizing the relay R3I0. A circuit is also completed at the springs 348 and 343 for energizing the indicating lamp 3I4 in parallel with the relay R310, this circuit dividing at the spring 349 with one branch extending through the lamp 3I4 to battery and the other branch extending by way of RA332 and the winding of R310 t0 battery. When RMI operates, itfunctions, in the manner described previously, to stop the operation of the switch 330 and to deenergize R340l and R300 so that voltage pulses are no longer applied to C333 and unit illustrated in Fig. 4, and of the other relays,

Aim

'circuit 362.

corresponding to R430., including in the various other switching units controlled over the line When R430 operates, it opens, at RA43I and RC432, apoint inthe common portion of the above-traced circuits for energizing the signaling devices at the intersection 430. The operation of R430 also results in the completion ofV obvious circuits for energizing the caution signaling devices 453 and 450. The energized condition of the two signaling devices noted prevails until such time as the key switch 34B is restored to its normal position. When this lastmentioned operation is performed, the operating circuits for R3I0, the indicating lamp 3|4, and R310 are interrupted. When R310 restores. the operating circuit for the polarized relay R430, and the other relays corresponding thereto, is opened. When R430 falls back the apparatus vembodied in the switching unit shown is again conditioned to respond to the voltage pulses of alternate opposite polarity impressed across C303 and C364 through the alternate operation of R340 and R350. The operation of the relays noted is initiated upon-the restoration of R3I0 to recondition the apparatus at the master control stationto operate in the normal manner as set forth above.

Although in each of the embodiments of the invention as described above the circuit connections for controlling the energization of the signaling devices are indicated as being of a permanent nature, it will be understood that manually operable switching meansymay be provided in each switching unit for changing at will the rotary switch bank contact multiple connections which govern the percentage of each operating cycle allotted to traiiic right of way in each direction. In certain installations this may be desirable for the purpose-of adapting the operation of the system to Widely .divergent trame along the north-south highway 55.

conditions occurring at diierent periods during the day. Considering specifically the arrangement illustrated in Fig. 2, it will be appreciated that-if the multiples between the contacts forming the set 286 and between the contacts forming the set 288 are arranged so that the first portion of each operating cycle is completed upon movement of the wipers of the switch over their respective associated first eight contacts, the portion o i' each operating cycle allotted to tramo right of way in the east and west directions will be muchgreater than with the particular multiple arrangement shown wherein twelve points of the switch are allotted to traffic right of way The same is true of the arrangement illustrated in Fig. 4.

` Hence, through the provision of suitable means -right of way in each direction may be varied to suit the requirements oi' any prevailing tramo condition.

incisa It is further pointed out that4 the operating cycles of the signaling devices located at the respective intersections need not necessarily 'coincide as regards the simultaneous energization of the corresponding signaling devices at each intersection. wherein the so-called progressive type of traiiic control is utilized, the corresponding signaling devices at successive intersections in any desired direction must necessarily be energized succes- Indeed. in those arrangementsv sively and not in unison. It will readily be apparent that this type of control may be secured with the arrangement illustrated by using progressive multiples in successive ones of the switching units so that the trame right of way change-over periods occur at different times and in a definitely spaced order.

While there have been described what are at present considered to be the preferred embodithat various modifications may be made therein without departing from the invention, and it is contemplated in the appended claims to cover all such modiiications as fall within the true spirit and scope of the invention.

1. A traflic signaling system for interfering tramc lanes comprising, in combination, a plurality of trafiic control signaling devices located at a tramo intersection, a switching unit for energizing said devices in a deiinlte cyclic order, a master controlstation, a line circuit interconnecting said unit and said station, means at said station for impressing voltage pulses on said line circuit, said pulses being of alternate opposite polarity, a switch included in said unit, said switch comprising contacts and a wiper associated with said contacts, a motor for driving said wiper over said contacts, means responsive only to pulses of alternate opposite polarity impressed on said line circuit for causing the operation of said motor, and circuit connections controlled by the movement of said wiper over said contacts for controlling the energization of saidsignaling devices.

2. A trafilc signaling system for interfering trafilc lanes comprising, in'combination, a plurality of trafiic control signaling devices located at a trame intersection, a switching unit forl energizing said devicesy in a definite cyclic order, a master control station, a line circuit interconnecting said unit and said station, means at said station for impressing voltage pulses on said line circuit, said pulses being of alternate opposite polarity, a switch included in said unit, said switchl comprising contacts and a wiper associated with said contacts, a motor for driving said wiper over said contacts, a pair of polarized relays including windings connected to said line circuit, said windings being so poled that one of said relays responds to voltage pulses of onel polarity impressed on said line circuit and the other of said relays responds to voltage pulses of opposite polarity impressed on said line circuit, an operating circuit for said motor, said circuit comprising two branches each including a switch controlled by said motor, said circuit branches being so connected and arranged that one thereof is completed upon operation of one of said'relays and is opened by the motor controlled switch included therein when the motor has operated through a predetermined cycle and the other thereof is prepared at the end of said predetermined cycle, is completed upon operation of the other of s aid relays and is opened by the motor controlled r ments of the invention, it will be understood N switch included therein when the motor has operated through another predetermined cycle, and circuit connections controlled by the movement of said wiper over said contacts for controlling the energization of said signaling devices.

3. A traiic signaling system for interfering traillc lanes comprising, in combination, a plurality of tramo control signaling deviceslocated at a tramc intersection, a switching unit for energizing said devices in a denite cyclic order, a master control station, a line circuit interconnecting said stationV and said unit, means including a relay at said station for impressing voltage of one polarity on said line circuit, means including a second relay at said station for impressing voltage of a polarity opposite said one polarity on said line circuit, a switch at said station, said switch including contacts, a wiper associated with said contacts and a motor magnet for driving said wiper over said contacts, means for generating spaced pulses, means operative in accordance with said pulses for energizing said magnet, circuit connections controlled by the movement of said wiper over said contacts for alternately energizing said relays, whereby voltage pulses of alternate opposite polarity are applied to said line circuit, a switch included in said unit, said lastnamed switch comprising contacts and a wiper associated with the contacts, a motor for driving said last-named wiper over the associated contacts, means responsive only to pulses of alternate opposite polarity impressed on said line circuit for causing the operation of said motor and circuit connections controlled by the movement of said last-named wiper over the associated contacts for controlling the energization oi' said signaling devices.

4. A traftic signaling system for interfering traiiic lanes comprising, in combination, a plurality of traffic control signaling devices located at a trailic intersection, a switching unit for energizing said devices in a dei'lnite cyclic order, a master control station, a line circuit interconnecting said station and said unit, means including a relay at said station for impressing voltage of one polarity on said line circuit, means including a second relay at said station for impressing voltage of a polarity opposite said one polarity on said line circuit, a switch at said station, said switch including contacts, wiper associated with said contacts and a motor magnet for driving said wiper over said contacts, means for generating spaced pulses, means operative in accordance with said spaced pulses for energizing said magnet, circuit connections controlled by the movement of said wiper over said contacts for alternately energizing said relays, whereby voltage pulses of alternate opposite polarity are applied to said line circuit, a pair of polarized relays included in said unit and including windings connected to said line circuit, said windings being so poled that one of said polarized relays responds to voltage pulses of one polarity impressed on said line circuit and the other thereof responds to voltage pulses of opposite polarity impressed on said line circuit, a switch included in said unit, said last-named switch comprising contacts and a wiper associated with the contacts, a motor for driving said last-named wiper over the associated contacts, an operating circuit for said motor, said operating circuit comprising two branches each including a switch controlled by said motor, said circuit branches being so connected and arranged that one thereofis completed upon operation of one of said polarized relays and is opened by the motor controlled switch included therein when the motor has operated through a predetermined cycle and the other thereof is vprepared atthe end of said predetermined cycle, is completed upon operation of the other of said polarized relays and is opened by the motor controlled switch included therein when the motor has operated through another predetermined cycle, and circuit connections controlled by the movement oi' said lastnamed wiper over the associated contacts for controlling the energization of said signaling devices.

5. A trame signaling system. for interfering traffic lanes comprising, in combination, a plurality of tranc control signaling devices located at a traic intersection, a switching unit including a cyclically operating switch for causing said signaling devices to be energized in a deflnite order, a master control station. a line circuit interconnecting said station and said unit, means for applying control voltage to said line circuit, means included in said unit and energized by said voltage for controlling the operation of said switch, a cyclically operating switch in said station, means energized in accordance with said voltage for causing4 said second-named switch normally to operate in synchronism with said first-named switch, and means controlled by said second-named switch for maintaining said switches operating in synchronism.

6. A traic signaling system for interfering traffic lanes comprising, in combination, a plurality of trafic control signaling devices located at a trailic intersection, a switching unit including a cyclically operating switch for causing said signaling devices to be energized in a deflnite order, a master control station, a line circuit interconnecting said station and said unit, means for applying voltage pulses of one polarity to said line circuit, a polarized relay included in said unit and energized by said voltage pulses for controlling the operation of said switch, a cyclically operating switch at said station, means energized in accordance with said pulses for causing said second-named switch normally to operate in synchronism with said first-named switch, said switches having corresponding predetermined operating positions, means operated in response to the operation of said secondnamed switch to its said predetermined position for applying voltage of a polarity opposite thatk of said voltage pulses toI said line circuit, a polarized relay included in said unit and energized only by said second-named voltage, and circuit means controlled by said last-named relay for causing said first-named switch to be operated to its said predetermined position only in the event said iirst-named switch has not previously been operated to its said predetermined position.

7. A trailic signaling system for interfering traffic lanes comprising, in'combination, a plurality of traiiic control signaling devices located at a traffic intersection, a switching unit at said intersection and including a stepping switch, said switch including contacts, a wiper associated with said contacts and a motor magnet for driving said wiper over said contacts, circuit connections controlled by the movement of said wipers over said contacts for energizing said signal devices in a denite cyclic order, a master control station, a line circuit interconnecting said unit and said station, an operating circuit for said magnet, a polarized relay connected to said line circuit and operative to complete said operating circuit, means for applying Voltage

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