US2212985A

US2212985A - Automatic traffic control system

Info

Publication number: US2212985A
Application number: US484334A
Authority: US
Inventors: Paul P Horni
Original assignee: Individual
Current assignee: Individual
Priority date: 1930-09-25
Filing date: 1930-09-25
Publication date: 1940-08-27
Anticipated expiration: 1957-08-27

Description

Aug. Z7, 1940. P. P. HoRNl AUTOMATIC TRAFFIC GON-TROL SYSTEM 4 Sheets-Sheet l Filed Sept. 25, 1950 A N E .MSS

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DION. wmouu ATTORNEYS Aug- 2,7, 1940 P. P. HoRNl AUTOMATIC TRAFFIC CDNTROL SYSTEM vFiled Sepf.. 25, 1950 4 Sheets-Sheet 2 auml n www Smw

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tu Pfl-hue www D( ON mmol u mgm QN NEN ATTORNEY 5 Aug. 27, 1940, PLP. HoRNl AUTOMATIC TRAFFIC CONTROL SYSTEM Filed Sept. 25, 193D 4 Sheets-Sheet 3 www Sw K n www SSN @QN www ATTORNEYS v Aug. 27, 1,940. p, HO'RNl I 2,212,985

AUTOMATIC TRAFFIC CONTROL SYSTEM Filed Sept. 25, 1930 4 Sheets-Sheet 4 ff@ v INVENTOR ATTORNEYS A Patented Aug. 27,

UNITED STATES PATENT GFFICE 2,212,985 AUToMATrC Teams comer. SYSTEM Pani numana las; Application September 25, i930, Serial No. 484,334 t claims. (ci. rarsari This invention relates to an automatic traffic control system of the type whose signals are subiect to control by the tramo.

Among the traffic control systems in use here-v tofore, a motor driven commutator or circuit- -breaker operated continuously to ash the traillc lights on and off to procure the successive signal cycles, whether or not the traiiic was such as to warrant continuous control. Usually a great deal lmore traillc traverses one street than the `other intersecting street, but with the usual continuous. trai'c signal the heavy traffic traversing one street must stop periodically even when there is no cross-traino requiring such action, thereby li causing unnecessary retardation of traillc, which `would move more rapidly if the traiiic signal did not interfere with it unnecessarily. Accordingly,

a continuous trafilc signal system, though warranted by a certain amount of cross-traine -at times such as during the rush hours, does more harm than good in such a case.

In many communities, in order to economize on power and save the equipment, it has become l the practice to shut oil' the continuous trafc control equipment during the hours between midnight and early morning when trailic is very light, but because night drivers usually travel at high speed, the control -of traffic becomes more necessary at night than during the day time, when the roads are not as free of traic as to permit high speed operation of vehicles. Accordingly, since the thoroughfares are without any trailic control whatever, because of the custom .of shutting the tramo lights of! late at night, a dangerous traiiic condition exists and many fatal accidents have occurred for this reason. Such a practice would not be necessary if the tramo system were normally inactive or dormant except at a time when converging or intersecting traillc made it 404 necessary. whether late at night or during the day, whereby the system would itself economize on power, extend the life of the lamps, reduce servicing, and save the equipment against wearing out rapidly due to continuous use.

Also in the instance where a continuously operating traillc signal is located at an intersection where the cross-traillc is lighter than is suilicient to warrant the continuous signal, a vehicle operator, upon seeing the green light ahead whue '50 still a considerable distance from the intersection, races to cross the intersection before the signal ilashes against him, which he would not do if there were no traiiic signal ahead of him. This is a source of considerable danger and might be largely. avoided ii the traillc signal were only employed when the cross trame warrants it, i. e. a discretionary tramo control initiated upon command, such as by a traiiic'omcer. is desirable.

It is accordingly the principal object of this invention to provide an automatic trame signal g control system whose operation is initiated'only upon command to dispose of whatever crosstraillc there may be atany one time, andv thereafter lapses into inactivity to permit the usual or heavy traiiic to ilowunimpeded until such timel0 that there is cross-traiilc which requires control of the intersection. This system. while fully mechanical in operation, is discretionaryin function in that it only operates when" traiiic conditions make traic control necessary, whereby the l# enumerated objections to traillc control systems employed heretofore are obviated. By means of this new system, trailic is -expedited and not hindered when there is no reason for stopping it, and the thoroughfares and `theirI intersections 20 are subject to -trailic control throughout the twenty-four hours of every day, whereby traillc is dispatched safely stall times and all of the time without excessive use of power and the equipment since` the system only operates upon coml mand when cross or convergent traiilc requires its operation. In fact, very much less power is used than by the continuous cycle tramo equipment, less servicing 'and repair work is needed, and the life of the lamps is extended. as 1s the me of the 3 equipment as a whole.

- Another object of this invention is to provide an automatic traillc control system which is entirely self-contained and is provided with its own local 35 battery, so that the system may be installed in outlying districts where outside power is not readily available. Furthermore, the system may be installed without the necessity of making arrangements with the power companies or running power. lines. often from considerable distances, to the intersection where the system is installed.

Another object of this invention is to provide I a system of the type described in which a complete signai cycle for controlling both the main highway and the cross street tramo is initiated by a vehicle or pedestrian approaching the intery section from the cross street. and this cycle of operations may be extended a predetermined 56 number of times by additional impulses caused by successive vehicles or pedestrians until a predetermined time interval has elapsed, whereupon the signals are restored to dispatch the main highway trame untilanothersignal cycle is com- 55 pleted when anotherl cross traveling vehicle` or pedestrian can again initiate the signal cycle.

Another object of this invention is to provide a signal system of the type described in which a vehicle seeking to negotiate a turn from one or" the streets of the intersection in a signal zone either appropriates the signals to his benefit from other vehicles which are under the control of the signals at that time or else initiates signals, if the signal system is not otherwise in operation, whereby other vehicles at the intersection are stopped until the turn has been completed by the vehicle who initiated or appropriated the signals.

A further object of this invention is to provide means along the roadside at a suicient distance ahead of the intersection under automatic traffic control to warn approaching vehicles that they are entering an automatic signal zone and must be prepared for a. change in signal, if signals are being shown, or prepared for the initiation of signals if none are shown.

These and other objects of this invention are realized in a preferred embodiment thereof, comprising a local battery which supplies current to the signal operating mechanism and the signal lights, this battery and the signal mechanism being conveniently located adjacent the intersection in any suitable way and no outside power is required for operation of the signal system. Placed in the surface of the cross street adjacent the intersection, in the sidewalk or otherwise adjacent the curb at opposite sides of the main highway at the intersection, and in some instances in the center of the main highway on the right-hand side of the same approaching the intersection, arecontact means whereby the Weight of an object closes an electrical circuit to initiate the operation of signal system or alter the operation thereof. 'I'he iirst contact means mentioned, i. e., those located in the surface of the cross street adjacent the intersection, are subject to operation by the weight of a vehicle approaching the intersection on the cross street from either direction; the second contact means, i. e., those placed on the sidewall: or adjacent the curb on opposite sides of the main highway, are adapted to be operated by the weight of a pedestrian seeking to cross the main highway whose traffic is normally* unimpeded by traffic lights; and the third contact means mentioned, i. e., those placed in the middle of the main highway adjacent the intersection are adapted to be operated by a vehicle seeking to negotiate a left turn from the main highway into the cross street. Any one, any two, or all three of these arrangements may be used in conjunction with each other, and in order to illustrate preferred arrangements of the invention I have described the combination of the cross street vehicle and pedestrian control as a complete system and also a cross street vehicle, pedestrian and left turn vehicle control as another separate and complete system.

Let it be assumed that a vehicle is approaching the intersection from a cross street with due care, having been warned several hundred feet ahead of the intersection that he is approaching the zone of automatic signal control. If no other vehicle has immediately preceded the vehicle in question toward the intersection along the cross street, the main highway tralc is traveling without interruption by the trac lights, as the traffic lights are not illuminated in this instance. As the cross traveling vehicle nearly reaches the intersection, the weight thereof closes the street aaiaaes contacts and the signal cycle is initiated by a series of steps which includes the starting of an electric motor which, by a series of cam controlled contacts, performs the successive operations necessary to complete the normal signal cycle which involves dashing the red, green and amber lights in proper succession against both the main highway traiic and the cross traveling Vehicle that has initiated the signal cycle. It will be apparent from `this discussion that the main highway traic is stopped until the cross traveling vehicle has crossed the main highway and proceeded on its way, after which time the signal lights are again extinguished and the normal main highway traic proceeds in the usual uninterrupted manner.

As mentioned above, means are also provided for permitting a pedestrian to control the traiiic at the intersection if he seeks to cross the main highway. Of course he can freely cross the cross street, as it is assumed that the traffic thereon is not as dense as main highway traiilc. Accordingly, if a pedestrian seeks to cross the main highway, he steps upon one of the pedestrians contacts on the sidewalk or otherwise adjacent the curb at an intersection at a position so that he can cross the main highway. The weight of the pedestrian operates this contact and the signal cycle just described in connection with the cross traic is initiated and when the red light is ashed against the main highway traffic and the cross street green lights are lighted, the pedestrian may safely cross the street, the time interval being sufficient to permit him to do so without danger. If a second pedestrian immediately following the first one steps on any one of the four pedestrians' buttons placed at the four corners of the intersection, the signal cycle is delayed so that the cross street green light and the main highway red light remain energized for a longer period. 'Ihis time can be extended by the successive operation of any one of the pedestrians buttons by four successive pedestrians, each of which tends to slow up the signal motor a longer time until the predetermined maximum time has elapsed, whereupon the signals are restored to their initial condition.

Means may also be provided for permitting a vehicle to make a left turn from the main highway into the cross street whether or not the signal cycle is in operation, either from initiation by a cross traveling vehicle or by a pedestrian seeking to cross the main highway. It is only necessary for the vehicle which seeks to negotiate a left turn to pull up to the center of the main highway adjacent the intersection, whereupon the weight of the vehicle closes the contacts to either initiate a new signal cycle or to interrupt the normal signal cycle which may be in operation at that time. The eiect of this interruption or new initiation of the signal cycle is to stop all cross traili'c and main highway trailc, except that in the direction from which the left turning vehicle seeks to turn into the cross street, and a separate motor is provided whose function is to control the signals in such a way that a predetermined period of time is allowed the left turning vehicle to negotiate the turn from the main highway into the cross street. After this special signal cycle has been completed, the signals are restored to their initial position, unless intervening circumstances such as mentioned above change them. It wi be seen that the left turning vehicle takes precedence, and this is desirable in order to clear the main highway of left turning vehicles immediately, as they otherwise obstruct traffic and retard normal ow of main highway tramo.`

Other details of the invention will become apparent in the following description of preferred embodiments thereof .which constitute complete signal systems which are automatically operated vby the traiiic only. under such circumstances when the operation is required by trafc conditions as otherwise the mechanism does not operate and its length of life is increased, its consumption of power is small, and by providing a self-contained system it is admirably suited for controlling trafiic in outlying districts or in such portions wherethe main highway traffic greatly exceeds cross trafc, whereby no signals are normally. required for. main highway traic except where infrequent cross trame appears.

For a better understanding of the invention, reference is made to the accompanying drawings, in which Figure l is a schematic electrical diagram of the automatic ltrahie control system of thisinvention;

tation of the traffic control system of this invention modified to include left-turning traffic control;

Fig. 3 is a diagram of a road or street intersection equipped with the new control system, showing the arrangement of the vehicle'and thed pedestrian contact;

Fig. 4 is a similar diagram including curb indicators for warning the operator of a vehicle that he is approaching a zone of traffic control;

and

Fig, 5 illustrates in enlarged detail the curb warning indicators.

In the arrangement of this invention, the traffic light housing II) is mounted in the center of the intersection of the cross'street with the main highway in the usual wayas shown in Figs. 3 and 4. Along the curb on either side of both the cross street and main highway are placed the warning indicators II and I2 which are placed several hundred feet ahead of the intersection and are reflectors, lights, or are otherwise arbitrarily arranged or inscribed with warning legend to inform an approaching vehicleoperator that he is approaching a zone of automatic signal y control, and that ne must `be watchful of signals. If the signals are inoperation because they were initiated by a cross-traveling vehicle, the approaching vehicle can observe the lights, but the indicatorsl and I I additionally warn him that the signal control is automatic.

The operating mechanism, other than the lights I0, the warning indicators Il and I2, and the pedestrianand vehicle-controlled contacts, is placed in a suitable housing, and the battery which feeds the mechanism may also be placed in the same oradjacent housing, whereby both the mechanism and the battery are readily accessible for inspection, repair and replacement,

Referring to the diagram of Fig. 1, it will be seen-that in the surface of the cross street in the path of 'traic approaching the intersection from either direction are placed the vehicle controlled

contacts

23 and 23. These contacts may be simply a treadle which is depressed by the weight 1 f f the vehicle to connect the contacts electrically or it may consist of a diaphragm which, when depressed, moves a column of liquid to close' a,

' and return through wire 26 to battery.

' are Open.

remote switch, or to operate lever or gear systems for the same purpose, and the like, it being understood that any' equivalent arrangement will serve the purpose, i. e., that of closing a switch when a vehicle comes to rest at the proper point on the cross-street.

Assuming that a vehicle on the cross-street is approaching the intersection from the north. If no vehicle immediately ahead has just negotiated the intersection from the cross-street, no traffic lights are visible and the main highway traic flows uninterrupted by traffic lights or cross traffic, the object being to dispatch the main' highway traic as quickly as possible. Several hundred feet before the approaching cross-street vehicle reaches the intersection, the operator thereof is warned that he Ais entering a zone of automatic signal control by the warning indicators I I and I2, shown in Figs. 4 and 5, and heeding the warning the operator slows the vehicle down.

Cross-street vehicle trac control Referring to Fig. 1, as the cross-traveling vehicle nearly reaches the intersection the vehicle closes street contact 23, and a' circuit is closed which is traceable from battery 2li,A closed line switch 2I, wire 22, contact 23, wire 24, relay 25 Relay 25 pulls down its armature 26 to close contacts` 21, which closes circuit from battery 26, wire 22, wire 28, contacts 21, armature 26, wire 29, separate wires 30 and 3l, which energize relays 32 and 33, respectively, which are connected by

wires

34 and 35, respectively, through wire 26 to battery 26.

Relayf32 pulls down its armature to connect contacts 31, thel armature being locked in closed povsition by pawl 38. Similarly, relay 33 pulls down its armature 39 to connect contacts 40, and the armature 39 is locked in closed position by pawl 4I.- Both relays 32 and 33 control the same circuits, i. e., the two circuits of the motor A, the former circuit being traced from battery 29, wire 22, wire 42, contacts 31, armature 36 of relay 32, wire 43, motor A, and

wires

44, 34 and 26 to batteryy2, while the latter circuit is traced from battery 20, wire 22, wire 45, contacts 46, armature 39 of relay 33, selector switch segment 46, switch arm I1, switch contact I8, wire I9, the motor A, and

wires

48, 44, 34 and 26 tor battery 26.

As the motor begins to rotate, cam 50, mounted on cam shaft 5I, driven by the motor A, drops its follower 52 olf its high point 53 to the no motion 'surface which comprises the greater proportion thereof. This action causes spring contacts 54 to close, which initiates the signalling operation. At this time high point 59 of cam 60 has not moved its follower 58 and contacts 6I are closed. Also follower 66 lies in the notch of cam 61 and contacts 11 are closed while contacts 68 As seen above, wire 41 was energized by closed relay 32 when the cross street vehicle contacts 23 were closed.' Therefore beginning with wire 41, a circuit may be traced through wire 55contacts 54, follower 52,

wires

56, 51 and 62, follower 58, contact 6I, wire 63, and terminal 64 where the circuit divides. One branch thereof follows wire 14 red cross lights 15,

wires

16, 34 and 26 back to battery 20, while the other branch circuit is completed from terminal 64, wire 65, follower 66, contact 11, wire 19, amber main lights 18,

wires

12, 13, 34 and 26 back to battery 26. It will be seen that the warning amber lights 18 are flashedto main highway trame, and the u red stop lights 15 to cross traic including the Vehicle which initiated the signals by closing street contacts 23 (or 23').

As cam shaft 5| rotatesfurther, follower 58 rides up on the high point 59 of cam 60 and contacts 6| are opened, thus breaking the circuit previously traced to the main amber lights 18 and cross red lights 15 and extinguishing them. Simultaneously, the follower of cam 90 drops in the notch thereof, and closes contacts 86, thus closing a circuit from energized wire 41, wire 55, contacts 54,

wires

56, 51 and 85. contacts 86, to terminal |06 where the circuit divides,.one branch following wire i 01, solenoid |08 and

wires

34 and 26 back to battery 20. Energization'of coil |08 withdraws locking pawl 38 and releases armature 36 of relay 32 to break the circuit across contacts 31 and thru wire 41 to a motor which was energized by the closing of street contacts 23 (or 23') by the cross trafiic. The circuit to motor is maintained, however, through the parallel circuit closed by solenoid 33 from battery 20,

Wires

22, 26, 45, contacts 40, closed by the armature 39 of relay 33, selector switch segment 46, switch arm I1, switch Contact I8, wire |9, motor,

wires

48, 44, 13, 34 and 26 back to battery 20, so the motor keeps on rotating.

It will be remembered that the circuit pre-1 viously traced upon closure of contacts 86 by cam 90 divided at terminal |06 and the remaining branch may be traced through wires 81 and |09 to main red lights ||0,

wires

12, 13, 34 and 26 back to battery 20. cordingly stop main highway traiic. Another division of this circuit may be traced from aforesaid terminal |06, wire 81, follower 8| of cam 80, closed contacts 84, wire I I, cross street green lights ||`2,

wires

16, 34 and 26 back to battery 20. Thus cross traffic receives the go signal by its green lights ||2 and main highway traiic simultaneously receives the stop signal by the red light |I0.

Next, the followers of

cams

60 and 80 drop oi the high point thereof and close contacts 6| and 83, respectively, and open contacts 84, the latter action breaking the circuit to the cross green lights H2, while the main `red light remains lit. This new circuit is traced from energized wire 41, wire 55, contacts 54,

wires

56, 51 and 85, contacts 86, terminal |06, wire 81, contacts 83, terminal |20 where the circuit divides, Wire 83, cross street amber lights 85', and

wires

16, 34 and 26 to battery 20. Thus the cross street green lights ||2 are extinguished and the cross street amber lights 85 are simultaneously lighted.

The other branch of the circuit just traced leads from terminal |20, through wire I2I, coil |22 and wire 26 back to battery. Vlnergization of coil |22 pulls pawl |24 away from ratchet |25 and causes the pawl |24 to knock pawl |69 also away from ratchet |25 to'permit spring |10 to return the step-by-step switch to its initial position so that its arm |1 engages the initial contact I8. This restoring action is ineffective when the step-by-step switch has not been actuated as is the case in the circumstances described, but the switch has a function which will be described later, and this is the manner in which it is restored after performing that function.

Now referring to the closure of contacts 6| by cam 60, this action takes place an instant after the action of cam and elects the illumination of cross red lights 15 and main amber lights 18. This circuit is traceable from wires 41 and 55, contacts 54,

wires

56, 51 and 62, con- The red lights ||0 acof cam rides upon its no-motion surface and opens contacts 86. The opening of contacts 86 breaks the circuit through the main highway red lights ||0 and the cross street amber lights 85, which had been initiated by contacts B3 of cam 80. Opening of contacts 86 also de-energized reset coil |08 of relay 32 so that it is ready for the next setting action. Immediately after the action just described the follower 60 of cam 61 rides up on the no-motion surface of the cam to open contacts 11 and close complementary contacts 68 to extinguish main amber lights 18 and illuminate green main lights 10, while cross red lights 15 remain illuminated. Thus main highway traiic is restored and cross trac is stopped by the red lights 15 after having passed the car which initiated the signal action by closing crossstreet contacts 23 (or 23'). Fig. l illustrates this condition of traffic control.

Meanwhile the motor continues to rotate until follower IDI of reset cam |00 drops into the notch |05 thereof to close contacts |02. The circuit thus established is traceable from battery 20,

wires

22 and 45, contacts 40 0f relay 33, wires 41 and 55, contacts 54, wires 56 and |04, contacts |02, and wires |03 to terminal II3, where the circuit divides, one branch traversing reset coil ||4, and wires ||5 and 26 to battery 20, and the other'branch traversing wire ||1, reset coil II8, and wire ||9 and 20 back to battery 20. The energization of solenoid I I4 pulls pawl 4| from armature 39 to release it so that the connection between contacts 40 is broken thus deenergizing the entire system and the motor stops rotating and all lights are extinguished, main highway traic continuing without interruption as the signal system is controlled by the cross trafiic. The follower 52 rides up on high point 53 of cam 50 to disconnect contacts 54. The energization of solenoid ||8 has no eect under traflic conditions just described and its function will be described later.

Pedestrian trafic control Provision is also made for control of the traic lights by pedestrians who desire to cross the main highway, which, it will be rememberedy if; normally open to trac at all times except vf a vehicle approaching from a cross street energizes the signalling system to stop the main highway traiic and permit the cross street tralc to cross the main highway. At opposite sides of the main highway at the intersection thereof with the cross street are placed the buttons |58, these buttons being preferably in the form of treadles upon which a pedestrian steps in the act of crossing the street, and are placed either on the curb, in the sidewalk adjacent the curb, or immediately below the curb. The buttons or treadles may constitute a movable contact which is depressed by the weight of the pedestrian to bridge contacts I5| to close a circuit, which may be traced from battery 20, wires 22 and |62, contacts |5| and |50, wires |53 and |54, contacts |55,normally bridged by the armature |56 of relay |51, wire |58, selector switch solenoid |59, and Wires |60 and 26 lack to battery 20.

wires

34 and 26 back to battery 20. Energization of relay 32 closes relay contacts 31 to close the circuit to the motor A to start the signal system into operation in the manner previously described. The se- 120 quence of 'signals varies from amber to red on thesmain highway, and from red to amber to green on the cross' street, which is the signal condition stopping the main highway traffic to permit the pedestrian to cross the main highway in safety.

It will be recalled that when the pedestrian stepped on one of the buttons |50 solenoid |56 of the selector or step-by-step switch was energized, this action causing the armature |61 to be '30 pulled upwardly about its pivot |68. At the end of the armature |61 there is a spring pressed pawl |69 engaging the toothed pawl |25 carrying the switch arm 1. Upward movement of the pawl causes ratchet |25 to rotate one notch against the tension of spring |10, so that contact arm I1 moves from the first switch p oint I8 to the second switch point |26. As these two switch points are connected in parallel to the motor lead I9, this action has no effect on the motor A, and it keeps 40 running at the same speed.

However, should a second pedestrian step on one of the vbuttons |50 after the first pedestrian initiated the signal action, the same operation takes place, and the second energization of coil |59 again pulls armature |61 to cause pawl |69 to move ratchet |25 a second notch in a clockwise direction. This swings switch arm |1 from switch point |26 to switch point |1|, thereby cutting in a low resistance unit |1| into the circuit 4.50- of the motor A, thus causing the motor to slow l down slightly to increase the cycle time, say five seconds, so -as to permit the second pedestrian to cross the main highway without danger of the signals initiated by the first pedestrian turn- 55, ing on him when he is partly across the main highway.

Should a third pedestrian step on one of the -buttons following the second pedestrian, coil t v|59 is again energized to advance the arm |1 of 60 the step-by-step switch from point |1| to point |13, thereby cutting in a second resistance unit |14 Ainto the motor A circuit to slow down the rotation of the motor still more, say another five seconds.

y Lastly, if a fourth pedestrian follows a third 7.5' had an opportunity of crossing the main highway in safety. Of course, many more pedestrians than foui-` may cross, but four in succession is suflicient to start the selective trafllc control by pedestrians, and successively increase the signalling time from say ten seconds to twenty-ve sec- ,5. onds or more or less. Thus, the pedestrian traffic may not retard the main highway traffic for more than the predetermined time, so that the system is fool-proof, there being only sufiicient interruption of the main highway traiiic to per- 10 mit the safe passage of pedestrians for a period of say 10 to 25 secondsthis time, of course, being variable by proportioning the resistance units |12, |1I and |16 in a predetermined ratio to procure the desired slowing up of the signal opera- 1 tion. This may be done by making the resistance units adjustable in accordance with common practice. t

It will be recalled Ithat when cam 80 closed contacts the completion of the cycle of signals 2 initiated by the cross trac, coil |22 was energized to pull pawl |24 away from the ratchet |25, this connection also knocking pawl |69 away from theratchet |25,A which is thus released so Athatl spring |10. is free to rotate the switch,-25 until switch arm I1 again engages starting with point I8, and all of the resistance units are cut out of the motor 'circuit in readiness for the next starting operation. It will also be recalled that at the time that con |22 'for' resetting thefto step-,by-step switch vwas energized, relay |51- was also energized, this action causing the armature |56 of the latter to break the circuit between the contacts |55, which also breaks the circuit through the selector or step-by-sten switch solenoidy |59, so that any further closing of the pedestrians buttons |50 would have no effect on the system. When this took place, locking pawl |11 engaged armature |56 to hold it-down after relay |51 was deenergized, so tha-tf' 4 the breakin the circuit occasioned .by energization thereof was maintained. When the entire signalling cycle wascompleted', cam |00 closed contacts |02 to, energize coil H6, which disengage pawl |11 from armature |56 of relay |51` 45 to reset the same in readiness for the next operation. Y

Inprecisely the same way that successive pedestrians may increase the signal time, successive cross-traveling vehicles may increase thef length of the signal cycle by arranging the

steel contacts

23 and 23 as the pedestrians buttons |50 are arrangedI to operate the selector switch, or another one like it connected in parallel therewith, to cut resistances |12, |1l and |16 suc-- sively into the circuit ofl motor A, so that the signalcycle time is increased, say, ve successive vehicles which engage either contact 23 or 23. The idea and circuit arrangement is identical, so it is deemed suflicient to describe one of them for a complete understanding of the other. This also applies to any other signal by cycle such as that initiated'by a left-turning' vehicle in the manner to be described later in .o5 connection with Figs. 2 and 2a. y,

It will .be seen that the automatic signalling system illustrated in Fig. 1 controlled indi-- vidualiy by the cross street traiic, or by the pedestrian trame, and that fit is only in operation when a vehicle approaching f-rom the cross street or a pedestrian seeking to cross the main highway initiates the operation thereof, and that it is otherwise out of operation because it is desirable to maintain main highway tramo continuous when there is no cross traflic to interrupt it. It is well known that when intersections such as the one described are not equipped with some kind of a signal system, or when the ordinary signal system of alternately cyclic operation of the main highway and cross street lights is employed, the main highway traflic is frequently needlessly stopped at periodic intervals when their is no cross traiiic requiring such action.

Accordingly, the present invention provides for energization of the signal system only when there is cross traffic requiring -the stoppage of the main highway tramo and at other times the main highway traiiic ows continuously without interruption, and the signal lights are not illuminated at all. Thus, the apparatus of the present invention is only used when necessary, and facilitates tramo ow and eliminates the use of the expensive continuously operating traic systems or the servicesof an attendant or traic omcer.

Now, referring to Figs. 2 and 2a, which are complementary drawings constituting one complete schematic circuit, this arrangement goes a step further than the traillc control system described in connection with Fig. 1 in that provision is not only made for controlling the signals by means of a cross street vehicle and pedestrians. but means are also provided to permit a vehicle seeking to make a left turn into the cross street from the main highway to appropriate to itself the signals if already initiated by a pedestrian or cross-traveling vehicle and, if this is not the case, to initiate such signals as will stop all tramo interfering with the left turn so as to permit it to make the turn by energizing the appropriate signal lights.

In genera-l, the mechanism controlled by the pedestrians and the cross street traino is the same as that described in connection with Fig.

' which form elements of the additional mechanisin mentioned above. For convenience, however, the circuits common to both Figs. 1 and 2-2a will be brieiiy traced, a cipher being added to the common reference characters of Fig. 1 in order to avoid confusion and yet enable the common elements of the two circuits to be compared most readily.

Assuming as before that a vehicle is approaching the intersection from the north on the cross street and that, a'tter having observed: the warning indicators and |2 several hundred feet ahead of the intersection, he proceeds cautiously until he engages street contact 230 (or 230'). From battery 200 the circuit may be traced to the cross trame vehicle contacts .230 (and 230') through closed switch 2|0, terminal 2||, where the circuit divides, wire 220, terminal 2| 2 where this branch of the circuit divides again, one branch following wire 2|3, terminal 2M, wire 2li, terminal 2|6, wire 2|1, terminal 2|8, wire 2|9, wires |520, street contacts 230 and 230', wir |530, terminal |53i, wire 240, solenoid 250, wire 260, terminal 26|, and wire 262 back to battery 200.

Energization of solenoid 250 causes armature 250' to bridge contacts 210, thus completing another branch circuit from terminal 2|6, wire 280, relay contacts 210, relay armature 250', wire 290, terminal 29| where the circuit divides, one branch including relay 330, which is accordingly energized, and

wires

350, 260, and 26| back to battery 200. The other branch of the last named circuit is traceable from terminal 29| through wir@ 300,

relay 320, and wires 32| and 262 back to battery 200. Energization of relay 320 pulls down armature 360 to bridge contacts 310, thus completing the branch circuit from terminal 2|2, relay contacts 310, armature 360, wire 31|, terminal 312, 5 where the circuit divides, one branch going to selective switch segment 460, wire 410, relay contacts 41|, normally closed by the armature 412 of relay 413, wire 414 to motor A, and return t0 wires 440, terminal 44|, and wire '442, to battery 10 200. When relay 320 was energized, its armature 360 locked in closed position by the pawl 38|, which is releasable by coil |080 in the manner to be described later. Similarly, the armature 29| of relay 330 is dropped in closed position by pawl 4|0, which is releasable by coil H40 in a manner to be described later.

As the motor A begins to rotate, cam 500 drops its follower 520 off its high point 530 to the nomotion surface that comprises the greater portion thereof. This action causes spring contacts 540 to close, which initiates the signalling operation. At this time, contacts 6|0 of cam 600 are also closed, and contacts '|10 of cam 610 are closed, while contacts 680 are open. Contacts 540 are connected by wire 550 to energized wire 414, mentioned above. This completes a circuit from contacts 540 through wire 560, wire 510, wire S20, contacts 6|0 of cam 600, terminal 6|| where the circuit divides, one branch following wire 630, wire 650, contacts 110, wire 190, both amber main highway lights 180, and wires 1| 0, 120, and 442 back to ybattery 200. Thus the warning signal is ashed on the main highway trailic which, in the absence of any cross tra-mc, is normally as iiowing without interruption from any signal lights.

It will be recalled that the circuit just traced divided at terminal 6H, and the other branch follows wire 6| 2, back contacts 6|3, which are normally closed by armature |4 of relay SI5, wire BIG, relay 6|1, which is accordingly energized, and wires SIS and 262 back to battery 200. Energization of relay SI1 causes its armature 6|! to bridge its contacts 62|. The closure of relay SI1 completes a circuit traceable from battery 200, terminal 2H, wire 622, wire 623, armature 6|9, and contacts 62| of relay 6|1, where the circuit divides, one branch following wire $23 to south cross street red light 624, and

wires

120 and 50 442 back to battery 200, the other branch of the vcircuit following wire 625 to north cross street red light 626 and

wires

120 and 442 back: to battery .200. Thus, in this condition, the signalling system for cross street traffic is stopped by red 56

lights

624 and 626, and the amber lights 180 are flashed on the main highway trailic.

The next action is causedby follower 580 riding up on the' high point 590 of cam 600 to break the connection between contacts BID. This 60 breaks the circuit to the main highway amber lights 180, which has just been traced, and also deenergizes relay SI1 so that its armature 6|! is released and is drawn upwardly by coil spring 621 to break the connection between relay contact 82| and the circuit to cross street red lights $24 and 626. Accordingly, the main highway amber lights 180 and the cross street

red lights

624 and 626 are extinguished.

Simultaneously with this action, the follower of cam 900 drops into the notch thereof and closes contacts 860, thus closing a circuit from energized wire 414, wire 550, contacts 540 of cam 500, wires 510 and 850, contact 860 of cam 92B, to terminal 86|, where the circuit divides, one 75 light 102 and wires 1I0, 120 and 422 back to battery 200. The other branch circuit may be traced from the other contact 694 of relay 69| via wire 103 to terminal 104 to terminal 134, where the circuit against divides, one branch to open contact 105 of relay 106 and the other via wire 101, the west main green light 108, and wires 1I0, 120 and 442 back to battery 200. Thus the main highway tralc is restored by the simultaneous energization of main

green lights

102 and 108.

As the motor A continues to rotate the fol-' lower of reset cam |000 drops into the notch thereof and closes contacts |020, thus establishing a circuit which may be traced from wire 414, wire 550, contact 540 of cam 500, wires 560, 510 and |040, contact |020 of cam |000, wire IO0I, terminal I 002 where the circuit divides, one through reset coil I |40, which disengages pawl 4I0 from armature 390 of relay 330 so that contacts 400 are again opened, the circuit being completed through wires |003, 260 and 262 to battery 200. The other branch of this circuit may be traced from terminal |002, reset coil |004, and wires |008, 260 and 262 to battery 200. Energization of reset coil |004 disengages pawl from armature |560 which again bridges contact |550 in readiness for the next operation. The signal system is now deenergized, and follower 520 rides upon the high point 530 of cam 500 to separate contacts 540, thus breaking the signal cycle initiating circuit and all signals are extinguished and main highway traiiic continues to flow uninterruptedly.

Left-turn signal control It will be observed that the operation of the circuit illustrated with reference to Figs. 2 and 2a is so far similar to the apparatus illustrated by Fig. 1, the diiference being principally the individual operation of the main and 'cross red and green lights by the interruption of the double contact relays 699, 81|, SI1, 69|, 886, |93 and 413, in the first named arrangement, and whose function procures no diierent results in ordinary traffic than the last named arrangement. These relays are, however, operative to procure a different combination of signals when a vehicle on the main highway desires to make a left turn into the cross street. ,For this purpose vehicle-controlled contacts 2000 and 2000' are placed in the main highway adjacent the center thereof as shown in Fig. 3, the main highway still being considered for convenience as running east and west and the cross street as running north and south, the latter having the vehicle controlled

signal initiating contact

230 and 230 and the former having the'pedestrian-controlled buttons |500, whose operation and the control of the signal cycle time being precisely the same as described in connection with Fig. 1, and further description is accordingly not necessary.

In operation of the left turn signal control, a vehicle about to enter the signal zone from the west on the main highway, for example, and desiring to execute a left-turn to the north into the cross street, draws to the center of the mainhighway stops and closes contacts 2000. It will be observed that vehicles seeking a right turn pass to the right of the main highway and avoid contacts 2000. The circuit controlling action of the latter is so arranged with a time lag, for example, as to be unresponsive to the momentary weight of passing cars and is responsive only to the weight of a car standing thereon.

Now referring to the circuit diagram of Figs. 2 and 2a, closure of left turn contact 2000 initiates a circuit traceable from battery 200, wires 220, 2I3,2I5,2I1 and 2I9, left turn contact 2000, wire 200|, relay 2002, and

wires

2003, 260 and 262 back to battery 200. Energization of relay 2002 pulls down its armature 2004 to bridge contacts 2005, the armature being locked in this position by pawl 2006. This completes a circuit traced from battery 200, wires 220, 2|3, 2I5, 2I1, 2I9, and 2001, relay contacts 2005, wire 2008, relay 2009, and wires 20I0, 260 and 262 back to battery 200. Relay 2009 pulls down one end of armature 20II, whih is pivoted at 20|2. This action causes contactors 20I3 and 20I4 to bridge contacts 20I5 and 20I6, respectively, and the depressed end of armature 20II is locked down by pawl 20|1.

Considering the effect of this bridging of contact 20I5 by contacts 20|3 rst, the circuit is traceable from battery 200, wires 220, 2|3, 2I5 and 2|1, terminal 2I8, wire 20|8 to contacter where the circuit divides, one branch being traceable through wire 20I9, relay '|06 and wires 6I8 and 262 back to battery 200, while the other branch is traceable from the other contact 20I5 of relay 2009, wire 2020, relay SI5 and wires 202|, 6I8 and 262 back to battery 200. Energization of relay 106 causes its armature 2022 to bridge contacts 105, thereby closing a circuit traceable from battery 200, wire 622, relay armature 2022 where the circuit'divides, one branch following wire 88|, east main red light 882, Wires 1I0, 120 and 442 back to battery, and the other branch is traceable from the other contact 105 of relay 106, wire 101, main west green light 108 and wires 1I0, 120 and 442 back to battery 200.

The aforementioned energization of relay SI5 caused armature 6I4 to break the normal connection between contact GIS and connect contact 2023. Thiscompletes the circuit traceable from battery 200, wire 622, contacts 2023 of relay SI5, relay 6I1 and wires 6I8 and 262 back to battery 200. Energization of relay SI1 causes its armature 6 I9 to bridge contacts 62|, thus completing a circuit traceable from battery 200,

wires

622 and 623, spring 621 and armature 6|9 of relay SI1 where the circuit divides, one branch following wire 623, south cross red light 624 and wires and 442 back to battery 200, while the other branch follows wire S25 from the other contact 62|, a relay 6I1, north cross red light 626 and

wires

120 and 442 back to battery 200. Thus the left turning vehicle entering the intersection along the main highway from the west engaged left turn contacts 2000 and initiated the signal cycle just traced whereby it obtained its right of way into the north cross street, ashing the west main highway green light for the turn, the east main highwayred light against west moving traflic so that the turn might be completed and also stopped cross street traffic so that no cross moving vehicles would interfere with its progress during the left turn.

It is lseen that this left turning vehicle immediately assumed control of the traillc mechanism the moment it closed left turn road contacts 2000 and it was enabled to take precedence over other traic, and this is desirable because left turning vehicles by stopping in the .middle of the highways from which they seek to turn interrupt trailic which would otherwisebe dispatched without interruption and with greater rapidity so it is of advantage to get the left turning traffic out of the way as soon as possible. This approrelay 2009.

' and as soon as the follower 2042 drops into the notch 2043 thereof, contacts-203| are closed y and the left-turning signal control mechanism is reset. 'I'his resetting action may be followed by tracingtheother branch circuit for contact 20|6 of relay 2000 from battery 200, wires 220, 2|3, 2|5, `and 2|1. terminal 2|`0, wire 20|0, connector 20|4, wire.2025, relay 2026 and wires 32| and 262 and back to battery 200. Energization of relay 202'0 causes its armature 2021 to bridgeA contacts 2020, thus initiating a circuit traceable from 4battery 200, wiresA 220, 2|3, 2023, which is not completed until normally open contacts 203| are closedA at Ythe end of the cycle by cam 2032 which is driven by motor B set in operation in the manner described. l

When follower 2042 of cam 2032 drops into the notch 2043 thereof, contacts 203| are closed and the -circuit is completed viawire 2033, contacts 2028 of relay 2026, wire 2034, terminal 2035 where the circuit-divides, one branch energizing reset coil 2063 and.v being completed through

wires

2003, 260 and 262 back to battery 200, while the other branch from terminal 2035 fol- -lows wire 2030 to reset coil 2031, wires 2038,

260 and 262 back to battery. Energization oi' re` set coil 2003 pulls pawl 2006 away from amature 2004 of relay 2002 and the connection between contacts 2005 is broken, thus restoring the relay 2002 which was energized by the closure of the left turn main highway contacts 2000. 'Iihe breaking of the connection between contacts 2000 of relay 2002 de-energi'zes relay 2003 and the energizatlon of reset coil 2031 oi this last named relay pulls pawl 20H away from armature 201| which is now released to break the connection between connector 20H and contacts 20|5 and between connector 2014 and contacts 20H6 of said The coil springs 2033 restore armature 20|| to its normal position shown in Fig. 2. Also during the time that the left turn signals are energized, which isdetermined by cam-2032 since this cam resets the left turn signal mechanism, the initial connection of contacts 20|6 of relay 2000 by connector 2014 energized relays 413-and |33, causing their respective armatures 412 and |32 to break connection between respective con-I It will be recalled that amature |02 normally completes one of the circuits to master motor A and that this circuit is therefore broken while the left. turn signal mechanism is in operation, and that amature 412 of relay 413 normally completes the other remaining circuit to theY master motor A vso that this circuit is also broken. Accordingly, while the left turn signal mechanism is in operation, the master signal motor A is stationary and all normal signals remain in the particular energized condition which'they were in. when the left-turning vehicle closed main highway contacts ma. 'rnus the len aiming vehicle appropriat toitself the signals which are necessary to permit it to negotiate the desired left turn and in so doing it also stops traillc moving against the alternative circuits to the master motor A which controls the normal signal cams. 0f

. course, ifl the normal signals are not in operation at the time that the left-turning vehicle engages street contacts 2000, the breaking of the circuit to motor A has no effect since the motor is not then in operation.

Precisely the same signal place when the vehicle approaching` from the east along the main highway moves to the center of the main highway and closes contacts 2000' in the first movement toward making a left turn to the south'into the cross street. .A different set of initiating elements are provided but these elements are connected in parallel with those controlled by left turn contacts 2000 and so: the cycle is exactly the same. For example, closing of contacts 2000' initiates a circuit traceable from battery 200, wires 220,213, 2|5 and 2|1, terminal 2|8, wire 2|9, ieft turn contacts 2000", wire 2045, relay 2046 and

wires

2003, 260 and 262 appropriation takes back to battery 200. Relay 2MB-corresponds to relay 2002 whose operation was described in derelay 2046 effects completion of a circuit traced from battery 200, wires 220, 2|3, 2|5, 211, 2|9 and 2001, contacts of relay 2046, relay 2041 and wire 260 back to battery 200. Relay 2041 swings armaturev 20H around its pivot 20|2 to bridge the sets of contacts 2040 and 2049-. Bridging of contacts 2049 completes a circuit traceable from battery 200, to terminal 2|8, wire 20|0 to contacts 2049, where the circuit divides, one branch being traceable through wire 2l I0, relay 603 backto battery 200, and the other branch following wire 2220 to relay 6|5 and back to battery 200. Energization of relay 603 bridges contacts 690, thereby closing a circuit from battery 200 to relay contacts 690, where the circuit divides, one branch following wire 10|, east main green light 102 and wire 120 back to battery 200, and the other branch follows wire 016. west main red light 611 and wire back to battery 200.

The aforementioned energ'lzation of relay 6|5 causes armature 6|4 vto break the connection between contacts 6|3 and bridge contacts 2023. As

before, this causes energization of relay 6|1,`

which bridges contacts 62|. The circuit completed by relay 6|1 divides, and one branch follows wire 623 to south crossl red light 624 and back to'battery. while the other branch follows wire 625 to north cross red light 626 and back to battery.

Y is lighted to start the vehiclev on its left turn, west main red light 011 is lighted tostop westtravelling traflic, so that thelcft-turning vehicle may ,Y

moveV south into the cross street, and both cross street red lights 624 and 026 are energized to stop cross tramo and permit the left-turning vehicle to complete its turn. The signal. cycle is restored as before. 1

Itis to be understood that each cross-travelling vehicle, pedestrian, or left-turning vehicle which initiates or otherwise controls a signal cycle is considered as a single traiiic unit. Thus, a pedestrian seeking to cross the main highway, is like a cross-travelling vehicle, a unit of trafiic, and if more than one vehicle or pedestrian Should engage a corresponding street or side-walk treadle or contact at the same time, or treadles or contacts which are connected in parallel, the aggregate oi this signal initiating or controlling are considered as a single traic unit. All following vehicles or pedestrians which reenergize the system after one cycle or reenergize the sei lector switch to increase the time of the signal cycle, whether one or more vehicles or pedestrians at the same time or withina predetermined time limit so that their joint actions procure a single eiect, are all considered successive units of traic.

It is desirable to facilitate right turns to or from the main highway inasmuch as no crossing of trafc is necessary when a- 'right turn is executed, and so the initiation or operation of the signal equipment is not necessary. As mentioned above in connection with the left turn, vehicles seeking to execute a right turn draw toward the curb and so avoid the left turn 2G00 or E contact in the main highway, which is spaced from the curb, so that it is not actuated to initiate or appropriate the signals. Where the width of the cross street is suiiiclent topermit it, the cross street contacts '23E and E38' are also preferably spaced from the curb to allow the right-turning traiic to avoid it. In this arrange- A ment the cross street contacts 236 and 230 resemble the left turn contacts 2060 and 2099' in position in the street. Of course, the cross street may be equipped with left turn control and if this is done, the right-turning traiilc will automatically avoid the contact, which is spaced from the Curb.

In the arrangement illustrated in Figs. 3 and e, a left-turning vehicle coming from the north actuates contact 23B, so that both main red lights, and both cross green lights are lighted in the manner described, thus permitting another left-turning vehicle coming from the south to execute a left turn at the same time. f course, either the main highway or the cross street or both may be equipped with both the straightway contacts Zil@ or 26ml' and the left turn contacts 225 and 23S', but as this complicates the situation considerably, it would probably not nd much use except under exceptional circumstances.

The term left turn as employed herein, refers primarily to the manner of turning from one tralc lane across another traic lane on the same street, as where an operator of a vehicle in traffic moving at the right-hand side of the street makes a left turn across the left-hand side of the street.' However, in locaiities where it is the custom for vehicles to travel along the left-hand side ofthe street, as is the case in many foreign countries, the same kind of turn would be a right turn, and it is to be understood that for the purposes of this invention. the term left turn used herein is synonymous with the term right turn in cases where traffic customarily travels on the left-hand side of the street.

The new invention provides many apparent advantages over the continuous cycle type of` traic control systems, in which a commutator or the like uniformly controlled the signals in opposite directions, or a special attendant or trac omcer was employed to throw aswitch from time to time'to regulate the trafhc in accordance with its density. In considering these advantages, it should be emphasized that the system of this invention is normally dormant or inactive so that the main trafc in one direction or right turns at theA intersection are not interfered with but allowed to flow freely with despatch. It is only when a vehicle, pedestrian, or other traffic unit seeks to make a left turn from or to enter the traiiic stream from outside such as from a .side or cross street, other than by a right turn,

that the signal equipment is energized and the operation of the signal cycle initiated.

It is to be understood however that the term intersection does not necessarily mean the intersection, crossing or mergence of straight streets, roads or thoroughfares, but broadly means the joining of two or more traiiic lanes whether or not any of these lanes is straight. For example, a traic carrying lane may curve such as around a corner, while the intersecting lane may enter at the corner in the shape of a T. In this case either the angle lane or the intersecting lane maye be the main highway. Also, main highway does not necessarily mean a boulevard, main street, or the like, but a tralc lane which carries either more or heavier traiiic or traic whose dispatch is considered more important or desirable for any reason, while cross street or side street means any traiiic lane entering the traffic lane dened as the main highway, whether or not the trame traversing either is vehicular, pedestrian, railway, or the like. However, for convenience and clarity, a trafiic lane which passes entirely through an intersection, whether on the straight-away, curve or angle, and which is formed by two aligned streets across the intersection, is called a main highway or simply highway while a traffic lane which approaches and terminates on the intersection is called a street or cross-street. By the present invention a. complete system may be installed conveniently at any intersection such as in outlying districts or along arterial highways where the highway trailc density greatly exceeds that entering the highway from the cross or side streets or crossing the same from the cross streets. Such intersections greatly outnumber those in which traffic is substantially uniform in cross directions; i. e., along the main highway and crossing or entering the main highway from cross or side streets. Accordingly, the control of the system by the relatively few vehicles entering or crossing the main highway from the cross or side streets, or by pedestrians seeking to cross the main highway,.or by vehicles seeking to make a left turn from the main highway into the side street, is greatly to be desired, and the system of this invention is adapted to provide these requirements. l

Also by providing preindicating signals or arbitrary warning indicators along the roadside several hundred feet ahead of the intersection for defining the signal zone, vehicles are warned that they are approaching a zone of automatic signal control and should proceed withdue care, these arbitrary indicators being so designed as to mean just this t0 the operator of a vehicle.

Furthermore, the system of this invention is entirely self-containedand is provided with its own local source of power for its operation so that it may be installed anywhere Without regard to outside power facilities. inasmuch as the system only operates when cross traflic or ,left-turning traic initiates .such operation, the mechanism is only in use a part of the whole day and is dormant for long intervals, especially at night, whereby depreciation because of excessive use and the expense caused by unnecessary power consumption is eliminated.

While a preferred embodiment of the invention has been illustrated and described herein, it is to be understood that the invention is not limited thereby but is susceptibleV of many changes in form and detail Within its scope, and any one, any two', or all of the several separately operated and coordinated signal controlling arrangements may beused at will so that the system of this invention may be adapted to suit all requirements of automatic traic control.

I claim:

l. A tratlic control system for two substantially parallel and opposite trailic lanes, comprising a stop signal for each lane, means so disposed as to be actuated only by a unit of traffic in one lane taking a position to make a turn across the other lane and not by through traiiic in said one lane, and means to be actuated by saidtraic actuatable means when said tramc actuatable -means is actuated to provide a stop signal for said other lane.

2. A traiiic control system for the intersection of a cross-street with a highway, comprising an electrical tramo signal, a source oi power therefor, switch'means in the circuit of said signal and said source for controlling the energization of said signal, timing mechanism for operating said switch means. an electric motor whose speed is responsive to the resistance of its circuit for driving said mechanism, an energizing circuit for said motor, devices at said cross-street adjacent the intersection operable by a traffic unit seeking to enter the highway and operativelyl connected to saidmotor for controlling the same, an electrical resistance in the circuit of said motor, and means actuated by a second operation of said devices for varying said resistance, whereby the motor speed is varied to vary the length of time of the signal cycle initiated by the first traffic unit.

3.l A traiiic control system for intersecting tramo highways, one of said highways comprising a plurality of traiiic lanes for traiilc moving in one direction, a Go signal for one lane of said plurality o'f lanes, a Stop signal for the other of said intersecting highways, and tramo actuable means in said Go signal controllable lane actuable by a unit of trailic in said'one lane taking a position to make a turn across an interfering traiiic lane in other of `said intersecting highways to actuate lsaid stop signal.

4. A traic control system for intersecting tramchlghways, one of the highways having a plurality of traic, lanes for traic moving in one direction and at least one trafilc lane for traiiic moving in substantially a parallel and opposite direction, comprising a stop signal for each of the lanes andv a go signal for one of the plurality of lanes moving in one direction, means so disposed as to be actuated only by a unit of traiiic in a preselected lane of the plurality of lanes moving in one direction taking a position to make a turn across the lane moving in the opposite direction and not by through traffic in the preselected lane, and means to be actuated by the trafc actuable means wherein said means is actuated to provide a stop" signal for the other lanes of tramo.

PAUL l?. HORNI.