US2249100A - Traffic actuated control system - Google Patents

Traffic actuated control system Download PDF

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US2249100A
US2249100A US346517A US34651740A US2249100A US 2249100 A US2249100 A US 2249100A US 346517 A US346517 A US 346517A US 34651740 A US34651740 A US 34651740A US 2249100 A US2249100 A US 2249100A
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way
approach
period
lane
vehicle
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Harry A Wilcox
John L Barker
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AUTOMATIC SIGNAL Corp
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AUTOMATIC SIGNAL CORP
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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

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  • This application relates to traic actuated tramo control systems and especially to systems of this kind for installation at a constricted section of roadway capable of permitting traflic flow only in one direction at a time, or at particularly wide road intersections or the like, where a relatively long time is required to clear one trac flow beyond the point of possible conct with another.
  • Such a system is of use in all locations where there is a relatively long or extensive controlled area and it is desirable to clear this area of one traffic flow before right of way is accorded to a conflicting traflic flow, and to so accomplish this without imposing unnecessary delay to the conicting traffic flow.
  • a traliic Acontrol system of this character in which the right of Way is accorded to either approach tothe relatively long Zone of interference in response to trac actuation on such approach, but before such accord of right of way to the first approach the right of way is interrupted on the other approach and right of way is maintained ticular value at a long narrow bridge or tunnel or a relatively narrow section of curved roadway where it is unsafe or impossible to permit tralc to pass in two directions for example.
  • Traffic actuated trafficvcontrol systems have in the past been built for numerous types of in ⁇ stallation and for many varied conditions of operation. For example systems of thejtrafic tuations of trafc detectors inthe lanes of .flow
  • period procures for itself extension of the change period beyond the normal duration ofthe period for safe passagegof the i actuatingtrafc unit through the intersection interrupted on the first approach for sufcient.v
  • the system preferably provides for the right of way to remain on the approach on which traffic has last arrived in absence .of any trafilc on the.
  • the present system is adapted par ⁇ ticularly for controlling vfor example traffic mov; ing along a roadway having a constricted section l of considerable length as caused for instance., ⁇
  • Trafc control I' signals mounted at the ends of the oonstrictedn area are governed by a controller under the inf-v"v fluence of traflic detectors set inthe approachesV to the constricted section, and inthe absence of J ⁇ other trac a single vehicle actuating a detector immediately receives accord of'right of'way fol- ⁇ lowing the usual brief amber ⁇ change period,jif o the control is not already showing right, ofway,
  • Itlistan object of the invention therefore,. to provide a traiic actuated traic controll system for. constr'icted.k roadway ⁇ sections, Wide intersections-'andthe likev which shalltransfer. andaccord. right of Way to interfering flows of traffic for-,varying time periodszin accordance with trafiic detector. actuations l and which. shall provide a minimum-clearance time period for every vehicle entering the controlled area before the completion of which period right of way. cannot be accorded to aconflicting traffic flow.
  • the yellow signal to be displayed for a very brief period vafter which .the red signal will be displayed to the rst approach as well'as maintained in the second approach for the balance of the overall clearance time.
  • Figures 1 and 2 together comprise a circuit diagram of 'an embodiment of a controller a ⁇ c' cording to the invention, and right of way signals and traflicdetectors for governing movement of traffic in one direction at a time throughl a conpasses across a narrow bridge for example.
  • the roadway shown is adapted generallytoV stricted section of roadway, where the roadway;
  • red signal indications may be presented by the signals G'A, ⁇ AA. l and RA for traflic onap-Y proach A' from which traic enters the restricted section from the left toward the right side of the Figure l, and by the signals GB, AB, and
  • the traiiic -control system disclosed may be used advantageously in many types of installations besides the one-way restricted traffic area shown. For example it may be used yat intersections of two particularly wi-de roads.r It isadvantageous for use'at other types of intersections', such as the crossing of a road of normal Ywidth with a'particularly broa-d road, or'wide crossings of more than two roadways, or in fact wherever it is desired that an assured clearance period of considerable duration for the last vehicle entering the controlled area be pro-A PBare open and ARS and BRSare closed as shown in Fig. 1.
  • This. ⁇ clearance time period is ordinarily of shorter ylength than the maximum time period .for zones of interference of'ordinary length al' though it would be possible under conditions of an extremely long zone l(if-interference and relatively light traffic that itV might be desirable to have the maximum time' period shorter than the :overallclearance time period'.
  • a timerv device is- Y alsoprovidedfor'the amber period.
  • timer are each reset to restart theirftiming period ⁇ responsive to each traffic mactuationA by vehicles arriving with the right of way and in the present preferred embodiment theseY timers aren reset at the moment ofactuation and measure their time period from that moment, butitwill be appreciatedV that similar but somewhat inferior results may beobtainedby the use of a recycling type of atimer which Will'be actuated in 4each successive4 extension time period to. add.; another timeA period' after completion of' i the current time period.
  • trafiic'signal controller represented therein comprises a number of setsof contacts for controllingwthe right of way signals Iiizandcircuitsfor-timing the display periods ofthe signals, these contacts beingoperated by a cam shaft whichis-moved step-by-step through a cycle by means of a solenoid' and ratcheting mechanism.
  • the stepping of the solenoidis govierned by atiming circuit employing a gaseousl discharge tube-condensertimerfarranged to have its timeperiodsvaried undervcontrol ofthe vehi'- cle .detectorsflocatedin the approaches to the restricted. area.
  • the controller utilizes a plurality oftiming circuits forthis purpose.
  • the controller is arranged to operate from-an alternating current supply I, 2.- 'Io providev dimi; rect current for the timing circuits a transformer- 3 supplies rectifier 4.
  • the ungrounded AC lead 211s denoted by a plus -in a circle and the ungrounded.
  • DC lead ⁇ Sis denoted by a plus in-a square.
  • 'Ihe' lcommon grounded AC and DC G51-lead. is represented-by a minus in a circle andl square.
  • yCamfoperated contacts are shown alignednear, the rightof the drawings and' thepositions of the cam shaft in which each contact pair. is closed in the sixpositioncycle areindi- Tfacated in the chart at. the extreme. right of ⁇ the drawings.
  • Condenser QJ over -a time period proportional to the amount of control resistance VA in circuit, is charged to a voltage in excess of that required to cause discharge through the gaseous discharge tube FJ, butas the circuit through the tube FJ paralleling the condenser QJ Via lead I4, relay contact T19, lead I5, relay contact K3, tube FJ, relay J, lead I6, relay contact bd3, cam contact C28, lead I1 to AC minus lead I, is open at contact bd3 in the absence of detector actuation, no discharge through the tube FJ can occur at this'time.'
  • relay BD is energized by a circuit from plus lead 2 via lead II, relay coil BD and detector D2 to minus lead I, and relay'BD is locked-'in over contact bd I, lead I2, cam con-l tact CIB, lead I3 to minus lead I. Operation of the relay BD enables the circuit previously traced parallelling condenser QJ to be completed via contact bd3.
  • cam shaft position 2 causes extinguishing of the A yapproach ambersignal AA by opening cam contacts CI Il, and en'- ergization of the A red signal RA by closure of camcontacts CI I in position 2.
  • B red signal RBl is maintained energized despite the opening of Since the voltage across con-l cam contacts C22 by circuitithroughcam con- ⁇ tacts C20 and closed contact 112.
  • the energization of relay RR upon the terminating of the A amber signal period in position I occurs when the amber period timing ends the period by operation of relay K which at contact lcI completes circuit'to energize relay RR from. plus lead 2, relay RR, contact kl, cam contacts C4 (closed in position I), lead 20 and closed switch ARS as previously described.
  • Relay RR is locked-in over contact W5, contact :i I to minus lead I.Y
  • the subsequent deenergization of relay RR to terminate the all-red display in position 2 is dependent upon the timing circuit involving condenser QL which is charged gradually during preceding cam shaft positions 6 and I.
  • This charging circuit extends from DC plus lead 5 over resistance RRA, cam contacts CI, lead 2l, condenser QLto minus lead I. Also, in positionsV 6 and I, a resetting circuit for this condenser isV Operation of relay RR as the cam shaft is Iad- ⁇ vanced to position 2 completes an operating circuit for the condenser QL via lead 2 I contact W8, lead I5, contact k3, tube FJ, relay J, lead I6, contact bd3, cam contacts C28, :and lead I1 ⁇ to minus lead I, and since there has been no resetting ofl condenser QL by vehicles the charge on condenser QL has exceeded the ilash voltage of tube FJ and relay J operates to cause immediate deenergization of relay RR by breaking the holding circuit of the latter at relay contact y'l.
  • the condenser QL would be reset to restart its timing of this 15 secondYK overall clearance period at the moment that'this vehicle crossed the A detector DI.
  • the A right of Way period would be ter-l minated after a few seconds by completion of the timing of condenser QJ in position 6 and the amber signal period in the following position I would be terminated by completion of timing by condenser QK after a brief period of 1 to 3 seconds for example.
  • the deenergization of relay RR. causes no movement of the cam shaft but extinguishes the B approach red signal RB and energizes the B approach green signal GB as previously Clescribed.
  • relay BD is deenergized by the opening of its locking circuit at camcontacts CI8, and by the closure of cam contacts C25 -a circuit for shunting or resetting condenser QJ upon further B approach detectoractuations is yprepared extendingvia lead I'I, through cam Contact C25, lead 21, contact bd4--when closedand lead 29, and low resistance ZY.
  • the maximum timing circuit for charging condenser QK extends over high resistance MB, cam contacts C26, contact ad5, lead I9, and condenser QK, and the resistanceZK to minus lead I, and is initiated e by closure of ⁇ contact ad5. If the spacing of B approach vehicles is suiliciently close to maintain condenser QJ below the ash voltage of tube FJ until condenser QK reaches the flash voltage oftube FK, the latter will operate relay K to effect advancement of the cam shaft into position 4, the B approach amber or right of Way change period.
  • the A approach initial green period is no timed by the charging of condenser QK over resistance IA.
  • the resettable or vehicle interval is timed in position 6 by charging condenser QJ over resistance VA, cam contacts C5, subject to resetting by A approach vehicles crossing detector DI and momentarily shunting QJ by low resistance ZY at contact ad4.
  • B approach detector actuation initiates the maximum timer circuit of condenser QK, charging ⁇ via resistance MA, cam Contact C23 and contact bd5, and also places tube FJ and relay J in parallel with condenser QJ by connecting relay J at lead I6 to minus lead I by contact 1x13 Via cam contacts C28 and lead I'I.
  • condensers QJ and QK are reset respectively by op eration of contacts S2 and S3 near the limit of the solenoid stroke, via small limiting Vresistances ZJ and ZK respectively, to assure that the condensers will be fully discharged and ready to commence their next timing actions following each operation of the solenoid to step the cam shaft from one position to the next.
  • Condenser QL 75 which is charged cumulatively over'several periods at a time is discharged in initial green periods 2 and 5 by low resistances ZRA and ZRB respectively. Thefsame resistances serve to reset condenser QL upon A approach vehicle actuations in positions 6 and I and upon B approach vehicle actuations in positions 3 and 4 as previously explained.
  • condenser QL is discharged by a circuit from QL over lead 2 I, cam contacts C I, low resistance ZRA, lead 323, contacts cd2, Trl, and lead 22 tominus lead I.
  • the switches PB and PA are so-called arterial or recall switches and each when closed assures that right of way will be returned to its associated approach in the absence of traffic thereon.
  • Their reiectfwith either one switch closed alone is to simulate the' action of the detectors when their respective approaches are not receiving right of way, byenergizing relay AD in Bright of way positions2 and A3 through switch PA or relay ⁇ BD in A right of waypositions 5 and 6 through switch PB.
  • These switches therefore produce no prolonging of right of way periods. With both vswitches closed the controllerwill operate to accord right of way cyclically for minimum periods extendable by traffic actuation.
  • ⁇ resistance RRA is for a period in excess of the sum of vehicle and amber intervals VAV and LA, and that of resistance RRB for a period in excess ofthe sum of the periodsproduced by VB and LB, all-redlperiods equal to their excess differences will be interposed in the cycle when no traiic' is passing.
  • Y v v InA some installations it vmay be desired to provide an overall clearance interval for travel from only vone direction of approach and in such instance oneof the switches ARS or vBRS is opened corresponding to the phase onwhich it is desired to omit the assured overall clearance and all-red period. If for example the overall clearanceperiod for the A approach is omitted switch ARS is opened.
  • the arterial or reverting switch 4for the opposing approach may be closed thus ensuring that inthe absence of traic right of way will always be returned to one approach and that an assured overall clearance period will be accorded to traflic entering the restricted area on such approach, and that following transfer of right of way to the opposite approach the right of way will subsequently be automatically retransferredto the first approach.
  • the red signal isI maintained displayed to the second approach to prevent vehicles thereon'from proceeding into the area, and red is also shown to the first approach to prevent any vehicles subsequently approaching on the rst vapproach from entering the restricted area.
  • the all red interval terminated as soon as condenser QL ldischarges through tube FJ and relay J, isthus of suflicient duration for the last vehicle entering the area from the rst approach to complete its passage through thelarea, ⁇ and the actuating vehicleon the second approach will be delayedonly so long as any vehicle, travelling at average speed, remains in the restrictedarea.
  • an amber signal is displayed'for a short periodfollowing the green signal period and before the red signal period on each lane, which is a very widely -used sequence of signal colors. It will be understood, however, that other suitable sequences of signal colors may be used with minor rearrangements of the signal connections or cams. For example, if it is desired to havela direct change from green to red and to omit the amber signal as is the practice in sorneV localities this can be accomplished by changing the position of switchesfSWA and SWB appearing in Fig. ⁇ 1. As shown in-Fig.
  • a trac control system for interfering traffic lanes in which the Zone of interference lbetween the lanes is relatively long including a 'right of way signal controller for according right fof wayalternately to the lanes respectively in respense' to traiiic arriving in the respective lanes and to' interrupt right of way in the other Vlane when right of way is accorded to one lane, means forming a party of said controller to interrupt 'right of way in both-lanes after termination of laccordfof right of way in one lane and before accord of right of way to the other lane in response to traffic arriving in the latter lane, and means for timing-such Vinterruption of right of way to ⁇ both lanes-'to provide an ultimate length of time sufcient to permit a unit of traffic to clear throughlthe zone of interference but to reduce thev time -ofv interruption" of right of Way to both flanes'rom such ultimate length in accordance lwithE theamount of time which may have Velapsed from' the arrival of thelast vehicle having right of way on
  • a traic lcontrol system fortwo approaches to a -relatively long zone of traffic interierenca including a signal controller to accord right of way alternately to the two vapproaches 'responsive to traiiic in the respective approaches, means forming a part of said controller to time each such accord of right of way and to 4provide a short period of extension of s uch right of way on either one approach following the arrival of a vehicle on said one approach while right :of way is accorded to said one approach, and :means providing an overall clearance time period Vfollowing the arrival of such vehicle with such clearance Vtime period of considerably greater length than the right or" way extension time period, means to interrupt right of way thesaid one approach while maintaining interruption of right of way in the second approach.
  • a traiilc control :system fortwo approaches to a relatively long Zone of traflic interference including a right of way controller for accord of right of way alternately to the respective approaches in response to traffic on the respective approaches, a timer for controlling the time of such accord of right of way and having a relatively short time period for prolongation of right of way from the arrival of each vehicle arriving in one approach while right of way is accorded thereto and at the end of such time period to interrupt right of .way on said one approach in response to traiiic arriving on the second approach, a second timer to time a longer time period than the rst mentioned period from the arrival of each vehicle having the right of way on said one approach and of sulcient time length to permit such arrivingvehicles to clear through the entire zone of interference, and means controlled by said second timer to delay accord of right of way to said second approach in response to arrival of the iirst vehicle in said second approach so that a period of interruption of right of way to Tooth lanes will ensue between termination of the time period of
  • Atraiiic control system for interieringtraffic lanes in which there is a relatively long zone lane while such go signalis so operated, means responsive toa -vehiclearriving on the-other lane and yto termination of said short timeperiod to operate said mechanism to its other position, andoperate the stop'signal onsaid first lane, and further timing-means timing a ⁇ further-time period longer than saidV short time period fromithe arrival of teach oi said series of vehicles onvsaid one lane lto maintain operation-ofthe stop'signal in the second lane and to delay operation ,of the go signal in said second lane in the said other position of said signalmechanism for a suicient time to Ipermit the 'last vehicle arriving on said one lane to clear :the zone of interference.
  • vA -trairlc control-system for interfering :trafc Alanes in which there is aA relatively long zone of interference Ybetween such lanes, including green, yellow and red trailic signals for the -respective lanes, traic signal control mechanism for displaying said green signal to one of the lanes at a time and the redsignal concurrently to the other lane, and Vfor'displaying the yellow signal after the green signal and before the red signal, timing means for controlling the .time of Y display of the green signal Vfora minimum period andfor yprolonging said y'display period for a short period following each -of -a Yseries of vehicles arriving in said one lane,V means responsive to arrival of la vehicle in the second lane while the green ⁇ signal -is displayed in the ⁇ irst lane to operatefsaid signalmechanism to'terminate display of the green signal Ain said-nrst lane and to initiate display of the yellow signaltherein vupon termination ofthe lastof
  • a traic control system fortwo approaches to a relativelylong Zone of -traiic interference including signalling means for according and interrupting fright oi' way to the respective approaches, tralic actuated means in the respective approaches to be actuated by traffic proceeding toward the said signalling means and said zone of interference, signal operating mechanism connected to said signalling means and said trafc actuated means for operating said signalling means lto accord right of Vwayto one approach and interrupt right of way vto the .other approach in responserto tramo actuation vvin the Aiirst approach, means forming a part of said mechanism to maintain right of way in said rst approach for a short time extension period following each of a series of actuations of the traffic actuated means in said rst approach by several units of traiilc, timing means for timing a longer time period following each of such series of traflic actuations, means for terminating accord of right of way to said rst approach by such signalling means upon expiration of said
  • a traiiic signal control system for two mutually interfering traffic lanes, sign-alling means for according and interrupting right of way on the lanes, trailic actuatable means in the lanes, control means connected to the signalling means and to the trame actuatable means and responsive to actuation of the trafc actuated means in one of the lanes to cause the signalling means to interrupt right of way on the other lane and to accord right of way to said one lane for at least a predetermined minimum period, means responsive to actuation of the trafc actuated means on said other lane to cause the signalling means to interrupt right of way on said one lane and to accord right of Way to said other lane after expiration of the minimum right of way period on said one lane, timer means for timing an overall clearance period of suicient length for a unit of traiTic on said one lane to clear the other interfering lane, means for initiating operation of said timer means by actuation of the traffic actuated means on said one lane during the
  • a traiiic control system for two mutually interfering trailic lanes, 'signalling means for according and interrupting right of Way to the lanes, trafc actuatable means in the lanes, control means connected to said signalling means and traiic actuated means and responsive to actuation of the traic actuated means in one of the lanes to cause the signalling means to interrupt right of way on the opposing lane and to accord right of way to said one lane for at least the sum of the duration of -a fixed initial interval and a vehicle interval, means responsive to actuation of the traffic actuated means on said one lane during said vehicle interval to prolong accord of right of way for a further vehicle interval, means responsive to actuation of the traffic actuated means on said opposing lane while4 right of way is on said one lane to cause transfer of accord of right of way to said opposing lane at the end of said further vehicle interval, timer means for timing an overall clearance time period in which a unit of tramo on said one lane entering the interference area during
  • traffic actuated means in the approach of each of the lanes to the area of interference, control means connected to the traiic actuated means and to the signalling means and operable responsive to actuation of the traffic actuated means in one of the lanes to cause the signalling means to accord of right of way to only said one of the lanes for at least a minimum period, means responsive to actuation of the traiic actuated means in another lane to cause transfer of accord of right of Way to said another lane after the minimum period on said one lane, means operative while right of way is accorded on said one lane, in response to traffic actuation of the traflic actuated means on said one lane to time an overall clearance period in which the actuating unit of traino will be assured time to pass entirely through the interference area and means for preventing the signalling means from according right of way to said another lane in response to
  • a trailic control system for two mutually interfering traffic lanes including signalling aaliaioo means for displaying accord and interruption of right of way to the lanes, traffic actuatable means in the approaches of the lanes to an area in which they are mutually interfering, control means connected to the signalling means and to the traiiic actuated means and responsive to actuation of the traic actuated means in one lane to cause the signalling means to accord right of way to said one lane and to interrupt right of way on the opposing lane for at least a predetermined minimum' period, and for a further extension period by further actuation during said minimum period, means including a timer initiated by actuation of the trame actuated means in said one lane while right of way is on said one lane to time an overall clearance period in which the unit of traic causing the actuation may pass entirely through the interference area, means responsive to actuation of the traffic actuated means in said opposing lane while right of way is on said one lane to cause the signal
  • a traffic controlled system for the accord of right of way alternately to two approaches to a relatively long Zone of traiic interference in response to traiiic on the respective approaches in which a series of short periods of extension of right of way are provided for a series of relatively closely spaced vehicles arriving on one approach while right of way is accorded thereto, and in which right of way is interrupted in said one approach upon termination of such extension period in response to the arrival of a vehicle on the other approach, means delaying accord of right of way to said second approach in response to said vehicles therein after such interruption of right of way in the rst approach, a timing device to control said last named means so as to terminate such interruption of right of way to both approaches upon completion of its time period, and means connecting said timing device to start a timing period from the arrival of each of said series of vehicles on said one approach, whereby accord of right of way to the second approach in response to a vehicle therein will be delayed following the last vehicle to arrive on the rst approach for a sufficient time to clear said last vehicle through the zone of interference.
  • timing means actuated by traiiic to time a short period following traic actuation on one approach while right of way is accorded thereto and to terminate accord of right of way thereto at the end of such period responsive only to traiiic in the opposite approach
  • a second timing means actuatedV by trafc for timing a longer period following such actuation in said one approach having the right of way to maintain interruption of right of way in both approaches for a sufficient time period following suchy termination ofY right of way in said rst approach t'o permit the last unit of tramo from said first approach to clear through the entire Zone of interference.
  • a Vvehicle trafilc control system for two interfering traiiic lanes in which there is a relatively long zone of interference between said lanes including go and stop traiiic signal circuits for the respective lanes, signal circuit switching mechanism having alternate control positions for said circuits includingV one position for normally energizing the go signal for one line and the stop signal for the second lane and a second position for normally energizing the go signal for the second lane and the stopfsignal for the first lane, traflc actuatable relay means individual to the respective lanes, a resettable time switch having a short timing period, electrical operating means controlled by said time switch and by the traffic actuated relay of the second lane in such one position to operate said mechanism to its second position at completion of said short timing period responsive to actuation of said relay, a second resettable time switch having a considerably longer timing period than the rst time switch, control circuits for said time switches connected with said mechanism and said tralc actuatable relay means to reset both of said time

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2705789A (en) * 1952-03-06 1955-04-05 Eastern Ind Inc Traffic actuated control systems
US2750576A (en) * 1952-08-26 1956-06-12 Gen Electric Vehicle actuated traffic signal apparatus
US3035246A (en) * 1954-06-08 1962-05-15 Gen Railway Signal Co Highway signalling system

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2705789A (en) * 1952-03-06 1955-04-05 Eastern Ind Inc Traffic actuated control systems
US2750576A (en) * 1952-08-26 1956-06-12 Gen Electric Vehicle actuated traffic signal apparatus
US3035246A (en) * 1954-06-08 1962-05-15 Gen Railway Signal Co Highway signalling system

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