US2265991A - Traffic control apparatus - Google Patents

Traffic control apparatus Download PDF

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Publication number
US2265991A
US2265991A US305233A US30523339A US2265991A US 2265991 A US2265991 A US 2265991A US 305233 A US305233 A US 305233A US 30523339 A US30523339 A US 30523339A US 2265991 A US2265991 A US 2265991A
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Prior art keywords
condenser
relay
way
lane
stepping switch
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US305233A
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English (en)
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John L Barker
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AUTOMATIC SIGNAL Corp
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AUTOMATIC SIGNAL CORP
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Priority to FR955388D priority Critical patent/FR955388A/fr
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Priority to US305233A priority patent/US2265991A/en
Priority to GB15276/43A priority patent/GB560527A/en
Priority to GB15760/40A priority patent/GB560488A/en
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Publication of US2265991A publication Critical patent/US2265991A/en
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    • G—PHYSICS
    • G08—SIGNALLING
    • G08G—TRAFFIC CONTROL SYSTEMS
    • G08G1/00—Traffic control systems for road vehicles
    • G08G1/07—Controlling traffic signals
    • G08G1/08—Controlling traffic signals according to detected number or speed of vehicles

Definitions

  • improved traffic control system or apparatus of I the trafiic actuated type employing traflic detecting devices or detectors in the intersecting lanes, trafilc right of way signals at the intersection and a time controlled operating mechanism operated by the detectors to display the right of way signals to the several lanes successively for time periods responsive to trafiic actuation of the respective detectors.
  • Some prior trafiic actuated signal systems have employed a resettable timing device for timing a part of the right of way signal period for a street under control of the traffic actuated detector of that street 'so that actuations of the detector by vehicles approaching the intersection during the right of way period reset the timing device successively and cause it to repeat its time period, and thus prolong the right of way signal display for such Vehicles.
  • the time period for such a timing device is usually of only a few seconds duration so as to be not much greater than the average time spacing between successive vehicles approaching in moderately heavy traific, and thus if one or more vehicles are waiting on one street against a stop signal for example the go signal period on the other intersecting street will be terminated and right of way transferred to the first street in event that the time gap between approaching vehicles on such other street exceeds a reasonable value indicating that approaching trafiic using the go signal is so widely separated that it would be more efiicient to transfer right of way to the waiting trafiic on the opposite street.
  • Serial Number 74,422 now 1 gressively reducing the time period of the resettable timing device for the right of way period on one street responsive to arrival of successive vehicles which increase the traffic waiting on the other street.
  • the present invention provides a further improvement in systems of this general character in that the timing period of the resettable timing device determining the gap interval at which right of way may be terminated is progressively reduced during the right of way period of one street by either one or both of two factors: (1) by the arrival of a series of quite closely spaced vehicles or (2) by the passing of time following the arrival of the first waiting vehicle on the other street which does not have right of way.
  • the effect of reducing the time period of the gap interval timer is to require moving traflic to maintain close spacing to retain right of way.
  • traflic flow has considerable variation from moment to moment as well as hourly, daily and seasonal Variations. Such variations may result for example in having only one or two vehicles waiting on a street at the beginning of the go signal period on a street and then after several seconds having a fairly closely spaced group of vehicles arrive. It is therefore unsafe to employ a short time setting initially for the resettable timer which establishes the gap interval which will release right of way, and the time ordinarily is started with a time period providing a considerable margin above the gap interval of closely spaced moving vehicles to avoid cutting off the right of way signal too early in the face of approaching trafiic.
  • any vehicles waiting for right of way on the other street should not be held too long and it is desirable to reduce the time period of the resettable timer to take advantage of any appreciable time gap appearing in the moving trafiic which indicates that the volume of flow of the moving traffic is decreasing.
  • the present invention provides apparatus for reducing the allowable gap interval in accordance with the factors (1) and (2) outlined above, both of which factors provide improved operation without the feature of progressive reduction of the gap interval in accordance with the number of waiting vehicles disclosed in the copending application, Serial Number 74,422, referred to above, but offer particularly marked efliciency and sensitivity to slight changes in flow of heavy trafiic in combination with this feature of the said copending application.
  • the invention is described and illustrated in its preferred embodiment in connection with the apparatus of the copending application and is also individually described.
  • the go period is preferably divided into at least two parts the first part being identified ordinarily as an initial interval or starting interval for the purpose of enabling accumulated waiting traffic to get into motion and the second part comprising a unit time extension interval which is repeatedly reset by vehicles in the stream of moving traflic.
  • the unit interval of the second part is variously designated in the art as a vehicle protection period, right of way extension period, gap limit interval or vehicle interval.
  • the first part will be referred to herein uniformly as the initial interval and the unit extension period of the second part will be referred to herein as the vehicle interval.
  • the actuation of traffic detector in a traffic lane in which the stop signal is being displayed causes the right of way to be transferred to that lane at the first opportunity. If there is no traflic entering the intersection from the lane in which the go signal is being displayed a caution signal is usually immediately displayed in said lane and after a short period the right of way is transferred to the lane in which the stop signal was being displayed.
  • the actuation of the traflic detector in the lane in which the stop signal is being displayed causes the right of way to be transferred thereto at the first break of a predetermined time in the said moving traffic. If no such break occurs in said moving traific the right of way will be transferred at the end of a predetermined maximum period usually provided by a different timing element.
  • This system like some previous traflic actuated systems is arranged so that the timing of the initial interval, the first part of the go period, I
  • the trafiic detector in the lane in which the stop signal is being displayed so that when said lane shall next be given the go signal the initial interval of said go signal display period will be timed in conformance with the volume of the trafiic waiting in said lane, to the end that a large number of waiting vehicles will be granted a longer initial interval than will be granted to a small number.
  • the traflic detectors can be located at a distance from the intersection customary in the older types but it is entirely feasible, especially if the variable initial interval is employed, to locate them considerably farther from the intersection (two or three hundred feet or more for example) thereby facilitating the counting of larger numbers of waiting vehicles which will increase the effectiveness of traflic approaching a stop signal in controlling the signal timing.
  • Cross traffic will however be protected against unreasonable interruption since the cross street initial interval is timed in advance in accordance with the number of vehicles waiting on the cross street and is not reducible by main highway traffic, and in addition either a maximum limit to right of way on the main highway or a reduction of the main highway vehicle interval by accumulation of waiting cross street traific, or both, serve to protect the cross street traflic.
  • Figure 1 is a schematic plan view of an intersection showing the location of traific detectors, signals and operating mechanism of a trafiic control system employing the present invention.
  • Figures 2 and 3 combined represent a schematic circuit diagram of a traflic control system employing the present invention in combination with one form of the apparatus of the copending application, Serial Number 74,422, new United States Patent Reissue 21,377.
  • Figure 4 is a schematic circuit diagram of the part of the apparatus of Figs. 2-3 providing adjustment of the time period of a maximum vehicle spacing limit timer responsive to the actual spacing of traflic moving having the right of way, in accordance with one feature of the present invention.
  • Figure 5 is a schematic circuit diagram of the part of the apparatus of Figs. 2-3 providing adjustment of the time period of a maximum vehicle spacing limit time responsive to passage of time, in accordance with another feature of the present invention.
  • Figure 6 is a plan view of a group of adjacent intersections equipped with this system showing one example of the location of signals, traffic detectors and timer housings.
  • Fig. 1 right of way signals [0 are shown at the center of the intersection of two streets NS and EW, traffic detectors l2 are located at some distance from the intersection on the NS street and traific detectors l3 are similarly located in the EW street. These detectors are located preferably in position to be actuated only by trafiic approaching the intersection but may if desired be of a directional type such as disclosed in Patent Number 2,077,924 granted to Charles D. Geer and John L. Biach on April 20, 1937, for example so as to be actuated only by trafiic approaching the intersection.
  • the control mechanism II is illustrated sche- Search matically as connected to the detectors and signals.
  • any type of visual or audible signal can be used in this system but the customary red, yellow and green trafiic lights are preferable inasmuch as motorists and pedestrians are now generally familiar with the significance of these colored lights.
  • the signals are illustrated in Fig. 1 as grouped at the center of the intersections but it will be appreciated that they may also be located at other appropriate points at the intersection either grouped or separated.'
  • the trailic detectors may be of any desired form such as a mechanical switch in which the pressure exerted by the weight of a passing vehicle flexes a resilient plate to make a contact, or an energy beam is directed across a trafiic lane so as to be interrupted by trafiic approaching the intersection.
  • a common form of the latter type is a light beam directed across a trafiic lane with a photo electric cell arranged as a receiver.
  • Still another type of detector is an electromagnetic device in which the vehicle disturbs a magnetic field and thereby operates a relay in the control. Any of these or other types of traffic detectors such as a push button for use of pedestrians will operate satisfactorily in this system.
  • the operating mechanism ll of Fig. 1 controls the signals under cooperative control by timing devices included in the mechanism and by the traffic detectors.
  • FIGs. 2 and 3 A preferred embodiment of this mechanism employing the invention in combination with one form of the apparatus of the aforesaid copending application, Serial Number 74,422, is shown in Figs. 2 and 3.
  • This embodiment employs a multiple rotary line switch or stepping switch and grid controlled discharge tubes and because of the sharply defined breakdown voltage of this type of tube great accuracy is possible in timing the Various intervals.
  • their grid potential determines their breakdown voltage these tubes can be adjusted to compensate for variations in tube characteristics by connecting the grid to an appropriate potentiometer tap when tubes are replaced.
  • the accuracy of the timing of the various intervals can be maintained independent of variation of tube characteristics in different replacement tubes.
  • the stepping switch shown in Figs, 2-3 has eight positions.
  • a stepping switch of more than eight positions can be used as an eight position switch if desired by providing rapid stepping through the extra positions in accordance with well known methods.
  • a complete cycle of operation of the signals by the stepping switch including right of way periods for the respective NS and EW streets and amber change periods for the same is outlined in the chart at the bottom of Fig. 3, showing the eight stepping switch positions and the corresponding signal indications and the names given to the several intervals in the respective stepping switch positions to more readily identify their functions.
  • Figs. 2 and 3 negative A. C. power is supplied through the wire designated by a minus sign enclosed in a circle and extending vertically through substantially the middle of the figures. At the bottom of Fig. 3 this wire is identified as grounded A. C. Positive A. C. is supplied through wires designated by a plus sign in a circle at the right and left sides of these figures and positive D. C, is designated by a plus sign in a square at the right and left sides of these figures. Negative D. C. power is designated by a minus sign in a square at the middle of the top of Fig. 3 and it will be noted is maintained at a relatively more negative potential than the negative A. C. by means of the potentiometer PZ6-PZ'
  • the six contact banks of the stepping switch are shown somewhat to the right of the vertical negative power wire near the middle of the figures and are identified as banks SBI to SE6 respectively with each of the contacts numbered l to 8 to correspond with positions I to 8 of the stepping switch.
  • the several wipers WI to W6 inclusive are shown in position between positions 4 and 6 and are arranged to be operated in unison across the contacts of their associated contact banks from one position to another by operation of the stepping switch driving magnet DM shown in the lower left part of Fig. 3.
  • the remainder of the apparatus represented on the part of Fig. 2 to the right of the negative power is in general effective to cooperate with the apparatus of Fig. 3 to call the right of way to the EW lane and to hold the right of way thereon.
  • the apparatus represented by that part of Fig. 2 to the left of the power wire is effective to cooperate with the apparatus of Fig. 3 to call or hold the right of way on the NS lane.
  • Fig. 2 At the top of Fig. 2 ar shown the two sets of signals representing the customary green, yellow and red lights, numbers Z48 to Z50 being displayed to the EW traiiic whereas numbers Z45 to Z4! are displayed to the NS trafiic.
  • the trafiic detectors located respectively in the NS and EW lanes are represented by Z5l and Z52.
  • Relay EZ is responsive to actuations of detector Z5! and relay FZ operates in response to actuations of detector Z52.
  • relay FZ starts a sequential operation which calls the right of way to the EW lane and when the right of way has been given to the EW lane, operation of this relay tends to hold it there.
  • relay EZ operates to call and hold the right of way on the NS lane.
  • switches Z68 and Z69 By opening or closing switches Z68 and Z69 the apparatus can be caused to normally operate as a reverting, arterial or floating system.
  • the 010- sure of both switch Z68 and switch Z69 will in the absence of traffic cause the right of way to normally revert periodically from lane to lane. This system of operation is commonly called the reverting system.
  • switch Z69 If switch Z69 is closed and switch Z68 open the system will operate arterial EW under which system the EW lane instead of the NS lane will be the artery. The right of way will normally remain on the EW lane until called by trafiic to the NS lane, from which lane it will revert to the EW lane when the NS trafiic has cleared the intersection or has held the right of way on the NS lane for a predetermined time.
  • switches Z68 and Z69 are both open the apparatus will operate as a floating system under which the right of way will normally remain on the lane to which it was last called until trafilc on the cross lane requires it.
  • each lane Under all of these systems of operation trafhe on each lane can hold the right of way up to' a predetermined period against waiting traffic in the cross lane and in addition automatically put in a call for the return of the right of way to the lane from which it is being transferred if at the time of such transfer a vehicle interval has been initiated by a detector actuation in said lane within a predetermined time prior to said transfer of the right of way or if the vehicle interval prevailing thereon at the time of such transfer has by waiting cross trafiic been reduced to less than a predetermined magnitude.
  • the various time intervals are timed by several timers including an initial interval timer, a maximum timer, a variable vehicle interval timer and a normal vehicle interval timer.
  • the several timers are of the static or electronic type employing the time required to charge a condenser slowly through a control resistance from a D. C. power supply to the breakdown voltage of a gaseous discharge tube which thereupon passes current to operate a relay.
  • the discharge tubes employed in the present embodiment are of the three electrode type in which the negative grid bias controls the breakdown voltage to initiate conduction in the anode-cathode circuit, the breakdown voltage being substantially proportional to the grid bias over a considerable range.
  • the initial interval timer has its time interval adjusted in accordance with accumulated waiting trafrlc for timing the initial intervals in positions l and 5 but is used as a definite interval timer also in the rest positions 2 and 6 and in the amber positions 4 and 8.
  • For timing the initial interval its time period is adjusted substantially in accordance with the number of waiting vehicles by charging a condenser during the initial interval from an initial voltage predetermined by the number of such waiting vehicles.
  • variable vehicle interval timer When the stepping switch is in its trafiic timed positions 3 or 1, three timers run concurrently. One of these, the maximum timer, is not subject to vehicle control.
  • the other two, the variable vehicle interval timer and the normal vehicle interval timer are both subject to reset thru plate condenser discharge by trafiic actuations in the lane in which the go signal is being displayed. Hence their periods start simultaneously after each such reset.
  • the variable vehicle interval timer is subject also to partial control by waiting cross traflic which decreases its operating period.
  • the normal vehicle interval timer on the other hand is not afiected by cross trafiic.
  • the Variable vehicle interval timer period is decreased by waiting cross trafiic thru having the grid potential of the tube timing this period rendered less negative by waiting cross traific thus causing said tube to become conducting at a lower plate voltage which correspondingly de- ELECTRIC SIGNALING.
  • variable vehicle interval timer in effect balances the increasing pressure to take the right of way exerted by accumulating waiting traffic on one street against the right of way retaining efiect exerted by moving trafiic on the other street.
  • the latter effect may be termed the holding power and is proportionate to the frequency with which said moving traffic resets the variable vehicle interval timer.
  • variable vehicle interval timer If the variable vehicle interval is decreased to less than the normal vehicle interval right of way will be yielded by action of the variable vehicle interval timer when traflie ceases to approach the intersection from the lane in which the go signal is being displayed.
  • the variable vehicle interval timer is arranged to automatically put in a return right of way call whenever it operates. If there is little waiting cross traffic and consequently the variable vehicle interval is not reduced to less than the normal vehicle interval, the normal vehicle interval timer will operate first to yield the right of way. The operation of this timer does not put in a return right of way call. Hence a right of way recall will be automatically put in if the vehicle interval at the time of right of way transfer has been reduced by waiting cross traffic to less than a predetermined period.
  • the predetermined period referred to is the normal vehicle interval timer period.
  • the fact that the maximum timer operates and the normal vehicle interval timer does not operate indicates that the normal vehicle interval timer was reset by a traflic actuation less than the time period of said normal vehicle interval timer, i. e. less than a predetermined time before the transfer of the right of way.
  • the stepping switch will remain in either of its two rest positions 2 or 6 unless the system is set for normally arterial or reverting operation or unless a cross trafiic call is put in by a cross lane detector actuation.
  • the stepping switch contact banks designated as SBI to SE6 inclusive, are shown in Figs. 2 and 3 to the right of the grounded power wire which extends from the bottom to the top of both figures just to the left of the center.
  • the stepping switch driving magnet designated as DM, is shown in the lower left corner of Fig. 3. This magnet DM drives the wipers WI to W6 in unison over the banks SBI to SBG respectively. Besid it is a rectifier used to supply D. C. for the driving magnet coil.
  • the signals shown at the top of Fig. 2 are controlled by relays ALR and BLR.
  • the apparatus to the left of the grounded power wire in Fig. 2 is in general efiective to cooperate with the apparatus of Fig. 3 to call and hold the right of way on the NS lane whereas that to the right of the grounded power wire similarly cooperates with the apparatus of Fig. 3 to call and hold the right of way on the EW lane.
  • Relay AM is energized thru contacts in stepping switch bank SBZ when the stepping switch is in positions 2 and 3, the NS rest position and the 'NS trafiic timed positions respectively.
  • Right of way can be called to the NS lane by the deenergization of relay AM which can occur in response to a NS traffic actuation when the right of way is not on the NS lane.
  • the relay AM will be deenergized thus putting in a call for the return of the right of way to the lane from which it is being withdrawn, in this instance the NS lane. It will be remembered that the placing of a return call has been mentioned as a function of both the maximum timer and the variable vehicle interval timer.
  • relay AM will not be deenergized but will remain locked in thru subsequent stepping switch positions unless it is deenergized by the actuation of a NS vehicle detector in order to call the right of Way to the NS lane.
  • Relay BM performs similarly with respect to the EW lane, being operated thru contacts of stepping switch bank SBI when the stepping switch is in position 6 or I, the EW rest and trafilc timed positions respectively. It is deenergized to put in an EW return call as the right of way is withdrawn from the EW lane if said withdrawal is caused by the maximum timer relay MXR or the variable vehicle interval timer relay VVR but remains locked in if said withdrawal of the right of way is caused by the operation of the normal vehicle interval timer relay YR.
  • Relay BM in subsequent stepping switch positions can be deenergized by action of relay FZ in response to an actuation of EW detector Z52 in order to call the right of way to the EW lane.
  • Relay AR which is energized by stepping switch contacts of bank SBI in stepping switch positions I, 2, 3 and 4, the NS right of way and amber positions, energizes signal relay ALR and completes certain of the timing condenser circuits as will later be explained in detail.
  • Relay BR is energized in stepping switch positions 4, 5, 6 and I to similarly energize signal relay BLR and connect other timing condenser circuits.
  • the maximum timer, effective in the NS and EW trafiic timed stepping switch positions 3 and I to limit the time during which moving trafiic can hold the right of way against waiting cross traffic includes relay MXR, plate condenser KMX and tube MXT.
  • the variable vehicle interval timer includes relay VVR, tube VVT, plate condenser KVV and grid condensers KGNS and KGEW. It times the variable vehicle intervals in stepping switch positions 3 and I, the charge in condensers KGNS and KGEW being afiected respectively by EW and NS traffic so as to decrease the variable vehicle interval in the NS and EW lanes respectively in accordance with the amount of waiting cross trafiic as previously mentioned.
  • Relay YR, tube YT and condenser KV c0- operate to time the normal vehicle interval, with the stepping switch in position 3 or I, which interval starts simultaneously with the variable vehicle interval after each vehicle actuation in the lane having the go signal.
  • the timing of the normal vehicle interval it will be remembered is not afiected by waiting cross traflic whereas the timing of the variable vehicle interal is afiected by waiting cross traffic.
  • Relay YR and tube YT cooperate with other condensers in difl'erent stepping switch positions to time other intervals as follows.
  • the NS initial interval, stepping switch position I is timed by relay YR, tube YT and condenser KINS, the charge in the condenser KINS at the beginning of this interval having been predetermined by NS vehicle actuations occurring during or before the preceding display of the NS stop signal in order to time the NS initial interval in accordance with the amount of NS trafiic waiting at the beginning of the NS go signal display period.
  • Relay YR and tube YT cooperate similarly with condenser KIEW to time the EW initial interval, stepping switch in position 5, in accordance with the amount of EW traflic waiting at the beginning of the EW go signal display period, the starting charge in condenser KIEW being predetermined in accordance with the amount of said waiting EW traffic.
  • the same relay and tube cooperate with condenser KY to time a minimum period during which the stepping switch remains in its rest positions 2 and 6 in order to ensure that when the go signal is given to a lane it will remain there for a reasonable minimum period. At the expiration of said minimum period the: right of way will be transferred to the other lane only if traflic or normal reversion requires it, hence the name rest position. This same group times the NS and EW amber or warning periods, stepping switch in position 4 and 8 respectively.
  • relay AR In this stepping switch position relay AR is operated, current being supplied thru the circuit starting at grounded power thence thru position I of stepping switch bank SBI to relay AR to A. C. plus power.
  • Relay AR when operated causes signal relay ALR to be energized thru the circuit starting at A. C. plus, thru relay ALR, wire 202 to contact earl of relay AR thence to grounded power.
  • Relay BR is deenergized in stepping switch position I, its circuit being open at stepping switch bank SB2. Hence signal relay BLR is deenergized since its operating circuit includes contact brI of relay BR.
  • Wipers WI and W2 are of the bridging type so that the relays energized thru them at their respective contact banks SBI and SB2 will not be deenergized as the stepping switch moves from one position to the next.
  • the NS go signal Z45 will be illuminated thru the circuit beginning at grounded power, thru signal Z45 thence to contact bZrI of relay BLR thence to contact alr4 of relay ALR and to A. C. plus power.
  • the EW stop signal Z50 is illuminated thru the circuit from grounded power to A. C. plus power including signal Z50 and contact alr2 of relay ALR.
  • the circuits to the other four signals are incomplete in stepping switch position I.
  • Relay AM has an operating circuit from grounded power thru wiper W2, stepping switch bank SB2 positions 2 and 3, wire 206, 205, coil of relay AM, wires 204, 216, 211, 221, contact dm2 to A. C. plus. It has in addition a holding circuit from grounded power thru contact cal of relay EZ, contact amI of relay AM, wire205, coil of relay AM, wires 204, 216, 21! to contact am2 of relay AM, wire 219, contact macrl of maximum timer relay MXR, contact curl of variable vehicle interval timer relay VVR, thence to A. C. plus power.
  • relay AM In stepping switch position 2 relay AM is energized thru the operating circuit described above. That part of the operating circuit supplying current to the left side of the coil remains complete from the time the stepping switch enters position 2 until it leaves position 3 after which it is broken at bank SE2. Wiper W2 is of the bridging type to insure continuity of the above circuit as the stepping switch moves from position 2 to 3.
  • That part of the operating circuit energizing the right side of the coil of relay AM will be opened at contact dm2 as the stepping switch moves from position 2 to 3. However that portion of the holding circuit paralleling the last named part of the operating circuit remains intact to supply relay AM with A. C. plus power While contact dm2 is open during the stepping switch movement. From the above description it can be seen that relay AM is always energized when the stepping switch is in position 2 or 3 and when it is moving from position 2 to position 3.
  • relay AM in subsequent stepping switch positions will be explained as the circuit operation in each position is considered.
  • the NS initial interval is timed by relay YR, tube YT and condenser KINS.
  • condenser KINS is connected to relay YR and to the plate of tube YT thru the circuit going from grounded power to condenser KINS to wires 282, 290, 284 to stepping switch bank SE3 position I to Wiper W3, wires 224, 225 to coil of relay YR, wire 260 to plate of tube YT.
  • condenser KINS is charged thru the circuit starting at grounded power, to condenser KINS, wires 282, 290, 284, to stepping switch bank SB3 position I to wiper W3, wires 224, 223 to timing resistance RZ5, wire 2I4, to stepping switch bank SE4 position I, to wiper W4, wire 225 to stepping switch driving magnet contact dmI to D. C. plus power.
  • condenser KINS is charged to a predetermined voltage the tube YT will break down, i. e.
  • the initial interval is timed substantially in accordance with the amount of waiting cross trafiic thru having the charge in the initial interval timing tarmacelegance.
  • condenser KINS While condenser KINS was being charged in stepping switch positions 2 and 3 as explained above and during succeeding intervals up to the EW amber period immediately preceding the next NS initial interval, i. e. while the stepping switch is in positions 2, 3, 4, 5, 6 and l, the charge of condenser KINS is subject to the removal of an increment of charge by action of condenser KZI at each actuation of NS detector Z5l.
  • stepping switch position 2 the NS go signal rest position; relay YR, tube YT and condenser KY time a predetermined minimum period at the end of which the stepping switch can be moved on into position 3 either by an EW traflic actuation or by normal reversion.
  • the circuit connecting relay YR, tube YT and condenser KY in stepping switch position 2 is as follows. Relay YR thru wires 225, 224, wiper W3 and position 2 of bank SE3 is connected to condenser KY thru wires 229 and 258. In addition a charging circuit is established for condenser KY starting at grounded power through condenser KY, to wires 258, 229, position 2 of bank S133, wiper W3, wires 224, 223, adjustable resistance RZI3, wire 2l3, position 2 of bank SE4, wiper W4, wire 226, contact dml of driving magnet DM to D. 0. plus power.
  • Wiper W3 is of the non-bridging type so that as the stepping switch moves from one position to the next there will be no interconnection of condenser circuits.
  • Contact dml is included in the charging circuit described above to prevent the plate of tube YT from being charged to flash-over voltage during the instant that condenser KY is disconnected therefrom as wiper -W3 moves from one stepping switch position to another.
  • the timing of the NS minimum rest position period can be adjusted by regulating resistance RZI3 to control the charging rate of condenser KY in stepping switch position 2.
  • the grid circuit of tube YT in stepping switch position 2 is connected thru wire 259, wiper W5 and position 2 of bank SE5, wire 29
  • Wiper W5 is of the bridging type to prevent fluctuations in grid potential as the stepping switch moves from one position to the next.
  • potentiometer PZ5 is permanently connected to D. C. minus but the positive end of PZ5 is connected to ground thru a circuit including wire 254 and contact bm6 of relay BM or EW arterial switch Z89.
  • switch Z69 and contact bmfi are open the potential of the grid of tube YT will be biased negative to such a degree that said tube will not break down even though plate condenser KY be charged to its maximum positive voltage. Therefore with contact bmB and switch Z59 open the stepping switch will remain at rest in-position 2 even after condenser KY has become fully charged.
  • switch Z69 is closed which will make the grid potential of tube YT less negative so that the tube will break down and operate relay YR thus causing the stepping switch to move from position 2 to 3 as soon as condenser KY is sufficiently charged, i. e. at the expiration of the stepping switch position 2 minimum period. If switch Z69 is not so closed the movement of the stepping switch from position 2 to 3 will take place at any time after the expiration of said minimum period upon actuation of the EW detector Z52 which will deenergize relay BM by opening its holding circuit at contact fzl of relay FZ.
  • relay BM causes contact b'm6 to complete a circuit connecting potentiometer PZ to ground thus making the grid potential of tube YT much less negative so as to cause the tube to break down and relay YR to operate, causing the stepping switch to move from position 2 to 3. If an actuation of detector Z52 takes place before the expiration of the rest position minimum period said stepping switch movement will take place at the end of this minimum period.
  • the NS go signal. and the EW stop signal remain displayed and three timers, the normal vehicle interval timer, the variable vehicle interval timer and the maximum timer ran concurrently.
  • the first two of these timers are subject to reset by NS detector actuations and the timing period of variable vehicle interval timer is in addition shortened by waiting EW trafiic in accordance with the amount of such waiting EW traffic.
  • the maximum timer is not affected by trafiic in either lane and sets a maximum limit beyond which NS traflic cannot continue to hold the right of way against the cross lane.
  • the normal vehicle interval timer includes relay YR, tube YT and condenser KV.
  • the grid of tube YT is in stepping switch position 3 connected to potentiometer PZB thru position 3 of bank SB5.
  • the circuit from relay YR to wiper W3 of bank SE3 has been traced.
  • condenser KV is connected to relay YR by wires 23!, 232, 233 and 234.
  • Condenser KV while the stepping switch was in positions I and 2, was being charged thru a circuit including grounded power to condenser KV, wires 234, 233, 232 and 230 to variable resistance RZII, wire 238, contact ar4 of relay AR to positive D. C. power.
  • condenser KV was also subject to discharge by NS detector actuations thru contact e24 of relay EZ, wire 231, contact 1112 of relay AR to ground. If, when the stepping switch enters position 3, the traflic in the NS lane has cleared the intersection condenser KV will have had suflicient time since the last NS detector actuation to become fully charged.
  • condenser KV In stepping switch position 3 condenser KV is connected to the plate of tube YT via relay YR. Hence if this condenser is fully charged when the stepping switch moves into position 3 tube YT will immediately break down and operate relay YR to move the stepping switch on into position 4 with no appreciable stop in position 3. If on the other hand NS detector actuations have recently discharged condenser KV the normal vehicle interval timer will continue its timing as long as the stepping switch remains in position 3.
  • the variable vehicle interval timer includes relay VVR, tube VVT, plate condenser KVV and, in stepping switch position 3, grid condenser KGNS.
  • plate condenser KVV is charged thru a circuit from grounded power to condenser KVV, wire 263, 26l, 222, Hi, 220, variable resistance RZ4, wire 2l2 to position 3 of bank SE4, wiper W4, wire 226, contact dml to D. C. plus power.
  • Wiper W4 is of the non-bridging type to prevent interconnection of charging circuits during stepping switch movement. Contact dml is included in this circuit to prevent tube flashover during the stepping switch movement as has been explained before.
  • Condenser KVV is subject to discharge upon actuation of NS detector Z5! thru circuit from the tap wire 3
  • the grid of tube VVT is connected to condenser KGNS thru the circuit including wire 249, contact MS of relay BR and wire 246 to condenser KGNS, thence to ground.
  • the charge of condenser KGNS has in previous stepping switch positions been made less negative by the removal of increments of charge by condenser KBNS, one increment of charge being removed for each actuation of EW detector Z52, so that the charge on condenser KGNS when the stepping switch is in position 3 has been reduced in accordance with the amount of waiting EW trafl'ic.
  • condenser KBNS is charged by condenser KGNS and then discharged to a predetermined potential once for each actuation of EW detector Z52.
  • This detector operates relay FZ whose contacts 126 and is! are effective to accomplish the above as follows. With contact is! closed condenser KBNS is discharged to a predetermined voltage thru the circuit including grounded power, condenser KBNS, wire 248, contact fz'l, wire 250 to potentiometer PZB.
  • the voltage to which condenser KBNS is so discharged is regulated by setting the point at which wire 250 contacts potentiometer PZG.
  • a vehicle actuation of EW detector Z52 opens this discharge circuit at contact fa! and connects condenser KBNS to condenser KGNS thru the direct circuit including contact I26.
  • the voltage on condenser KBNS which was regulated to be less negative than that of condenser KGNS, will therefore cause the voltage on condenser KGNS to become less negative.
  • the charge in condenser KGNS will have been reduced in accordance with the total of all the increments removed by condenser KBNS in response to EW trafiic actuations and substantially in accordance with the number of such EW actuations since the right of way last left the EW lane.
  • condenser KGN S in stepping switch position 3 acts as the grid condenser for tube VVT of the variable vehicle interval timer it follows that the time required for the plate condenser KVV to be charged to a voltage sufficient to cause tube VVT to break down, i. e. the variable vehicle interval, will be decreased substantially in accordance with the reduction of negative charge in condenser KGNS hence substantially in accordance with the amount of waiting EW traffic.
  • variable vehicle interval relay VVR When the variable vehicle interval relay VVR so acts to cause the stepping switch movement into position 4, it is obvious that its period had been reduced by waiting cross trafilc to less than that of the normal vehicle interval timer. Hence the right of way return call put in by relay VVR is occasioned by the reduction of the variable vehicle interval by cross trafiic to less than a predetermined time.
  • the maximum timer will after a predetermined time act to move the stepping switch into position 4 and so transfer the right of way from the NS lane.
  • the maximum timer consists of relay MXR, tube MXT and plate condenser KMX.
  • condenser KMX is charged by a circuit from grounded power to condenser KMX, wire 268, thru variable resistance R22 to position 3 of bank SBB thence thru wiper W6 to D. C. plus power.
  • the timing of the maximum period can be regulated by varying resistance RZZ.
  • tube MXT When condenser KMX reaches a predetermined voltage tube MXT will break down and operate relay MXR by discharging condenser KMX thru the circuit from grounded power thru condenser KMX, wires 268, 269, coil of relay MXR, tube MXT, to ground.
  • relay MXR causes the stepping switch driving magnet rectifier to be energized thru contact 'mxrZ and so moves the stepping switch into position 4.
  • both circuits previously traced to the right side of the coil of relay AM are opened.
  • Relay AM is therefore deenergized to put in a NS right of way return call.
  • relay AM causes the return of the right of way to the NS lane by moving the stepping switch out of the EW rest position 6. This is accomplished as follows.
  • condenser KY is discharged thru driving magnet contact dm3
  • condenser KVV is discharged thru contact (11114)
  • condenser KMX is discharged thru contact ($1125 to prepare them for timing their next intervals.
  • relay BR is energized thru wiper W2 and position 4 of bank SBZ.
  • Contact 111'! of relay BR being thereby closed light relay BLR is operated which extinguishes the NS go signal Z by opening contact blrl and illuminates the NS amber signal Z46 by closure of the contact blr2.
  • relay AM While the warning or stop signal i being displayed in the NS lane, stepping switch in position 4, 5, 6, l or 8, relay AM, as previously explained, depends for its current on a holding circuit which includes contact eel of relay EZ. Therefore thru the opening of contact eel relay AM will be deenergized by a NS vehicle actuation occurring during the NS warning or stop signal display period. Relay AM will thereupon function to call the right of way to the NS lane in the manner previously explained.
  • the NS amber or warning period, stepping switch in position 4 is timed by relay YR, tube YT and condenser KY which is connected to plate circuit of tube YT thru relay YR and wiper W3 and position 4 of bank SE3.
  • Condenser KY is charged during this period thru a circuit from grounded power to condenser KY, wires 258, 229, position 4 and wiper W3 of bank SE3, wire 224, 223, variable resistance RZI,
  • the duration of the NS amber period can be regulated by adjusting resistance RZI to control the charging rate of condenser KY during this period.
  • the grid of tube YT i connected to potentiometer PZG.
  • Stepping switch positions 5, 6, I and 8 correspond respectively to positions I, 2, 3 and 4 except that the go signal or the amber signal is being displayed to the EW lane instead of the NS lane and the functions of the NS and EW detectors are in general interchanged so that EW actuations tend to extend the timing periods while the NS actuations tend to decrease them.
  • the EW initial interval, stepping switch in position 5, is timed by relay YR, tube YT and condenser KIEW just as the NS initial interval is timed by the same relay and tube cooperating With condenser KINS.
  • Condenser KIEW has been prepared for timing the EW initial interval in accordance with the waiting EW traflic by having its initial charge, introduced during the last EW go signal period thru contact bm4 and resistance RZ I 6, decreased during and subsequent to this charging period by the removal of charge increments by condenser KZ2 in response to EW actuations, just as condenser KINS was prepared to time the NS initial interval.
  • condenser KIEW The removal of increments of charge from condenser KIEW by condenser KZ2 is accomplished thru contacts fzZ and 23 of relay FZ.
  • condenser KIEW is recharged thru the circuit from ground to condenser KIEW, wire 283, position and wiper W3 of bank SE3, wires 224, 223, 2
  • tube YT becomes conducting and permits condenser KIEW to discharge thru wire 283, position 5 and wiper W3 of bank SB3, wires 224, 225, coil of relay YR and tube YT to ground.
  • Relay YR thereupon operates and the stepping switch moves on into position 6, the EW rest position.
  • relay BM When the stepping switch is in position 6 relay BM is operated.
  • the circuits and functions of this relay are similar to those of relay AM except that they apply in general to the EW lane instead of the NS lane. It has an operating circuit from grounded power thru wiper WI and position 6 of bank SBI wires 209, 208, coil of relay BM, wires 201, 216, 211, 221, contact dm2 to A. C. plus power.
  • relay BM operates an additional source of A. C. plus power thru a holding circuit independent of contact (11122 is connected to the left side of the coil of relay BM thru wire 201, 216, 218, contact bm2, wire 219, contact macrl and contact vvrl to A. C. plus power.
  • relay BM When relay BM operates an additional source of grounded power is connected to the right side of the coil of relay BM thru wire 208, contact bml and fzl thence to grounded power.
  • These last two described additional circuits taken together constitute a holding circuit similar to that previously described in connection with relay AM.
  • the conditions under which this holding circuit will be broken to deenergize relay BM and so call the right of way to the EW lane are similar to those efiective in the case of the corresponding holding circuit associated with relay AM and will be described in detail later.
  • the EW rest position, relay YR, tube YT and condenser KY cooperate to time a minimum period at the expiration of which the stepping switch can be moved on into position 1 by normal reversion if NS arterial switch Z68 is closed or by an actuation of NS detector Z5l just as it is moved into position 4 if switch Z69 is closed or EW detector Z52 is actuated.
  • the timing circuit is substantially the same as that effective in position 2 except that condenser KY is charged thru variable resistance RZI4 instead of variable resistance RZI3 and that the grid of tube YT is connected to potentiometer PZ4 instead of PZ5 thereby making the movement of the stepping switch out of position 6 dependent upon NS arterial switch Z68 or NS trafilc thru deenergization of relay AM instead of EW arterial switch Z69 or EW traffic deenergization of relay BM.
  • stepping switch position 1 the EW traflic timed position, the normal vehicle interval timer, the variable vehicle interval timer and the maximum timer, run concurrently just as they did in the corresponding stepping switch position 3, the NS traflic timed position.
  • the charging circuit for condenser KV of the normal vehicle interval timer in stepping switch position 1 includes variable resistance RZ I 8 instead of variable resistance RZI'I which was in this circuit in stepping switch position 3.
  • timer condenser KVV charging circuit resistance RZ9 replaces the corresponding resistance RZ4
  • the maximum timer condenser KMX charging circuit resistance RZ1 replaces the corresponding resistance RZ2.
  • the substitution of these resistances permits the timing of the corresponding NS and EW intervals to be independently adjusted.
  • condenser KGEW is included in the grid circuit of variable vehicle interval timer tube VVT in place of condenser KGNS which was attached to the grid of tube VVT in stepping switch position 3.
  • the negative charge in condenser KGEW is decreased by the withdrawal of an increment of charge by condenser KBEW thru the operation of contacts e26 and e21 of relay EZ, at each NS detector actuation in order to decrease the EW variable vehicle interval in accordance with the amount of waiting NS traific just as the NS variable vehicle interval was decreased in accordance with the amount of waiting EW traific thru the removal of negative charges from condenser KGNS by condenser KBNS thru contacts I26 and 1'21 which has been previously explained.
  • relay BM will be deenergized to put in a call for the return of the right of way to the EW lane just as relay AM was deenergized if either of these relays moved the stepping switch from position 3 to 4, which has previously been described.
  • This deenergization of relay BM will result from the removal of A. C. plus power connections from its coil thru the opening of its holding circuit at contact curl of relayVVR or contactmxrl of relay MXR and the opening of its operating circuit at contact (21122, both of which circuits have been traced from A. C. plus power to the left side of the coil of relay BM.
  • tube YT Search than grid of tube YT so that tube YT will break down 5 when its plate condenser becomes sufliciently charged and operate relay YR to carry the stepping switch out of the said NS rest position.
  • Stepping switch position 8 is the EW amber or warning period position.
  • Relay BB. is ener-, 10
  • the duration of the EW amber period is timed by relay YR, tube YT and condenser KY just as the NS amber period was timed by them except that condenser charging resistance RZ6 replaces resistance RZl so that the timing of the EW and NS amber periods can be independently adjusted.
  • driving magnet DM moves the stepping switch into position I at the same time discharging condenser KY thru contact dm3 to prepare it for timing subsequent intervals. This completes the signal display cycle.
  • intervals are timed as follows by the apparatus of the embodiment of my invention shown in Figs. 2 and 3.
  • the NS initial interval, stepping switch in position I, is timed by regular charging of condenser KINS which has previously been subject to the removal of unit charges by NS traffic actuations. The replacement of these removed charges times this period in accordance with the amount of such waiting NS traffic.
  • the EW initial interval, stepping switch in position 5, is timed similarly by condenser KIEW from which unit charges have previously been removed by EW traflic.
  • the NS traific timed right of way period, stepping switch in position 3 is timed concurrently by three timers, the normal vehicle interval timer, the variable vehicle interval timer, and the maximum timer.
  • the NS normal vehicle interval is timed by regular charging of condenser KV subject to reset discharge by NS returns actuations. This condenser is being so charged and discharged in stepping switch position 2, the NS rest position, so that the normal vehicle interval timer will be efiective to move the stepping switch out of position 3 into position 4 thus transferring the right of way without delay if all NS trafiic has cleared the intersection when the stepping switch moves into position 3.
  • the NS variable vehicle interval is timed by regular charging of condenser KVV which, in stepping switch position 3, is subject to reset discharge by NS traific actuations. At the same time the period of the variable vehicle interval timer is governed by the charge in condenser KGNS which has been previously regulated in accordance with EW traffic actuations.
  • the EW traffic timed right of way period, stepping switch in position 1, is similarly timed by the same three timers.
  • condenser KGEW replaces condenser KGNS so that the period of the variable vehicle interval timer when timingthe EW lane will be governed by waiting NS traffic.
  • two additional gas discharge tubes DT and ET of the grid controlled type similar to tube VVT are connected with the anodes and cathodes in parallel with the anode and cathode respectively of tube VVT, so that tubes DT and ET each serve in addition to tube VVT as elements responsive to a particular level of charge and corresponding voltage on condenser KVV in timing the variable vehicle interval.
  • each tube has its grid bias individually adjusted in accordance with certain trafiic or other conditions to determine the level of charge on condenser KVV at which the anode-cathode circuit of the tube will become conducting to operate relay VVR by discharge of condenser KVV, and thus to operate stepping magnet DM and step the stepping switch from the right of way position for the lane for which the variable vehicle interval or traffic timed interval is being timed.
  • the grid bias of tube VVT is reduced progressively by a small amount for each of a series of actuations by traffic arriving (and waiting) against a stop signal as described above, and this is one of the features of the copending application.
  • the grid bias of tube DT is reduced progressively by a small amount for each of a series of actuations by trafiic moving with the go signal, in accordance with one feature of the present invention, these latter actuations being the same traflic actuations which momentarily discharge condenser KVV to reset its timing action to prolong the go signal period. Between such actuations the grid bias of tube DT is increased gradually, tending to restore it to the original value it had before the reduction in bias by actuations.
  • the reduction of grid bias on tube DT by traffic moving on the g0 signal is provided as follows. Assume that the stepping switch is in the NS trafiic timed position 3 in which the green signal is displayed to NS and the red signal is displayed to EW, and in which relay AR (Fig. 2) is in energized position and relay BR is in deenergized position. In this position the grid of tube DT has initially a relatively high bias provided by its connection via small limiting resistance RX2, wires 3l9, 348, contact br'l of relay BR, wire 3, control resistance RZZI, wire 32'! to potentiometer PZ6. Condenser KD is connected via resistance RXZ and wire 3I9 between the grid of tube DT and the ground wire, to
  • This condenser is of large capacity (of the order of mid. for example).
  • the relay EZ Upon actuation of the NS trafiic detector Z5
  • Relay EZ is deenergized again after each momentary actuation and in its deenergized position via contact e29 connects condenser KDNSI via wire 3
  • PZG potentiometer
  • a small increment of charge is removed from condenser KD by small condenser KDNSI. This reduces the bias potential of the grid of tube DT and makes the later responsive to a lower potential on the main variable vehicle interval timing condenser KVV.
  • An auxiliary condenser KDNS2 similar to KDNSI is provided for connection in parallel with KDNSI by switch 343 to increase the increment of charge removed from condenser KD with each trafiic actuation if desired.
  • Switch 343 is set in one position or the other manually to balance the actuation effect on the grid bias for two and four lane streets, for example.
  • a similar arrangement may be used to provide adjustable capacity for condensers KBNS and KBEW for example, and is useful in compensating for differences in the number of non-interfering lanes receiving right of way simultaneously at different types of street intersections.
  • the grid bias of another tube ET is reduced at a slow time rate to reduce the vehicle interval gradually during the right of way period.
  • this slow reduction of the grid bias to reduce the vehicle interval is under control of the respective relays AM and BM which are released responsive to trafiic approaching a red signal and begins with the arrival of the first vehicle to wait against the stop signal on the street not having right of way.
  • one or the other or both switches 334 and 338 may be set in their open position and the timed gradual reduction of the grid bias of tube ET and the consequent reduction of the vehicle interval will proceed throughout the right of way period Without waiting for the first vehicle to arrive against a red signal.
  • switch 338 open the timed reduction of the EW vehicle interval starts automatically at the beginning of the EW green period and timed reduction of the NS vehicle interval is dependent upon EW vehicle actuation.
  • switch 334 open the timed reduction of the NS vehicle interval starts automatically with NS green but timed reduction of the EW vehicle interval is dependent on NS vehicle actuation.
  • both switches open the timed reduction of vehicle interval on each street will start automatically with the green on that street.
  • Condenser KE is connected between ground and the grid of tube ET via limiting resistance RX5. Condenser KE controls the grid potential of tube ET in connection with one or another of the control resistances RZ23 and RZ24 and its capacity is selected with respect to these high resistances to serve as a timing condenser in controlling grid voltage bias reduction.
  • relay AB. is energized and relay BR is deenergized. Assume switches 338 and 334 closed as shown in Fig. 3, and assume that no traflic is yet waiting on the EW street, and relay BM is therefore energized as described above.
  • condenser KE and the grid of tube ET are connected via limiting resistance RX5, wire 325, contact br9 of relay BR, contact bm'l, wires 335 and 336 to a high bias point on potentiometer PZB which maintains the grid at its initial bias.
  • relay AR After termination of NS right of way and shift of the stepping switch to NS amber position 4, relay AR remains energized and relay BR becomes energized as will be noted by reference to banks SBl and $32 of the stepping switch.
  • the grid control condenser KE is restored to a high bias voltage again as a starting point for control of the EW vehicle interval in the following EW right of way period, this restoration being accomplished by connection of condenser KE via wire 325, contact D18, wire 328, contact M9, and wire 33'! to a high bias point on potentiometer PZB.
  • Fig. 4 shows th condenser KD and tube DT and associated apparatus provided in accordance with the feature of the present invention of reducing the vehicle interval or gap limit interval by closely spaced traffuc having the right of way, or by what might be termed the volume or density of traffic having right of way.
  • the tube WT and associated grid control condensers KGNS and KGEW and unit charge removing condensers KBNS and KBEW are omitted, as are also the tube ET and grid control condenser KE and associated circuits.
  • Fig. 4 should be viewed in conjunction with Figs.
  • Fig. 4 illustrates par ticularly the apparatus and circuits providing reduction of the vehicle interval for right of way by trafiic having the right of way as one of the features of the present invention, together with repetition of certain elements and circuits common with Fig.
  • Fig. 5 which like Fig. 4, also repeats certain of the other c0mmon apparatus from Fig. 3 to permit the complete operation of the vehicle interval timing device to be viewed separately as controlled by the timing action of condenser KE on the reduction of grid bias of tube ET. It is believed that Fig. 5 will assist in an understanding of the individual novelty of this latter feature of the invention.
  • the initial interval be varied in accordance with the amount of tralfic waiting as described above in connection with Figs. 2 and 3 and that a predetermined initial interval might be employed for each street for example or the initial interval might be omitted entirely as a separate part of the cycle by making the reduction of the vehicle interval in accordance with one or another feature of the invention quite extensive, starting with a sufficiently long vehicle interval at the beginning of the right of way period to serve to permit standing traffic to get into motion, and then reducing this vehicle interval progressively at a rather rapid rate early in the right of way timing period by the vehicle interval timer, with a slower reduction as the right of way period is prolonged progressively by moving trafiic, along the lines of the tapering off of the discharge curve of the grid control condensers.
  • the vehicle detectors would preferably be set nearer to the intersection for most efficient results.
  • the initial interval is preferably automatically varied in accordance with amount of waiting traflic as described in connection with Figs. 2 and 3, for improved efficiency of operation.
  • the present invention may be employedwith advantage in combination with the apparatus of the copending application to obtain a marked coordination of timing of the signals at a series of intersections along a street or through a group of intersections forming a grid of which a small part is illustrated in Fig. 6 for example, without interconnection or forced resynchronization of any kind.
  • the feature of the reduction of vehicle interval in accordance with the density of. moving traflic having the right of way as illustrated in Fig. 4 is of particular advantage in this regard in combination with the feature of reduction of vehicle interval in accordance with the amount of traflic arriving against a red signal.
  • the trafiic detectors are preferably set back further from the intersection than would be the case for control of the intersection as an isolated unit, in order to enable the control mechanism to reduce the vehicle interval in accordance with the approach of a considerable group or fleet of vehicles against the red signal before any considerable part of such group reaches the intersection and is required to stop.
  • the traffic may be organized into fleets of vehicles traveling through the series of intersections progressively with the green signal periods appearing to travel along the street in either direction, the gaps appearing between fleets of vehicles matching the red periods on the common street to permit the cross streets to receive the green signal.
  • the apparatus of Fig. 4 aids in recognizing promptly the end of the main fleet of vehicles in any group since the closely spaced vehicles in the fleet will progressively reduce the vehicle interval setting a gap limit progressively closer to the actual gap between vehicles in the fleet and as soon as the main fleet has passed, the spacing of vehicles will increase rather rapidly and the right of way will be terminated promptly and transferred to traffic on the cross street.
  • the present embodiment resets the vehicle interval timing action by discharging the condenser KVV to a predetermined value considerably above complete discharge and determined by the tap 3 on potentiometer PZ'I and wire 3
  • the stepping switch magnet DM resets condenser KVV by contact dm4 and a limiting resistance and the connection with condenser KX and the tap 3 on potentiometer PZl, and the traffic actuated reset of condenser KVV to prolong right of way is connected via contact e25 and contact art; or via contact fz5 and contact ar1, through wire 350 to the tap 3! l.
  • the condensers KBNS, KBEW, KZI, KZZ, KDNSI, KDNSZ, KDEWI, and KDEW2 may preferably be of the order of 0.1 to 0.4 mfd., the capacity of these condensers depending upon the number of parallel traffic lanes on the streets and the degree of effect desired to be obtained for each trafiic actuation in connection with the several circuits for removing charges from the main condensers by small unit charges responsive to trams actuations.
  • a traffic control apparatus for according right of way successively to each of a plurality of interfering traffic lanes, means responsive to each of a plurality of traffic units in one lane during right of way accord therein to prolong such right of way for a small increment of time, and further means to reduce the length of said increment responsive to closely spaced such traffic units.
  • a traiiic control apparatus for according right of way successively to each of a plurality of interfering tramc lanes, means responsive to each of a plurality of traffic units in one lane during right of way accord therein to prolong such right of way for a small increment of time, and further means responsive to such traffic units in said one lane to adjust the length of said increment substantially in accordance with the time spacing between such trafiic units.
  • a traffic control apparatus for according right of way successively to each of a plurality of interfering traflic lanes, means responsive to each of a plurality of traffic units in one lane during right of way accord therein to prolong such right of way for a small increment of time, and means responsive to traffic in another of said lanes during right of way accord in said one lane to reduce said increment gradually in accordance with the length of time such traffic in said other lane has been waiting for accord of right of way.
  • a traffic control apparatus for according right of way successively to each of a plurality of interfering trafiic lanes and having means responsive to each of a plurality of traflic units in one lane during right of way accord therein to prolong such right of way for a small increment of time
  • a trairlc control apparatus for according right of way successively to each of a plurality of interfering traffic lanes and having means responsive to each of a plurality of trafiic units in one lane during right of way accord therein to prolong such right of way for a small increment of time
  • a write control apparatus for according right of way successively to each of a plurality of interfering traflic lanes and having means responsive to each of a plurality of traflic units in one lane during right of Way accord therein to prolong such right of way for a small increment of time
  • a trafiic control apparatus for according right of way successively to each of a plurality of interfering traffic lanes and having means responsive to each of a plurality of traffic units in one lane during right of way accord therein to prolong such right of way for a small increment of time, the combination of two concurrently acting timing means for timing independently adjustable time intervals for determining the length of said increment of right of way prolongation, the first of such two means acting to reduce its time interval responsive to close spacing of moving trafiic units in said one lane having right of way, and the second such means acting to reduce its time interval gradually re- Search Rant sponsive to the length of time traflic has been waiting for right of way on said other lane, means responsive to each of a plurality of trafiic units in said one lane during right of way accord therein to reset both of said timing means substantially simultaneously to retime their intervals concurrently.
  • a traffic control apparatus for interfering traffic lanes having right of way signals for the respective lanes, trafiic actuated devices for the respective lanes, and a control mechanism for operating said signals responsive to actuation of said devices
  • said control mechanism including a timer operated during operation of the right of way signal for one lane to provide a time interval and adapted to be reset to repeat its time interval, means connecting said timer to the trafiic actuated device for said one lane having the right of way signal operated therein to so reset said timer responsive to trafiic actuation, means operated by said timer at completion of its time interval in absence of such resetting actuation to operate said control mechanism to terminate operation of the right of way signal in said one lane and timing means for reducing progressively the time interval of said timer during operation of the right of Way signal on said lane.
  • a traffic control apparatus for interfering 'trafiic lanes having right of way signals for the respective lanes, traffic actuated devices for the respective lanes and a control mechanism for operating said signals responsive to actuation of said devices, said control mechanism includinga timer operated during operation of the right of way signal for one lane to provide a time interval and adapted to be reset to repeat its time interval, means connecting said timer to the traffic actuated device for said one lane having the right of way signal operated therein to so reset said timer responsive to trafiic actuation, means operated by said timer at completion of its time interval in absence of such resetting actuation to operate said control mechanism to terminate operation of the right of way signal in said one lane and timing means for reducing progressively the time interval of said timer, when operated, and means connecting said timing means to the traflic actuated device of said another lane to operate said timing means by actuation of the last named device.
  • a traffic control apparatus for interfering traflic lanes having right of way signals for the respective lanes, traffic actuated devices for the respective lanes and a control mechanism for operating said signals responsive to actuation of said devices, said control mechanism including a timer operated during operation of the right of way signal for one lane to provide a time interval and adapted to be reset to' repeat its time interval, means connecting said timer to the trailic actuated device for said one lane having the right of way signal operated therein to so reset said timer responsive to traflic actuation, means operated by said timer at completion of its time interval in absence of such resetting actuation to operate said control mechanism to terminate operation of the right of way signal in said one lane and means operating responsive to actuation of the traffic actuated device on said one lane during operation of the right of way signal therein to reduce progressively the time interval of said timer.

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US305233A 1939-11-20 1939-11-20 Traffic control apparatus Expired - Lifetime US2265991A (en)

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US305233A US2265991A (en) 1939-11-20 1939-11-20 Traffic control apparatus
GB15276/43A GB560527A (en) 1939-11-20 1940-10-28 Improvements in traffic control apparatus
GB15760/40A GB560488A (en) 1939-11-20 1940-10-28 Improvements in traffic control apparatus

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2750576A (en) * 1952-08-26 1956-06-12 Gen Electric Vehicle actuated traffic signal apparatus
US2925583A (en) * 1956-02-13 1960-02-16 Crouse Hinds Co Control apparatus responsive to traffic density
US2991448A (en) * 1956-03-28 1961-07-04 Otis Elevator Co Elevator announcing system
US3241108A (en) * 1960-09-12 1966-03-15 Lab For Electronics Inc Traffic actuated control system
CN109035813A (zh) * 2018-10-10 2018-12-18 南京宁昱通交通科技有限公司 快速路出口匝道与地方道路衔接交叉口信号动态控制技术

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CN112614357B (zh) * 2020-12-15 2021-09-28 东南大学 一种智能车交叉口左转相位信号优化方法及装置
CN114419889A (zh) * 2022-01-24 2022-04-29 上海商汤智能科技有限公司 时段划分方法、装置、电子设备及存储介质
CN115331432B (zh) * 2022-07-25 2023-09-26 重庆大学 一种抑制隧道入口区域交通流负效应的网联动车控制方法

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2750576A (en) * 1952-08-26 1956-06-12 Gen Electric Vehicle actuated traffic signal apparatus
US2925583A (en) * 1956-02-13 1960-02-16 Crouse Hinds Co Control apparatus responsive to traffic density
US2991448A (en) * 1956-03-28 1961-07-04 Otis Elevator Co Elevator announcing system
US3241108A (en) * 1960-09-12 1966-03-15 Lab For Electronics Inc Traffic actuated control system
CN109035813A (zh) * 2018-10-10 2018-12-18 南京宁昱通交通科技有限公司 快速路出口匝道与地方道路衔接交叉口信号动态控制技术

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FR955388A (enrdf_load_stackoverflow) 1950-01-14
GB560527A (en) 1944-04-06

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