TRAFFIC ACTUATED CYCLE LENGTHS SELECTOR APPARATUS Filed April 10, 1958 Nov. 12, 1963 a. E. FIESER ETAL 4 Sheets-Sheet 1 m m m m GARLAND E FIESER FRANK W H/LL Attorney ,1963 e. E. FIESER ETAL 3,110,380

TRAFEIC ACTUATED CYCLE LENGTHS SELECTOR APPARATUS Filed April 10, 1958 4 Sheets-Sheet 2 GEAR SHIFT 64 ELECTRIC CHANNEL SELECTOR A 84 MECHANISM PROGRAMMING DEVICE I 1 (MASTER STEPPING l I DEVICE 1 Y 7 68 as 86 57 82 75\ f 62-60 MASTER CONTROLLER 59\ LOCAL INTERSECTION CONTROLLER INVENTORS GARLAND E. FIESER FRANK W. H/LL Attorney N v- .63 a. E. FIESER ETAL 3,110,880

TRAFFIC AGTUATED CYCLE LENGTHS SELECTOR APPARATUS Filed April 10, 1958 f 4 Sheets-She et 3 TRAFFIC SlGNAL-' 2-2- MOTOR I I GEAR TRAIN GEAR SHIFT MECHANISM MASTER TRAFFIC QCONTROLLER 47 48' 50] 5| 51 |s4 5 5 ill I IIHI llllllllllll Fig.5

IN VEN TORS GARLAND E. FIESER FRANK WH/LL flame,

Attorney Nov. 12, 1963 e. E. FIESER ETAL 3,110,830

TRAFFIQAGTUATED CYCLE LENGTHS SELECTOR APPARATUS United States Patent 3,116,880 TRAFFlC ACTUATED CY CLE LENGTHS SELECTQR APPARATUS Garland E. Fieser, East Moline, and Frank W. Hill, Molina, lll., assignors, by mesne assignments, to The Gamewell Company, Newton, Mass, a corporation of Delaware Filed Apr. 10, 1%8, Ser. No. 727,741 9 Claims. (Ql. 349-35) The invention relates to means to select one of a plurality of cycle lengths at a local traffic signal controller. More specifically, the invention relates to means permitting the selection of traific cycle lengths where a constant speed motor drives the cycle length controlling device through a series of successive speed reducers, each speed reducer permitting a choice of a plurality of ratios.

Preferably the relative choice of speed reductions at each speed reducer is different so that a device having N speed reducers, each with a plurality of ratios, gives a selection of different speeds equal to the plurality of ratios raised to the power equal to the number of speed reducers. For example, four speed reducers, each with a choice of two speeds, gives a choice of 2 or 16 speeds.

The several speed reducers are preferably built into one structure, having a plurality of axially movable shafts each located between an idler shaft. One axially movable shaft, together with two adjacent idler shafts, form one speed reducer.

Preferably the axially movable shafts are moved by a solenoid into one of the plurality of positions. In a simplified version, each movable shaft is biased to one of two positions and is shifted to its other position by an electric solenoid.

The invention provides means whereby a master con-' troller at a central station can vary the trafiic cycle created by a local traffic signal controlling device.

This may be accomplished by sending out signals from the master controller over a single channel to an electric channel selector at each intersection. The electric channel selector energizes the proper circuit to actuate the proper solenoid, each solenoid moving one of the movable shafts in a stepped speed transmission unit to one of its plurality of positions, thus enabling the constant speed motor at the intersection to drive the traffic signal controlling device at the proper speed. Such an electric channel selector is disclosed in patent application 473,080, filed December 6, 1954, now abandoned, and continued in application Serial No. 9,653, filed February 18, 1960, now U.S. Patent 3,605,188, by George Donald Hendricks, and in United States Patent 2,832,069, issued to George Donald Hendricks et al., April 22, 1958.

The principal object of the invention is to permit the choice of a large number of traific cycle lengths by the proper selection of the speed reduction ratios in each of a number of successive speed reducers, each reducer capable of a plurality of speed reductions. The term traffic cycle length is defined as the time required for the traific controlling signals to complete one full set of signal changes. In the usual street trafilc controller it is the interval that elapses from the time green signal comes on to one lane, through amber and red until green signal comes on again.

Another object is to obtain precise, accurate control of traflic controller cycle speeds utilizing a synchronous motor and a remotely electrically shifted multi-speed transmission.

Another object is to remotely shift the proper gears of a multi-speed transmission with a number of solenoids controlled by an electric channel selector.

Another object of the invention is to shift the device to N different positions utilizing only N/ 2 solenoids and control conductors.

Another object is to secure at least two different trafiic cycle lengths for each circuit actuating one of said speed reducers.

Reference will be made to the following figures, of which:

FIGURE 1 is a plan view of one form of the transmission and solenoid gear shifting apparatus.

FIGURE 2 is a section along 22 in FIGURE 1.

FIGURE 3 is a section along 3-3 in FIGURE 1.

FIGURE 4 is a partial view of a second form of the gear shifting apparatus utilizing push-pull solenoids on each shaft.

FlGURE 5 is a section parallel to elevation of apparatus shown in FIGURE 4.

FIGURE 6 is a schematic diagram of a gear shift mechanism incorporated into a local trafllc controller and electrically connected to a master.

FIGURE 7 is a schematic diagram of the gear shift mechanism electrically connected to a signal impulse responsive electric channel selector in a local traffic controller.

FIGURE 8 is a schematic diagram of a plurality of traffic detectors, a master traffic controller of the computer type, an interconnecting cable connected at each local controller, a plurality of local controllers, each equipped with a gear shift mechanism and trafilc light circuits.

Referring to FIGURE 1, the gear shift assembly 19 consists of a pairof side frame members 11 kept in parallel relationship by posts 12, and having a plurality of shafts 13 to 21 positioned therein. The input shaft'13 may be driven directly by the motor 22, or by a motor gear train combination 22, 23. Suitable bearings, not shown, are provided on the ends of each rotating shaft 13 to 21.

Positioned at alternate locations between the input shaft 13, the idler gear shafts 15, 17, 19 and the output shaft 21, are the axially movable gear shafts 14, 16, 18, 20. Each set of shiftable gears 2526, 30-31, 3435, 38 39 is positioned on an axially movable shaft 14, 16, 18, 2t) which is free to rotate and free to slide in suitable bearings under urging from the operating solenoids 47, 48, 50, 51.

Each shiftable shaft 14, 16, 18, 20 is equipped with G- type return springs 43, 45, the shaft being free to turn in both ends of the spring. The ends of the shafts 14, 16, 13, 20 are equipped with rotatable collars 44 which have in them a groove for the end loop of the C springs 43, 45. Each shiftable shaft 14, 16, 18, 20 is also equipped with an operating mechanism consisting of an operating spring 45, an armature 46, and an electric solenoid 47, 48, 5t), 51. Each solenoid and its flexibly attached gear shaft is operable singly or in combination with one, two, or all of the other solenoids to give the maximum number of gear ratios.

The choice of the proper gear ratio permits smooth progression from a given speed to a lower or higher speed in a number of approximately even steps. For purposes of illustration, the following ratios have been selected:

Gear N 0. Number of Reduction Teeth First reduction Second reduction Third reduction Fourth reduction wHMwMMw toctmocnocn companying operating mechanisms, on the opposite frame member ill. Then, with all solenoids deenergized, a 1 to 1 ratio would result.

By energizing various ones of solenoids 47-53%, singly or in groups, 16 different speed reductions are available.

Referring to FIGURE 1, with solenoids 47, 5G energized and solenoids 43, 51 deenergized, a l to 1 ratio between shafts 13 and 21 would result because the following gears would be in mesh with each other: 24, 26, 28 30, 32, 35, 37, 38, 41. Since all of the gears have 24 teeth, a 1 to l raitio would result. We will call this condition 1.

Under condition 2, solenoid 5% would be energized and 4 33, 32 with 35, 35 with 37, 37 with 38, 38 with 41. All of the gears have 24 teeth except gears 31 and 35, which have 22 and 26 teeth respectively, resulting in a 22/26 reduction.

The detailed description of operation under conditions 5 1, 2, and 3 sufiices to indicate the operation of the remaining conditions, The results of conditions 1 through 16 are outlined in Table I.

Table I shows that sixteen different speed reductions are available simply by energizing or deenergizing four solenoids. In the usual transmission one gear is shifted for each speed change desired; if 16 different speeds were desired, sixteen gears would have to be shifted.

TABLE I Gear Reduction and How Obtained solenoids 47, 48, 51 deenergized, causing the following gears to be meshed: 24 with 26, 25 with 27, 28 with 3%, 30 with 32, 32 with 35, 35 with 37, 3'7 with 38, 38 with 41. All of the gears operating under this condition have 24 teeth except gears 25 and 27, which have 23 and 25 teeth respectively, resulting in a 23/25 reduction between shafts 13 and 21.

Under condition 3, solenoids d7, 48, 5% are energized and solenoid 51 deenergized, causing the following gears to be meshed: 2d with 26, 26 with 28, 28 with 3d, 31 with shown here to illustrate the usefulness of the gear shift mechanism lb.

The dial unit 61 in its common form initiates impulses at preset intervals, to energize a solenoid 62 which steps a camshaft 63 of a step switch 69 to cause a change in signal lights in the traffic signal 64 energized through the light circuit contacts 65. A common form of the solenoid 62, camshaft 63, and light circuit contacts 65 is shown in United States Patent 2,815,4l0 mentioned above.

By transmitting electric current from a master trafiic controller 66 located at a distant centralstation over one or more control conductors 52-59, the appropriate one of a number of cycle lengths can be selected.

The relationship between cycl length, motor speed, and gear ratio will now be explained. In this embodiment of the invention the speed of the motor .42 is a constant 60 rpm. The gear box 23 reduces this speed to 10.28 rpm. With the gear shift mechanism It shifted for a l to 1 ratio, the output shaft 21 will revolve at 10.28 rpm. A gear reduction of 6 to l is built into the dial unit 6T. Thus, a speed of 1.71 rpm. or a cycle length of 35 seconds will result. The cycle lengths available in the present embodiment are as follows, but are not limited to the following:

It is to be noted that the steps are in useful, even more ments of approximately the same percent increase. This is necessary in traffic control if the device is to be utilized to the best advantage.

it is well loiown to those skilled in the art of traific control that most expeditious traffic flow can be obtained by one certain cycle length for each set of trafhc conditions along a highway. That is, one certain cycle length is best suited for a certain volume of traffic; the greater the traffic flow, the longer the cycle length. The proper cycle length can be determined from information gained from traflic studies. Also, the hourly and daily pattern of trafiic flow can be determined by studying trafiic counts, and traffic cycle changes programmed accordingly using a suitable program device. Such a program device is shown in patent application 481,891, filed January 14, 1955, by George Donald Hendricks, now Patent 2,832,071, issued April 22, 1958.

Electric impulse signals, originating in the programming device and transmitted to the various local controllers, thus put into operation the proper cycle length for each trafiic condition.

In another application of the invention, the gear shift mechanism is equipped with a modified solenoid operating mechanism similar to the one shown in plan view in FIG- URE 4, and in sectional view in FIGURE 5. Each shiftable shaft l4, 16, 18, 2% is equipped with two operating solenoids. Thus shaft 16 is equipped with solenoids 48, 655, one solenoid 48 to urge the shaft in one direction, and one solenoid 68 to urge the shaft back to its former position. A spring detent mechanism 69 retains the armature and gear shaft in its shifted position after the solenoids 48, 68 are deenergized. Thus, only a pulse of current is required to shift the mechanism. However, in

this form of the invention, double the number of control conductors 54, 55, '74, 75 are required, one pair for each solenoid as shown in FIGURE 5.

To overcome this disadvantage, the gear shift mechanism 81 is connected to an electric channel selector 82, FIGURE 7, of the type described in patent application 473,080, filed December 6, 1954, now abandoned and continued in application Serial No. 9,653, filed February 18, 1960, by George Donald Hendricks, and in United States Patents 2,826,752 and 2,832,060, issued to George Donald Hendricks et al., March 11, 1958 and April 22, 1958, respectively.

The electric channel selector 82, is also known as a local responder and is designed to permit the master trafiic controller 33 at the central station to choose and energize any one of a number of functions at a plurality of local controllers 84. Thus, shifting of the gears at the local controllers 84 is accomplished by the master controller 33 on a programmed or traffic actuated basis.

in the programmed type a master controller chooses the cycle length at preset times. However, the traflic density may through any suitable device energize the electric channel selector 82.

The former arrangement is shown in schematic form in FIGURE 7. The master controller 83, under the control of a programming device 65, transmits impulses of 60 cycle alternating current at a frequency of approximately 10 impulses per second. The number of impulses sent is dependent upon the function desired, in this case the gear ratio desired. The electric channel selectors 82 at the various local intersection controllers 84 maintain step with the master stepping device 86. The mechanism is disclosed in detail in application 9,653 and in Patents 2,826,752 and 2,832,060 mentioned above. When the responder 82 has selected the terminal immediately ahead of the terminal connected to the selected gear shift solenoid or 68 for example, a longer pulse is transmitted by the master stepping device 86 to step the electric channel selector $2 one additional step and to energize the solenoid 43 or 68 which shifts the proper gear in one of the pairs 2526, 30-3l, 34-35, 3839, in this case, gears 39-411. Thus by successively moving one or more of the movable shafts '14, 16, 13, 20, cycle lengths can be programmed from the master controller 33 using only a two conductor interconnecting cable 87 or other single channel.

In the operation of the invention the master controller 83 sends only a synchronizing pulse over lines 87 as long as the cycle length is to remain constant. The synchronizing pulse will not be registered by the electric channel selector 32.

When the cycle length is to be changed, the master controller 83 sends over lines 87 an appropriate number of short impulses followed by a long impulse. These impulses are received by a number of local controllers -34. The electric channel selector 82 is each local controller 84 Will respond to the number of short impulses and, upon receipt of the following the long impulse Will place current on one of the solenoids 47, 48', 50, 51, 67, 63, 7d, 71. This will change one gear ratio and thus change the cycle length. The operating solenoids 4'7, 4%, 50, Si, 67, 63, 71 need not be continuously energized because spring detent mechanism 69 holds each shaft in its selected position.

In a typical application in traffic control it is usually desired that any change in cycle length, progression, offset, other function be made smoothly and not abruptly. The operation of the gear shift mechanism to effect change in cycle length is preferably made step-by-step, either up or down, for smooth change from one cycle length to the next longer or shorter cycle length. For example, if the cycle length is 70 seconds (condition 9, Table I) and traffic conditions change so that the next longer cycle length is desired, it is only necessary that the master controller 83 transmit the appropriate coded pulses over interconnecting cable 37 to each local electric channel selector 82, causing current to flow over line 73 to energize solenoid 67. Solenoid 67, becoming energized,

shifts shaft 14 causing gears 25, 27 to mesh, resulting in further gear reduction in the ratio of 23 to 25. The total reduction of X results in the desired cycle length of 76.1 seconds (condition 10, Table I).

The master controller 83 can send successive signals each consisting of a series of impulses, to actuate subsequent solenoids and put into effect various gear ratios. Because the axially-movable shafts 14, l6, 18, 2d are retained by spring detents 69 in the position to which they were last moved, an actuating impulse of only short duration is required. This frees the electric channel selector 82 for other duties. The actuating impulse must be of sufiicient duration so that the solenoid 48, for example, exerts an attraction on the armature 46 which in turn exerts a force through spring 45 on the movable shaft 16 causing gears 39. 32 to disengage and a moment later causing gears 31, 33 to engage.

To illustrate another application of the gear shift mechanism as used in traflic control, apparatus is shown in FIGURE 8 which is capable of detecting traffic in each lane of a highway, counting trafiic in each lane per unit of time, discriminating which is the heavier rate of trafiic flow, and adjusting the gear shift mechanism at each local controller to give a trafiic cycle length for most expedious trafiic flow.

Referring to FIGURE 8, a plurality of local intersection traffic controllers 84 are shown each connected to an interconnecting cable 87 originating at a master trathc controller 38. Each local controller 84 and the master controller 88 is connected to an appropriate source of 115 volt alternating current power.

Located in, on, over, under, or near each traflic lane is a trafiic actuated detector 9t}, which for purposes of illustration may be a pressure-sensitive type detector. Detectors of other types may "be used, or combinations of types; however, to simplify the drawing and description pressure-sensitive type detectors are shown.

Uni-directional traflic detectors 90 are used in lanes on which trafiic moves in one direction. Dual-directional or directionally selective traflic detectors, not shown, are used in the lane or lanes on which traffic moves in one direction at one time and in the opposite direction at other times. Such detectors are shown in United States patent application 723,038, filed March 31, 1958, by Garland E. Fieser.

Traffic detectors 90 are of the two contact type with one contact wired to ground through wire 91, and to low voltage relay coils 92, 93 through wires 94. The opposite ends of said relay coils 92, 93 are connected to a source of low voltage power 89, through wires 95. The primary coil 96 of the transformer is connected to a suitable source of i115 v. alternating current power through lines L1, L2.

Relay coil 92 is mounted on and a part of a suitable relay having contacts 97, 98, 99. Contacts 97, 98 are connected across capacitor C1. Capacitor C11 is connected between movable contact 98 and ground wire 1M. Capacitor C2 is connected between a source of power L2 and a rectifier SR1, so that vehicular actuation of detector 90 in lane 105 closes a path to ground for relay coil 92 causing said relay to close contacts 98, 99 permitting capacitors C1, C2 to charge through rectifier SR1 from power source L1, L2. Opening of detector 94} circuit causes relay coil 92 to deenergize, opening contacts 98, 99, closing contacts 97, 98 shorting out capacitor C1. Capacitor C2 now discharges slowly through variable resistor R2. Further actuations of detector 90 in lane res repeat the cycle of charge causing capacitor C2 to carry a charge dependent on and representative of traffic density on the corresponding highway lane 105.

Relay coil 93 is similarly connected to a detector 90 in lane 1% and to a source of low voltage power 89 0 through wire 95. Actuation of the detector 9% in highway lane 1% similarly causes capacitors C3 and C4 to charge through rectifier SR3 and now-closed contacts Ital, 1935 from power source L1, L2. Opening of detector 99 circuit in lane 166 causes relay coil 93 to deenergize and open contacts 1M, 163 and close contacts till, 1G2, shorting out capacitor C3. Capacitor C t discharges slowly through variable resistor Re. Continued actuation of detector 99 in lane 1% repeats the cycle of charge causing capacitor C4 to carry a charge representative of trai'fic density on highway lane 31%. The ohmic value and setting of variable resistor R4 in relation to the value of capacitor C4 determines the drain-oft time of capacitor C4 and consequently the duration of the averaging time interval. Increasing the ohmic value of variable resistor R4 increases the duration of the averaging interval.

Thus, circuit points 107, 1% are at potentials representative of the density of traffic upon highway lanes 105, 1%, respectively. If trafiic is heavier on lane 1% than 135, the voltage appearing at point 1% will be higher than that appearing at point 1G7.

Three components connected between points Hi7 and 1% form a discriminating circuit. Relay coil 11% is designed to pull in at a higher voltage than the voltage supplied by power source 111, and to drop out at a slightly lower voltage. Rectifier SR5 is provided to prevent a potential at point M7 higher than the sum of the battery 111 voltage plus the potential at point MS from pulling in relay 119.

The voltage appearing across relay coil 116* is equal to the voltage supplied by power source 111 plus the potential supplied by capacitor C4, minus the potential supplied by capacitor C2. Thus, if the potential at point 197 is higher than that appearing at point 163, relay will remain quiescent as shown in FIGURE 8 and will feed capacitor C2 potential to DC. motor 112 over contacts H3, 114 through an amplifier A.

If the potential at point N38 is higher than that appearing at point 107, relay 11d will pull in and feed capacitor C4 potential to the DC. motor 112 over contacts 114, 1E5, through an amplifier A. Thus, motor 112 is always fed with the higher of the potentials 107 or 1%, representative of the higher rate of traific flow.

Motor 112 is equipped to drive the wiper arms 121424 of a rotary step switch device 120 and the rotary arm 116 of a potentiometer R6, which is a part of the rotary step switch 12%. A DC. potential is supplied to one end of the potentiometer R6 from capacitor C5 fed from a power source L2 through rectifier SR7. The other end of the potentiometer R6 is connected to ground. Thus, the voltage appearing across motor brushes 117, 118 is equal to the difference of potentials derived from the higher of capacitors C2 or C4 and the potential appearing at the tap on which rider 116 resides. If a change occurs in traflic flow rate, the potential at brush 117 will change and motor 112 will start to rotate, driving wiper 116 until substantially zero potential difference exists across the motor.

For example, if trafiic flow rate on lane 1% increases, the potential at point .198 rises. If point 108 was already at a higher potential than point 107, relay contacts 114, will have been closed. The increase in potential at point 1% is fed through amplifier A to motor brush 117, Where it causes motor 112 to rotate wiper lilo to find a new position of substantially equal potential. Stepping switch wiper arm 116 carries the additional wipers 12l 124 which control the operation of the gear shift mechanism it) at each local controller 84.

The wiring of the step switch is also illustrated in FIGURE 8. Wiper arm 116 carries with it wiper arms 121-124 which switch L2 power to outgoing lines 52, 54, 56, 58 connected to solenoids 47, 43, 5e, 51 as shown in FIGURE 6. The return lines for these solenoids are connected to one line 59 and return to the step switch 120 or are grounded at the controller 84.

On the step switch 120, L2 power is wired to each of those contact positions at which it is desired to energize the solenoid associated with that bank of the step switch.

For example in the topmost or 16th position of the step switch 120 as. shown in FIGURE 8, wiper arm 121 is in contact with a segment not wired to L2, therefore not energizing conductor 52 and thus none of the solenoids 47' connected to it. Wiper arm 122' is in contact with a segment wired to L2, thus energizing conductor 54 and all solenoids 48 connected to it. Wiper arm 123 is in contact with a segment not wired to L2, not energizing conductor 56 and thus none of the solenoids 50 connectcd to it. Wiper arm 124 is in contact with a segment wired to L2, energizing conductor 58 and all solenoids 51 connected to it. As a result, condition 16, Table I, is placed in operation with gears shifted by the gear shift mechanism It to effect the longest cycle length, in this embodiment, 125.9 seconds;

As the density of traffic reduces, the potential of points 107,108 reduces, causing a potential difference to appear across motor brushes 117, 118. The potential difference results in motor 112 operating which moves wiper arm 116 to a tap of lower potential and wiper arms 121-124 to position 15, for example, which results in the energization of line 52 land all solenoids 47 connected to it. The condition of lines 54, 56, '58 remains unchanged. The solenoids 47, 48, 5t}, 51 are in condition to give a cycle length corresponding to condition 15 or 115.8 seconds in this embodiment. Thus, change in traffic density results in change of traffic cycle length to allow most expeditious trafidc flow.

The invention is particularlysuitcd to be used in connection with local tr aliic signal controllers or" the type shown-in United States patent application 642,469, filed February 26, 1957, and entitled Multiple Program Traffic Control System. The invention replaces a variable speed motor so which is normally used to drive a resynchronizing timer (624 7) and traffic cycle split con-trolling cams (lilo-166). Thus, one or the other of two optional traflic cycle duration determining means may be provided to satisfy the majority of timing requirements.

Having described several embodiments of the invention, we make the following claims.

We claim:

1. A trailic control system for accurately and exactly regulating the duration of a cycle of trafiic signal change, including traflic signals at each of a plurality of intersections controlled by a plurality of respective synchronous trafiic controllers, each of said controllers having a trafiic signal energizing electric step switch, an electric impulse device connected to periodically step said step switch, a remotely shiftable speed reducer including a plurality of gear reductions, a constant speed synchronous motor driving said impulse device through said speed reducer, a master controller, a signal coding device at said master controller and a signal decoding device at each local controller interconnected by a single channel, means at the master controller to transmit a coded signal to each of said local controllers to shift at least one gear of said reductions to vary the length of a cycle of traffic signal change identically at each local intersection.

2. A traffice control system comprising:

a plurality of local traffic controllers;

a master controller having program timer means for selecting different traffic cycle lengths at preset times; means for interconnecting said timer means of said master controller and said local trafic cont-rollers;

a gear changer including a constant speed driving motor in each of said local controllers;

said gear changer controlled by said timer means through said interconnecting means;

a step switch and trafhc signal lights connected thereto in each of said local controllers;

an impulse initiating means in each of said local controllers and driven by said gear changer for electri- 10 cally stepping said switch and thereby energizing and controlling said traffic signal lights through a plurality of selected trafiic cycle lengths.

3. A traffic control system for regulating the duration of a cycle of traffic signal change, including:

a plurality of local synchronous traflic controllers;

trafiic signals at each of a plurality of intersections controlled by said local controllers; each of said controllers having an electric step switch and an electrical impulse device connected to said switch for periodically stepping said step switch;

each of said controllers having a remotely solenoidally shiftable speed reducer including a plurality of gear reductions, and a constant speed synchronous motor for driving said impulse device through said speed reducer;

a master controller;

a multi-conductor cable for interconnecting each of said local controllers and said master controller;

and means at the master controller for energizing at least one of said conductors in said cable to shift at least one of said plurality of gear reductions at each local controller to accurately vary the length of a cycle of trafiic signal change identically at each local intersection.

4. A traflic control system including in combination:

traffic signals;

local controls for controlling said trafiic signals;

local timer means and shiftable local gear reducer means in said local controls;

said local gear reducer means'for controlling the speed of said local timing, means;

master controller means;

master timer means electrical-1y connected to said master controller means;

said master controller means acting in response to said master timer means and cooperating with said local gear reducer means for remotely shifting said gear reducer means to thereby remotely initiate a precise change in speed of said local timer means and exactly vary the length of a cycle of trafiic signal changes.

'5. In a traffic control system as in claim 4, said local gear reducer means having multiple gear reducer stages shiftable singly and in combination to vary the speed of said local timer means in a number of increments, each of said increments when taken in ascending order being a substantially constant percentage of the prior lower speed.

6. In a traific control system as in claim 4, said local gear reducer means having successive gear reducer stages, each stage having two orders [of gear reduction and a remotely controlled shifting means to thereby provide a number of possible speeds, said number of possible speeds being equal to two raised to a power which is the number of gear reducer stages.

7. A traflic control system comprising: a master trafiic controller including program timer means to select at preset times one of a number of traffic cycle lengths; an interconnecting cable having a plurality of conductors on which current is placed by the master controller corresponding to the particular cycle length selected; and a plurality of local intersection tratiic controllers to which said interconnecting cable is connected; each said local controller having a step switch, an impulse timer connected to impulse said step switch through a cycle of ltraflic signal change, a substantially constant speed motor, a remotely controllable multi-speed transmission coupling said motor to said impulse timer; each said muLti-speed transmission connected to said interconnecting cable and being remotely controlled therethrough said program timer means :to vary the length .of said cycle.

8. A tlraflic signal control system including in comb-ination: master trafiic control means; trafic detectors in the trafiic lanes of a roadway; individual electronic traflic counting means for each direction of traiiic flow on said roadway; each of said counting means adapted to produce an output proportional to the average rate of traflic flow counted thereby; amplifier means; electric balancing means connected to sense the output of each of said counting means, and adapted to connect the output of the counting means having the higher output to said amplifier means to provide an amplified DC. output; stepping switch means including a stepwise potentiometer across a DC. potential source, said stepping switch means including a plurality of contact banks each having a tap arm slidable there-over in unison with the movement of an arm of said potentiometer, said banks connected to a potential source to provide at each step switch position a distinct combination of tap arm conditions, a tap arm having two conditions as energized and non-energized from the last said source, step switch driving motor means connected be tween said potentiometer arm and the output of said amplilier means and adapted to drive said potentiometer arm in a forward or reverse direction until the potential across said driving means is substantially Zero, said stepping switch means thereby caused to proportionally follow the traliic counting means whose output is higher; a plurality of local tiraific signal controllers some of which are located at intersections along said roadway; and means interconnecting said stepping switch tap arms at the master control means to each of said local traffic signal controllers; each of said local trafiic signal controllers comprising a remotely controlled multi-speed transmission, a constant speed motor driving said transmission, an impulsing means driven by said mul-ti-specd transmission, a step switch impulsed by said impulsing means, the trafiic signals at each intersection connected to and controlled by said step switch of a respective local controller through successive cycles, electromechanical gear shift actuators operative in conjunction with said multi-speed transmission and controllable through said interconnecting means by said stepping switch means in said master control to vary the length of the traflic cycle in relation to traific density in the direction of heavier flow.

9. Trams: signal cycle length control apparatus for traflic signals at each of a plurality of intersections along highway lane-s: the apparatus at each intersection including a remotely controlled rnulti-speed transmission, a substantially constant speed motor driving said transmission, an electric impulse originating means driven at one of a plurality of constant speeds by said motor through said transmission, and a signal controlling device urged through one cycle of operation by electric impulses originating during one cycle of said impulse originating means; traific control signal lights energized through said signal controlling device; traflic actuated detectors in each highway lane; a master controller including means connected to said detectors to detect and measure the time rate of trafiic flow individually in each direction over the highway lanes, means responsive to measured said rates of traffic flow to determine the heavier rate of traffic flow, and means responsive to the rate of heavier flow to control the position of a reversible step switch device; and means connecting said step switch device in said master controller with each said remotely controlled multi-speed transmission to shift the transmission and effect precise change in the traflic cycle length proportional to the rate of trafiic flow on the heavier lane.

References Cited in the file of this patent UNITED STATES PATENTS 2,076,396 Blue Apr. 6, 1937 2,133,157 Turner Oct. 11, 1938 2,288,601 Barker July 7, 1942 2,535,632 Herr Dec. 26, 1960 2,542,978 Barker Feb. 27, 1951 2,618,983 Bliss Nov. 25, 1952 2,657,375 Paul Oct. 27, 19-53 2,761,120 Wilcox Aug. 28, 1956 2,796,595 Schulenberg June 18, 1957 2,834,001 Wilcox May 6, 1958 2,925,583 Jeffers Feb. 16, 1960 FOREIGN PATENTS 486,171 Canada Sept. 2, 1952