US2213409A

US2213409A - Traffic control system

Info

Publication number: US2213409A
Application number: US78379A
Authority: US
Inventors: Quilliam Leslie
Original assignee: Nachod & United States Signal
Current assignee: Nachod & United States Signal; Nachod & United States Signal Co Inc
Priority date: 1936-05-07
Filing date: 1936-05-07
Publication date: 1940-09-03
Anticipated expiration: 1957-09-03

Description

Sept. 3, 194% I... QUILLIAM 2,213,409

TRAFFIC CONTROL SYSTEM Filed May '7, 1936 2 Sheets-Sheet 1 ti- BSTQEET :1 up Fi 1 t -I& TO COn rroL g, 28 h q VEHICLE 5% DETECTOR Fig., '21

Cyde i I :IEQEEN ASTQEET i1 IEIYELLOWI] RED :GQEEN 1:] 8 SWEET Q HIIYELLOW 1: MENTOR {III RED l :2 LESLIE QUILLIAM 1 HQ, k fl y $2 2 g" ATTORNEY Sept. 3, 1940. QUILLIAM TRAFFIC CONTROL SYSTEM Fild Ma}; '7, 1936 2 Sheets-Sheet 2 LESUEQUILLIAM. 3Y0; f ATTORNEY trafflcalong the Patentecl sept. 3, 1940 Leslie Quilllam, Stretched, England, ssc'lgnor Nmhotl do United dilated Si sated, houisvilie, lliy. a col Application "6, N36, Scale-l No.

53 illaimo My invention relates to trafilc control systems and has particular relation to those used at ma jor highway intersections.

Under ordinary circumstances, tsaiidc=control systems are arranged to provide a fixed signs timing that will best accommodate the traiilc conditions encountered at the highway intersec tions where they are intended to he utilized. it has been. observed, however, that at certain pe= riods'oi the day the trafdc along one lane of an intersecti'on is comparatively h avy while the traffic along an intersecting lane is comparatively light. at other periods of the d y the trafdc along the ly heavy, while the lane is comparatively During the remaining periods, the traffic light.

It is accordingly an object oi my invention to application to a highway intersection at v hich the trafdc along one lane is heavy as com= pared with the traflic along an intersecting lane at certain periods while the converse is true at certain other periods. I

a further object of my invention is to provide a trafilc=control system that has particulas' ap= plicatlon to an mtersection wherein the ratio of the density of the traffic in one direction to the density of the trafdc in an intersecting direction varies considerably from time to time.

Another object of my invention is to provide apparatus or" the type that is responsive to the condition of traffic along a plurality of intersect= ing lanes; the apparatus being adapted to regulate the operation or a traffic signaling device that normally operates to cause the go signal to remain on thethcroughfare on which the ve= hicles were last operating.

Another object of my invention is to provide a vehicle actuated trafilo-oontrol apparatus adapted to be utilized at the intersection of a plurality of lanes; the apparatus being of such structure that a traffic signalling device will be controlled by a vehicle moving along one lane to indicate a go" signal for that particular lane with a "stop signal for all intersecting lanes, which signals will continue to be displayed until a vehicle approaches on one of the intersecting lanes.

Another object of my invention is to provide a motor-driven, cam-controlled contact mechanism for controlling the trafic signal indications, which mechanism may be adjusted to provide any desired sequence of signal indications with- Co. Inco po== ration further object oi my invention is mom. a motor-driven, cam contiolled contact -echariism for controlling the signal lights, which mechanism will determine the minimum or initial time of display oi the go signal it has been called to a lane.

A still further object o1 my invention is to pro= vide a. non=resetta7ole timing mechanism adapted to be operated vehicles moving along a lane to me out the go signal from being transieised to an intersecting lane until the go si al continued to display for a predetermineo time, and until the said timing mechanism has restored to normal from a previous vehicle operation.

More concisely stated, it is the object of my invention to provide a vehicle-operated, trafficcontrol apparatus in which the vehicles moving g along a lane, having a "go signal shall cause the "go signal to be extended a definite time for each vehicle o eration, such that the time of the "go signal for a following vehicle will not be= come effective until the timing for the preceding vehicle has elapsed...

A further object of my invention is to provide an extension control for the display of the go signal which, under continuous vehicle operation, shall regard the vehicles as moving in groups, and provide out a single extension for each of said groups. v

Another object of my invention is to provide an extension control for the display of the go signal that will not be responsive to bring about a further extension of the g0 signal by a following vehicle, unless such vehicle approaches a predetermined time after the' extension control commenced its operation for a previous vehicle.

A. still further object of my invention is to pro vide a maximum timing-mechanism that will begin its operation at the initial establishment of the "go signal to a lane for permitting transfor of the go signal to an intersecting lane, when a vehicle approaches on the intersecting lane at anytime after the maximum timing mechanism has completed its operation.

A still further object of my invention is to provide apparatus to be operated by a vehicle approaching on a "stop signal, and which will 59 remain operated until the go signal is trans=- ferred to that vehicle.

One of the fundamental objects of my inven tion is to provide a system in which the operation of the motor controlling the cam-operated,

contact-mechanism governing the display of the signal lights is stopped or'arrested in order to maintain the go signal displayed.

Another object of my invention is to provide a vehicle-operated, traflic-control apparatus having a plurality of stages or conditions of operation; the particular conditions of operation to be utilized at various times dependent upon the condition of the traffic along the lanes forming the intersection.

According to my invention, I provide a trafficcontrol system comprising a plurality of street devices located along the lanes of a particular intersection, and adapted to be controlled by vehicles moving along the lanes, which devices will hereinafter be referred to as "vehicle-detectors. The vehicle detectors are associated with a system of relays, motor-driven, cam-operated con tact mechanisms and a signaling device.

Under normal circumstances the signaling device displays a "go signal long the lane on which vehicles were last operating with a stop signal displayed to all other lanes. A vehicle approaching on a lane having a stop signal causes actuation of a vehicle detector which in turn responds by co-acting with a system of relays to cause the go signal to be displayed to the lane onwhich the vehicle approaches and a "stop signal to all other lanes. A vehicle approaching the intersection on the lane having the go" signal causes actuation of a vehicle detector which in turn responds by co-acting with the system of relays to cause the "go signal to be extended for a definite time interval. A vehicle following a predetermined time thereafter and causing actuation of the vehicle detector will register its presence, and thereby effect a further extension of the go signal for a predetermined time after the extension interval of the previous vehicle has elapsed. The "go signal thus controlled by the vehicles persists until a vehicle moving along an intersecting highway causes actuation of its vehicle detector whereupon the "go signal will be immediately transferred to the approaching vehicle when vehicles cease to move on the highway having the right-of-way or, in the case of continued vehicle operation, of the go signal on the street having the right-of-way, when the maximum time control mechanism operates.

If two vehicles should appear at the intersection, each along separate lanes, the "go signal will be given to the vehicle first arriving at the intersection whereupon it will be transferred to the waiting vehicle at the earliest opportunity.

In further describing my invention reference is made to the accompanying drawings, in which- Figure l is a plan view of an intersection showing the relative location of the signal and the vehicle detectors in the various lanes comprising the intersection.

Fig. 2 is a sectional view in perspective of one of the vehicle detectors.

Fig. 3 is a schematic wiring diagram showing the system of electrical connections employed to bring about the various objects of my invention.

Fig. 4 is a graphical representation showing the particular color sequence employed in this disclosure of my invention.

Referring to Figure 1, it will be noted that my invention comprises a vehicle-detector positioned in each lane and arranged to be actuated by vehicles approaching the intersection. At the intersection, a conventional suspension-type colorlight signal is diagrammatically represented with the various connecting wires to the control mechanism indicated. For simplicity, my invention has been shown as applied to a usual four-lane intersection, however, it will be obvious to those skilled in the art that my invention may be utilized at an intersection involving a greater, or lesser number of lanes than indicated. To assist in the understanding of my invention, the intersecting lanes have been designated as "A Street and B Street. In A Street, a vehicle detector I8 is indicated to the left, while a second vehicle detector connected in multiple therewith is indicated at the right. In B Street, a vehicle detector 28 is indicated at the lower end, while a second detector connected in multiple therewith is indicated at the upper end. It will also be obvious to those skilled in the art, that any number of vehicle detectors may be connected in multiple to accommodate other conditions according to the particular requirements of the intersection to be signaled. Hereinafter, in the description, only the vehicle detectors l8 and 28 will be specifically dealt with.

For the construction of one form of vehicledetector used with my invention reference is made to Fig. 2. This particular form of detector illustratesthe type which comprises a yieldable tube enclosing electric contacts and arranged between rigid side bars having profiled or inclined faces to protect the tube. This form of vehicledetector is narrow, and has a contact mechanism, which mechanism rests on resilient material so that when the tube is depressed, the side bars substantially take the load of the vehicle. The mechanism of the vehicle-detector comprises an upper, flexible contact-strip 56, which strip is located in a channel-section resilientstrip 55 of insulating material. The resilient strip 55 rests on a lower flexible contact strip 58 and has its base formed with a series of holes for the passage of contact points 51 carried by the contact strip 58. The lower contact strip 58 rests on a cushion comprising a perforated thick rubber strip 59. A resilient cord 3 is seated in the channel of member 55 above the upper contact strip 56. All these parts are enclosed in a rubber tube 53, which tube is sealed at both ends to exclude moisture and dirt. At one end of the tube, the

contact strips

56 and 51 are brought into a junction box so that electrical connections may be made to the detector. The contact mechanism encased in the rubber tube 53 rests in a suitable recess fashioned in a rigid supporting base 50 and is covered by a rubber, tire-like cover 52. The cover 52 is preferably constructed according to principles employed in the construction of automobile tires, and is secured in place by side bars 50a and 50b, which side bars are secured to the rigid base 50 by fiat head screws 5|. Pressure of a vehicle wheel is transmitted to the strip 56 by cord 54, and, if the pressure is great, the cord 54, strip 56 and channel member 55 move downwardly as a unit owing to the yielding strip 59, so that the wheel rests on the side bars 50a and 50b thereby preventing any damage to the cover 52. In the downward movement of the cord 54, the upper contact strip 56 is brought into engagement with one or more of the contact points 51 by reason of the resiliency of' the channel member 55. The engagement of the contact member 56 and contact points 51 completes an electrical circuit, which circuit is utilized in the operation of my invention. When it is necessary to provide a vehicle-detector that will operate the signal mechanism only upon the approach of a vehicle, two or the contact mechanisms sealed in the rubber tube 53 are arranged parallel in a single rigid base 50, and provided with separate covers 52. With this arrangement, a relay system is employed. that will cause operation of the signal when the detectors are successively operated in one direction and not in the other. I

While I have shown and described one type of a detector, it is to be understood that other types may also be employed in the control of my invention. Such other types may comprise a trolley wheel and trolley contactor of an electric railway, electrostatic, magnetic inductor, photoelectric cell, sound or microphonic, and I do not desire to be limited to the-use oi the specific type of detector described.

For a complete understanding of the electrical connections employed to bring about the various objects of my invention, reference is made to Fig. 3. The central vertical dotted line of Fig. 3 is provided to distinguish the control relays and signal lights for A street from those for B street. The dotted rectangles are provided to indicate the mechanism included in each relay so outlined.

The motor-driven, cam-operated contact mechanism T represents a conventional form of traffic-signal timer having cams that may be adjusted to provide any'color sequence desired, and which may be further adjusted to provide any timing interval as may be required. As illustrated, the mechanism T has its cams arranged to provide a color sequence of indications graphically shown in Fig. 4. To assist in the understanding of my invention, it will be assumed that the mechanism T, when placed into continuous operation, will require 26 seconds to complete one cycle of operation. With this adjustment the green .interval for each street is set at 10 seconds and the yellow intervals at 3 seconds each. With the disconnect switches R and S, in the position indicated, the

til

mechanism T is normally held at rest at either points a or b as indicated in Fig. Thus it will be apparent that when the mechanism T is placed in operation, say, for instance from point a, the green on A street is immediately extinguished and a yellow displayed to both streets A and B with the red continued for three seconds on street B. After three seconds both the yellow and red will be extinguished and a green displayed to B street and a red displayed to A street. After the transfer, the mechanism T will continue to operate for 10 seconds, whereupon it will stop its operation at point in to maintain the last mentioned signal conditions until again placed into operation in response to an approaching vehicle on A street. When again placed into operation, the same sequence of indications will be presented with the exception that green will be transferred to A street and red to B street whereupon the mechanism will be stopped id seconds later when the point a of Fig. 4 is reached.

The motor-driven timing-mechanisms H and. 0 are identical in construction and operation. Accordingly only the operation of the timing mechanism H will be described. Normally the timing mechanism H is at rest, and assumes the condition indicated in Fig. 3. When the connecting wire 2la is potentialized from the vehicle-detector l8, current flows through contact 8a., contact arm 8, wire 22, through the motor D2 to the return of the line (32!. Instant to this operation, the operating coil 83 of relay I is energized, bringing the armature 38 into engagement with contact 38a. The operation of armature 38 completes a stick circuit for relay 1, and a retaining circuit for the motor D2 of mechanism H, tending from BX through contact 1a, contact arm 2, wire 24, armature 38, contact 38a, wire 2Ib, wire 2M, contactv 8a, contact arm 8, wire 22 and motor D2 to CX. With motor D2 energized, the cams are rotated in the direc tlon indicated by the arrow appearing in cam C9. Shortly after the cam 68 begins its rotation, contact arm 8 disengages contact. 8a, and the arm 8 immediately engages contact 81), which engagement establishes running circuit, for the motor D2. After the running circuit is established, the cam 01 causes the contact arm 1 to disengage contact la, thereby opening the stick circuit for relay I permitting the latter to restore to normal. The cam C1 is also adjustable so that it may be set to operate contact arm 1 to open the stick circuit for relay I at any time after the operation of contact arm 8. This feature is provided since following vehicles operating detector l8, immediately after the timing mechanism H commences its operation, need not set-up a control to bring about a repeat operation of mechanism H. Thus the cam Cl is adjusted to determine the period for repeat operations of mechanism 1-! according to the particular requirements of the intersection. Incident to the operation of motor D2, and before operation of the contact arm 8, cam C9 caused its contact arm 9 to disengage contact 91!, thereby opening the circuit via

wires

26 and 25 connecting motor Di of mechanism I. With the running circuit for motor D2 held closed by cam C8, the motor will continue to operate until the notch of cam C8 permits the contact arm 8 to disengage contact 8b, which is one revolution of the cam Ct. The speed of the cams oi the timing mechanism H is adjustable, and, for purposes of this description, it will be assumed that they are adjusted to complete one revolution in 5 seconds. The timing mechanism H is not of the resettable type, and therefore must complete one cycle of operation before it can again be operated. In this respect it will be noted that the interruption of the stick circuit for relay I by cam Cl is an intermittent operation. Therefore, a potentialization of wire Zia at any time during the operation of the timing mechanism H will cause the relay I to be retained operated until the contact 8 is restored into engagement with the contact 80., whereupon the starting circuit for motor D2 will be completed from wire fi l to cause a continued operation of the motor D2.

Relays E, F, 1', J, M, N, P and Q are of the quick-acting type, well known in the art, while relays K and L are of the retarded pickup type. Such a retardation may be accomplished by many well known principles, such as a dash-pot or escapement meci'iansim. The relays K and L are of, the type in which the contacts are restored to their normal condition immediately upon de-energization of their operating coil. The relays K and L are employed to control the maximum time 'a go" signal may be held from a waiting vehicle. Noting in particular relay K it will be seen that as long as current is ilowing to the A street green signal lamp G, the coil S5 is energized. At the expiration of a predetermined period, say, 30 seconds, the armature 37 will engage contact 31a. In this respect it is important to note that no further operation will be effected unless the wire 36a was previously place at positive potential through the operation armature 35 of relay Q.

As previously stated, mechanism T is assumed to be adjusted to time a 10 second initial display of the go signal to each street, while mechanisms H a'ndO are adjusted to time a second extension of the go signal. While these timings have been specified, it must be understood that they may be set to any timing desired. Ordinarily, the extent of the initial timing of mechanism T is determined by the time required to move all vehicles through the intersection accumulated between the detector and intersection on a stop" signal, while the timing of the extension controls H and O is determined by the time required for a vehicle to move from the detector through the intersection on a-go" signal. The maximum timing of the go" signal, by relays K and L, is determined by the amount of trafiic that-- may be permitted to accumulate on a stop signal in any one lane, or the maximum delay which should be imposed on a vehicle arriving on a stop signal immediately after a signal transfer.

From the foregoing it will be apparent that since my invention is responsive to trafilc its operation will, of necessity, vary with diiferent traiflc conditions and difierent adjustments of the controlling mechanisms. Therefore, having thus described the fundamental operation of my invention, I will now give specific illustrations of its operation under various conditions of traffic and adjustments.

ADJUSTMENT 1 Referring to Fig. 3, of the drawings, I will assume that disconnect switches R and S are positioned so that wires 36?) and 3212 are connected to wires 36a'and 32a respectively.

With these adjustments, the go signal will remain on the street to which it is last actuated, and, as shown in Fig. 3, the go signal is now on the A street. Assuming that no vehicles have operated the vehicle-detectors for some time, the following illustrations outline the specific operation of my invention under certain conditions of traiflc. It will be understood, however, that many other conditions of trafiic may prevail other than those specifically outlined. Therefore, the operation of my invention is not to be regarded as applicable-only to the particular conditions provided hereinafter.

, Condition 1 Single vehicle approaching on B street:

To further explain the operation of my invention, I shall assume that signal G of A street, and signal R of B street, are displaying, and that the motor driven mechanism T has advanced to position a indicated in Fig. 4. As long as vehicles do not approach on either street, the signals will remain continuously in this condition.

A single vehicle approaching on B street, and operating the vehicle-detector 28, will close a circuit from BX through the detector 28, contact 28a, wire 29, armature 30 of relay M, contact 30b, wire 3|, coil SIO of relay G to the return of the line CX, thus operating

armatures

34 and 35 of relay Q. When the armature 34 engages contact 34a, a stick circuit is completed from BX through armature 32 of relay M, contact 32a, wire 33, armature 34, contact 34a, wire 3|a, coil S to the return of the line CX, thereby retaining the

armatures

34 and 35 in their operated positions. When the armature 35 engages contact 350, a

circuit is completed from BX through armature 32, contact 32a, wire 33, wire 33a, armature 35, contact 35a, wire 36, contact 2311, armature 23, wire 21, contact arm l2, contact lZd, wire 28, contact 9a, contact arm 9, wire 25 to motor DI thence to the return of the line OK. This energization of the motor DI will cause its associate cams to rotate in the direction indicated by the arrow appearing on cam C5, whereupon the contact arm 6 will engage contact 6a to complete a running circuit for motor Di through Wire 2511. With the motor DI thus energized, thegreen of A street will be extinguished anda 4-way amber indication displayed for 3 seconds, whereupon the green signal G on street B, and the red signal R on A street will be displayed. As described hereinbefore, the motor DI will continue to operate for 10 seconds after this transfer occurs, to time the initial display of the green signal to B street. Incident to the display of the green signal G for B street via wire l3, relays L and M were operated via wires I3a and I3!) respectively. With relay M operated its armatures 30 and 32 disengage contacts 30b and 32a respectively and the armature 30 engages contact 30a. The disengagementof armature 32 from contact 32a opens the stick circuit for relay Q and the starting circuit for motor DI via wires as, as, 21, 2s and 25,

etc. Thus, when the motor DI advances its cams to the position 1), indicated in Fig. 4, the contact arm 6 disengages the contact 6a and opens the running circuit for the motor DI. If no further vehicles operate on either streets A or B the signals will remain continuously in the condition to which they were last operated.

Condition 2 engaging the vehicle-detector I'8, completes a cir-' cuit from BX through the detector l8, contact 18a, wire i3, armature 20, contact 20a, wire 2i,

operating coil S3 of relay I to the return of the line CX. The resultant energization of operating coil S3 raises armature 38 into engagement with contact 38a, and establishes a stick circuit for coil C3 from BX through contact la of timing mechanism H, contact arm 1, wire 25, armature 38, contact 3811, wire 2|b, coil S3 to the return of the line CX. With wire 2lb potentialized from BX as described, a circuit is also completed from wire 2|b, through wire 2la, contact 8a, contact- Condition 3 Single vehicle on A street followed within 5 seconds by a single vehicle on B street:

I shall now assume the condition of operation set forth in Condition 2 with a vehicle approaching on B street while'the timing mechanism H isin operation.

Sit

The approaching vehicle on B street engaging the vehicle detector 28 completes a circuit from BX through the detector 28, contact 28a, wire 29, armature 30, contact 30?), wire 3|, operating coil SID of relay Q to CX, thus energizing coil S l 0, and thereby raising

armatures

34 and 35 into 'engagement with their respective contacts 34a and 35a. With the armatures raised, a stick circult is completed for relay Q via wires 33 and 3la. Wire 26 is also potentialized via

wires

33, 33a, 36 and 21. contacts 9 and 9a are disengaged, the wire 25 will not be potentialized until the timing mechanism H is brought to rest, and the contacts 3, 9o permitted to close. Thus the call-on" relay Q remains operated to bring about a transfer of the go signal to B street, as soon as timing mechanism H is restored to normal.

Condition 4 Single vehicle on A street followed within 5 seconds by a second vehicle on A street and a single vehicle on B street:

I shall now assume the conditionsset forth in Condition 3 wherein a following vehicle engages the vehicle-detector l8 while the timing mechanism H is in operation. It will be remembered that the cam Cl momentarily interrupts the stick circuit of relay I shortly after the timing mechanism H is placed into operation. Therefore, the relay I has been restored to normal from the previous vehicle operation.

When the following vehicle on A. street engages the vehicle detector It a circuit is completed from BX, through the detector l8, contact lBa, wire l9, armature 20, contact 2%, wire 2i, coil S3 to the return of the line CK, thus energizing coil S3, and raising armature 38 into engage ment with its contact 38a. With armature 38 raised, a stick circuit is established for relay I via contact Ia and wire 24. Wire 2|a is also potentialized, as described for the previous operation of the timing mechanism H, but, since the timing mechanism H is now in operation, the contact 8a is disengaged by the contact arm 5, therefore no further operation will be effected until the cam C8 permits the contact arm 8 to engage the contact 8a, whereupon the potentialize'd wire 2 la will again energize the motor D2 via wire 22 to start a second cycle of operation. Thus, the effect of a second vehicle operation is to prevent the timing mechanism H from assuming a rest position. It will also be observed that, although the timing mechanism H iscontinued in operation, the cam C9 will permit the contacts 9 and 9a to close for a very short interval shortly before the contact arm 8 disengages contact to. However, this engagement of the contacts 9 and So will have no effect on the motor DI of mechanism T since as long as the motor D2 is energized the relay P is operated via potentialized wire 22a. With relay P operated, its armature 23 disengages contact 23a thereby preventing energization of motor Di via

wires

36 and 21 even though a vehicle should approach on street 13 and operate the vehicle detector 28. Thus the transfer of the go signal to B street can not take place until the repeated operation of time mechanism H, in response to the second vehicle on A street, is completed. It has also been found, with wire 2m potentialized, that contact arm 8 moving the very short distance from contact 817 to contact So does not permit the armature 23 of relay P to release. However, it is evident that a definite continuity of circuit connection, via wires 22 and 22a, may be established It will be noted, however, that, since the the timing mechanism H, only a single repeat operation of the timing mechanism will be effected. Thus it may be observed that the vehicles are divided into groups, so to speak, such that all vehicles moving in a single group automatically cause a further extension in the display of the go signal as soon as the timing of the previous group has elapsed.

Condition 5 Vehicles continuously approaching on A street for a definite time with a single vehicle waiting on B street:

I shall now assume the conditions set forth in Condition 4 with vehicles continuously approaching on A street such that the timing mechanism H is held in continuous operation until the go signal is transferred to 3 street. In this respect it will be noted that as soon as the cam C2 of the mechanism T brought the contact arm 2 into engagement with the contact 2a. to establish the go signal on street A, a circuit was completed through wires Ida, Mb, Me, operating coil S4 of relay J to the return of the line OK. The relay J maybe termed a selector relay in that it determines whether the impulse from the vehicle detector i8 is to be transmitted to the call on control relay E or the time extension" relays I and H; Incident to the operation of relay J the.

operating coil 85 of relay K is energized via wire Mb. Thus after a predetermined time, say 30 seconds, the armature 31 of relay K engages its front contact 31a. As assumed in Condition 4, the wire 36 is being held potentialized through an operation of relay Q in response to a vehicle approaching on the B street red signal. Thus, as soon as armature 31 engages contact 3742, a circuit is established from BX through armature 32 of relay M. contact 32a, wire 33, wire 33a, armature 35, contact 35a, wire 36, wire 36a, wire 3%, armature 31 of relay K, contact 81111, wire 25b, wire 25a, to the motor Di, thence to the return of the line CX. This energization of motor Di will cause the timing mechanism T to transfer the go signal to B street, whereupon the mechanism T will continue to operate until the position b of Fig. 4 is reached.

Condition 6 Vehicles continuously approaching on A street with only a single vehicle approaching on B street:

I shall now assume the conditions set forth in. Condition 5, wherein vehicles continue to approach on A street after the go signal has been transferred through action of the timing relay K and the call-on) relay Q. Incident to the transfer of the go signal from Astreet to B street, wire Mb is de-energlzed, thereby resulting in relays J and K being immediately restored to their normally deenergized positions. Thus a vehicle arriving on the A street red, and operating the vehicle-detector i8, completes a circuit from BX through the detector I8, contact I811, wire l9, wire 20, contact 2027, thence to the operating coil Si of the call-on relay E. ,As soon as the mechanism T arrives at the position b indicatecl in Fig. 4, and with no further vehicle operation of detector 28 during the B street go signal, a circuit for continuing the operation of the motor DI is completed from BX through armature 39 of relay J. contact 39a, wire 40, wire 40a, armature 4!, contact ila, wire 42, contact 53a, armature 33, wire 21a, wire 21, contact arm l2, contact I211, wire 26, contact 911, contact arm 9, wire 25, to the motor DI, thence to the return of the line CX. Continuing the operation of the motor Di in this manner, will cause the go signal to return to A street, whereupon the cams of mechanism T will continue to revolve until they reach position at indicated in Fig. 4.

Condition 7 Vehicles continuously approaching on both streets A and B:

I shall now assume that vehicles continuously approach on both streets A and B. In this condition of operation it will be obvious that the stream of vehicles approaching on the go signal, for instance A street, will retain the timing mechanism H continuously in operation while'the approaching vehicles on B street would have operated the call-on relay Q to bring about a transfer of the go signal to B street, which will not be effected until the relay .K operates as previously described. When the go signal is transferred to B street, the vehicles continuously moving thereon will likewise retain the timing mechanism 0 continuously in operation, and the vehicles approaching on-the A street red will operate the call-on relay E to bring about a transfer of the go signal to A street, which will not be effected until the timing relay L has completed its operation. Thus under continuous vehicle movement on both streets A and B, the go signal will be alternately and repeatedly displayed to streets A and B as determined .by the timing of relays K and L.

ADJUSTMENT 2 The operations described in Conditions 1 through 7 inclusive permitted the go signal to remain on the street to which it was last actuated when trafiic ceased to operate on either street.

It can readily be seen, from an inspection of Fig. 3, that the go signal will always return to A street by positioning disconnect switch S so that wire 42b is connected to BX. In this manner the go signal will always return to A street 30 seconds after its transfer to B street in the event vehicles do not approach on A street and cause an earlier transfer.

ADJUSTMENT 3 It can readfly be seen, by inspection of Fig. 3, that the conditions described for streets A and B will be interchanged, and the go signal will always return to the B street if the disconnect switch S is positioned as indicated and disconnect switch R positioned so that wire 36b is connected to BX. I

ADJUSTMENT 4 If it is desired to arrange the system so that the go signal will normally, alternately and repeatedly transfer from one street to the other, in the absence of vehicle operation, both disconnect switches R and S are positioned so that wires 36b and 42b are connected to BX. With the disconnect switches so positioned, armatures 31 and 44 of relays K and L are directly connected to BX, and the motor DI of mechanism T will be automatically set into operation to transfer the go signal 30 secondsafter the g0 signal is established on either street. Vehicles approaching a stop signal will shorten the duration of the go signal on an intersecting street, if there are no vehicles operating on the street then receiving the right-of-way, and effect an immediate transfer of the go signal to the street on which the vehicle approaches. If, however, vehicles are operating on the street receiving the go signal, the

continuous operation of its respective 5 second" minimum time control H or 0 will retain the go signal for the full normal time of its respective maximum time control relay K or L.

Under this plan of operation the go signal is normally displayed to A street for 30 seconds,

then to B street for 30 seconds and so on cyclically.

The operation of my invention under Adjustments 2,, 3 and 4 is quite similar to that described in Conditions 1 through 7 inclusive, and since the difierence in operation resides principally in the normal condition of the signals in the absence of vehicle operation, the operation outlined under Conditions 1 through 7 is readily applicable to similar operations under Adjustments 2, 3 and 4.

It is to be further understood that, although I have described my'invention as controlled by the movement of vehicles over suitable vehicle- .detectors installed in the various lanes comprising the intersection, it is also intended that my invention be controlled by push buttons operated by pedestrians when such pedestrian operation is a requirement. In the provision of pedestrian operated push buttons, as many buttons as desired may be arranged in multiple to connect the wires I9 or 29 to BX.

Particular emphasis is made of the novel manner in which an extension of the go signal is effected in my invention, wherein a vehicle approaching while theextension control is in operation, does not efiect a further extension unless it approaches a predetermined time after the previous operation. Thus it is to be observed that the extension control provides a predetermined time of extension of the go signal in response to an approaching vehicle, and that all other closely following vehicles which may clear the intersection on the same time extension do not effect any further operation of the extension control.

In the foregoing description the term go signal was employed to designate the indication displayed to permit trafiic to proceed, however, it is to be understood that the expression right-ofway is to be regarded as its equivalent.

Although I have shown and described certain specific embodiments of my invention I am fully aware that many modifications thereof may be made without departing from the spirit of my invention. My invention therefore is not to be restricted except as set forth in the appended tor DI; means Cl, C2, C4 and C5, operated by the said motor in accordance with a predetermined cycle, and constructed and arranged to actuate the said signals alternately; control apparatus for the said motor responsive to the approach of vehicles in each of said lanes, the apparatus for each lane comprising, a vehicle-detector 28 adapted to be actuated by a vehicle approaching the said intersection, a retaining device O, which device, when operating, retains the go signal actuated on the corresponding lane for a predetermined period of time, a call-relay Q, which relay, when actuated, functions to provide for an operation of the said motor Di to transfer the go signal to the corresponding lane, and timing means L having a time period of operation greater than that determined by the said retaining device, which means, when actuated, functions to provide for an operation of the said motor Di to discontinue the actuation of the go signal on the corresponding lane; the apparatus for each lane also comprising a first starting circuit Bx, 32-32a, 33, 33a, 35-35a, 36, 230-23, 2?, I2-i2a, 26, 9a9, and ca: for the said motor Di including a correspondingnormally closed switch i2i2a of each retaining device and a normally open switch 35-350 of the corresponding call-relay, and a second starting circuit Br, 32-32a, 33, 330:, 35-35% 36, 36a, 36b, 3l-3ia, 25b, 25a and car: for the said motor Di including a normally open switch 3'i-3la of the corresponding timing means, and a normally open switch 3535a of the corresponding call-relay; a

running circuit Bx, 6-6a, 25d and ca: for the said motor Di including a normally open switch 6-Ea i closed and opened by the operation of the said motor Di at predetermined points in the said cycle, for intermittently operating the said motor, so as to actuate alternately the said signals and to retain alternately the said actuation of the signals; means Cl and C2, operated alternately by the said motor Di, for actuating alternately the timing means of each lane according to the alternate actuation of the said signals; and selector means JM actuated alternately by the said motor Di according to the alternate actuation of the said signals, for placing alternately each corresponding retaining control and call-relay in the control of each corresponding vehicledetector.

2. In a traffic signaling system for interfering traific lanes A and B having, in combination, stop and go signals for each of the said lanes; an electric motor Di; means Ci, C2, C4 and C5, operated by the said motor in accordance with a predetermined cycle, and constructed and arranged to actuate the said signals alternately; a running circuit Bx, 66a, 25d and Ca: for the said motor Di including a normally open switch S-fia; means C8, operated by the said motor, constructed and arranged to close the said switch ii-Eia for a predetermined portion of each cycle, for maintaining the said motor operating to provide for an alternation in the actuation of said signals, and to open said switch at predetermined points in the said cycle, for stopping operation of the said motor to retain alternately the actuation of the said signals; a startaing circuit Bax, 32-32a, 33, 33a, 3535a, 36, 23a'23, 2i, i2--i2a, 26, 9a 9, 25 and Ca: for the said motor including a normally open switch 35-35a and a normally closed switch Sl-Qa in series therewith; a ve-= hicle-detector l8 and 28 in each of the respective lanes; means Q, operatively associated with one of said detectors 28 and actuated by an operation thereof, when the corresponding lane B does not have the go signal actuated thereon, for closing the said switch 35-35a to complete the starting circuit 25, and thus place into operation the motor Di to provide for an alternation in the actuation of the said signals; and timing means H, operatively associated with the other of said detectors is and actuated by an operathus prevent operation of the said motor Di during the time of actuation of the said timing means H.

3. A trafflc control system for interfering trafiic lanes A and B having, in combination, sto and go signals for each lane; a cyclic switching mechanism T for alternating the cncraization of the said signals, the said mechanism having a predetermined period of operation following much alternation of the said signals for compelling energizatlon of the corresponding signals for at least a predetermined minimum time between each alternation of the said signals, and having a position of rest following 'each period of operation for maintaining the energization of the corresponding signals beyond the timev of the corresponding minimum period; a vehicle detector i8--28 in each of the said lanes; means E-Q operating in response to an actuation of a detector in a lane on which the go signal is not energized, for initiating operation of the said mechanism '1, to provide the aforesaid alternation in the energization of the said signals; means H-O operating in response to an actuation of a detector in a lane on which the go signal is energized, for retaining the said mechanism T in its corresponding position of rest, to retain the corresponding energization of the said signals; and selector means J-M, having alternate operating positions, and actuated according to the alternate energization of the said signals, for placing alternately the said initiating means and said retaining means in the control of the tcorresponding detector.

4. A trafiic control system for interfering traffic lanes A and B having, in combination, stop and go signals for each lane; an electric motor Di; a cam-operated switching-mechanism operated by the said motor for alternating the energization of the said signals, the said mechanism having a predetermined period of operation following each alternation of the said signals for compelling energization of the corresponding signals for at least a predetermined minimum time between each alternation of the said signals, and having a position of rest following each period of operation for maintaining the energization of the corresponding signals beyond the time of the corresponding minimum period; a vehicle detector i828 in each of the said lanes; means E-Q, operating in response to an actuation of a detector in a lane in which the go signal is not energized, for initiating operation of the said motor, and thus operate the said mechanism to provide the aforesaid alternation in the energization of the said signals; means operatively associated with the said mechanism for retaining the aforesaid operation of the said motor until the said mechanism reaches its successive position of rest; timing means I-IQ, operating in response to an actuation of a detector in a lane on which the go signal is energized, for rendering the said motor inoperative for a predetermined period of time following the said actuation of the said detector, and thus retain the mechanism in its corresponding position of rest to retain the corresponding energization of the said signals for at least the said predetermined period of time; and selector means JM, having alternate operating positions, and actuated by the said mechanism according to the alternate energization of the said signals, for placing alternately the said initiating means and said retaining means in the control of the corresponding detector.

5. In a tramc control system according to claim 4, comprising, a timing device for each lane having a period of operation longer than the said predetermined period of the said timing means, and alternately placed into operation according to the alternate energization of the said signals, for limiting to a predetermined maximum time the energiz'ation of the corresponding go signal.

6. A tramc control system for interfering trafiic lanes A and B having in combination, stop and go signals for each lane; a vehicle detector l8-28 in each of the said lanes; a cyclic switching mechanism T for alternating the energization of the said signals, the said mechanism having a predetermined period of operation following each alternation of the said signals for compelling energization of the corresponding signals for at least a predetermined minimum time between each alternation of the said signals, and having a position of rest following each period of operation for maintaining the energization of the corresponding signals beyond the time of the corresponding minimum period; means E-Q, operating in response to an actuation of a detector in a lane on which the go signal is not energized, for initiating operation of the said mechanism T, to alternate the energization of the signals, and thus energize the go signal on the lane of the said actuation; and means C6, operated by the said mechanism T for retaining the said mechanism operating until the said mechanism reaches its corresponding position of rest as aforesaid.

7. A traflic control system for interfering traiiic lanes A and B having in combination, stop and go signals for each lane; a

vehicle detector

18 and 28 in each of the said lanes; and a cyclic switching mechanism T, operating in response to an actuation of a detector in a lane not having the go signal displayed thereon, for alternating the energization of the said signals so as to display the go signal on the lane of the actuated detector, the said mechanism operating a predetermined period of time following each alternation of the signals for compelling energi zation of the corresponding signals for at least a predetermined minimum period of time between each alternation, and having a position of rest following each period of operation for maintaining the energization of the corresponding signals beyond the time of the corresponding minimum period.

8. In a tramc control system according to claim 7, comprising, a timing device Kand L'for each lane having a period of operation longer than the corresponding predetermined period of time of the said cyclic switching mechanism, and alternately placed into operation according to the alternate energization of the said signals, for limiting to a predetermined maximum the energization of each corresponding go signal.

LESLIE QUILLIAM.