US2088697A - Traffic control system - Google Patents

Description

Aug. 3, Q 1 ER 7 2,088,697

TRAFFIC CONTROL SYSTEM Original Filed April 25, 1933 4 Sheets-Sheet l A-jrezsr a ,I H

INVENTOR. BY CHA2L5 0.6552

A TTORNEYS.

3, 1937. c. D. GEER 2,088,697

TRAFFIC CONTROL SYSTEM Original Filed April 25; 1950 4 Sheets-Sheet 2 u ww eo 33 v .26 W i I /5/ lvsz INVENTOR.

\ CHA/zzzs D. 6552 A TTORNEYS.

1937- c. D. GEER 2,088,697

TRAFFIC CONTROL SYSTEM Original Filed April 23, 195:) 4 Sheets-Sheet s INVENTOR. C'HAQL E5 D. 6552 BY wMcLJ BoMJY/L/ j A TTORNEYS.

TRAFFIC CONTROL SYSTEM Original Filed April 25, 1953 4 Sheets-Sheet 4 INVEN TOR. CHAQL 5a 0 6552 BY ,A e (S W, bmv rofi.

. A TfTOR/VEYS.

Patented Aug. 3, 1937 master PATENT oFFicr TRAFFIC CONTROL SYSTEM Charles D. Geer, New Haven, Conn, assignor to The Engineering & Research Corporation, (formerly The Stirlen Engineering & Research Corporation), a corporation of Connecticut Original application April 23, 1930, Serial No. 446,480. Divided and this application April 7,

1936, Serial No. 73,156

10 Claims.

This invention relates to a traffic system capable of use in numerous different associations but primarily intended for employment with vehicle lanes such as roadways, and particularly at points of intersection of roadways, the present invention aiming to provide an automatic system by means of which traflic will be expeditiously handled and which system to the greatest extent if not completely will be controlled in its functionings by the presence of traffic along the vehicle lanes.

This application is a division of application Serial No. 446,480 filed April 23, 1930, and relates particularly to and claims the periodic call feature and a traffic control system embodying said periodic call feature, both said feature and said system being disclosed but not claimed in said application Serial No. 446,480.

The present application discloses but doesnot claim the speed proportional control feature of application Serial No. 446,480. feature is completely disclosed and claimed in application Serial No. 446,479 filed April 23, 1930, by Frederick G. Kelly, Jr., which application issued on June 23, 1936, as Patent 2,044,907.

The present application also discloses but does not minimum delay periods and in which moreover the system will embrace a factor of safety such that the danger of accidents between vehicles or between vehicles and pedestrians will be reduced to a minimum, if not entirely eliminated.

A further object is that of providing a system of this character, the several units of which will be individually simple and rugged in construction and embrace relatively few parts, these units when assembled providing a system operating over long periods of time with freedom from mechanical and/or electrical difficulties. Moreover, these units to the greatest extent will be capable of individual adjustment so that while at the time of their manufacture, conditions may generally be approximated, adjustments may be made at the time of or subsequent to their installation at an actual trafiic intersection so as to take into account the characteristics individual to the traflic flow along the vehicle lane comprising such intersection.

This latter A still further object is that of providing a traffic control system in which in the functionings of the system, account will be taken not alone of the density of the traffic but also of the speed with which it is moving so that on the one hand undue delays will not be incurred and on the other hand, the danger of a relatively slow moving vehicle becoming trapped at the intersection will be reduced to a minimum.

Another object is that of providing a system in which even in the absence of vehicular traffic, the system will function to permit pedestrians to traverse the intersection without danger.

A further object is that of providing a trafiic actuated right of way signalling system for traffic lanes in which transfer of right of way from either one traffic lane to another will be assured after a relatively long right of Way period in the one lane even in the absence of traffic actuation on such other lane.

An additionalobject is that of providing a traffic actuated right of way signalling system in which in the presence of trafiic right of Way istransferred from one lane toanother in response to trafiic actuation and in which after arelatively long period of right of way on one tramc lane with absence of trafilc actuation on another lane artificial actuation is produced on such other lane to simulate the effect of traffic actuation on such other lane so as to 'cause'subsequent transfer of right of way to such other lane.

Still another object is that of construction of a system, the several units of which will function in the event of one condition of traffic to substantially instantaneously transfer the right of way from one vehicle lane to the intersecting vehicle lane upon the approach of a vehicle along the latter, but in the event of vehicles passing along the first vehicle lane and approaching the intersection will delay thistransfer of right of way for a period adequate to assure safety to transfer.

With these and further objects in mind, reference is had to the attached sheets of drawingsillustrating one practical embodiment of the invention and in which:

Figure 1 is a diagrammatic view showing a highway intersection employing a signal system embodying our invention;

Figure 2 is a detailed view showing a section of a vehicle actuated control device;

Figures 3 and 4 show diagrammatic representations of timing mechanisms;

Figures 5 and 6 are a diagrammatic view showing the circuits of an apparatus for operating the signal at intersecting trafiic lanes.

A self regulating automatic trafiic control system embodying my invention may comprise three parts: a vehicle actuated control, traffic responsive device or detector, placed in or at the side of a road or vehicle lane, an electrical time limiting control system, and a signal device to indicate right of Way to traffic. A function of the vehicle actuated control device is such that vehicles approaching on the several trafiilc lanes actuate various electrical control circuits. These actuations control the operation of the electrical time limitation control system, which in turn 7 controls the right of way device. The right of way device, to inform the traffic in each street when to go and when to stop,,may be the standard red, yellow and green lights now in general use, but may also be any other convenient or desirable form. The vehicle actuated control may be of several types as hereinafter mentioned:

One means actuated by the approaching vehicle may be of a mechanical nature such as a mechanical switch located in or at the side of the street, an electrical contactbeing made upon passage of the vehicle.

Another means for detecting and recording the presence of an approachingvehicle may be a beam of light projected across the highway and received upon a photo-electric or light sensitive electrical cell, so that an approaching vehicle causes an interruption or fluctuation'in an electrical current passing through the photo-electric or light sensitive cell.

An electrical magnetic device located in this street or at the side of the street may also be could be used.

ing a suitable warning signal, transfers right of way to B street. B street now has the right of I way and vehicles approaching on it may cross the intersection. The rightof way will be transferred back to A street under any one of the.

' following conditions:

Condition I.-If a vehicle approaches on A street and all B- street traflic has passed the intersection.

Condition II.If a vehicle approaches on A street and B street traffic is still moving. at the end of a predetermined period, (such as 30 seconds) the right of way is transferred to A street.

Condition III.-If no vehicles approach on A f street, then after preferably a greater predeter mined period, whether or not traflic is moving on B street, right of way will be called for on A street as if a vehicle had approached there and right of way will be transferred to A street as under Conditions I and II above.

The various periodsare controlled by suitable timing mechanisms.

Provision to transfer the right of way to A street as outlined under Condition I above is accomplished thru the use of a timing mechanism on A street.

which provides sufiicient time for the individual B street vehicles to cross the intersection. This timing mechanism is reset toward its starting position each time a vehicle operates the B street actuating means. Hence, if no further vehicles approach on B street, this timing mechanism will eventually complete timing the period it is set for; and when such time is reached, the

right of Way is transferred to A street. The action is of course similar when the. right of way is transferred from A street to B street.

To provide for Condition II mentioned above, in which continuous B street trafiic must be interrupted, another timing mechanism is provided which is not reset by vehicles on B street, and which starts timing when the vehicle approached When it has timed the period it is set for, the right of way is transferred to A street.

To care for Condition III mentioned above,

there is provided another timing mechanism which starts timing B street right of wayas soon as right of way appears on B street. When it has timed the period it is set for, it callsfthe right of way to A street, similar to the way in which right of way would be called to A street by a vehicle approaching on A street and thus simulates the effect of actuation of the vehicle actuated control on A street by such a vehicle. After right of way has been called in this manner, it will be transferred as outlined in either Condition I or Condition II, depending upon conditions in B street.

When right of way istransferred as in Condition II, vehicles are on B street which have not had sufficient time to cross the intersection, even though they have actuated the B street actuating;

means. The control system is left in such ,a condition that as soon as A street traffic permits, right'of way will be transferred to B street without requiring any additional actuation of the B street vehicle actuated means.

The timing mechanism which is reset by trafific; is so arranged that it may be reset in accord with the speed of the vehicle causing the resettingj And thus the time or protection period given each vehicle is commensurate with the speed of the.

vehicle. In this manner, no vehicle receives an unnecessarily long protection period; thus avoid ing needless delay in the interfering lane.

The chief function of the warning signal when it indicates to moving vehicles that they are about to lose right of way, and accordingly the vehicles must be brought to a stop. The warning signal thus acts as a very important safeguard.

Whenever right of way is transferred asout- But when right of way is transferred,-

longer warning signal should be given. This is.

accomplished by providing a mechanism which times the warning signal in a different way, de-

pending Whether the right of way is transferred :as outlined in Condition I, or whether it is transferred as outlined in Condition II.

If several vehicles have passed the actuating means while being given the stopv signal, some time will elapse, after they have been given the right of way signal, before the last of said vehicle-s gets into motion. This time may be quite considerable, and may exceed the protection period provided by the resettable timing mechanism. There is accordingly provided an additional timing mechanism, the time period of which is. proportional to the number of vehicles that have passed the actuating means, but are not allowed to proceed. This timing mechanism begins to time as soon as right of way appears on its street; and only after it has finished timing its period, may the resettable timer begin to operate.

While there has been described above the self regulating automatic trafiic control system em.- bodying this invention, and there has been shown that this invention may comprise three interconnected parts, there will now be described in detail the construction of one complete and specific system embodying the invention:

Referring to Fig. 1 of the drawings, there is shown a complete self regulating automatic traffic control system applied to intersecting streets A and B. The vehicle actuated controls are indicated by the numbers 2, 3 and 4. The signal means in this; particular embodiment is, as preferred, visual, and is indicated at 5. It embraces red and green. electric lamp reflectors or lenses visible from either direction on A street, but not visible on B street; red and green electric lamp reflectors, or lenses, visible from either direction on B street, but not visible on A street; and preferably a yellow electric lamp lens or reflector visible from both streets. The electrical time limiting control is indicated by 6. The unshaded lines indicate controlling circuits. the vehicle actuated devices in A street control the electrical time limiting control 6, and so do the vehicle actuated devices in B street. The time limiting control 5 controls the signal 5.

Fig. 2 shows one form of vehicle actuated device consisting of a ramp l hinged at 8 and forced into an elevated position by spring 9. The top surface of the ramp may be substantially at the level of the street. When the wheel of a vehicle passes over the ramp, the weight of the vehicle depresses ramp 7, causing contacts IE! and H to be pressed together, closing circuit between wires I2 and 53. When the wheel leaves ramp 7, spring 9 forces the ramp l into an elevated position, breaking circuit between wires i2 and it by separating contacts iii and ii. The vehicle actuated devices in A street are connected in parallel. The vehicle actuated devices in B street are also connected in parallel.

The time limiting control uses several timing mechanisms. One embodiment of such a timing mechanism is shown in Fig. 3. When a source of voltage supply is connected between wires I l and I5, current flows from wire l4 thru wire 56, relay ii, and wire iii, to wire l5, operating relay ii. This allows current to flow from wire l4 through adjustable resistance I8, contact 20, armature 2i, wire 22, wire 23, condenser 24,

wire 25, to wire I5. Thus the voltage of the supply is applied to condenser 24 through resistance l9, and the voltage of the condenser begins to build up at a definite rate determined by the size of the condenser, the resistance l9, and the voltage of the supply. shunting condenser 24! is a circuit including a glow tube 25, and a relay 21. The glow tube comprises a bulb containing a suitable gas into which electrodes 28 extend. This tube has such a characteristic that it is normally non-conducting, but when the voltage across its terminals reaches a certain critical or threshold value, the gas ionizes and becomes a good electrical conductor and will not become conducting again until the voltage across its terminals has dropped considerably below the critical ionizing voltage. The voltage of the supply is greater than the critical voltage of the tube. When the voltage across the condenser is built up to the critical voltage of the tube, the tube suddenly becomes conducting, causing current to flow momentarily'from condenser 2 through tube 26, and relay 2i, causing relay 27 to operate. This would effect only a momentary closure of the relay were it not for the locking circuit com.- prising contact 29, armature as, and wire 3!, which is established when relay 2? ope-rates. This places relay 2! directly across the supply, and relay 2i remains energized.

The interval elapsing between the application of the supply voltage to wires I4 and I5, and the operating of relay El, is the period timed by the mechanism. By suitable adjustment oi resistance is, any desired interval may be obtained. When relay 2' operates it may be used to actuate one or more armatures in addition to armature 38. These additional armatures will be used as described below.

Relay 2? remains energized as long as the supply voltage is connected between wires 14 and 55. If the supply voltage is disconnected, the energizing circuits of both relay ii and relay 2? interrupted, both relays become deenergized and drop to their deenergized positions. When relay I! becomes deenergized, it causes armature 2! to touch contact 32. This shunts adjustable resistance 33 across the terminals of condenser 24, and any energy that may be stored in condenser 24 is dissipated in resistance 33. The rate of dissipation of energy may be varied at will by proper adjustment of resistance 33.

Wires M and I5 may be called conveniently the energizing wires of the timing mechanism and are accordingly marked EE.

Connection I .-Figs. 5 and 5 combined show the wiring diagram of a trafiic control system embodying the invention. With the variousswitches, in the positions indicated, the system is so arranged that right of way remains showing on the street which last had right of way, in the event that there be no traffic on either street. Assuming that A street last had right of way, instan taneous operating relay 3% will be energized, thus lighting the A street green light and B street red light through wire 35, wire 35, contact 31, armature 38, and wire 39. It will also be noted that timing mechanisms lil and i! are energized, and also instantaneous operating relay 42. The action of the apparatus under various trafiic conditions will now be described.

Case ISing'le vehicle approaching on B street.Assume a vehicle approaches on B street actuating one of the vehicle actuated devices located there, closing circuit between wires 52 and I3. The B street vehicle actuated control 'de vices are connected tb wires 43 and M; thus whenever one of the B street vehicle actuated devices is actuated, the actuating circuit of relay 45 is closed and it operates. This momentarily closes the energizing circuit of relay 5.6 through wire it, wire 48, wire 59, contact 50, armature 5i and wire 52. Relay til causes armature 92 to touch contact es, locking in relay 46 through wire 94, contact 95, armature 90, wire 9i and wire 62. This locking circuit is necessary because relay 45 operates only momentarily, and were it not for this locking circuit, relay 46 would also operate only momentarily. The operating of relay 46 interrupts the energizing circuit of timing mechanism 40, which has been made through wire 41, armature 53, contact 54, wire 55, contact 56, armature 51, wire 58, wire 59, contact 60, armature 6 I, and wire 62. Timing mechanism 40, its energizing circuit being broken, allows its relay 21 to drop to its deenergized position, operating armatune 63. The energizing circuit of relay 34 which had been'made through wire 64, armature 63, contact 65, wire 66, switch I45, wire 61, and the contact of switch I45, contact 66, armature 69, wire 10, contact 1|, armature 12 and wire 13, is now broken by the deenergizing of timing mechanism 40, and relay 34 drops to its deenergized position. Armature 38 separating from contact 31 extinguishes the A street green light and B street red light. At the same time, the yellow light is energized through wire 39, armature 38, contact 14, wire 15, wire 16, contact 11, armature 18, and wire 19. At the same time, timing mechanism 80 is energized through wire 8 I, armature 82, contact 83, wire 84, wire 05, armature 86, contact 81, wire 88, contact 89, armature 90, wires 9| and 62. Timing mechanism 80 is similar to the timing mechanism shown in Fig. 3, and. similarly, EE represents the energizing wires. Assume that the resistance I9 in this timing mechanism is adjusted so that the mechanism times an interval of 3 seconds. When relay 34 was deenergized, it deenergized relay 42 because the energizing circuit of relay 42, consisting of wire 13, armature 96,

4 contact 91, wire 98, wire 99, contact I00, armature 82, and wire 8|, is broken when armature 82 separates from contact I00. After timing mechanism 80 has been operating for 3 seconds, its condenser discharges through its tube in the manner described above, and its relay, corresponding to relay 21 operates, causing armature IN to separate from contact I02, and to touch contact I03. When armature IOI leaves contact I02, it breaks the operating circuit of timing mechanism 4| and timing mechanism 4| becomes deenergized. The energizing circuit of timing mechanism 4| consisted of wire I 04, armature IOI, contact I02, wire I05, switch I06, Wire I01, contact I08, armature I09, and wire IIO. When armature |I touches contact I03, relay III is energized through wire I04, armature IOI, ,contact I03, switch I46, wire 2, wire ||3, switch I46, contact II4, armature H5, wire II6, contact ||1, armature 53, and wire 41. Relay III operates armature 18. Armature 18 separates from contact 11 extinguishing the yellow light and touches contact II 8, lighting the B street green light and A street red light through wire 19, armature 18, contact II8, wire H9 and wire I20. The right of way is now being given to 13 street and the vehicle which approaches there may cross the intersection. Timing mechanism |2I is the mechanism which provides the necessary time for the individual vehicles on B street to cross the intersection. This timing mechanism is also similar to the mechanism shown in Fig. 3,-EE representing the energizing'wires. Assume that the resistance corresponding to resistance I9 is adjusted so thattiming mechanism |2I times a period of 10 seconds. The energizing circuit of timing mechanism I 2| is made through wire 52, armature 5|, contact I22, wire I23, switch I24, wire I25, contact I26, armature 63 and wire 64. It will thus be noticed that this circuit is completed when timing mechanism 40 becomes de-energized.

Case II-Single vehicle approaching on A street immediately after transfer of right of way to B street.-The action of the apparatus is similar to the action as described under Case I, up to the time right of way is actually transferred to B street.

A street operates, for example, ramp 2. The

ramps in A street are connected across Wires I21- and I28, and thus the vehicle on A street causes a momentary operation of relay I29. This causes relay 42 to operate by energizing it through wire I I0, armature I09, contact I30, wire I3l, and wire 13. Relay 42 looks itself in through armature 96, contact 91, wire 98, contact I32, armature I33, wire I34 and wire 8|. Contact between armature I33 and contact I32 is made because when relay I29 operated, it separated armature I09 from contact I08, thus breaking the energizing circuit of timing megchanism 4|, which immediately dropped to its deenergized position. Assuming that only a single vehicle was approaching on B street, then, after 10 seconds, timing mechanism |2I will operate and armature 90 will separate from contacts 95 and 89. In separating from contact 89, armature 90 breaks the energizing circuit of timing mechanism 80 which becomes deenergized, causing armature |0| to leave contact I03. This deenergizes relay I I I, which allows armature 18 to separate from contact H8, extin guishing the B street green light and A street red light. At the same time armature 18 touches contact 11, lighting the yellow light as described above. ture 6| to touch contact 60, which reestablishes the energizing circuit of timing mechanism 40. Timing mechanism 40 is similar to the mechanism shown in Fig. 3; and We shall assume that its resistance, corresponding to resistance I9, is so adjusted that the mechanism times a period of 3 seconds. After being energized for 3 Seconds,

The single vehicle now approaching on In deenergizing, relay III allows armatiming mechanism operates, separating arma-' ture 63 from contact I26, and allowing armature 63 to touch contact 65. In separating from con tact I26, armature 63 breaks the operating circuit of timing mechanism I2I, which becomes deenergized. At the same time, armature 63, in touching contact 65 energizes relay 34. Relay 34 operates armature 38, which leaves contact 1 extinguishing the yellow light, and touches contact 31, lighting the A street green light and B street red light, and the right of way is again being given to A street and the vehicle which approached there may cross the intersection.

The above two cases describe transfer of right of way from one street to another in response to.

a vehicle approaching on this street where right of way is not being given. It will be noticed that once a vehicle has been given right of way, it will retain right of way for a certain minimum period, for example, 10 seconds; and even though a vehicle approached on the other street, right of way cannot be taken away until the end of this minimum period which we assume is suflicient time for the vehicle tozcross the intersection. If all traffic has ceased, then the timing mechanism which provides this minimum period, (for street A this would be timing mechanism 4|), is inits operated condition, and should a vehicle approach on the other street, right of way will be transferred immediately. If trafiic has not ceased, the above mentioned timing mechanism will not be in its operated condition, and should a vehicle ap-.

proachon the other street, it must wait until this timing mechanism has operated.

Case III--Single vehicle approaching on street followed within ten seconds by a second vehicle on B street.Assuming the right of way is being shown to A street and there is. no traffic on A street, then the first vehicle approaching on B street will transfer right of way to B street as described in Case I. If a second vehicle approaches on B street, actuating either ramp or 3, this will cause relay' i5 to operate momentarily breakingcincuit between armature 5i and contact I22. This will break the energizing circuit of timing mechanism I2 I. We have assumed that timing mechanism l2l times a period of 10 seconds. Assuming the second vehicle to have approached within 10 seconds from the time the first vehicle approached, condenser it of this timing mechanism will not be charged up to the critical voltage of tube 26, and relay 2? will not have operated. The breaking of the energizing circuit deenergizes relay I7 and the charge which has accumulated on the condenser will be dissipated in resistance 33, as described previously. Relay 45 is of course energized only for a short time, and consequently the energizing circuit of timing mechanism l2i is immediately reestablis'hed. But it will-be noticed that condenser 2t has been (lo-energized, and consequently a full 10 seconds must elapse before the condenser will again be charged to the critical voltage of tube 526. The operation of the system under Case II has shown that right of way cannot be taken away from B street once it has received it, until timing mechanism l2! has operated. Thus, whether or not, in the meantime, a vehicle has approached on A street, the second vehicle that approached on B street receives a full 10 seconds in. which to cross the intersection. It is apparent that this operation will be repeated if additional vehicles approach on B street. As soon as vehicles cease approaching on B street, timing mechanism i2! will,-iaft er 10 seconds have elapsed since the last actuatio'nof either ramp l or 3, operate, and assuming a vehicle to have approached on A street,

the right of way will be transferred to A street, as described under Case II. Once right of way has been transferred to A street, the operation or" the system, should more vehicles approach on A street, is precisely as described above. Relay 529 performs the same function for A street that relay 35 performs for B street; and, similarly, timing mechanism 4i operates when right of 'way is being given to A street, just as timing mechanism l'Zl operates when right of way is being given to B street.

In describing Case III, it was assumed that after right of way was transferred to B street, a vehicle approached on A street. If vehi les approach on A street, then after the last car has passed B street, timing mechanism l2l will operate and, right of way will simply remain on B street. -,This is because, even though the energizing circuit of timing mechanism 8!! is interrupted when armature 9B separates from contact 89,

timing mechanism 80 remains energized because power continues to be applied through wire -i35, contacti36, armature l2, and wire it. This is because, since no vehicle has approached on A street, relay 42 is de-energized. If vehicles should again come on B street, timing mecham'sm l2! will again be de-energized, as described above. The B street traffic will again be pro tected and it cannot lose rightof way until all of 7 113; hasassed ,the intersection. It is ap that as long as no Vehicles approach on A street, B street trailic can retain right of way indefinitely.

Case IV-Continuous trajfic on B street with a. vehicle waiting on A street.When this condition occurs, timing mechanism I2l will be continually deenergized or reset by the B street vehicles, and right of way would remain indefinitely on B street. This is permissible if there is no trafilc on A street. But should vehicles approach on A street, there must be some limitation to the length of time B street can continue to hold the right of way after vehicles have approached on A street. This is accomplished with timing mechanism I31. This timing mechanism is again similar tothe type shown in Fig. 3, and we shall assume that its resistance I9 is so adjusted that the mechanism times a period of 30 seconds. This timing mechanism does not begin to operate until a vehicle approaches.on A street. When this happens, relay 42 becomes energized and current flows from wire l3, through armature 12, contact ll, wire I38, the energizing wires E--E of timing mechanism [37, wire i253, contact 526, armature 63, and wire $4. It will furthermore be noticed that this timing mechanism is not reset by vehicles on B street, and once energized, uninterruptedly continues to time until the end of its timing period, for example, 30 seconds. Assuming B street traffic to be continuous, then after 30 seconds, timing mechanism i3l will operate armature 86, separating it from contact 8?. This deenergizes timing mechanism 8B which in turn. deenergizes relay :1 l i, and right of way is transferred to A street as described above under Case II. The difference is that relay 46 remains energized because its looking circuit continues to bemade through contact 95 and armature 95, since timing mechanism [21 has not been energized long enough to operate. Thus, after right of way is transferred to A street relay 46 is energized, which is equivalent to the approach of a vehicle on B street. The system thus provides that without requiring an additional actuation of either vehicle actuated control I or 3, right of way will return to B street as soon as traffic on A street permits. This procedure is necessary because a vehicle may approach on B street within .a second or two from the time right of way is going to be taken from B street, and not having had sufficient time to cross the intersection, these B street vehicles I would be stranded. The system is thus arranged so that when'right of way is transferred, due to the operation of timing mechanism lZi, relay 46, during such a transfer, becomes tie-energized.- But, should timing mechanism l3! transfer right of way, relay 46 will not become deenergized, and right of way will .thus be recalled to B street, so that'vehicles on B street which did not receive a full; 10- seconds in which to cross the intersection, will be given ample time to do so. Timing mechanism i3i performs the same I function for A street that timing mechanism it? performs for B street; The energizing circuit of timing mechanism I 39 consists of wire 47, armaturetB, contact H1, wire Mil, energizing wires EE, wire Hi5, contact Hi2, armature Hill, and wire HM.

There. is thus provided a very flexible traflic control system; It is arranged that once right of way isgiven to a particular street, in re-' sponse to vehicles approaching there, each ve-.

hicle. receives a certain protection period from the timeit ac'tuates the ramp in the street, during whichit may cross the intersection, and is protected against opposing traiiic. If a vehicle approaches on the street where the stop sign is being given, right of way will be transferred to it immediately if traffic has ceased on the intersecting street. If traflic has not ceased, this vehicle must wait until thelast vehicle on the intersectingv street has had a full minimum period in which to cross the intersection. However, vehicles do not have to wait indefinitely should there be continuous traflic on the opposing street. The system provides that the vehicle need not wait more than a certain predetermined time. At the end of this time, the continuous traflic on the opposing street is interrupted to allow the waiting vehicle or vehicles to cross the intersection. The system, however, is left in such a condition thatwithout requiring the approach of further vehicles, the right of way will eventually revert to the street where continuous traffic was interrupted, to allow the-vehicles which did not have suflicient timeto cross the intersection to do so.

In describing the operation of the. embodiment of the timing mechanism shown in Fig. 3, it was stated that the rate of discharge or reset could be varied at will by proper adjustment of resistance 33. This resetting occurs whenever the energizing circuit E-E is interrupted. While the rate of discharge may be determined by resistance 33, the actual amount of discharge depends upon the length of time the energizing circuit is interrupted. If this time is long, practically all of the stored energy will be dissipated in resistance 33. Thus when the energiz ing circuit is re-established, charging of conenergy in the condenser, and the time-required to charge the condenser will be the time necessary to charge it from zero voltage to the critical voltage of tube 26. If the time of reset'is short, condenser 24 will not be completely reset, and thus when the energizing circuit is reestablished, charging of condenser 24 will start with a residual voltage on the condenser, and the period timed by the mechanism will be the period necessary to charge condenser from that voltage to the critical voltage of tube 28. The time period will be shorter by the amount of time that would have been necessary to charge condenser 24 from zero voltage to the residualvoltage. It is thus apparent that the amount of reset depends upon thelength of time the energizing circuit is interrupted. a

The above is the action of the apparatusif the energizing circuit is always interrupted when condenser 24 has beencharged to some particular voltage. In practice, as will appear later, the interrupting of the energizing circuit may occur at all sorts of difierent voltages. Considering the operation of the device more in detail, it will 60 appear that actual amount of discharge, while depending upon the length of time the energizing circuit is interrupted, also depends upon the voltage ;to which the condenser has been charged when the energizing circuit is interrupted. Thus, 'for example, a resetting impulse of a certain length of time, if occurring when the voltage of the condenser is 180 volts, resets the condenser to a voltage of '120; a resetting impulse of the same length of time; if occurring when the condenser 70 voltage is 150 volts, will reset the condenser to 100 volts. It thus appears that for a particular setting of resistance 33, resetting. impulses of a certain length of'time will reset the voltage of the condenser to a certain fraction of its voltage. 7 5'This becomes apparent from'a consideration of "denser 24 will start with practically no stored the discharge equation of a condenser. equation is:

This

E0 is the voltage of the condenser when discharge was started; E: is the voltage of the condenser after t seconds; e is the constant value 2.7183 R is the value of the resistance 33; and C the cav C is of course fixed, and Thus pacity of the condenser. R is assumed set at some particular value.

it is obvious that for a particular value of t, the; condenser will always be discharged to the same portion of the voltage. 7

Referring now to Fig. 2, it will be noticed that the vehicle actuated device consisting of ramp 1 is so arranged that circuit between wires l2 and the circuit closed by ramps I and 3, relay 45 will be energized only while the wheel of the vehicle is actually on the ramp, and consequently the length of time armature 5| is separated from contact I22 depends entirely upon the speed of the vehicle. The energizing circuit of timing mechanism I2! is made through armature 5| and contact l22,and further, the energizing circuit of timing mechanism l2l is interrupted for a length of time which depends entirely upon the speed of the vehicle causing such interruption. Re: ferring now to the above description of the operation of the timing mechanism, it becomes ap'' parent that timing mechanism I2l, although giving the first vehicle a full 10 seconds in which to cross the intersection, gives succeeding vehicles an additional period which is dependent upon their speed, and consequently, succeeding vehicles are given just suflicient time to cross the inter-' section, instead of receiving a full, unnecessary 10 seconds. The faster the vehicle travels, the less the reset, and consequently the less is the time given the vehicle. But, the faster a vehicl travels, the less time it needs.

The above would be the action if succeeding Vehicles continually approach just before timing mechanism |2l is about to operate and separate armature 90 from contacts 89 and 95. In practice, traffic rarely approaches in just that manner. For example, the second car may approach within a second or two from the time the first car approached. Thus, if there were no resetting. at all, the second car would receive possibly 8 .or 9 seconds in which to cross the intersection,

which might be ample. But, the apparatus automatically takes care of just such a condition. 11' the second car approaches, say, after 2 seconds, timing mechanism [2| will have been energized for only 2 seconds and the voltage built up in its condenser will be quite small. Since, as ex-' plained above, the resetting does not reduce the voltage of the condenser by a certain number of volts, but instead reduces the voltage by a certain portion of the voltage built up, the. amount of reset will be very small, and the additional time given the second vehicle, very small. 7

Timing mechanism M, constructed similar to timing mechanism l2l, performs the same operation for street A. V Cmmeotion-II.-The operations described above occur when the various switches are in the positions shown in Figs. and 6. It may be seen from an inspection of Fig. 5 that if switch I 4| is closed, relay 42 is continuously energized, there- 5 by causing the right of way to return to A street not later than 39 seconds after having been given to B street, if B street traiiic is continuous, or as soon as B street traffic ceases.

Connection IIL-It can be readily seen by in-- spection of Figs. 5 and'6 that if the switches are as shown, except that switch M2 is closed, the operation is as described under Connection II, except that the conditions described for A street and B street are interchanged.

Connection IV.It can be seen that with switches MI and i 32 closed, the right of way is granted alternately to each street and is held by each street for any period between and 30 seconds. If no vehicles actuate the ramp in a particular street during a period of 10 seconds, the 10 second timing mechanism functions to yield the right of way 10 seconds after it is granted. If, on the other hand, when said street is given the right of way, vehicles operate either ramp in said street so that the 10 second timing mechanism continually resets, the 30 second timing mechanism functions to yield the right of.

way seconds after it is granted.

Connection V.The circuit is so arranged that traffic actuated means, this can be accomplished by throwing switches M3 and M4 to their down positions. Under these conditions, relays 42 and 6 are continuously energizedand the energizing circuits of timing mechanisms M and IZI are continuously interrupted. "The'system will then function to give right of way alternately to A street and B street for periods of 30 seconds each. Connection VI.-If it is desired to operate a system by hand, this can be accomplished by using switches I45 and M6. If both switches are open, relays 34 and HI are deenergized, and the yellow light will be shown to both streets, as described previously. If switch I45 is .then thrown to the down position, relay 34 will be energized and the A street green light and B street red light will be shown. By. again opening switch I45, the yellow light will again be shown to both streets. If, then, switch I46 is 50 thrown to the down position, relay I I I will be energized, thus lighting the B street green light and A street red light. By opening switch M6, the yellow light will again be shown to both streets. Thus the lights can be operated'manually in any desired manner.

Connection VII .By closing switch Hi1, or by applying power to the two wires marked To fire headquarters, this will, through wires Hi9 and I50 energize relay I 48. This will operate armatures B5) and H5, separating them from contacts 68 and i I4 respectively. This interrupts the energizing circuits of both relays 3 1 and I l I and consequently both of these relays become de-energized. This lights the yellow light visible from both streets. This feature is introduced to provide for emergency control either at the intersection or from a distant point.

Connection VIII .-It will be noticed that when right of way is transferred from A street to B 70 street, timing mechanism 86 times the warning interval during which the warning signal or yellow light is shown. As mentioned before, this timing mechanism is the same as the one shown in Fig. 3, and its resistance It! was assumed ad- 75.justed so that it timed a period of 3 seconds.

if, for any reason, it is desiredto disconnect the 4. This difference consists in Wires EM and I52. Wire I52 is connected to one end of resistance I9 as shown, while wire I5I may be adjusted along resistance l9 by tap H33. If circuit between wires I5I and I52 is closed, this will shunt out a portion of resistance l9, and consequently the period timed by the mechanism will be less than 3 seconds, and may be, for example, 1 second. It will be noticed, furthermore, that if right of way is transferred from A street to'B street, through the operation of timing mechanism M, then the circuit between wires I5I and I52 is closedbecause timing mechanism ll, in operating, causes armature I54 to touch contact I55. Thus the timing mechanism 8!] will provide a short warning period, namely, 1 second. If the transfer is caused by the operation of timing mechanism E39, then circuit between wires El and l52 is not closed, and the warning signal provided by timing mechanism 30 will be 3 seconds in length because no portion of its charging resistance has-i...been shunted out. When the transfer of rightiof way is from B street to A street, timing mechanism Ml performs in a manner similar to timing mechanism 8%.

since traffic has ceased on A street, no longer warning signal need be given because there are no vehicles on A street to be warned. The action is similar when timing mechanism lZl transfers right of way from B to A street. If timing mechanism I39 transfers right of way from A street to Y B street, it means that continuous A street traffic is being interrupted, and consequently a longer warning signal should be given so that the vehicles in A street may have ample time to be brought to a stop. The action is similar when timing mech-.

anism I31 transfers a right of way from B to A It will be noticed that the mechanism street. providesa long or a short warning period in ac cord with the needs of the traffic.

Connection IX.If all the switches are as:

shown in Figs. 5 and 6, except that switch ISO is closed, then as soon as right of way is given There is one slight difference in its construction, and its complete wiring diagram is shown in Fig.

In this case the shunting out of a pore.- tion of the resistance is accomplished through.

This Variable warning signal .is in to B street, armature Iil touches contact MI and the energizing circuit E --E,of timing mechanism N2 is made through wire H63, wire I64, switch I60, contact 5!, armature 5i and wire 52. This timing mechanism is similar to the one shown in Fig. 3, and we shall assume that its resistance I9 condenser will be discharged, and another 2 min.

utes of continuous B street right of way must be shown before timing mechanism I62 will operate.

Assuming there is no A streettraffic, .then right of way would remain on B street indefinitely, were it not for timing mechanism I62. After right of Way has been showing for 2 minutes on B street, timing mechanism I62 operates, causing armature I65 to. touch contact I66. This through wire I63, contact I66, armature I65, wire I61 and wire 13 energizes relay 42. It will thus be noticed that the operation of timing mechanism I62 operates relay 42, thus performing the very same function that a vehicle approaching on A street would have performed. If, when relay 42 operates, B street traffic has ceased, right of way will be transferred to A street. If B street traffic has not ceased, then right of-way will eventually be transferred, as described above in the several cases, depending upon trafl'lc conditions in B street. We thus have a system which, 15 in the event there is no traffic on one street, does, after a certain length of time, shift right of way to that street in order to allow pedestrians to cross. An additional important feature is that it does not arbitrarily transfer right of way at the end of the 2 minutes. It merely puts in a call on the street where the red light is being shown, and the system then takes care of that call just as though it had been caused by a vehicle approaching on A street. The fundamental object of this system is to operate the signal lights in such away that traffic is controlled most efficiently. Timing mechanism I62 does not disrupt that operation but merely insures that right of way will eventually be given to an opposing street even though there be no traffic upon it, in order to allow pedestrians to cross the intersection.

If switch I68 is closed, timing mechanism I69 will be energized when right of way is given to A street. This is accomplished through wire 8|, armature 82, contact I18, wire I1I, switch I68, energizing circuit EE and wire I12. Timing mechanism I69 is similar to timing mechanism I62, and performs the same function for B street that timing mechanism I62 performs for A street. When timing mechanism I69 operates, it closes contact between armature I14, and contact I13, and thus through wire I12, contact I13, armature I14, wire I15, wires 48 and 41, operates relay 46.

Right of way is now being called to B street and will be transferred, as described above in the several cases. Briefly reviewing the operation, it will be noticed that when right of wayhas been showing continuously on one street for 2 min- 50 ute's, right of way is called to the other street, and will be transferred to that street after not more than 30 seconds. With both switches I and. I68 closed at the. same time, and in the absence of traffic on both streets, when right of 55 way has been showing continuously on one street for two minutes right of way is called to the other street and will be transferred to that street after not more than thirty seconds, and after right of way has been showing continuously on the other 60, street for two minutes right of way is called back to the firststreet and will be transferred thereto after not morethan thirty seconds'. Accordingly, in the absence of traflic, right of way reverts between the streets at long intervals.

- Co nnection X.--In all of the above description, it was noticed that timing mechanism 4I began to operate as soon as right of way appeared on A street. Experience has shown that it is, in

most instances, necessary to place the vehicle 70 actuated devices quite some distance from the inters'ection. This occurs because vehicles should 'register'their presence some time before they reach the actual intersection. This will allow the mechanism to either give them time to cross gthe intersection, or if right of way is to be taken away from the approaching vehicles, give them ample distance in which to stop. Suppose, for

' and the vehicles will be given time to cross the intersection; in this case, 10 seconds. If all the vehicles got into motion at once, this time would be ample because the period provided should be sufficient to allow a moving vehicle, which has just actuated one of the vehicle actuated devices,-

to cross the intersection. However, the vehicles will not all move simultaneously. If, say, 10 vehicles are waiting, approximately 15 seconds will elapse before the last vehicle in the line getsinto motion. Assuming there are no further operations of the vehicle actuated controls, the vehicle protection timing mechanism on that street will not be reset, and will, after 10 seconds, transfer right of way to the opposing street. This obviously will occur sometime before the last vehicle in the line has begun to move, and several of the vehicles will be stranded, without, however, leaving the system in such a condition that right of way'will again be given to the stranded vehicles without requiring further actuation. It

is thus necessary to provide an initial timing perequired to allow waiting vehicles to get into motiming mechanism is similar to the one shown in Fig. 3.. When power is supplied to the two wires EE, .current flows through Wire I11, relay I18, and wire I19, operating relay I18. This causes armature I to touch contact I 8|, and con.- denser I82 would be charged through resistance I83. The amount of this resistance is variable by means of contact I84. condenser I82 is a glow tube I83 similar to the one previously described. When condenser I82 is charged to the critical voltage of tube I83, the tube becomes conducting and the energy stored in. I 82 discharges through tube I83 and relay I84, momentarily operating relay I84. This relay locks itself in through contact I85, armature I86, and wire I81. Contact I84 is mounted on a rack-arm I85, mounted so that it can slide longitudinally. This rack-armv is pulled against stop I86 by tension spring I81. When switch I88 is moved so that it touches contact I89, current flows from wire I99 through magnet I9I, switch I88, contact I89, and wire I92, and magnet I9I will be continuously energized. Magnet I9I The arby magnet I9I, causes finger I96 to engage the teeth I 91 of rack-arm I85. Thus if the rackshunting V arm is moved to the left, the mechanism operated III ' When right of way is being given to B street, relay 34 is deenergized and current flows from wire 39, armature 38, contact I98, wire I99, relay 200 and wire 20I, operating relay 200. Relay 200 operates armature 202 and locks itself in through contact 203, armature 202, wire 204, contact 205, armature 206, and wire 201. Assume that one or more cars are waiting on A street, and right of way is about to be transferred from 13 street to A street. In the above description it will be remembered that timing mechanism 4| begins to operate as 'soon as right of way is transferred to A street. With'switch I08 open, however, the energizing circuit of timing mechanism 4| is interrupted and will not be closed until relay Z88 operates, which will close the energizing circuit of timing mechanism 4| ,through wire 209, armature 2I0, contact 2, and wire 2 I2. Relay 208 does not operate immediately as Will appear from the following description. When right of way has been transferred to A street, relay 34 will be energized, which allows current to flow from Wire 39 through armature 38, contact 2I3, wire 2I4, wire I11, relay I18, wire I19, contact 2|5, armature 2|6 and wire 28I, operating relay I18. This establishes the charging circuit of condenser Wire 2I4, condenser I82, armature I80, contact I 8|, contact I84, resistance I83, contact 2|5, ar-

mature 2I6, and wire 20I. Thus, the voltage of the supply is applied to condenser I82 through resistance I83, and the voltage ofthe condenser will begin'to build up. As assumed before, 10 seconds will elapse before condenser I82 is charged up to the critical voltage of tube I83. Although right of way is being given to A street, timing mechanism 4| has not begun to operate, and the vehicles waiting on A street are given opportunity to get into motion and start across the intersection. They are in no danger of having timing mechanism 4| prematurely take away right of way. After 10 seconds have elapsed, condenser I82 reaches the critical voltage of tube I83 and the energy stored in condenser I82 discharges through tube |83 and relay I84, operating armature I86 which locks in relay I84 through contact I85, armature I88, wire I81, contact 2|5, armature 2I6, and wire 20L Relay I84 also or)- erates' armature 2|1, causing it to touch contact 2|8. This allows current to flow from wire 2|9, through contact 2I8, armature 2|1, wire 220, relay 208, and wire 201, operating relay 208. This closes contact between armature 2I0 and contact 2| I, completing the energizing circuit of timing mechanism 4|.

It thus appears that the waiting vehicles have been given a period of 10 seconds in which to get into motion, and after this period, timing mechanism 4| provides the usual protection period, which of course is resettable by additional vehicles approaching on A street. The action from now on is just as described in the above cases. When relay 208 operates it causes armature 2I8 to touch contact 22 I, looking in relay 208 through contact 22I, armature 2 I 0, wire 209, wire I05, contact I02, armature I0| and wire I04. At the same time relay 208 causes armature 208 to separate from contact 205, interrupting the locking circuit of relay 200 which becomes deenergized. When relay 200 becomes deenergized, armature 2|6 separates from contact 2I5, interrupting the energizing circuit of timing mechanism I16, and relay I18 becomes deenergized. This shunts adjustable resistance 222 through contact 223 and armature I80 across the terminals of condenser I82, and any energy stored there will be dissipated in resistance 222. If traflic approaches on B street, then eventually right of way will be transferred to B street. The moment A street loses right of way, relay 34 becomes deenerg-ized, establishing the energizing circuit of relay 200, which operates. The locking circuit of relay 200 is not completed until the end of the warning period. At the end of this period, timing mechanism 80 operates, separating armature IOI from contact I02 which interrupts the locking circuit of relay 208 which becomes deenergized, allowing armature 206 to touch contact 205, and the locking circuit of relay 200 is complete. The mechanism has now returned to the condition at the beginning of operations.

Timing mechanism 224 performs the same function for B street that timing mechanism I18 performs for A street. Similarly switch I24 must be opened. Switch 225 when moved to touch contact 22%? cause magnet 221 to be continuously energized through wires 228 and 229. The armature Z38, operated by magnet 22?, is similar to the armature operated by magnet HM, and is arranged to engage the teeth 225i of rack-arm 232. This rack-arm is pulled toward stop 283 by spring 288. When right of way is being given to A str et, relay III is deenergized, and through wire 235, wire contact 231, armature 18 and wire i9, energizes relay 238. This relay locks itself in through contact 239, armature 240, wire 24I, contact 242', armature 243 and wire 244. When right of way has been transferred to B street, current flows from wire 19 through armature I8,

contact 245, wire 248, relay 281, wire 1388, contact 249, armature 258, and wire 235, operating relay 241. This establishes a circuit from wire 19, armature 18, contact 245, wire 246, condenser 25I armature 252, contact 253, contact 254, relay 255, contact 2'49, armature 250 and wire 235. Assume that rack-arm 283 is so adjusted that the amount of adjustable resistance 255 is of such a value that 10 seconds are required to charge condenser 25I up to the critical voltage of tube 258. After 19 seconds haveelapsed, the energy stored in con denser 25! discharges through tube 258 and relay 251. Relay 251 locks itself in through contact 258, armature 259 and wire 288. At the same time a circuit is established through wire 28L contact 282, armature 263, and wire 28 i, through relay 265, and throughwire 244. When relay 285 operates it looks itself in through contact 268, armature 291 and wire 268, at the same time through contact 289 and wire 218 completes the energizing circuit of timing mechanism I2I. The operation of the device from this time on is similar .to the operation of timing mechanism I16, except that the functions for A and B streets are interchanged.

The above connection provides for an initial period during which vehicles may get into motion. While this may be satisfactory, in a great many installations, the device may occasionally be inefficient because the timing period, although adjustable manually, is fixed. Thus if, for exampie, 5 vehicles are waiting, the 10 second period may be just right. If more than 5 are waiting, a longer period may be desirable, and then again, if less are waiting, a shorter period would be ample. Thus it is desirable to provide an initial period that is proportional to the number of vehicies wait ng. This may be accomplished on .A street, for example, by closing switch Z'II and moving switch I88 so that it touches contact 212. When right of way is being given to B street, and

no vehicles are waitingon A'street, relay 288 will be energized, as described previously, and so will magnet I8I, although the energizing circuit of magnet I8I is somewhat different, being made through wire 21-3, contact 2I5, armature 2I6, and wire 28I. As will appear later, rack-arm I85" is resting against stop I86. 1 Everytime a vehicle approaches on A street, it momentarily operates relay I29, allowing current to flow from wire 214., contact 215, armature 218, wire 21.1.,contact 218, armature 219, wire 288, switch 21I, magnet 28l, and'wire I98, momentarilycperating magnet 28I.. This attracts armature 282--which is similar. to the armature operated 'by magnet I8I. Finger 283 engages the teeth of rack-arm I85 notching the rack-arm forward by the "distance of one tooth. Magnet I8I is so arranged that when the rack-arm is moved forward the distance of one tooth, finger I96 engages the teeth and prevents the return motion of rack-arm I85. Thus, magnet 28I is momentarily energized every time a vehicle causes relay I28 to operate, and the rackarm I85 is moved a distance proportional to the number of vehicles that have approached on A street, while right of way is being given to B street. This provides that, since contact I84 moves with rack-arm I85, the amount of resistance I83 in series with condenser I82 is proportional to the number of vehicles waiting, and when timing mechanism I18 begins to time, the period timed by it will be proportional to the number of waiting vehicles. The operation of the device otherwise is the same. At the end of the period timed by mechanism I18, relay I84 operates and thus causes relay 208 to operate, all as described previously. At the same moment, relay 288 becomes deenergized and armature 2I8 separates from contact 2I5. This deenergizes timing mechanism I18, but, in addition, also deenergizes magnet I9I, allowing finger I98 to move out of engagement with the teeth of rack-arm I85, and rack-arm I85" is pulled against stop I86 by spring I81. Thus the mechanism has returned to its starting position, so that the next time vehicles register their presence on A street while B street is being given right of way, will again provide themselves with an initial period proportional to their number. It will furthermore be noticed that when right of way appears on A street, armature 219 separates from contact 218, interrupting the notching circuit of magnet 28l, and thus the initial period will not be increased by further vehicles registering on A street.

The operation of timing mechanism 224 which provides the initial period for B street, can be adjusted similarly by closing switch 284 and moving switch 225 so that it touches contact 285. Thus, whenever a car operates one of the Bstreet ramps, relay 45 operates momentarily, allowing current to flow through wire 288, contact 281, armature 288, wire 288, contact 288, armature 29I, wire 292, switch 284, magnet 293, and wire 228. Thus, magnet 293 is operated every time relay 45 operates. Magnet 283 operates armature 294,

notching rack-arm 232 in a manner similar to the notching of rack-arm I85. It will again be noticed that vehicles registering on B street, after right of way has appeared on B street, do not increase the initial period because the notching circuit is interrupted at contact 288 and armature 29I, which are caused to separate when relay II I operates.

While the above mechanism provides for an 7 5 initial period that is proportional to the number of vehicles waiting it may, under certain may be accomplished for, A street by-closing switch 285, and as a consequence the notching circuit is not interrupted whenvright of way ,appears on A street. If further vehicles approach on A street, they will continue to operate gmagnet 28l, moving rack-arm I85 'so as to increase the charging resistance. Switch 296 is provided to perform the same function for B street.

From the foregoing, it will be'seen that a traffic control system is provided which operates-in such a way that:

1. The right of way is given successively to several traffic lanes in an order which may be predetermined, but in such a way that thelength of time one lane retains the right of way is dependent upon either the approach ;of vehicles in said lane or upon approach of vehicles in one or more other lanes,'or upon both.

2. That a traflic lane which does not require the right of way cannot hold itto the disadvantage of one which does. v v

3. That a vehicle whoseprogress is prevented by a continuous stream of opposing traffic may not be required 'to wait more than a predetermined period of time, and that not later than the end of said predetermined period of time 'said vehicle is given right of way for a period of time sufiicient for it and following vehicles tocross the intersection,

4. That interfering lanes of traffic shall :not be-given right of way simultaneously.

5. That a vehicle which has passed an actuating means is protected against opposing 'tramc for a period of time sufficient to permit said vehicle to pass the intersection "of the traffic lanes.

6. That a vehicle which approaches an intersection on any lane of traflic is .given immediate right of way on condition, and only on condition that there be no opposing traflic in or immediately approaching the intersection.

7. That when. a vehicle is not given immediate right of way or has right of way taken trom it, before it has had .sufilcient time to cross the intersection, the system will be left in :such a condition that right of way will return to the delayed vehicleas soon as traflic-conditions per mit.

8. That periodically right of way shifts to another lane even though there be .no vehicular traffic on that lane, in orderto allow pedestrians to cross the intersection.

9. That when the signal means and timing system is disconnected from the trafiic factuated means, right of way maybe given .successively to the various trafiic lanes according to,

a predetermined sequence and toeach lane for a predetermined time interval. 1 10.. That the signal means may be disconnected from the traffic actuated means and timingsysa 12. That the warning signal may be interposed between. right of way and stop signals, the timing of said warning signal being in accordance with the traflic conditions existing at the moment.

13. That each vehicle is protected against opposing traflic for a period commensurate with its speed.

14. That if one or more vehicles, after passing the actuating means, do not receive right of way immediately, they will be protected against opposing traffic when they do receive right of way, for a period of time suflicient to allow the last of the waiting vehicles to get started.

Summarizing certain of the salient features of the present invention, it will primarily be understood that an extremely efficient traffic control system is herein provided and by means of which among others, the several objects of the invention as specifically afore referred to are achieved. These objects to a great extent are 1 accomplished by a number of factors which for the purpose of convenience may be identified (a) as variable amber, (b) periodic calls, (0) variable increment, and (d) speed proportional control.

Dealing primarily with the question of variable amber, it will be understood that in the case of traffic approaching the intersection along one vehicle lane, and with no traffic in the second vehicle lane, there will be no necessity for a relatively delayed amber or transfer period. Accordingly, and by means of the present disclosure, the system will serve to transfer right of way to the vehicle lane over which traffic is approaching the intersection with a minimum delay period. On the other hand, where need for this delay period exists, as for instance, where there is a continuous stream of tramc along the vehicle lane which has the right of Way and vehicles on the intersecting lane are awaiting the right of way, the transfer of right of way will only be completed after a maximum i. e. a' threesecond delay period. 45 Dealing with the question of periodic call, it will be observed that by means of the present invention, a functioning of the vehicle actuated control in effect occurs periodically even in the absence of vehicles. More particularly, as 50 set herein for example, even if there is no.

traific along one vehicle lane and continuing traffic along the other vehicle lane, the right of way over the latter will be interrupted at the end of a two minute and thirty second period for minimum of ten seconds. This will allow pedestrians to cross. The reason for this will readily be understood in that the two-minute timers in the event of continuing traffic along one lane have their functioning qualified by the thirty ,60 second timer, the former permitting the initiation of functioning of the latter after two minutes have elapsed. In the case of traffic over neither lane, the two-minute timers would of course operate periodically to permit pedestrians 65 to traverse the intersection without fear of traffic. It will, of course, be appreciated that this periodic call is entirely qualified in the case of continuous traffic approaching the intersection over both vehicle lanes. 7Q With regard to the variable increment feature, it is understood that as previously brought out there is grave danger in the case of a number of vehicles awaiting right of way and all of which have operated the vehicle actuated con- 75 trol due to the necessary sluggishness of the last vehicles of this group. Consequently the right of way once accorded this group of vehicles would be liable to be transferred before the last of the vehicles could negotiate the intersection. This difficulty, however, is anticipated by means of the present disclosure in that a timer functioning after right of way has been accorded such a vehicle group does not begin actually until a time period has elapsed proportionate to the number of vehicles which are awaiting the transfer of right of way. Accordingly, the last vehicle of this group will still be accorded a minimum right of way time period to negotiate the inter-T section. As a practical matter, it may of course be in many instances desirable according to the present invention to manually set this portion of the apparatus to approximate for this condition, but in any event, the time factor will be adequate and the system will take into account those vehicles arriving just after right of way has been accorded and which vehicles necessarily slow down as they become part of the group which is negotiating the intersection.

With respect to the speed proportional control, it will be understood that by the present disclosure, the timer resetting is not simply effected in an arbitrary manner which might in one instance result in undue delay to transfer of right of way and in another instance result in the transfer being effected at such an early moment as to trap a vehicle at the intersection, but that the resetting of this timer will actually be in proportion to the speed of the vehicle which is. approaching the intersection.

Obviously, one or more of these factors might under certain instances be dispensed with and the several units of the apparatus while preferably embodying a construction substantially of the type illustrated and described, might be changed in numerous respects without departing from the spirit'of the invention as defined by the claims.

I claim:

1. A traffic control system for interfering traffic lanes including a signal operable to accord and interrupt right of way to the several lanes, vehicle actuated devices in the lanes, a timer connected to said signal and devices adapted to operate said signal so as to accord and interrupt right of way over said lanes, means forming a part of said timer to cause each accord of right of way to be maintained for minimum and up to maximum right of way periods according to 'actuations of the vehicle actuated devices, and

means forming a part of said system and acting only in the event of the vehicle actuated device of one lane remaining non-actuated for a period of time in excess of such maximum period to cause transfer of right of way for a certain period to the lane of said non-actuated device even in the absence of traffic.

2. A traific control system including, in combination, signalling means to be disposed adjacent the point of intersection of traffic lanes and operable to accord and interrupt right of way to the several lanes, a timer for operating said signalling means to accord and interrupt right of way over said lanes, a traffic actuated device disposed in each lane in advance of said intersection and connected to said timer to govern the operation thereof, timing means forming a part of said timer and acting in response to a functioning of any one of said traflic actuated devices to accord, through said signalling means, right of way to the lane of said one device for a minimum period of time, resetting means for said timing means and acting in response to a functioning of said one device during such right of way period to cause said timing means to supplement said right of way period by a further time interval inversely proportionate to the speed of the traflic which actuated said device, and means acting periodically in the absence of trafiic actuated device actuation in one lane to transfer to such lane right of way indication for a period of time.

3. A traffic control system including, in combination', a signalling means for according and interrupting right of way to traffic moving over intersecting lanes, a timer connected toand controlling the operation of said signalling means, a traffic actuatable device for each lane and connected to said timer to cause said signalling means to accord, responsive to actuation of said device'in either one lane, right of way to such one lane, means forming a part of said timer for maintaining the right of way so accorded to any lane for at least a minimum period and in the absence of actuation in any remaining lane for maintaining right of way beyond said minimum, and means forming a part of said timer and functioning in such absence of actuation of said device in any remaining lane after a period, always longer than said minimum and beginning substantially with said accord of right of way to automatically simulate an actuation of said device for said one of said remaining lanes whereby to transfer right of way through said means to the lane of the last mentioned controller.

4. A trafiic control system including in combination a'signalling means for according and interrupting right of way to traffic moving over intersecting lanes, a timer connected to and controlling the operation of said signalling means, a 40 traffic actuatable device for each lane and connected to said timer to cause said signalling means to accord, responsive to actuation of said device in either one lane, right of way to such one lane, means forming a part of said timer for maintaining the right of way so accorded for at least a minimum period, means forming a part of said timer and functioning in response to further device actuation in such one lane during the right of way for such one lane for assuring maintenance of right of way up to a maximum period after any actuation in another lane, and means operable only after a period of such right of way, with absence of actuation in the other lane, longer than said maximum to automatically cause I transfer of right of way to such other lane.

5. In a trailic control system for interfering traffic lanes, a signal operable to accord and interrupt right of way to the several lanes, traffic actuated devices for the lanes, a timer connected to said signal and including control means for such lanes and connected to such devices and operablein response to actuation of such traflic actuated' devices to operate said signal so as to accord'right of Way to either one lane in which such actuation has first occurred, and to interrupt right of way in the other lanes, and means acting only after right of way has been accorded to any one lane for a predetermined time, without actuation in any other lane, beginning substantially with such accord'of right of way to said one lane to automatically produce the same effect on saidcontrol means as that of actuation in another lane.

6. In a traffic control system for interfering traflic lanes, a signal operable to accord and interrupt right of wayto the severallanes, trafiic actua'ted devices for the lanes, a timer connected to said signal and including control means for such lanes and connected to such devices and operable in response to actuation of such traffic actuated devices to operate said signal so as to accord right of way to either one lane in which such actuation has first occurred and to interrupt right of way in the other lanes, means forming a part of said timer to cause such accord of right of way to be maintained for at least a minimum period and to be extendible by actuations on said one lane up to and within a maximum period initiated by any actuation occurring on another lane, and means operating'only after right of way has been accorded to said one lane for a pre-de-' termined period of absence of actuation on another lane, said period beginning substantially with such accord of right of way to said one lane, to affect said timer like such an actuation on another lane so as to assure transfer of right of way from said one lane to such another lane within said predetermined maximum period thereafter.

7. In a trafiic signal system for interfering traffic lanes, a signal operable to accord andinterrupt right of way to the several lanes, vehicle actuated devices in the lanes, a controller connected to said signal and devices for operating said signal in response to actuations of said vehicle actuated devices so as to accord right of way to any one lane in which such actuation has occurred and to interrupt right of Way in the interfering lanes and means acting only in theevent of a-relatively prolonged predetermined period of absence of actuation of the vehicle actuated device in such interfering lanes, said period beginning substantially with such accord of right of way to the said one lane, to simulate a functioning of such device in one of the interfering lanes to cause transfer of right of Way from said one lane to the last said interfering lane.

8. A traflic control system including, in combination, signalling means to be disposed adjacent an intersection of trafiic lanes and. operable to accord and interrupt right of way to the several lanes, a timer for operating said signalling means to accord and interrupt right of way over said lanes, trafiic actuated devices in said lanes and in advance of said intersection and connected to said timer to cause the latter to function in response to actuation of the former, timing means forming a, part of said timer and acting through operation of said signalling means to provide alternately in such lanesupon actuation of the devices in both lanes right of way periods variable between minimum and maximum limits, said minimum right of .way periods being extendible through said timing means and through operation of said traffic actuated devices up to said maximum periods, means acting while right of way is accorded to one lane and in the absence of operation of the traiiic actuated device in the other lane, to extend the right of way period in said one lane beyond said maximum, and means acting only thereafter, and despite continued absence of operation of the trafiic actuated device in such other lane, to automatically transfer right of Way to such other lane.

9. A trafiic control system for a plurality of of the latter, the timer including relay means for each lane and connected to the corresponding trafiic responsive means for repeating to the timer the efiect of traffic actuation of the traffic responsive means and cooperating with the timer to store the effect of actuation until the timer is in condition to accord right of way to the actuating trafiic, said timer also including means operable upon operation of such relay means to accord right of way alternately to the lanes between minimum and maximum periods in accordance with traffic actuations, and means associated with said timer but independent of the maximum timing means mentioned and. operable only after right of way has been accorded to any one lane for a predetermined period, and in absence of actuation on the other lane, to operate said relay means for such other lane to produce the same effect on the timer as that of traffic actuation on said other lane.

10. A traffic control system for a plurality of interfering traflic lanes comprising signalling means adapted to accord and interrupt right of way in such lanes, traffic responsive means in each of said lanes, a timer connected to the signalling means and traflic responsive means to govern the former in accordance with actuations of the latter by trafiic, the timer including relay means for each lane and connected to the corresponding traffic responsive means for operation by trafiic actuation of the latter, means associated with said relay means and cooperating with the timer to maintain said relay means so operated in the event it is operated momentarily while right of way is interrupted in its corresponding lane and until the timer causes the signalling means to accord right of way to the lane of such actuation, said timer also including minimum timing means to maintain the right of way for a minimum period when accorded and adapted to prolong right of way beyond the minimum by actuations in the same lane, and also including maximum timing means for providing a limit to such prolongation, means forming a part of said timer cooperating with said minimum and maximum timing means to cause said signalling means after such minimum and such prolongation, if any, to interrupt right of way in one lane and accord right of way to another lane when the relay means of the latter is operated, and super-maximum timing means also forming a part of said timer and active, to time, while the right of way is accorded to any one lane, a period longer than said maximum at the end of which it operates said relay means for the other lane whereby the timer will be actuated to accord right of way subsequently to said other lane even in the absence of trafiic actuation on said other lane.

CHARLES D. GEER.

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