US2879497A

US2879497A - Street traffic control system with selective automatic time direction

Info

Publication number: US2879497A
Application number: US695057A
Authority: US
Inventors: Jr Charles Adler; Henry A Barnes
Original assignee: Individual
Current assignee: Individual
Priority date: 1957-11-07
Filing date: 1957-11-07
Publication date: 1959-03-24
Anticipated expiration: 1976-03-24

Description

March 24, 1959 c. ADLER, JR, ET AL 7 2,879,497

STREET TRAFFIC CONTROL SYSTEM WITH SELECTIVE Filed NOV. 7, 195'? AUTOMATIC TIME DIRECTION 2 Sheets-Sheet ,1

FIGJ.

INVENTORS CHARLES ADLER, JR. HENRY A. BARNES WW 4%,; 4w)

ATTORNEYS Maw}! ,1959 ,C.ADLER,JR.. ETAL 2,379,497

STREET TRAFFIC CONTROL SYSTEM WITH SELECTIVE I AUTOMATIC TIME DIRECTION Filed Nov. 7, 1957 1 2 Sheets-Sheet 2 TO CUMENT SUPPLEY RC AC GC FIGJ g sum STOP I34C I F 4 a- RP I o r 3 I54 CURRENT SUPPLY S TART INVENTOR CHARLES H EN 3 Y A.

ATTORNEYS United States Patent-O STREET TRAFFIC CONTROL SYSTEM WITH SELECTIVE AUTOMATIC TIME DIRECTION Charles Adler,-Jr., and Henry A. Barnes, Baltimore, Md. Application November 7, 1957, Serial No. 695,057

' 4 Claims. c1. 340-42 v This invention relates to street name control systems, and, in particular, to an improvement in street trafiic control systems which allows for unidirectional trafiic movement on certain thoroughfares duringpredetermined times of the day.

It is an object of this invention to provide an auxiliary means for controlling street signals whereby the signals for certain main streets or thoroughfares are maintained in acondition for one-way'traific travel during certain periods of the day, and whereby the signals for the same streets or thoroughfares are maintained for two-way traffic during other periods of the day;

It is a further object of this invention to provide an auxiliary means of the above-described type which may be used in connection with any conventional main signal system which controls traffic indicators.

It isa:still further object of this invention to provide a selective trafiic control means in which provision is made for only changing the signals at a time when the trafiic is in a condition for a change.

Still a further object of this invention is to provide an auxiliary system includingmeans to inform the operators of vehicles approachingthe selectively-controlled thoroughfare that the vehicle may travel across the thoroughfare, or that it may travel inonly a selected direction along the thoroughfare, or that it may travel in any direction with respect to or along the thoroughfare.

Yet another object of this invention is to provide an auxiliary system which may be put in condition forcontrolling traflic along the thoroughfare by means of a single switch.

Other objects and the particular advantages of this invention will become apparent to those of ordinaryskill in the art when the following description is considered in conjunction with the annexed drawings, wherein:

Figure 1 is a plan view'of several intersections along a thoroughfare which has been equipped with signaling Inean's in accordance with the provisions of this invention;

Figure 2 is a schematic diagram of the auxiliary control means and means for operating the same by this invention for accomplishing the objects abo've set forth;

Figure 3 is a schematic diagram of a push-button switch which may be used with the circuit of Figure 2 according to this invention; and

Figure 4 is an elevational view of a preferred type of accessory signal means which may be used in conjunction with conventional signal means in accordance with this invention.

Referring to Figure l, a thoroughfare is indicated at and, as is customary, this thoroughfare carries, at certain periods of the day, a heavy load of trafiic,-for instance, incoming to a central city, and at other periods of the day carries a heavy volume of trafficoutgoin'g from that central city. During the time when the traffic volume is considerably-lessened, trafiic'may move onthe thoroughfare in either direction-but at the peak periods,

provision is'made for one-way travel only on the-thori- I 2,879,497 Patented Mar. 24, 1959 green indicators and directional indicators 13. These indicators comprise lamps in front of which are disposed colored glass faces, as is customary. One piece of equipment-isprovided on each of the four corners of the intersection. However, one or more units may besuspentl'ed over the intersection, as customary, for instance, at the point X without departing from the operation of' the system of this invention.

Associated with the signals visible to traffic moving over the cross street 14 are automatic directional indi cators having signal arrows 15 and 15' which will show drivers approachingthe intersection on the cross street 14 when trafiic is-directional on the thoroughfare, and the direction of same.

Associated with the signals which face traffic moving on the thoroughfare 10 are directional indicators having arrows signals 16 and 16' whereby when a vehicle is traveling north or south, and the boulevard control is changed to one direction or another, these arrows -will direct a-driver, who istraveling against the single direction, to turn-01f of the thoroughfare to the right or. left;

In the operation of the selective system, when'the signals are-operating-normally, the

arrows

15, 15, 16 and 16' will not be energized. When the peak load'is traveling south on the boulevard 10, the automatic control acts to lock the red indication of signal means 12 on the NE corner of intersection 11. The red indication locks only during the red interval when traflic is moving across the thoroughfare and then holds red. The red does not come on suddenly, in the midst of a green boulevard period, as this would tend to cause sudden stops and rear-end collisions.

In the operation of an ordinary trafiic control system, when both the north and south lanes of thoroughfare 10 are being utilized for two-way tralfic so that thenorthsouth indicators present green, the indicators for the cross street 14 are red on each'side. When the green indicators are about to change, due to the normalautomatic operation of the control system, the east-west signalswill remain red, while the green signals go to the amber indication. Thereafter, when the north and south indicatorschange to red to permit cross-street travel, the eastwest indicators change to green, and the north-southindicators remain red, while the east-west indicators, in their normal operation before another change, present amber to opposite sides of the thoroughfare. Thereafter, of course, the east-west indicators turn to red, and the north-south indicators return to green.

7 When the auxiliary control means is operative, as provided bythis invention, the above pattern is not fol lowed. For example, when the southbound trafiic is presented with a green indication, all northbound traflic will be presented with a red indication and the direc tional indicators, with arrows 16 associated with the northbound indicators 12 on the NE corner,'will indicate toany drivers who are moving in the northbound direction that they should turn to the right o'rleff f0 leave the boulevard and at this time the indicatorson tlie east-west cross street indica'te'red. When southbound traffic is presented with an amber indication, northbound trafliewill Still be presented With r'ed' indications; east-west'traflic' will remain= presented with red indies thoroughfare 10. When southbound traffic and northbound trafiic are both presented with red indications, and

east-west traflic indications are about to be changed, in p the normal operation of the indicators from green to red, the indicators will first show amber, and after eastwest trafiic indicators show red, then the southbound trafiic indicator will again show green, but the northbound indicator still shows red.

When it is desired to have northbound traflic only on the thoroughfare 10, southbound trafiic will be presented with a red indication and the directional indicators, with arrows 16, will inform an operator of a vehicle that a left or right turn must be made. The northbound trafiic indicators will present a green indication, and a red indication will be presented to east-west trailic. In the normal operation of the indicators for permitting the passage of east-west traffic, there is presented, during the sequential operation, an amber indication to northbound I trafiic, while the red indication remains presented to south-bound traffic and a red indication remains presented to east-west traffic, but during a succeeding portion of the cycle, the latter indication is changed to green. Directional indicators, with the proper arrow 15, will show the direction of flow of traffic on the thoroughfare 10. When the change occurs, of course, both southbound and northbound trafiic are presented with red indications.

By reason of this invention, it will be apparent that the normal conventional operation of traffic signals may be maintained. However, the flow of trafiic maybe directed during peak periods of a day. This control of .direction of traffic on the boulevard speeds the traffic up, yet safety is provided for in that no change in indications occurs when traffic is moving in both directions on the boulevard 10 during off-peak periods until 'a driver is given ample warning of a change in the indications. A red signal is on when the change is effected for traffic travel in one direction on the thoroughfare, and although a red indication is given to traffic traveling in the other direction along the thoroughfare, directional indicators will indicate to the driver faced with the contimious red signal that he should make a turn into the east-west street, as is most convenient.

Having thus generally set forth the operation desired of the traffic control system, attention will be directed to the circuit provided for carrying out the invention. The components of the system are shown in Figure 2 position for travel along thoroughfare 10 in the south direction. One of the pieces of signal equipment 12 is designated as SW, indicating that it is on the southwest corner of the intersection. Similarly, the designation NE indicates that the signal so designated is at the northeast corner.

vices, including the types specifically set forth above, which will perform the necessary functions, are well known to those skilled in the art.

A basic structure used to perform the timing operation would comprise cam-operated switches geared to a clock mechanism and connected to a suitable source of power.

The circuit is connected to a main traffic control system which feeds current to particular connections within the circuit in the proper sequence.

The letters RC, AC and GC designate leads through which a signal is transmitted from a control network within the main system to the red, amber and green indications, respectively, shown in the form of lamps covered by colored glass, to the signal equipment on the northeast corner of the intersection. Of course, without the auxiliary control means provided by this invention the leads RC, AC and GC would be connected directly to red, amber and

green signal lamps

101, 102 and103, respectively. If the system is under normal operation, that is, two-way trafiic on the main thoroughfare is maintained, then no current is being supplied to v relay 51 through lead 119 or to relay 68 through lead 120. In this instance, when current is fed into red control lead RC, current flows through relay 61 from the connection of lead RC to that relay and to ground which is designated in the usual way. This current causes relay 61 to pull

blades

62, 63 and 64, which are mechanically linked together, to the left in Figure 2. When current is no longer fed through lead RC, relay 61 opens. It will be noted, however, that when current is fed through lead RC, the red indication or lamp 101 is energized by virtue of the fact that lead 65 connects with lead RC and one side of the lamp 101. The other side of the lamp 101 is grounded.

During normal operation at any time when current is not being fed through lead RC, the

blades

62, 63 and 64 of relay 61 are in the dotted line position shown in Figure 2. When the blades are in such position, current may be fed into lead AC and, as a result, amber lamp 102 is energized since one side of the lamp is grounded and the other side is connected through lead 66 to blade 63 and lead AC. Also, when the blades are in such position, current may be fed into lead GC, in which case it would pass through blade 64 and lead 68 to one side of green lamp 103, and through green lamp 103 to ground.

During the normal operation the directional indicator, with arrows 16 associated with the northeast corner signal equipment 12, would not be energized since they are connected to lead 60 through blade 64 only when current is fed into red control lead RC, and, of course, when current is being fed into lead RC, no current is being fed into lead GC by the main control network.

The directional indicators 13 are designated in the same way to show their respective locations.

In Figure 2, the

numerals

119 and 120 are leads from a timing unit 100. This timing unit supplies current at a particular interval of the day to relay 51 through lead 119 and at another interval of the day it supplies current to relay 68 through lead 120. The timing unit may be a centrally located (remote) time clock which is responsible for signals during a certain period of the day, a trafiic actuated central (remote) cycle computer, which functions to supply proper signals, or any other suitable timing means, located centrally or at individiual intersections.

The details of construction of the timing unit form no part of this invention. The timing unit need only be I,

responsible for sending a current through

lead

119 or 120 at particular times of a. day,.and manytiming d6? alternating or direct current, .75

The equipment 13 on the southwest corner functions in the same manner as that on the northeast corner. However, the contacts associated with relay 74 are responsible for current transmission to

lamps

105, 106 and 107 and the directional indicators with arrows 16. The relay 74 corresponds to relay 61,

blades

75, 77 and 79 correspond to

blades

62, 63 and 64, respectively, and the input leads RC, AC and GC', connected to the main control system, correspond to leads RC, AC and GC, respectively.

Assume now that current is fed from timing unit through cable 119 so that the system will be set to indicate one way traffic southbound on thoroughfare 10. The current fed through cable 119 flows through relay 51. to ground, thereby energizing that relay and causing blade 52 to move to the left. When blade 52 moves to the left it makes connection with a lead 57 extending from any suitable auxiliary current supply. Since the system would operate the same whether powered by lead 57 has been stated as generally connected to an auxiliary current supply. When .either A.C. or DC. is used, one side of the supply may be grounded and the other side connected to lead 57. When blade 52 connects with the current supply lead 57, relay 53 is energized by current flowing from the supply, through blade 52, lead 56 and relay 53, to ground.

. Energization of relay 53 causes blade 54 to move to the left and connect with lead 59, which connects with

lamps

113 and 116. Since lead 55 connects blade 54 to the current supply lead 57, when blade 54 moves tothe'left, current flows through lead 55, blade 54 and lead .59 to one side of

lamps

113 and 116 and through the lamps to ground. Lamp 113 illuminates an arrow 15 within directional indicator 13 on the northwest corner. This illuminated arrow points southward, and thus any motorist approaching intersection 11 traveling west is informed that he can not turn right. Lamp 116 illuminates an arrow 15' within directional indicator 13 on. the southeast corner. This illuminated arrow also points southward and, hence, any motorist approaching intersection 11 traveling east is informed that he can not make a lefthand turn. In other words, the arrows indicate the direction of travel on thoroughfare 10.

It will be noted that lead 60 connects with, lead 56 which, in turn, connects through blade 52 to the current- -supply lead 57. Thus, when relay 51 is energized, lead 60 connects with a current supply. Becauseof this, and

,. plete the connection from an auxiliary currentsupply to relay 61. Moreover, the blades associated with relay 61 only lock in the left position after relay 51 is energized and after a current has been supplied to relay 61 through lead RC. Thus, the sequence of operation in normal conditions will not be interrupted such that red or stop lamp '101 is energized continuously until that lampv is energized during the normal sequence of signals received from the control network within the main traffic control system. Of course, lamp 101 is initially energized when a current is sent through lead RC because it. is connected ,.to. lead RC through lead 65. It remains energized when blade 62 locks in its left-hand position because .then lamp 101 receives current from the auxiliary current supply through lead 57, blade 52, part of lead 56,: lead 60, blade 62, lead 58 and lead 65.

When the blades associated with relay 61 are locked in their left-hand position, blade 63 makes no connection with amber lamp 102 or any other load and, hence, p any current entering through lead AC sees an open circuit. The blade 64, when locked in its left-hand position, does not connect with lead 68 but, instead, connects with lead 67 which, in turn, connects to one side of directional indicatorv 13 on the northeast corner. Thus, when current is supplied through lead GC for potentially energizing the green or go indicator during what i would normally be the portion of the cycle during which a green indication appeared, it flows through blade 64, lead 67, and lamps 109 and 110 to ground but does not 1 flow through lamp 103. Lamps 109 and 110, therefore,

are energized and inform northbound trafiic that it must turn to the right or left, but cannot proceed directly ahead. It is apparent that the energization of lamps 109 and 110 only occurs when it is permissible for that traffic to turn, that is, when the signal equipment 12 on the northeast corner would normally show a green signal.

Because the circuit is connected with a main traflic controlsystem supplying sequential control signals, this indication occurs when the indicating equipment on the southeast corner and that on the northwest corner both 6 show a red indication stopping traflic traveling on side street 14. i

When the period during which, current is supplied to lead 119 terminates, relay 51 is de-energized and the

blades

62, 63 and 64 associated with relay 61 assume their dotted line positions. Of course, no irregular signal will be given that requires sudden action on'the part of trafiic because there would be no traflic facing the northeast corner, at such time, and, moreover, the signals would be given in accordance with the selection made by the main control systems control network. It will be apparent that when current is fed to line 120, relay 68 is energized. Blade 69 moves to the left energizing relay 70, causing blade 71 to move to the left and connect lead 72 and lamps 114 and 115 to the auxiliary current supply through current supply lead 57'. Relay 74 would be locked in its left-hand position when current was fed to lead RC; the red control lead connected to the main control systems control network, because relay 74 is connected to lead RC through lead58' and because lead 73 connects through lead 56, and blade 69 to current supply lead 57'.

Blades

75, 77 and 79 would move to their left positions and, as a result, one side of red lamp 105 would be connected to the current source through lead 76, lead 58, blade 75, lead 73, part of. lead 56', blade 69 and lead 57. At the same time, blade 77 would. make no connection with a load, and blade '79 would connect with lead 81 so that the lamps 111 and 112, associated with directional indicator 16, would be energized when current was sent into lead GC from the main control systems control network for potentially passage of current through lead 119, however.

energizing green indicator lamp107.

Of course, current would only be supplied through lead when it was desired to maintain the signals on thoroughfare 10 in condition for one-way northbound traflic.

When current is not being sent through leads 119. or 120, connections are made between input leads RC, AC, GC, RC, AC and GC such that the main control systems control network operates the red, yellow and green lamps in a normal selective cycle.

As is apparent from the foregoing, passing. current through lead 119 establishes. connections for maintaining the, signals at an intersection of the thoroughfare, 10 in condition for one-way southbound trafiic. The signals viewable by the southbound tratfic are not affected by They are controlled by the main systems control network for proper traffic flow, and the main system signals are .fed through leads RC, AC and GC directly tothe lamps associated with each lead.

Similarly, passing current through lead 120 establishes connections for maintaining the signals at an intersection of the thoroughfare 10 in condition for one-way northbound traffic. The signals viewable by the north bound trafiic are in this instance not affected by the auxiliary control means, but, instead, are controlled by the control network of the main system for proper traffic flow.

It should be understood that although the auxiliary control means has been described above in conjunction with indicators which incorporate lamps, the auxiliary control means may be used with any indicators which may be electrically energized. For example, electromagnetic sign indicators maybe used. Moreover, foroperation of the invention, amber indicators are-not essential. Any traffic control-indicating equipment that has at least stop and go indicators will allow for utilizationofthe invention.

In Figure 4 is shown the preferred type of directional indicator for use with this invention. It comprises a housing having one face which carries directional indicators in the form ofarrows 151 and 152. Of course, these arrows are illuminated by lamps (not shown) disposed within the housing. Any suitable colored glass may-be used as a cover for the arrow'face, however, it is 7 preferable to use green, and in a conventional system, green should be used.

Although the auxiliary control means shown in Figure 2 has been applied hereabove to traffic control at one particular intersection, it is readily apparent that the means may be used to control traffic flow at a plurality of intersections. One auxiliary control means such as that shown in Figure 2 may be associated with each intersection and leads 119 and 120 may comprise cables extending along the thoroughfare for carrying the auxiliary control signals for setting the indicators at the intersections for one-way tratfic. Such a system may be desired where there is sequential control of intersectional flow along the thoroughfare 10, that is, where like indicators disposed at a series of intersections along a main street and facing in one direction for a series of blocks are not controlled by a single signal from the control network of a main system, or such a system may be employed for the purpose of convenience.

It may be more convenient, however, to use a single auxiliary control means for effecting maintenance of oneway trafiic operation, and such may be utilized by merely connecting the auxiliary control means to the main control network at the place where the main control network is located. The single auxiliary control means may be conveniently used where like indicators disposed at a series of intersections along a main street and facing in the same direction are controlled by a single control signal from the main network.

Referring again to Figure 2, it will be noted that a double-pole single-throw switch 153 has been provided for disconnecting the timing mechanism from

cables

119 and 120. Of course, this switch provides a means for disconnecting the

leads

119 and 120 from the timer during days when one-way traffic maintenance is not desirable, such as on Sundays or holidays.

Also, in Figure 2 is shown a switching means 121 connected to a current supply 154. The arm 125 of this switch connects with

contacts

122, 123 and 124. When the arm engages contact 122 current is sent through lead 122' and through lead 119 and the auxiliary control means controlling northbound traffic establishes the proper indications for one-way southbound tralfic on thoroughfare 10. When the arm engages contact 124, current is sent through lead 124 and lead 120, and the auxiliary control means controlling southbound traffic establishes the proper indications for one-way northbound traffic on thoroughfare 10. Contact 123 is a dead connection which arm 125 engages when the switching means is not being used for control. It is desirable to have a switching means, such as the illustrative one designated by the numeral 121, so that on particular occasions when heavy traffic is traveling along a particular thoroughfare to attend a particular event, such as an athletic contest, one-way traffic may be maintained. The switching means may be disposed in a central location or may be disposed near one of the pieces of indicating equipment.

In Figure 3, a push-button switching means, which may be used instead of switching means 121, is shown. The numeral 134 designates push-buttons which control

switch blades

128 and 129 associated with the

relays

130 and 131. The parts of the push-button switching means are shown in the position they occupy when an auxiliary control signal is being sent through lead 120. Blade 128 is connected through lead 155 to a current supply. Lead 132 connects with blade 128 and, as a result, when the blades are in the positions shown. current flows through lead 155,

blade 128 and lead 132 to lead 120. This would cause energization of the auxiliary control means for establishing one-way northbound traffic on thoroughfare 10. If t the stop button 134A were pushed, no contact would be made with

leads

132 or 133 and, as a result, no auxiliary control signal would pass through the switch to

leads

119 or 120. When the button 134D is pushed, blade 129 engages lead 133, and an-auxiliary control signal is passed to lead 119 and the auxiliary control means for establish- 8 1 ing one-way southbound traffic on thoroughfare 10 is energized.

Relays

130 and 131 have been provided for maintaining the

blades

128 and 129 in the position set by the push-buttons.

When the blade 128 is set by push-button 134B in contact with lead 132, relay 131 is energized since current flows from an auxiliary current supply through lead 155, blade 128, part of lead 132, lead 135, and relay 131 to ground. Energization of relay 131 causes blade 128 to lock in the position shown. Pushing button 134A causes a break in the circuit as blade is disengaged from lead 135, relay 131 is de-energized and blade 128 no longer engages lead 132 as spring 142 urges that blade away from contact.

When it is desired to send an auxiliary control signal through lead 119, push-button 134D is pushed such that blade 140 engages lead 141. Relay 130 is thus energized and blade 129 will lock in position since current fiows from an auxiliary current supply, through lead 155, blade 129, part of lead 133, lead 133 blade 140, lead 136, and relay 130 to ground. Pushing button 134C removes the auxiliary signal from lead 119 as relay 130 is de-energized and the spring 142 causes blade 129 to no longer contact lead 133.

Lamps

143 and 143 may be provided in parallel connection with

relays

131 and 130 respectively if it is desired to have an indication of when an auxiliary signal is being sent through lead 119 or lead 120.

Referring again to Figure 1, it will be noted that the directional indicators 13 are disposed beneath the indicating equipment 12. It should be understood that this invention is not limited to such a disposition, and that the directional indicators may be disposed in any position near the indicating equipment, whether on the side of, on top of, or below the indicating equipment.

It should also be understood that particular relays having a particular number of contacts have been shown only for illustrative purposes, and that any suitable arrangement of relay contacts, and even of relays, may be used to control the indicator operation, as taught by this invention.

From a consideration of the foregoing description and annexed drawings, it will be apparent that the objects set forth above, and others which became apparent during consideration of this disclosure, have been successfully accomplished. Various modifications, other than those set forth herein, will become apparent to those of ordinary skill in the art and, for that reason, it is intended that this disclosure be interpreted as illustrative and not in a limiting sense when consideration is given to the appended claims.

We claim:

1. A traffic control system for use at an intersection of streets, said system comprising first and second trafiic controllers facing in opposite directions on the same street and having electrically energizable stop and go indicators, a main control means for sequentially supplying at least electrical stop and go signals to said indicators to alternately energize the indicators to control movement across the intersection along said same street, a first auxiliary control means electrically coupled to said main control means and to said first trafiic controller and including stop indicator lock-in means for maintaining the stop indicator of said first trafiic controller energized and go indicator lock-out means for maintaining the go indicator of said first traffic controller deenergized during a first extended period of a day in response to an electrical signal, second auxiliary control means electrically coupled to said main controlmeans and said second traffic controller and including stop indicator lock-in means for maintaining the stop indicator of said second traffic controller energized and go indicator lock-out means for maintaining the go indicator of said second traffic controller de-energized during a second extended period of a day in response to an electrical signal, timing means electrically coupled to said first and second auxiliary control means for supplying electrical signals to said first and second auxiliary control means during said first and second periods of said day respectively, means coupling said first auxiliary control means to said main control means for preventing energization of the stop indicator of said first traffic controller until an electrical stop signal is received from said main control means for energizing said stop indicator of said first traific controller, means coupling said second auxiliary control means to said main control means for preventing energization of the stop indicator of said second trafiic controller until an electrical stop signal is received from said main control means for energizing said stop indicator of said second traflic controller, a first directional trafiic sign disposed to face in the same direction as said first trafiic controller and having first energizable arrow indicators pointed in opposite directions, means coupling said first arrow indicators to said first auxiliary control means for energizing said first arrow indicators in response to electrical go signals normally fed to said first trafiic controller go indicator from said main control means during said first period of the day, a second directional traflic sign disposed to face in the same direction as said second tratfic controller and having second energizable arrow indicators pointed in opposite directions, and means coupling said second arrow indicators to said first auxiliary control means and said main trafiic control means for energizing said second arrow indicators in response to electrical go signals normally fed to said second trafiic controller go indicator from said main control means during said second period of the day, whereby one-way traffic can automatically be maintained on said same street in opposite directions during two diiferent periods of a day.

2. A tralfic control system as defined in claim 1 and further including a third directional trafi'ic sign disposed to face in one direction on the street intersecting with said same street and having third energizable arrow indicators pointed in opposite directions, a fourth directional traflic sign disposed to face in the opposite direction to said third directional traflic sign on the street intersecting with said same street and having fourth energizable arrow indicators pointed in opposite directions, means coupling one of said third arrow indicators and one of said fourth arrow indicators to said first auxiliary control means for causing said one third arrow indicator and said one fourth arrow indicator to be energized during said first period of a day, and means coupling another one of said third arrow indicators and another one of said fourth arrow indicators to said second auxiliary control means for causing the other third arrow indicator and the other fourth arrow indicator to be energized during said second period of a day whereby trafiic approaching the intersection along the street intersecting with said same street will be informed as to the permissible direction of turn at the intersection during said first and second periods of said day.

3. A traific control system as defined in claim 2 and further including power means, and switching means disposed near one of said trafiic controllers and coupled to said power means and said first and second auxiliary control means for supplying an electrical signal to either of said auxiliary control means at periods of a day other than said first and second periods.

4. A traffic control system as defined in claim 3 wherein each of said auxiliary control means comprises an electrical network including a plurality of electromatic switching devices.

References Cited in the file of this patent UNITED STATES PATENTS 1,871,894 Lichlenstein Aug. 16, 1932 1,917,165 Thompson July 4, 1933 2,001,440 West May 14, 1935 2,006,675 Ferguson July 2, 1935 2,531,153 Pennell Nov. 21, 1950 2,555,994 Pennell June 5, 1951