US3196388A - Auxiliary traffic controllers - Google Patents

Description

y 0 1965 F. w. HILL 3,196,388

AUXILIARY TRAFFIC CONTROLLERS Filed April 10, 1959 5 Sheets-Sheet 1 DB E Q usv CONDITIONI FIG 3 l6 l7 PB, o I m9 I9\ I [P MAIN ST. E i I I J2. :L; Li PHASE A I DA I v PB PB INVENTOR FRANK w. HILL GROSS ST l DB ATTORNEY July 20, 1965 F. w. HILL AUXILIARY TRAFFIC CONTROLLERS 5 Sheets-Sheet 2 Filed April 10, 1959 moi w mmo OTEO mJrZTEO 0 J54 7E0 INVENTOR FRANK w. HILL Byzfiww Gil-4% ATTORNEY July 20, 1965 Filed April 10, 1959 F. HILL AUXILIARY TRAFFIC CONTROLLERS 5 Sheets-Sheet 3 DB h 1 415v CONDITION 2 PHASE 9 I IS IT P84, m M We D49 :s- I I I x n I A :1 i UDA MAIN 5T. 1 F I8 I 5 F L35 I PHASE A :4 [Mi] -I i 1: I x

1 m9 194: I I PBSL 9 CROSS s1.

I5 "5V CONDITION 5 F I G 5 PHASE 8 IS H I! IL. 1 P5 EFF 1 [Us 191: i 1K3) J MAIN $1. I l P I v :5 E5 :5 I PHASE A I l I: D49 I94]: 1

cRoss INVENTOR D FRANK w. HILL ATTORNEY July 20; 1965 F. w. HILL 3,196,388

AUXIBIARYI TRAFFIC CONTROLLERS Filed April 10., 1959 5 Sheets-Sheet 5 CRi-INT-C CRI- IO U1 1 Ar I cRs-l 40 FIG 7 GRl-INT-C CRl-IC Li FIG 8 r 're\ 'INVENTOR FRANK W. HILL BY mo CAL 42w ATTORNEY United States This invention relates to auxiliary apparatus suitable for use in connection with an intersection trafilc signal controller and adapted to add into the normal traffic signal cycle one or more pedestrian or traffic moving intervals after pedestrian or vehicle detector actuation. The normal traffic signal cycle may be timed by a standard intersection trafiic signal controller. The auxiliary apparatus is connected into the terminal facilities associated with the intersection controller and has a controlling influence over the intersection controller. The accessory controls and times its intervals electronically.

It is well known to control the indication and duration of a plurality of trafic signal lights at an intersection through one cycle of operation under certain conditions of trafiic and through a different cycle of operation following the actuation of a traffiic detector. The above operation requires a two or three phase tratlic controller designed specifically for such application.

What is believed to be new is to provide an electronic control and timer accessory which is able to insert an additional phase movement upon pedestrian or vehicle actuation thus enabling an existing controller to produce an additional phase for most eiiicient traffic movement.

A large number of trailic controllers in use today have an operating sequence limiting them to use on a two or three street intersection. The invention provides auxiliary means to add a pedestrian or vehicle actuated phase to an existing two or three phase controller.

A phase is here defined as one trafiic movement and normally includes a go interval and a caution interval to trahic on one street. An interval is defined as one timed portion of the trailic signal cycle. Normally, one interval is given over to each different signal indication. The purpose of the invention is to provide two or more additional intervals when actuated by a unit of traftic.

One example of the type of traflic signal controller suited for use with the invention is described in United States Patent 2,2659% entitled Traflic Control Apparatus. It is preferable that the controller be of the trafilc actuated type so that timing of one of the intervals may he stopped. If the invention is to be added to Phase A, for example, the controller timing circuit will be interrupted during one of the phase A intervals to permit the auxiliary intervals to be inserted. The auxiliary trafiic signal lights are ener ized and controlled from the auxiliary timing unit. The existing controller and trafiic signal wiring need not be disturbed; the auxiliary unit is merely connected into the controller terminal panel wiring.

Another use of the auxiliary timer unit is in conjunction with a minor movement controller. Normally, at an intersection of two streets with a third smaller street, a two phase controller with a minor movement is employed. The traffic signals may dwell giving the right of way to the main street. fhen a vehicle approaching on the cross street actuates the detector, the right of way is given to the cross street. If the right of way is with the cross street when a vehicle approaches from the minor street, the controller gives the right of way to main street before giving it to the minor street. This is necessary because the minor movement is associated with the cross street movement and can start only from the beginning Patented July 20, 1%65 of the cross street phase. The only Way to get into the cross street phase is through the main street phase.

The invention provides in-phase cycling of such a minor movement controller. That is, if right of way is presented to the cross street when the minor street detector is actuated by an approaching vehicle, right of way is given to the minor street without going street movement, thus making for more efilcient traflic flow. Of course, a three phase controller could have been employed at the intersection. A three phase controller has the ability to skip streets having no traliic and would relieve the condition described. However, minor intersections do not warrant the extenditure for a three phase controller. The inven tion makes it economically feasible to improve tralfic flow at such intersections at modest cost.

The principle object of the invention is to provide an auxiliary electronic timing unit for use with an intersection traliic controller.

Another object is to provide a unit which acids one phase to an existing intersection traffic controller.

Another object is to provide a timing and control unit which upon actuation adds one or more pedestrian or trafiic moving intervals.

Another object is to provide an auxiliary multi-interval electronic timer started into operation by actuation of a pedestrian pushbutton to control and time pedestrian signals and prevent the intersection trafiic signal controller from showing conflicting signals.

Another object is to provide an auxiliary multi-interval electronic timer started into operation by trafiic actuation on a minor street which inserts one or more trafiic moving intervals within one of the normal trafiic moving phases.

Another object is to provide an auxiliary timing unit which converts a two phase controller to three phase operation.

Another object is to provide an auxiliary pedestrian actuated electronic timing unit to control and time the illumination of walk-wait tratfic signals.

Another object is to provide an electronic circuit initiated through a timed signal display sequence controlled by and also controlling an intersection trafiic controller.

Another object is to provide a timer which will control and time pedestrian traffic signals through walk and guaranteed clearing intervals upon pedestrian actuation prior to the walk interval, and upon pedestrian actuation during the guaranteed clearing interval if no vehicle actuation has occurred on the opposite phase.

Another object is to provide an electronically timed pedestrian interval timer having a memory device which will remember pedestrian actuations made during times when the walk sequence cannot be awarded almost immediately.

Another object is to provide a delayed green interval timer unit for use with an intersection traflic signal controller which will illuminate and time a signal display which will permit vehicles to clear a boulevard crossing after the normal right of way interval has transpired.

Another object is to provide a selective circuit which will reduce the guaranteed wait interval and permit the walk signal to be illuminated almost immediately after a pedestrian actuation during the guaranteed wait interval only if no vehicle actuations have occurred on the other phase.

Other objects and advantages will be disclosed throughout the description which follows. Reference will be made to the following drawings in which FEGURE 1 is an isometric view of the exterior of the interval timer in its housing.

FIGURE 2 is a side view of the timer chassis with housing removed showing the electric components.

FIGURES 3, 4, and are plan views of an intersection controlled by a two phase full-actuated controller with the auxiliary unit interconnected.

FIGURE 6 is a line to line schematic diagram of the timer circuit.

FIGURE 7 is a line to line diagram of the timing capacitor charging circuit.

I FIGURE 8 is a line to line diagram of one of the timing circuits.

A general view of the timer unit is shown in FIGURE 1. The housing is comprised of a rectangular canister 1 having one open end 2 closed by a rectangular cover 3 to which the chassis is assembled. Two multi-pin connector plugs 4, 5 are inset into the face of the timer. Connector 4 has eleven pins through which connection is made to the terminal facilities within the intersection traf'ric signal controller cabinet, not shown. Connector 5 has nine pins through which connection is made to auxiliary apparatus also within the controller cabinet, not shown. Connectors 4 and 5 are standard; a wiring harness having cooperating eleven terminal and nine terminal sockets are normally provided to facilitate permanent connection into the terminal facilities. The timer unit may be removed or replaced simply by disconnecting the two connectors.

Two manual adjustment knobs 6, 7 are provided on the face of the unit to permit adjustment of the duration of the timed intervals. Gradations of dials 8, 9 indicate the duration of each interval. The unit shown in FIG- URE 1 carries the designation Walk below dial 8 and Clearance below dial 9. The inscriptions may be changed 'to reflect the usage of the timer as, for example, .Delayed Green and Traffic Clearing in another application of the invention described. Normally, the settings are made when the unit is first applied at an intersection and remain unchanged thereafter until intersection or'other conditions change.

r A side view of the timer unit is shown in FIGURE 2 with the canister removed. The formed chassis 10 is attached to the cover 3, and supports most of the electric components. The step switch CR1 is located on the upper level of the chassis. The check circuit relay CR2 is shown immediately below. The detector relay CR3 is hidden behind the transfer relay CR5. Both are attached to the vertical portion of the chassis 10. The load relay CR4 is hidden behind the transfer relay CR6. Both are located on the lower rear of the chassis. Plate circuit relay CR7 is attached to a bracket above relay CR6. The various resistors and capacitors shown in the schematic diagram of FIGURE 6 are mounted on insulated panel 18. The filament heater transformer is shown at 19, and the gas-filledtetrode tube V1 above it. Potentiometer R1 which controls the duration of the walk interval is shown mounted through front cover 3; potentiometer R2 which controls the duration of the clearance interval is located directiy behind potentiometer R1. The wiring has been omitted from FIGURE 2 in the interest of clarity.

The step switch CR1 is of the OCS type shown more fully on page 88 of Automatic Electric Company bulletin entitled Relays and Switches for Industrial Control, 1958. As illustrated in FIGURE 2 herein three cams 11, 12, 13 control the operation of contacts CR1-1B and CR1-1C, CR12B and CR12C, and CR1-3B and CR13C, respectively. The B in the contact nomenclature indicates a B stack, or a pair of normally closed contacts; C indicates a C stack, or single pole, double throw contacts. The'cams 11, 12, 13 are cut according to the inset shown as part of FIGURE 6. Cams 11 and 13 are cut in the first or reset interval. Cam 12 is cut in the second or walk interval. The B stack is closed during the cut interval. The C stack transfer during the cut interval. FIGURE 6 is drawn to illustrate the position of the contacts during the first or reset interval.

- energized. Contacts CR1INT-C are interrupter contacts, C stack, which transfer while coil CR1-C is energized.

INSTALLATION The auxiliary electronic timer unit may be used in conjunction with an intersection traffic controller to accompiish a variety of control functions. The most important applications are as a pedestrian walk and guaranteed clearance interval timer, as a minor phase movement and clearance interval timer, or as a delayed green and clearance interval timer. In each of these applications the auxiliary unit is actuated into its timing and traffic signal controlling sequence by trafiic actuation. Actuation is by pedestrian pushbutton in the first named application or by vehicle detector in the vehicle controlling applications.

The intersection traffic signal controller to which the unit is connected is normally a two phase unit, either semi-actuated or full-actuated. Semi-actuated controllers have trafiic detectors in one intersecting street, usually the minor or cross street. Full-actuated controllers have detectors in both intersecting streets. The auxiliary unit may be connected into the cross street phase and used as a pedestrian unit to permit pedestrians to cross the main street while the cross street traffic is moving. Or it may be connected into the main street phase to permit pedestrians to cross the minor street while main street trafiic is moving. If used as a minor movement timer unit it permits minor movements such as left turns during a portion of the main street phase. If used as a delayed green timer unit it is connected to be actuated once each cycle to provide additional signal indications suclii as a delayed green movement across a wide boulevar The auxiliary unit is operated in conjunction with the compatible phase of the trailic signal cycle. The function of the auxiliary unit is to call the controller to the compatible phase, permit non-interfering traflic to flow, retain the controller in that phase until the inserted intervals have transpired, and then return control to the intersection controller.

The various trafiic movements are illustrated in FIG- URES 3, 4, and 5. The phase A movement which corresponds to traffic flow on street 14 is shown in progress in FIGURE 3. Since traffic is permitted to flow across cross Walk 18 the DONT WALK signals 19 are illuminated. Traffic is stopped on street 15.

A pedestrian wishing to cross street 14 depresses one of the pushbuttons PB located at each corner of the intersection and waits for the WALK signal. The WALK signal is illuminated after the proper clearance signal is given to phase A traffic on street 14. Traflic is stopped on street 14 and permitted to flow on street 15. The WALK signals 19 are illuminated for a time and then extinguished. The DONT WALK signals are then illuminated for a guaranteed pedestrian clearance interval. At

the expiration of the guaranteed clearance interval right of way is returned to street 14 if a detector actuation has occurred thereon.

A second condition is illustrated in FIGURE 4. The phase B traffic movement is in progress with traffic flowing on street 15 and stopped on street I4. If a pedestrian arrives at the intersection while the phase B movement is in progress and wishes to cross street 14 he depresses one of the pushbuttons PB and is given the WALK light almost immediately if no vehicle has actuated one of the phase A detectors DA, The function of the auxiliary unit under this condition is to illuminate and time the WALK signals 19, and then to extinguish the WALK signals and illuminate the time the DONT WALK signals 3,19e,sss

for a guaranteed pedestrian clearance interval. At the expiration of the guaranteed clearance interval the auxiliary unit 17 transfers control hack to the intersection controller 16.

A third condition is illustrated in FEGURE 5. The phase B movement is in progress with traffic moving on street 15 and stopped in street 14. A vehicle V has rossed detector DA has entered a call to the intersection controller 36. A pedestrian desiring to cross street 14 at this time and depressing one of the pushhuttons PB will not be given the WALK signal immediately even though the controller 16 is in the compatible phase. The circuit is designed to award right of way on a first come, first served basis and will grant right of way to vehicle V before granting right of way to the pedestrian.

While vehicle V is being granted the right of Way additional vehicles may arrive at the intersection and actuat d detectors DA. They will extend the time right of way is given to street but they will not be able to retain right of way longer than a phase A maximum period. T hen right of way will be returned to the phase B movement at which time the WALK signals will be illuminated. The WALK signals will be extinguished after a short interval and the DUNT WALK signals illuminated for a guaranteed pedestrian clearance interval. After the guaranteed interval the auxiliary unit will relinquish control and the right of way will be returned to street if the phase A maximum period has expired or it another actuation occurs on street 14.

These three conditions are enumerated below. The operation of the auxiliary unit will be described with reference to each of these conditions.

Condition 1. The intersection controller is dwelling in phase A with the right of way signals illuminated to street 14 permitting trafiic to cross the pedestrians path. N vehicle calls are in when the pedestrian pushbutton PB is depressed. This condition is illustrated in FIGURE 3.

Condition The intersection controller is dwelling in phase B with the right of way signals illuminated to trellis on street 15' parallel with the pedestrian crosswalk. No vehicle calls are in when the pedestrian pushoutton PB is depressed. This condition is illustrated in FlG- URE 4.

Condition 3. The intersection controller is in phase B illuminating the ri ht of way signals on street T to Radio parallel with the pedestrian crosswalk. A vehicle V has actuated the vehicle detector DA and has approached the pedestrian crosswalk when the pushbutton is depressed. This condition is shown in FZGURE 5.

The functioning of the auxiliary unit through its vari ous phases will be described with reference to FIGURE 6. FTGUM 6 is in the form of a line to line schematic wiring diagram of the device. The relay coils CRl-C to CRT-C are arranged across the sheet in spaced apart relationship. Contacts associated wi n each relay are shown in vertical alignment with their controlling coils, for the most part, so that reference is iacilitated. The input and control terminals are located along the left margin of the drawing. The common return line ill is drawn along and parallel to the right margin.

operation of the timing and control circuit will be escribed following operati n of the detector actuator during each of three conditions enumerated above.

Condition 1 As defined above, concition 1 exis s when the intersec tion trafiic signal controller is dwelling in the opposing phase, phase A, with no recent vehicle actuation when a cell is placed on the auxiliary unit. A call is placed when a pedestrian depresses the pushbutton PB. The pushbutton PS admits Ll power to terminal Sil. Power flows from a 12 volt source, through the 12 volt terminal 33, through lead 41, the coi CRB-C of relay CR3, lead terminal and to ground through the ushbutton PB.

Relay CR3 is thus energized while the pushbutton (or 0t er detector) is depressed. The various contacts on relay CR3 close or transfer. Contacts CRS-l close to temporarily seal in relay CR3 through lead id, contacts CR12C, lead 4:5, and common line 42%. Contacts CRT- 2C are in the position shown because the timer is assumed to be dwelling in the reset interval. Contacts CR3-3 close permitting Lil power to flow to the phase B detector terminal on the intersection controller 16. This puts in a call to the controller to cause it to award right of way to phase B. it is necessary to stop trafilc on street 1 before pedestrians can be allowed to cross. The circuit includes Ll line so, lead 35, contacts CRT-2C, lead 44, lead 36, closed contacts CR52, lead 47, now-closed contacts CR33, lead 43, lead 49, phase detector terminal 29, to the detector terminal for the phase B.

Contacts CRE-d close and permit Ll power to flow to the phase B density detector terminal 36. The circuit includes L1 line 4% lead 68, contacts CR1-3C, lead 9 3, nowclosed contacts CR3-4, lead 95, contacts CR54, lead 96, and terminal 36. Li power applied to the phase B density detector terminal of a volume-density type intersection controller aids in urging the intersection controller to the phase B movement which is compatible with the pedestrian movement.

Contacts CR35 close to complete an auxiliary control circuit through terminal 22, lead s2, now-closed contacts CRS-S, lead 63 and terminal 23. The auxiliary control circuit may be employed to condition auxiliary equipment to restrain it from operation until the pedestrian cycle is completed for example.

Contacts CR32 also close when the pedestrian pushbutton PE is depressed. They admit L1 power to energize the step switch relay coil CRT-C The circuit is from L1 line 4i lead 51, contacts CR11B, lead 52, interrupter contacts CRl-INT-B, lead 53, now-closed contacts CRS-Z, lead 54, through the parallel circuits consisting of lead 56, contacts CR21, lead 57, and lead 55, contacts CR53, lead 58, through lead 59, step switch relay coil CRi-C, lead 93, rectifier DR3, lead 6%, to L2 power terminal 2%.

l hen step switch relay coil CRT-C is energized it opens interrupter contacts CRlTNTB and transfers interrupter contacts CRllNT-C. Opening the former contacts deenergizes step switch relay coil CRT-C. The transfer of the later contacts has no effect on the circuit because another contact CRT1C in series with them is open.

When step switch relay coil CRll-C is deenerrized it ratchets the step switch CR1 into the walk interval. Reference may be made to the step switch contact diagram inset in FIGURE 6. Contacts CRT-1B open, contacts Gill-"B close, and contacts CRT-3B open. Contacts CRLEC, CRl-ZC, and CRT-3C transfer.

The unit is now in the walk interval but the WALK si nals are not yet illuminated and timing has not yet started.

Contacts CRll-llB open and disconnect the portion of the circuit which energized the step switch CR1 out of the reset interval. Another portion of the circuit which includes the plate circuit relay CR7 and the two timing circuits now comes into play.

Contacts CRl-ZB close to ready the circuit including the load relay coil CR l-C.

Because the intersection controller has been given a call, it deenergizes the right of way signal on street 14 (phase A) and illuminates the amber signal. At the end of the clearing interval the amber signal is deenergized and the stop signal illuminated. The right of way is given to street is with the energization of the phase B green signal. Energy is also supplied to the phase B green signal terminal 34.

When terminal 34 is energized from the right of way signal circuit controlled by the intersection controller power flows over lead 64 to energize relay coils CRd-C, (IRS-C, and CRtZ-C. One circuit includes lead 64, new

7 closed contacts CRLZB, lead 65, relay coil CR4-C, lead 66, to L1 return 40. The second circuit includes lead 64, relay coil CRC, lead 66, and L1 return 40. The third circuit includes lead 64, relay coil CR6C, lead 67, nowtransferred contacts CR1-3C, lead 68, and L1 return40.

L1 power is fed out on terminal 35 over lead 68, nowtr-ansferred contacts CRl-SC, lead 67, lead 69, and terminal 35 for other control purposes.

Relay coils CR4-C, CRS-C, and CR6C actuate their respective contacts simultaneously. Their action will be described individually after the timing and charging circuits are explained.

The timing of the walk and guaranteed clearance intervals is effected through an RC timing circuit including capacitor C1 and resistors R3 and R9. The charging circuit is shown by itself in FIGURE 7. The cathode 72 and the screen grid 73 within tube V1 are employed as a rectifier to permit line voltage to charge capacitor C1. When line L2 is negative with respect to line L1 the charging circuit includes L2'terminal 24, lead 71, cathode 72, grid 73, current limiting resistor R4, timing capacitor C1, lead 74, contacts CR51, lead 75, and L1 return 40. During the half cycle when line L2 is positive with respect to line L1 no current flows in the reverse direction because of the rectifier action of tube V1. The left side of capacitor C1 charges to peak line potential of 150 volts. This negative potential prevents tube V1 from conducting.

The discharge or timing circuit for capacitor C1 includes resistor R9, variable resistor R3, and lead 81. Variable resistor R3 is set to provide a sufficiently long delay interval. vals are determined also by the voltage divider circuits which include otentiometers R1, R2, resistor R5, R6, linearity resistors R7, R8, and coupling resistor R10.

The timing circuit for the walk interval is shown by itself in simplified form in FIGURE 8. Line voltage is applied'across the potential divider consisting of potentiometer R1 and resistor R5. The circuit includes L2 terminal 24, lead 71, lead 76, lead 77, resistor R5, potentiometer R1, lead 78, and L1 return 40. During the half cycle when line L2 is positive with respect to line L1, tube V1 is prevented from firing because a positive potential is applied to its cathode 72 and a negative potential is applied to its plate 80. During the half cycle when line L1 is positive with respect to line L2, the timing capacitor C1 is carried positive by an amount determined by the setting of the potential divider R1, R5. Assume for example that the potential divider R1, R5 is set to provide +50 volts on lead 79. This +50 volts is applied to the right side of capacitor C1 from L1 line 40, through lead 78, part of potentiometer R1, lead 79, contacts CR4-2 when transferred, coupling resistor R10, and lead 81. This makes the potential appearing on the left side of capacitor C1 less negative, and with the decay of potential on capacitor C1 due to current leakage through timing resistors R9 and R3, the grid 73 becomes sufiiciently less negative to permit tube V1 to fire. i

Having described the operation of the timing circuits the function of relays CR4, CR5, and CR6 will now be explained. 7

When the phase B green signal was energized indicating thatthe walk interval could start, terminal 34 was energized. Relay coils CR4-C, CRS-C, and CR6-C were energized as described above. Contacts CR41 transfer energizing the WALK signals and deenergizing the DONT WALK signals. The signal lights are placed across street 14 and permit pedestrians to cross street 14- when the WALK signal is illuminated. Power is fed from L2 terminal 24, through lead 71, lead 76, lead 84, now trans- .ferred contacts CR4-1, lead 86, to WALK signal terminal 26. Power is removed from lead 85 and DONT WALK signal terminal 25.

Contacts CR4-2 transfer and complete the walk interval timing circuit shown in FIGURE 8. Timing of the walk interval may be set for seconds, for example, to

The duration of the walk and clearance inter- 0 allow a number of pedestrians to start across the street. Across busy thoroughfares the walk interval may be reduced to prevent undue delay to main street vehicular traffic. The walk interval has no relationship to the time it takes to cross the street. This is the clearance interval and is timed during the next period.

Contacts CR5-1 transfer and complete the plate circuit which includes plate 80, relay coil CR7C, lead 82, interrupter contacts CR1lNTC, lead 83, now-transferred contacts CRT-1C, lead 87, now-transferred contacts CR5-1, lead 75, and L1 return 40. Tube V1 does not fire as soon as contacts CR5-1 transfer; it must wait until the negative potential applied to grid 73 has decayed sufiiciently to permit firing.

When contacts CR5-1 transfer they open the normal charging circuit for capacitor C1. When capacitor C1 is to be charged again between the Walk and the clearance intervals it is charged over a different circuit which is described below.

Contacts CR5-2 open to prevent a backfeed from sealing in the pedestrian actuated relay CR3 if the pushbutton PB is pressed during the walk or clearance intervals. Without contacts CRS-Z the circuit would be completed from L1 return line 40, lead 78, lead 88, lead 39, nowtransferred contacts CR61, lead 48, momentarily closed contacts CREE-3, lead 47, lead 46, momentarily closed contacts CR3-1, relay coil CR3-C, lead 42, lead 41, and the twelve volt supply terminal 21.

Contacts CR5-3 open to break one-half of the parallel circuit to step switch relay coil CR1-C. Contacts CR5-3 and CRZ-l are both open under Condition 3 and will be described in that section.

Contacts CR5-4 open to break the call placed on the phase B density detector terminal 36. The call was actually broken when contacts CR1-3 C transferred at the beginning of the walk interval. The function of the phase B density detector terminal 36 was explained above.

Contacts CRfi-l transfer and remove L1 power from the density yield terminal 28 and lead 90. L1 power is applied to the phase B detector terminal 29 over lead 49. Contacts CR61 are transferred and feed L1 power to detector terminal 29 all during the walk and clearance intervals to place arcontinuous call on the intersection traffic signal controller to maintain it in phase B. After the guaranteed clearance interval has transpired contacts CRT-3C transfer and open the L1 circuit to relay coil CR6C. Contacts CR61 transfer back to the position shown in FIGURE 6 and remove the call from the phase B detector terminal 29. The intersection traffic controller is then free to answer calls on the other street.

Contacts CR6-2 transfer, breaking the auxiliary control circuit between terminals 37 and 38 and making the auxiliary control circuit between terminals 38 and 39. A left or right turn arrow might be turned off by the opening of the first contacts and a flasher might be energized through the closing of the second contacts to flash the DONT WALK signals during the guaranteed clearance interval. 7

The walk interval expires when the voltage on grid 73 decays below the value required to prevent conduction. Tube VI fires, energizing relay coil CR7-C. During the half cycle when the plate 8t is positive electrons flow from L2 terminal 24, over lead 71, cathode 72, plate 80, relay coil CR7C, lead 82, contacts CRl-INC-C, lead 33, nowtransferred contacts CRll-IC, lead 87, now-transferred contacts CR5-1, lead 75, to L1 return 40. 7

Relay contacts CR'72 close and energize step switch relay coil CR1C. During one half cycle current flows from L1 line 40, lead 91, now-closed contacts CRT-2, lead 92, step switch relay coil CR1C, lead 93, diode rectifier DRZ), lead 60, to L2 terminal 20. During the next half cycle no current flows between lines L2 and L1 because of the high back impedance of diode rectifier DR3. The decay current of coil CR1C is maintained through diode Q rectifier DRZ, however, to increase the average current through the coil.

As the step switch coil CRl-C is energized it pulls in its armature and near the end of travel transfers the interrupter contacts CRl-INT-C. This breaks the plate circuit and also provides a path for charging the timing capacitor Cl. The circuit includes L2 terminal 24, lead 71, cathode 72, grid 73, limiting resistor R4, capacitor C1 lead '74, now-transferred contacts CRlINT-C, lead 83, contacts CRl-lC, lead 37, now-transferred contacts CRl, lead '75, and L3 return Current flows only during the half cycle when the grid '73 is positive with res set to the cathode '72-.

The step switch relay coil CRT-C is energized for only a short period because the transfer of interrupter contacts CR1INTC opens the plate circuit and deenergizes relay coil CR7-C. Contacts CRI -Z open and deenergize step switch relay coil CRT-C. n the deenergized stroke the armature steps the step switch out of the walk interval and into the clearance interval. interrupter contacts CRldNT-C transfer back to the position shown in FIG- URE 6 and complete the plate circuit.

Contacts CRl-ZB open and deenergize relay coil CRd-C. Contacts CR4 Z transfer back to the position shown in FIGURE 6 and insert the potential divider consisting of resistors R2- and R6 into the timing circuit. Contacts C1244. transfer back to the position shown in FIGURE 6 deenergizing the WALK signal terminal 26 and energizing the DUNT WALK signal terminal 25. The clearance interval is set to provide sui'licient crossing time for a pedestrian stepping off the curb when the WALK light is extinguished. Consideration must be given to slower walking persons to permit them suiiicient time to cross the intersection.

The guaranteed clearance interval expires when the voltage remaining across capacitor C1 is no longer suiticient to prevent conduction of tube V1. When tube V1 fires, relay coil CR7-C is energized. Contacts CR7-2 close and energize step switch relay coil CRT-C. As the coil is energized its armature actuates interrupter contacts CRT-INT-C interrupting the plate circuit and deenergizing plate circuit relay coil CR7-C. Contacts CR72 open and deenegize the step switch relay coil CRlC. 0n the deenergized stroke the armature steps the step switch out of the clearance interval and into the reset interval where it resides until the next pedestrian actuation.

Contacts CRl-lE close as shown in FIGURE 6 preparing the circuit containing leads 5259 for the next actuation.

Contacts Rl-TrC transfer to the position shown in FIGURE 6. When contacts CF54. move to the position shown they complete the timing capacitor CI charging circuit.

Contacts CRT-3C transfer to the position shown so that when contacts CR4 close with the passage of the phase B green signal a call will be entered on the phase density detector terminal 36 when contacts (IRS-4 close momentarily with a new pcdestrain actuation. The circuit includes Ll return 4t lead 63, contacts CRl-3C, lead 94, contacts CR3- lead )5, contact CRE r, lead 96 to phase B density detect .r terminal 35. The auxiliary unit is thus ready for a new actuation.

Condition 2 Condition 2 has been defined as the condition when the intersection controller is dwelling in phase B with the right of way signals illuminated to tratfic on street parallel with the pedestrian crosswalk 13. No vehicle actuations have occurred when the pedestrian pushbutton PB is depressed. The condition of the auxiliary unit just prior to pushoutton actuation will be described.

Referring to FIGURES 4 and 6, the phase B green traiiic signals are illuminated and the phase B green terminal 34- is energized. Therefore relay coil CR5C is energized. Contacts CR51 have transferred and provide a path for maintaining the charge on timing capacitor C1. Contacts CRS-Z are open and will prevent relay coil CR3-C from sealing in when the pushbutton is depressed. Contacts CR5E are open. Contacts CHZ-ll are closed because no vehicle actuation has occurred on the other phase. It a call had been entered on street 14 the check circuit terminal 32 would have been energized with Li. power and relay coil CRZ-C energized over lead 61. Contacts CR5 4 are open preventing energization of the phase B density detector terminal as.

Relay coils CRd-C and CR6C are not energized because their leads are open through contacts CRl-2B and CRl3C, respectively, as shown in FIGURE 6.

When one of the pushbuttons PB in FIGURE 4 is depressed, terminal in FIGURE 6 is placed at Ll potential. The circuit to relay coil CR3C is completed and relay CR3 is energized. Contacts CR3-l close momentarily sealing in relay coil CR3-C through contacts CR1- ZC. Contacts CRS-Z close and energize step switch relay coil CRT-C through contacts CRl-lB, CRl-INT-B, CR3-2 and CRZ-l. Energization of the step switch relay coil CRft-C causes its armature to actuate the interrupter contacts CRl-INT-B and CRl-INT-C. The former interrupt the circuit to coil CRl-C deenergizing the step switch. The latter transfer momentarily but have no effect at this time. Deencrgization of step switch coil CRi-C causes its armature to step the switch into the walk interval.

At the beginning of the walk interval all of the step switch contacts reverse positions.

Contacts CRl-IB open making the circuit containing leads 51-5? inoperative during the walk and clearance intervals. Contacts CRT-1C transfer and complete the plate circuit of tube VI.

Contacts CRT-2B close and energize load relay coil CRd-C. Contacts CRl-ZC transfer and break the sealing circuit for the detector relay coil CRPy-C.

Contacts CRl-SC transfer and remove the Lil call from the phase B density detector terminal 36. In transferring they complete the L1 circuit to relay coil CRdC permitting it to be energized.

When relay coil CR4-C is energized, contacts CRd-l transfer and extinguish the DONT WALK signals and illuminate the WALK signals. Contacts CR42 transfer and complete the walk timing circuit shown also in FI URE 8. The walk interval is now timing.

When relay coil CRd C is energized, contacts one-r transfer and remove L1 power from the density yield terminal 28 and place a continuous call on the phase B detector terminal 29. Contacts CR-Z transfer for auxiliary control control purposes.

The walk interval is still timing. When the net potential on the left side of timing capacitor C1 is no longer suiticient to prevent conduction, tube Vl. fires, energizing plate circuit relay coil CR7-C. Contacts CR7-2 close and energize step switch relay coil CRTC. Upon energization, interrupter contacts CRI INT-B and CRl-INT-C are actuated. The former open but have no effect. The latter transfer and perform two functions. They open the plate circuit of tube Vl and deenergize coil CR7-C, and they close the charging circuit for timing capacitor C1.

When coil CR7C is deenergized, contacts CR7-2 open and deenergize the step switch relay coil CRl-C. The step switch steps out of the walk interval and into the clearance interval. Contacts CRlINT-C retransfer to the position shown in FIGURE 6, breaking the charging circuit and completing the plate circuit.

Contacts CR1-2B open and deenergize the transfer relay CR4. Contacts CRl-ZC remove L31 power from auxiliary control terminal 33 and close the memory circuit to the detector relay coil CRE-C. Contacts CRd-l transfer and deenergize the WALK signal terminal 26 and energize the DONT WALK signal terminal 25.

The clearance interval is now timing. When the net potential on the left side of timing capacitor C1 can no longer prevent conduction, tube V1 fires, energizing plate circuit relay coil CR7-C. Contacts CR7-2 close and energize the step switch relay coil CRl-C. Interrupter contacts CR1INTC transfer, breaking the plate circuit and completing the charging circuit to timing capacitor C1. Interruption of the plate circuit deenergizes relay coil CR7C and opens contacts CR7-2, deenergizing the step switch relay coil CRl-C. The step switch ratchets out of the clearance interval and into the reset interval.

Contacts CR1-1B close to make the portion of the circuit containing leads 51-59 effective. Contact-s CR-1C transfers to close the charging circuit to timing capacitor C1. Contacts CR1-3C transfer and deenergize relay coil CR6-C. Contacts CR6-1 transfer and remove the continuous call from the phase B detector terminal 29 and place it on the density yield terminal 28.

The auxiliary timer unit is thus in the reset interval ready for another pedestrian actuation. It will answer pedestrian calls continuously in this condition until a vehicle actuation occurs on phase A. A vehicle actuation of detector DA as shown in FIGURE causes a call to be entered on the intersection controller which feeds an L1 It will be recalled that condition 3 is identical with Condition 2 except that a vehicle has approached on street 14 and actuated a detector DA as shown in FIG- URE 5. The auxiliary timer unit is designed to award passage time to the various phases in the order of their actuation. Since a phase A vehicle actuation occurred prior to the pedestrian actuation, the controller will answer the vehicle call first. Actuation of detector DA will cause the intersection controller to apply L1 power to the check relay coil CR2C. The phases B green signals energize terminal 34 which in turn will energize the transfer relay coil CR5C and will attempt to energize relay coils CR4-C and CR6-C. Local relay coil CR4C and transfer relay coil CRo-C will not be energized because their L1 leads are open through step switch contacts CRl-ZB and CR1-3C, respectively, as shown in FIG- URE 6. The pedestrian pushbutton PB has not yet been depressed and the step switch is in the reset interval.

When the pushbutton PB is depressed under these conditions the detector relay coil CR3-C is momentarily energized and is then sealed in through now-closed contacts CR3-1, lead 44, contacts CRl-ZC, lead 45, and L1 return 44). Contacts CR3-2 close and attempt to energize the step switch relay coil CRl-C. It is prevented from doing so because contacts CR2-1 and CRS-S are both open because relays CR2 and CR5 are both energized. Relay CR2 being energized indicates that a vehicle detector actuation has occured on street 14. The auxiliary unit therefore remains in the reset interval until the intersection controller answers the phase A vehicle call.

The intersection controller stops trafiic on street and awards right of way to street 14. When the phase B green signals are extinguished, terminal 34 and relay coil CRS-C are deenergized. Contacts CR5-3 close and energize step switch relay coil CR1C. The interrupter contacts CRl-INT-B and CRl-INT-C are actuated. The former open and deenergize step switch relay coil CRl-C. The latter transfer but have no eiiect.

When coil CRl-C is deenergized the step switch moves into the walk interval but the WALK signals are not illuminated and timing does not start until the phase B green signals are again energized.

Contacts CR1-1B openand disconnect this path to the step switch relay coil CR1C. Contacts CR1-1C transfer and close one of the gaps in the plate circuit. The other gap is not closed until contacts CRS-l transfer when the phase B green signals are energized.

Contacts CR1-2B close and complete the circuit to load relay coil CR4C- Coil CR4-C is not energized until the phase B green signals are energized. Contacts CRl-ZC transfer and break the memory circuit to the detector relay coil CR3-C. Relay CR3 is .thus deenergized at the beginning of the walk interval. The WALK signals are not illuminated until the phase B green signals are energized.

Contacts CR1-3C transfer and break the L1 lead to the phase B density detector terminal 36, and make the L1 circuit to auxiliary control terminal 35.

The auxiliary unit is thus in condition to illuminate and time the WALK signal as soon as the right of way is returned to the street parallel with the pedestrian crosswalk. The total delay to the pedestrian is relatively short and is equal to the sum of the clearance interval to phase B traffic and the initial, vehicle, and clearance intervals to phase A traflic. The delay may total 10 to 15 seconds, for example, unless continued vehicles arriving on street 14 cause extension of the vehicle interval. The greatest delay which could occur is equal to the phase A maximum interval which is timed by the intersection controller. As soon as the right of way signals are illuminated to the street parallel with the crosswalk the phase B green terminal 34 is energized and relay coils CRd-C, CR5-C, and CR6-C are energized because contacts CRl-ZB are already closed and contacts CR1 -3C are transferred as noted above.

Contacts CR4-1 transfer and extinguish the DONT WALK signals and illuminate the WALK signals. Contacts CR42 transfer and complete the walk interval timing circuit. Contacts CR51 transfer and open the timing capacitor C1 charging circuit and complete the plate circuit. Contacts CR6-1 transfer and remove L1 power from the density yield terminal 28 and enter a continuous call on the phase B detector terminal 29 to hold the intersection controller in phase B for the duration of the walk and clearance intervals.

At the end of the walk interval the voltage appearing on the left side of timing capacitor C1 becomes insuflicient to continue to prevent tube V1 from firing. Tube V1 fires and energizes plate circuit relay coil CR7-C which closes contacts CR7-2. Step switch relay coil CR1C is energized and transfers interrupter contacts CR1INTC which break the plate circuit and close the charging circuit to timing capacitor C1. When the plate circuit is broken, contacts CR7-2 open and deenergize the step switch relay coil CR1C. The step switch ratchets its cams into the guaranteed clearance interval and contacts CRl-ZB open and contacts CR12C transfer.

The opening of contacts CR1-2B deenergizes load relay coil CR4-C.

Contacts CR4-1 transfer back to the position shown in FIGURE 6, extinguishing the WALK signal and illuminating the DONT WALK signal. Contacts CR4-2 transfer to the position shown in FIGURE 6 and connect the clearance interval timing circuit. The guaranteed clearance interval is thus timing.

When contacts CRT-2C transfer to the position shown in FIGURE 6 they restore the detector relay memory circuit which may be completed to seal in detector relay coil CR3C when the pedestrian pushbutton PB is again depressed. If no vehicle detector actuations occur on phase A the pedestrian unit can continue to answer pedestrian calls.

Near the end of the guaranteed clearance interval the charge and potential remaining on capacitor C1 becomes insufiicient to keep tube V1 from firing. Tube V1 fires and energizes plate circuit relay coil CR'7-C. Cont-acts CR'7-2 close and energize the step switch relay coil CR1- C. Interrupter contacts CR1INT-C transfer and open the plate circuit and close the charging circuit. Opening the plate circuit deenergizes the step switch relay coil CRl-C and causes it to rotate its cams out of the clearance interval and into the reset interval.

Contacts Clll-lll close as shown in FIGURE 6 to make the portion of the circuit containing leads 51-59 effective when the detector relay CR3 is energized. Contacts CRi-EC transfer and open the plate circuit and close the charging circuit. Contacts CRl3C transfer as shown in FIG RE 6. The auxiliary unit is thus in its reset condition.

PEDESTRIAN RECALL A circuit is provided within the auxiliary unit to permit a pedestrian actuating the pushbutton during the clearance interval to obtain a walk indication immediately if no vehicle actuation has occurred on the opposite phase, phase A. The circuit includes relay contacts CR22 and CHE-:7, PZGURE 5.

When the unit is timing the guaranteed clearance interval and tie pedestrian pushbutton is depressed, detector relay coil Ci 3-C is energized. Contacts CR3l close and seal in relay coil CR3-C through contacts CRs-ZC and leads 44, 45". Contacts CR3-6 transfer and admit Ll potential to the right side of timing capacitor Cl from L1 return 4% through lead 97, contacts CHE-2, lead 98, now ransferred contacts ORB-6, contacts CR i2, coupling resistor R14) and lead 31. During the half cycle in which L1 line 49 is positive with respect to line L2, the net voltage appearing on the left side of timing capacitor Cl is positive and permits tube V1 to fire. The step switch ratchets out of the clearance interval and into the reset interval in the manner described previously.

In the reset interval contacts CRl-IB close as shown in FIGURE 6 and since detector relay contacts CR3-2 are already closed, the step switch coil CRl-3 is energized. The circuit includes Ll line 4% lead 53;, contacts CR11B, lead 552, contacts CRl-lNT-B, lead 53, contacts CR3-2, lead 54, lead o, contacts CR21, lead 57, lead 59, step switch coil CRl-C, lead @3, diode rectifier DR3, lead 60, I012 terminal 29.

Upon energization of the step switch coil CRi-C interrupter contacts CRl-lNT-B open and deenergize step switch coil CRl-C. The step switch moves out of the reset interval and into the walk interval. At the beginning of the wall; interval, contacts CRll-ZB close and energize the load relay coil CR i-C. Contacts CRd-l transfer and illuminate the WALK signal and contacts CRd-Z. complete the walk timing circuit as described previously. The timer has thus answered another pedestrian call substantially immediately after actuation during the clearance interval.

The above cycle would have been delayed if a vehicle actuation had occurred on phase A as in FIGURE 5 because check relay CR2 would have been energized from the intersection controller. Contacts CRZ-Z would have transferred out of the position shown in FIGURE 6 thus connectin the normal clearance timing circuit back into the circuit. The wall; interval would be delayed un til the intersection controller answered the call on phase A and then returned to phase B. Contacts CR21 would also be open preventing the step switch coil CRlC from being energi-ed when contacts CR3-2 are closed by pushbutton actuation. The memory circuit seals in and remembers the pedestrian call until the unit can answer it. This is the same as Condition 3.

The function of the various terminals Ell-39 not already explained in detail will now be explained.

MANUAL FEATURE During periods of abnormally heavy trailic flow as may occur for example after a sporting event it may be desired that a trafiic ofiicer have control of the traffic signals. A key switch, not shown, may be provided on the intersection controller cabinet to make the normal timing circuits in the controller ineli ective and to connect a hand operated pushbutton into the control circuits. The pushbuttc-n energizes the ratchet motor within the intersection controller. Upon release of the pushbutton the ratchet motor is deenergized and ratchets the camshaft into the next interval thus changing the trafiic signal indication.

During manual operation of the intersection controller it is desired that the pedestrian sequence be inserted once each cycle during the compatible vehicle right of way interval. That is, the walk and clearance intervals are to be inserted during the phase B green portion of the cycle for a time determined by the officer and not to exceed the times preset on the timing dials.

A transfer relay Within the intersection controller is energized during the phase B right of way interval to transfer the pushbutton initiated impulse-s from the ratchet motor in the intersection controller to manual terminal 21 of the auxiliary unit. The impulses energize the step switch coil CR1-C and cause it to step the step switch during the proper interval of the phase B right of way period. The circuit includes manual terminal 21, lead lead 59, coil CRl-C, lead 93, diode rectifier DR3, lead 650, and L2 terminal 2%. The contacts controlled by the step switch do not change until the step switch coil CRl-C is deenergized. In the walk interval contacts CRl-ZB are closed and since phase B green signals are energized, load relay coil CR4C is energized. Contacts CR41 transfer and illuminate the WALK signals and extinguish the DONT WALK signals.

Timing of all intervals is done by the ofiicer unless they exceed the times preset on the timing dials. He may terminate the walk interval and start the clearance interval by pressing and releasing the manual pushbutton, ratching the step switch CR1. The WALK signals are extinguished and the DONT WALK signals illuminated by the retransfer of load relay contacts CR41.

When the ofiicer desires to terminate the pedestrian clearance interval he presses and releases the manual pushbutton. A second relay in the intersection controller has opened the impulse transfer circuit during the clearance interval to permit the manual control to again be connected to the ratchet motor in the intersection controller and disconnected from the step switch in the auxiliary unit. This transfer relay may be energized from auxiliary control terminal 35 which is energized during the walk and clearance intervals through contacts Gill-3C.

Thus a phase of pedestrian movement is included in each manually controlled cycle.

AUXILIARY CONTROL CIRCUIT The auxiliary control circuit including terminals 22 and 23 and detector relay contacts CR3-5 is provided to eliminate an external relay normally required when the auxiliary timer unit is used with a railroad or other we emptor circuit. A pilot light may also be connected in circuit with a source of power and terminals 22, 23 to indicate when a pedestrian actuation has occurred and a call is in.

When used in conjunction with a railroad preemptor, the terminals 22, 23 are connected to the preemptor to indicate when a pedestrian call is in. The preemptor circuit may then include a pedestrian phase with a railroad actuated phase, or if the intersection configuration prevents this, delay the pedestrian phase until a compatible vehicle phase.

This circuit eliminates an external relay.

POWER TERMINAL L2 Power for the auxiliary unit is supplied to L2 terminal 24. Potential is fed over lead 71 to the cathode 72 of tube Vl, to the screen grid of tube V1. Power flows over lead 76 to the primary coil of filament heater transformer Til, over lead 84 to the WALK and DONT WALK signals, and over lead 77 to the walk and clearance timing circuits. The other end of the primary coil of transformer T1 is connected to L1 line 88. The center tsp of the low 1 voltage side of transformer T1 is connected to L2 line 76 over lead 50. L2 power is also supplied at terminal 20.

DENSITY YIELD The density yield terminal 28 is connected to L1 line 40 through normally-closed contacts CR6-1 to permit an intersection controller of the density type to operate. A density type controller is here defined as one which weighs the arrival of vehicular traffic during the red signals and adjusts the initial portion of the green signal duration on the opposite phase accordingly. When L1 power is removed from terminal 28, as during the walk and guaranteed clearance intervals, the intersection controller is prevented from stepping to the next interval. After the clearance interval, contacts CR61 close again and permit the intersection controller to operate. 1

PHASE DETECTOR TERMINAL The traffic detector relay for the vehicle phase compatible with the pedestrian phase is connected to the phase detector terminal 29. It is connected also to the detectors DB in the phase B street 15, FIGURES 3, 4, 5.

The'purpose of terminal 29 is to stimulate a vehicle call on phase B so that the intersection controller will provide a phase B right of way interval so that a pedestrian sequence can be initiated parallel thereto. In FIGURE 6 it is evident that terminal 29 is energized with L1 power when detector relay contacts CR3- 3 are closed upon pushbutton actuation. The circuit includes L1 line 40,. lead 45, contacts CR12C, leads 44, 46, contacts CR5-2, lead 47, now-closed contacts CR3-3, leads 48, 49, and terminal The phase detector terminal 29 serves an additional purpose. When the intersection controller has advanced 'to the phase B right of way interval it is kept there by the continuous call placed on its phase B detector relay 'through contacts CR6-1. During the phase B right of CHECK CIRCUIT The purpose of the check circuit is to prevent the pedestrian unit from starting its sequence even though the intersection controller is in the compatible right of way interval if a vehicle actuation has occurred on the opposite phase. The check circuit terminal 32 is energized with L1 power whenever the detector relay on the opposite phase is energized. The check relay coil CRZ-C is thus energized if the detector relay within the intersection controller is energized. Contacts CRZ-l open and break onehalf of the parallel circuit to step switch coil CRl-C.

Since the phase B green terminal 34 is energized, relay coil 'CRS-C is energized and contacts CR53 are open, thus breaking the other half of the parallel circuit to stop switch coil CRl-C. The auxiliary unit therefore cannot be started out of the reset interval until the phase B green terminal is deenergized and contacts CR53 closed. When the phase B green terminal is deenergized the auxiliary unit will be able to move to the first portion of the walk interval without the walk light illuminated and remain there until the phase B green terminal 34 is again energized. This does not occur until the intersection controller has answered the vehicle call on the opposite phase A and then returned to the compatible phase B.

AUXILIARY TERMINAL 33 L1 power is supplied to auxiliary terminal 33 during the walk interval to be used with a delayed green timer unit.

1 a PHASE GREEN TERMINAL from the compatible vehicle right of way signal to insure safe operation.

It is thus impossible to illuminate the WALK signal until the compatible vehicular movement is initiated after cross trailic has been stopped. Timing of the walk interval is likewise not started until cross traflic is halted and compatible traflic is given the right of way. This is a safety feature.

AUXILIARY TERMINAL 35 This terminal is energized with L1 power only during the Walk and clearance intervals. It may be used for various auxiliary control functions external to the pedestrian unit. For example, it may cause an external relay to be energized in parallel with transfer relay CR6. It may be used to extinguish conflicting turn signal indications during the walk and clearance intervals to permit safer pedestrian crossing.

PHASE DENSITY DETECTOR TERMINAL This terminal is normally deenergized and is closed to L1 power when a pedestrian actuation occurs. The closure is momentary if the intersection controller is in the conflicting phase. The pulse serves to call a density type intersection controller to the compatible phase. Contacts CR1-3C transfer as soon as the step switch CR1 is energized and deenergized and thus deenergize terminal The terminal 36 is not pulsed at all if the intersection controller is already in the compatible phase because contacts CR5-4 are then open.

The density type of controller to which the density yield terminal 28 connects is hown for example in United States Patent Numbers Re. 21,377, 2,265,991, 2,199,571, 2,090,619 and 2,044,907.

AUXILIARY TERMINALS 37, 38, 39

These terminals are transferred when relay coil CRfi-C is energized. This occurs when the phase B green terminal 34 is energized after the auxiliary unit is in the first portion of the walk interval. The contacts serving the auxiliary terminals 37, 38, 39 are heavy duty and may be used to control traffic signals. For example, terminals 37, 38 may be connected in a circuit supplying power to left or right turn arrow signals which may be deenergized during the walk and clearance intervals to prevent vehicles from turning into the pedestrian crosswalk. Terminals 38, 39 may be connected into a circuit which flashes the DONT WALK signal during the guaranteed clearance interval to draw the pedestrians attention.

This completes the description of the circuit shown in FIGURE 6. It is understood that one skilled in the art may make various changes in the circuit Without altering its function. It is also understood that the circuit may be applied to control different apparatus through diiferent operations without departing from the spirit of the invention.

What is believed to be new is the invention of an auxiliary electronic timer unit capable of being interconnected with a multiphase, trafiic actuated, intersection controller for the purpose of controlling an additional phase through two or more timed intervals. The form of the invention shown herein is described in relation to a pedestrian sequence. The unit is equally adapted to use as a minor trafiic movement controller or as a delayed green and clearing interval timer.

What I desire to protect by Letters Patent is described in the appended claims.

I claim:

An electronic pedestrian interval timer comprising a three bank step switch operable through a reset interval, a walk interval, and a clearance interval, a pedestrian actuable detector, a detector relay connected to be energized by said detector and operable to close a memory circuit and to energize said step switch out of said reset interval, a first interrupter contact on said step switch operable to deenergize said step switch, said step switch thereby stepped into a first portion of said walk interval, a timing circuit comprised of a triode gas filled tube having a plate circuit, a cathode circuit, and a grid circuit, an RC timing circuit connected in said grid circuit and adapted to be charged during said reset interval and recharged between said walk interval and said clearance interval and having a first timing circuit connected thereto during said walk interval and a second timing circuit connected thereto during said clearance interval, a load relay connected to be energized during a compatible traffic movement, said load relay when energized adapted to energize a pedestrian walk signal and to connect said first timing circuit to said RC timing circuit, a plate circuit relay connected in said plate circuit and energized therefrom when said RC timing circuit can no longer prevent said gas filled triode from firing, contacts on said plate circuit relay connected to energize said step switch relay out of said walk interval, said interrupter contacts on said step switch operable to deenergize said step switch, said step switch thereby stepped into said clearance interval, contacts on said step switch operable during said clearance interval to deenergize said load relay, said load relay when deenergized energizing a pedestrian clearance signal and connecting said second timing circuit to said RC timing circuit, said plate circuit relay energized therefrom when said RC timing circuit can no longer prevent said gas filled triode from firing, said contacts on said plate circuit relay eflective to energize said step switch relay out of said clearance interval, said interrupter contacts on said step switch again deenergizing said step switch, said step switch thereby stepped into said reset interval, said circuit thereupon readied for another pedestrian actuation.

References Cited by the Examiner UNITED STATES PATENTS 1,954,992 4/34 Geer et a1 340-31 2,126,431 8/38 Von Opel 340-31 2,143,668 1/39 Turner et al 340-44 2,144,536 1/39 Horni 340-44 2,199,572 5/40 Paul 340-31 2,201,145 5/40 Barker 340-31 2,227,552 1/41 Olafson 340-36 2,796,595 6/57 Schulenburg 340-37 2,883,643 4/59 Du Vivier 340-31 XR 2,887,643 5/59 Miyata 320-1 2,905,879 9/59 Starr 320-1 2,925,583 2/60 letters 340-37 NEIL C. READ, Primary Examiner.

E. JAMES SAX, BENNETT G. MILLER, Examiner,

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