US2136955A

US2136955A - Traffic control signal

Info

Publication number: US2136955A
Application number: US681051A
Authority: US
Inventors: Renshaw Percy Bailey
Original assignee: Automatic Telephone and Electric Co Ltd
Current assignee: Automatic Telephone and Electric Co Ltd
Priority date: 1932-07-23
Filing date: 1933-07-19
Publication date: 1938-11-15
Anticipated expiration: 1955-11-15

Description

NOVQ IS', 1938. p, E s w I 2,136,955 I TRAFFIC CONTROL SIGNAL Filed July-l9, 1935 4 Sheets-Sheet 1 Pas/77am INVENTOR. Pmcr 5/1/15) Ems/MW '4 azwwadm ATTORNEY Nov. 15, 1938 v REN HAW- 2,136,955

TRAFFIC CONTROL SIGNAL Filed July 19, 1955 4 Sheets-Sheet 2 MSrSTREEr Ewo E M '5 TEEET EWD INVENTOR BYPERCY BAI EY PEA/sum; M MM or. ATTORNEYS.

Nov 15, 1938.- v P. B RENSHAW 2,136,955

TRAFFIC CONTROL SIGNAL Filed July 19, 1955 4 Sheets-Sheet 3 IN VEN TOR. 'PEPCY BAILEY PEA/SHAW ATTORNEYS.

NOV. 15, 1938. p B) s w 2,136,955

TRAFFIC- CONTROL SIGNAL Filed July 19, 1935 4 Sheets-Sheet 4 Me: i 610:: VI

I N V EN TOR. PEQCV 5M5 y PE/VsHA w BY I M,@nm ATTORNEYS.

Patented Nov. 15, 1938 UNITED STATES PATENT OFFICE TRAFFIC CONTROL SIGNAL England Application July 19, 1933, Serial No. 681,051 7 In Great Britain July 23, 1932 1'7 Claims.

The presentinvention relates to traflic control systems for use at road junctions or the like and is more particularly'concerned with systems in which the operation of the signals is produced by the traiiic passing on the roads to be controlled. Systems of this type in present use give excellent results where the trafiiic is reasonably continuous and have without doubt been instrumental in reducing congestion and promoting safety. In times of light trafiic, however, the driver of an oncoming vehicle seeing the signals set in his favour when he is a considerable distance from the crossing may be tempted to excessive speed and then not be able to pull up if the signals change when he is close to the crossing due to a vehicle arriving on a conflicting road. This difiiculty is particularly likely to occur late at night or in the early morning at crossings where the normal day traffic is heavy and the detectors have therefore to be located comparatively near to-the crossing. The object of the invention is to overcome this possible disadvantage by arranging that the signals do not change to the clear position until the traffic requiring their use is comparatively close to the crossing. If it is arranged that the signals are extinguished at times of light traffic and only brought into operation when actually required an appreciable saving in current consumption may also be realized.

According to one feature of the invention in a traffic control system adapted when there is no trafiic on any of the traffic routes controlled thereby to display to each of the routes the same signal which is different from any displayed when the signal controlling equipment is in operation traffic-operated devices are arranged to initiate the effective operation of the signal controlling equipment which is adapted to give right of way to the various trafiic routes in turn in accordance with the traffic thereon.

According to another feature of the invention in a traffic control system a caution signal is provided prior to a change of the signals only when the right of way is about to be forcibly removed from a particular approach.

Reference is had to the attached sheets of drawings illustrating practical embodiments of the invention and in which:

Fig. 1 illustrates one form of wiring diagram which may be utilized to provide a system in accordance with the teachings of the present invention;

Fig. 2 shows a layout of apparatus such as may be employed at an intersection;

Fig. 3 shows a wiring diagram whereby a slightly difierent method of operation may be secured from that which follows the diagram of Fig. 1;

Fig. 4 is a plan view of a timing and controlling mechanism which preferably forms a part of the system;

Fig. 5 is an end elevation of the same;

Figs. 6 and '7 are fragmentary transverse sectional views taken along the line 6-6 and 'I1 and in the direction of the arrows as indicated in Fig. 4; and

Fig. 8 shows a chart by means of which the position of the various switches shown in the preceding views may be followed.

Figure 9 shows a wiring diagram for a modification of Figure 1 where the green signals are to be extinguished when the amber signals are lighted.

Figure 10 shows a wiring diagram illustrating a modification of Figure 1 along lines somewhat similar to the modification shown in Figure 3 but which illuminates an amber globe instead of flashing signals or ordinary signals in the absence of traffic.

Figure 11 shows a wiring diagram illustrating a further modification of Figure 1 to provide for the more usual amber signals for each change of right of way.

An alternative connection via switch GZ is shown dotted in Fig. 1 due to the fact that the controller is arranged to function either on a single-colour or a three-colour lamp scheme. In the former case the alternative connection via switch GZ may be omitted or the switch GZ opened and the controller will then normally show a red light to all approaches, this light being extinguished on the road securing the right of way. A warning bell is caused to ring when the right of way is about to be transferred from one approach to the other after the maximum period allowable. When the alternative connection is used, the controller will still show a red light to all approaches but this is replaced by a green light on the road securing the right of way and moreover the warning signal is given by an amber light instead of a bell, the bell in this case preferably being disconnected by opening the switch BZ.

Referring now to Fig. 1, it will be appreciated that the controller is arranged for operation from alternating current mains and suitable rectifying arrangements are provided in the form of a thermionic valve VLV and transformer HV by means of which direct current is obtained for operating the neon lamps. Conveniently the live side of the alternating current mains is connected to terminals TC and TD of the transformers HV and LV while the earthed side is connected to the terminal TA. By means of the transformer LV a reduced potential of 12 volts A. C. is available at the terminal TP for operating the relays in the controller, while the filament of the valve is lit bya small tapping on transformer I-IV.

One preferred form of switch controlling andtiming mechanism has been shown in Figs. 4 to 7, in which the numeral 30 indicates a rotatably mounted shaft to which cams 3| are secured. The shaft and cams are rotated as, for example, by means of having an annular ratchet 32 secured to the shaft, the teeth of this ratchet being engaged first by a pawl 33 which prevents (as shown) other than a clockwise movement of the shaft, and a further pawl 33 which is connected by a link 34 to the armature 35 of the electromagnet S. As shown, the pawl 33' is preferably urged into contact with the teeth of the ratchet by means of a spring, and a stop 36 limits the movement of this member. An energization of the electromagnet S causes the pawl to override one tooth of the ratchet, and a subsequent deenergization of the electromagnet causes the armature 35, the link 34, and the pawl to move upwardly, thereby advancing the ratchet one tooth and rotating the shaft 30 to a corresponding extent. This result obtains in view of the fact that a lever 37 is rockingly mounted upon the shaft 30, and has one end secured to the link 34, its opposite end being attached to a spring 38 which normally urges this end downwardly. In line with the latter end of the lever are switch members 5 8 and s and each time the magnet S is energized the lever engages these members to close the same. In view of the fact that these switches include merely a pair of contacts mounted upon spring arms, it will be obvious that as the lever has its end drawn downwardly by the spring 38, these switch elements will resume their normal open condition. The dwell and land portions of the cams 3| serve to cause opening and closing of switch elements to 0 inclusive, as shown in Figs. 1 and 3. As illustrated, the cycle of operation of the system includes six steps, and accordingly the shaft 30 must advance through six positions to complete a cycle. In order to avoid difficulty incident to advancing the shaft by pawl and ratchet mechanism, the ratchet may include, as shown, eighteen teeth, and each cam may provide, in triplicate, operative portions. In this manner it will only be necessary to rotate the shaft 30 through 120 degrees to complete one cycle, and it will additionally be noted that the cams may operate more than one switch element 39, so that accordingly the entire size of this unit may be considerably diminished.

In order that the condition of the various switches may readily be followed throughout the several positions of the apparatus, reference may be had to Fig. 8, in which a chart having six sub-divisions corresponding to the several positions is shown, and in which the switches are identified by characters and numerals adjacent the left hand margin of the chart. The heavy lines indicate a closed condition of the switches, and extend throughout the position in which such closing occurs.

. If it is assumed that the controller is working on the single colour plan, and that the cam shaft is in its sixth position, the red lamps REW,

Fig. 1, on the east-west road will be lighted over cam contacts CH, while the timing condenser QA, Fig. 1, will be charging from potential supplied by way of the valve rectifier over a circuit including the cam springs C4, Fig. 1, and the variable resistance controlled by the vehicle interval switch VNS. Four such variable switches are shown in Fig. 1 and the terminals of these switches are connected as shown with tapping points X2 to XII! of the common resistance. Conveniently the common resistance may be built up of a plurality of 200,000 ohm resistances connected in series, each of which in the circumstances assumed represents a charging time of the condenser QA equivalent to one second, so that in the extreme case each switch may be set to a time period of 10 seconds. Further traffic along the north-south road will intermittently operate relay E, Fig. 1, from the road pad NSD, and this relay at armature 62, in conjunction with the cam springs C and the armature 92 of relay G, shunts. the condenser QA by the resistance YD so that itis unable to at tain the striking voltage of the neon lamp FA.

If it is now assumed that there is no traflic on the east-west road, and a prolonged gap ocours in the traffic on the north-south road, the condenser QA will continue to charge until it reaches the striking potential of the neon lamp FA which is however, prevented from flashing at this time since the cam contacts C1! are opened, and although the cam contacts C6 are closed there is no circuit over armature (12 because there is no trafiic on the east-west road to operate relay D.

The charging of condenser QA will therefore continue until it reaches the strilnng potential of the neon lamp PC, which thereupon flashes and operates relay C. It should be explained that the neon lamp F0 is specially chosen to have a striking voltage at least volts higher than the striking voltage of the lamp FA so that when both lamps are in circuit the lamp FA will always strike first. Relay C at armature cl, Fig. l, operates relay F which looks over its armature fl and the cam springs C8, at armature f2 opens the circuit for relay C and at armature f3 connects the red lamps RNS for northsouth in parallel with the red lamps REW for east-west, thereby showing a red signal to all roads.

It now a further vehicle crosses one of the north-south road pads, relay E will operate, and at armature e3 releases relay F so as to extinguish the red light on the north-south road and provide this traffic with the right of way. Relay E also at armature e2 shunts the condenser QA and after a period allowing suflicient time for the vehicle to clear the crossing which period is determined by the charging time of condenser QA over the vehicle interval switch VNS, the neon lamp FC will again flash to bring up relays C and F so that the latter then locks in the circuit previously traced and re-lights the red lamps on the north-south road.

Should a vehicle now cross one of the eastwest road pads designated EWD, relay D operates and locks over cam contacts Cl and completes a circuit at armature d2 over cam contacts C6 for discharging the condenser QA through the neon lamp FA and relay A. Relay A therefore energizes and at armature ai completes a circuit for the solenoid S which advances the cam shaft into its first position, and also at springs S3 operated thereby shunts the condenser QA third position.

by way of resistance YA. In this position the red lamps for north-south and east-west are lighted over the cam springs C2l and CH regardless of the condition of relay F which may possibly be released by a call from the northsouth road, and a charging circuit is completed for the condenser QA over the cam springs CIS and variable all red after north-south switch ARN which connects with the common resistance X2 to X!!! in Fig. 1. After a comparatively short period the lamp FA again strikes over armature 112 and cam contacts 06 and the cam shaft is advanced into its second position where the red lamps for east-west are extinguished by the opening of cam contacts CH and the red lamps for north-south are maintained lighted over cam contacts C22. The charging circuit for the condenser QA is now completed over cam springs CM and the adjustable resistance controlled from the initial interval east-west switch IEW, and after a further short period the lamp FA will again strike to advance the cam shaft into its In this position the red lamps for north-south are maintained lighted over cam contacts C22 and relay D is released by the opening of cam contacts Cl. If continuous traiiic is encountered on the east-west road, the intermittent operation of relay D from the road pad E-WD will intermittently shunt the condenser QA over armature d2 of relay D, cam contacts C16, armature Q2 of relay G and resistance YD to prevent it attaining the striking voltage of the neon lamp FC, and this condition will ob tained indefinitely provided there is no call for right of way from the north-south road. It will be noted that the neon lamp FA cannot strike in position 3 of the controller in response to the operation of the relay D as the cam contacts C6 are opened.

If during this condition a vehicle crosses one of the north-south road pads relay E operates and locks over its armature el and cam contacts C18, and at armature e2 in conjunction with the cam contacts CI'I provides a charging circuit for a maximum timing condenser QB, Fig. 1, in series with the appropriate resistance controlled from the maximum east-west switch MXE and cam contacts CIZ. A similar maximum switch is provided for north-south trailic designated MXN and connected with cam contacts Cl and as shown in the drawings, the contacts of these switches connelct with tapping points Xl2 to XI! on the common resistance. In this case the common resistance is conveniently built up of a series of separate resistances of the order of 1 or 2. megohms each, and assuming the capacity of the condenser QB to be the same as that of condenser QA, it will be appreciated that timing periods of much longer duration can be provided for. Relay E moreover connects the neon lamp FA in circuit with the condenser QA but as this circuit is being intermittently shunted at armature d2 as a result of the continuous stream of traffic passing over the east-west road detectors, the lamp FA is prevented from striking. The charging of the maximum timing condenser QB however continues without interruption regardless of the traffic along the east-west road, and when the full period has elapsed, the neon lamp FB will flash and operate relay B. Relay B at armature bl, Fig. 1, looks the road relay D in parallel with the road relay E, and at armature b2 operates relay G which looks over its own contact 91, the cam contacts CIS and contacts of relay D. Relay G moreover at armature gl opens the shunt path to the condenser QA and at armature g4, Fig. 1, completes a circuit for ringing the warning bell ALB. Owing to the opening of armature 92 the condenser QA is now able to complete the last vehicle interval extension by charging to the striking voltage of lamp FA. When the requisite voltage is attained, the lamp FA flashes and operates relay A which in turns completes the circuit of the solenoil S to step the cam shaft into its fourth position, thereby lighting the red lamp-s to both roads over the cam springs C22 and Clll, and over cam springs C2 and the adjustable switch ARE corresponding to all red after east-west completes a charging circuit for the condenser QA. Relay G is released by the opening of cam springs CIB but it will be noticed that relay D remains held over springs S2 operated by the solenoid, and subsequently when the cam shaft has completed its step this relay looks over cam springs C1.

The artificial operation and locking of the respective road relays on roads from which the right of way is forcibly removed is particularly important, since it ensures that the right of way will eventually revert back to this road in order to liberate any vehicles which may have stopped between the road pad and the crossing. Normally the stopping of vehicles between the road pad and the crossing will not happen since the vehicle interval timing allows a suflicient period for vehicles travelling at the normal speed to get clear, but in case a vehicle is forced to slow down or stop by interference with other signals or pedestrians or for some other reason it may be unable to clear the crossing, and if the signals were not arranged to revert, this vehicle would then become isolated between the road pad and the crossing until a further vehicle operated the corresponding road pad.

Whenever the maximum period elapses in the cycle of operations the warning bell ALB will ring for the remainder of the last right of way extension, thereby giving a warning of the impending change to a driver who was between the crossing and the pad when the bell started ringing. If a gap occurs in the line of traflic on the road in possession of the right of way, no vehicle will be nearer to the crossing than the pad when the signals change, so that no bell warning is required and the non-discriminating period is commenced immediately. In this manner the best use is made of the time available for each cycle of signals and no time is wasted on unnecessary warning periods.

It may be mentioned that the contacts c4 and (14. by cutting in additional resistance when actuated while the cam shaft is in position I or position 4 respectively serve to give a so-called all-red extension to prevent the right-of-way being given before the crossing is clear. This extension under control of contacts ed and (14 may be rendered eifective or inefiective if desired by operation of the switch-es AZN and AZE shown, closure of the respective switches rendering the respective extensions ineffective. The switches EW and NS are so-called arterial switches and the operation of either ensures that the cam shaft will take up such a position that from the all-red condition due to no trafiic the right-of-way may be given to the associated road immediately the road pad is operated, switch NS when closed alone causing the cam shaft to return to rest in position 6 and switch EW when closed alone causing return to rest in position 3 in the absence of traffic.

When both switches ill NS and EW are closed the controller operates continuously in the absence of trafiic, remaining in

positions

3 and 6 for minimum periods.

The normal preferred form. of operation with switches NS and EW shown open will now be summarized. If the cam controller has stopped in position 3, and there has been no traffic on either street for some time, tube FC functions and causes a display of all red in all directions with relay F locked in energized position. The apparatus stays in this condition as a normal condition in the absence of traffic.

Case I.If now a single actuation on EW street occurs with no NS actuations, right of way is immediately given to the EW street and relay F released. After a predetermined period tube FC again functions to rest-ore the said normal conditions.

Case II.If instead of a single actuation there is a continuous stream of EW traific with no NS traflic, right of way is maintained to EW traffic independently, but if EW traific' ceases again the tube FC again functions to restore normal all red.

In both of the Cases I and II the controller has not been moved from position 3. It is obvious that with the controller in position 3 as in Cases I and II above, an NS vehicle can arrive:

(a) While the signals are in so called normal conditions, that is, red displayed in all directions due to operation of tube FC and relay F because of no traffic; or

(b) While right of way is displayed to EW due to a single EW actuation (Case I) or due to continuous actuation (Case II).

Considering these cases in more detail it is noted that Case (a) If the apparatus is in the normal state, displaying all red indications, and a single actuation on NS only occurs, this immediately actuates the controller to position 4 wherein all red is continued for a predetermined period and then the controller moves to position 5 where right of way is given to the NS street only, by extinguishing the NS red signal. After a predetermined time the controller goes to position 6 but no change of signals occurs. In this position the signal display will ultimately restore to all red thru operation of relay F by tube FC if there is no further traflic.

Case (b) .If the apparatus is displaying right of way to EW (by maintaining the EW red signal only extinguished) due to EW actuation as in Case I, and a single NS actuation occurs, a circuit for relay A is closed so that when condenser QA is charged to 'suflicient value for tube FA, or if already charged thereto but not sufficient to discharge tube FC, tube FA breaks down and steps the controller to position 4 from which it proceeds as described above to position 6, and ultimately gives all red indications in this position by operation of relay F by tube FC, if there is no further traffic.

If the apparatus is displaying right of way to EW (by maintaining the EW red signal only extinguished) in either Case I or Case II and a single NS actuation occurs the maximum timer is initiated into action. This has no ultimate effect in Case I but in Case II where substantially continuous EW actuation occurs the maximum timer continues to complete its timing action to permit condenser QB to operate relay B thru tube FB after the maximum time interval to permit tube FA to operate to step the controller to position 4 from which it proceeds thru position 5 to position 6 as above described. After remaining in position 6 for a minimum time interval for the NS trafiic or for an extended interval up to the NS maximum if further NS actuations occur, the controller proceeds automatically thru positions I and 2 back to position 3 because relay D has been locked in energized position by operation of the maximum timer when the controller last left position 3. With no further NS actuations the controller remains in position 3.

Case III.-With continuous traflic' in both directions the right of way alternates dependent upon the time of charging condenser QB plus the increment of time necessary to bring condenser QA up to full charge after relay G has operated to remove additional shunting of condenser QA by subsequent vehicles as above described.

In case the controller is required to work on the three colour system, the switch GZ may be closed and the bell ALB may be omitted or disconnected by opening switch BZ. Potential is thus connected over the back contact of armature 14 to the cam springs C9 and C20 which serve for lighting the green and amber lamps. The operation of the controller insofar as its timing functions are concerned is identical with that already described but in this case when relay F releases to disconnect the red signal for the road enquiring the right of way, a circuit is completed over armature f4 and the cam springs C9 or C20 for lighting the appropriate green signal lamps. Moreover when the right of way is about to be forcibly changed as a result of its being retained by one road for the maximum period, the operation of relay G brings up relay GU which at armatures gal and guZ connects the amber signal lamps in parallel with the green signal lamps for both roads. By this means the amber signal lamps for the road in possession of the right of way are lit in addition to the green signal lamps to warn the moving trailic that the right of way is about to be removed. Clearly it would be readily possible by extending the connection to the green lamps over back contacts of armature gal and guZ to arrange that the green lamps were extinguished when the amber lamps were lighted. Such a modification is shown in Fig. 9.

Although in the example described it has been arranged for the lanterns to show an all-red signal in the absence of trafiic requiring the right-of-way, it will be appreciated that this particular signal is by no means essential, since substantially the same result could be obtained by providing for instance a flashing amber signal or in fact any type of signal which would serve to indicate the presence of the controller without discriminating between the difierent traffic routes. It is further conceivable that the actual control signals themselves may be completely extinguished by energization of relay F and their presence indicated by a special signal for instance an amber globe located above them which could be illuminated permanently by continuous connection to the mains, to or alternatively might be connected to the mains by a front contact on armature f5 for example as shown in Figure 10 show only during periods of absence of traflic. A further possibility is to dispense with all signals entirely during periods of absence of trafiic but in these circumstances it would be probably be desirable to position the road detectors further away from the crossing than is normally the case in order to allow the lighting of the signals in time to be effective on approach of traffic which may be unaware of their presence. As an alternative to the remote positioning of the detectors two sets of road detectors might be employed, arranged for example as in U. S. Patent No. 2,016,325 issued on October 8, 1935, to Charles D. Geer, one set comparatively distant from the crossing to render signals effective and a second set position as in usual practice to control their operation. In such arrangements with the signals normally extinguished in the absence oi": traffic, the approach of the first vehicle on the street which last had the right of way would immediately illuminate the signals to accord right of way to that street thru the energization of relay F. If the first vehicle however approached on the street opposite to that which had previously had the right of way, the signals would be illuminated to accord right of way to the street of the vehicle as soon as the cam shaft had shifted thru the clearance position or if it were desired to have clearance signals illuminated immediately it is obvious that the cam contacts C3 and CIS could be arranged to be made only in

positions

6 and 3 respectively thus interrupting the locking circuit of relay F in the clearance positions I and 4.

The modifications to the circuits for the first of these alternative arrangements are shown in Fig. 3, this arrangement making it possible to show a flashing amber signal during periods of light trafiic in place of the all-red signal previously described. It will be seen that relay F in operating breaks the circuit between points PI and P2 at armature f as shown in Fig. 3 and together with armature f4 as shown in Fig. 1, now disconnects the supply from the ordinary red and green signal lamps so that they are extinguished, and completes a circuit for the amber signal lamps connected in parallel with the coil of an interrupter FL. The interrupter FL controls a pivoted armature f I provided with an adjustable balance weight by means of which it may be adjusted to vibrate at a low speed, and at a contact controlled by this armature provides a flashing circuit for the amber signal lamps. With this arrangement a display of red in all directions will still take place when right-of-way is being transferred during ordinary operation.

It will be understood that the invention is also readily applicable to give the more usual signal sequence in which a warning signal is given each time right-of-way is transferred and not only when forcible transfer takes place. In this case the signals might be arranged to be operated by the cam contacts in the more usual fashion as shown for example in Figure 11, the cam contacts being closed in the same positions as indicated in the table in Figure 8 but the cams CB and Cl 9 in the lock-in circuit of relay F might preferably be closed only in the

positions

6 and 3 respectively. In this case the switch GZ would be closed but the coil of relay GU preferably disconnected, as for example by a switch GUZ. They would then operate normally as long as traffic was reasonably continuous and to be extinguished entirely when there was no trafiio requiring their operation, their presence being indicated if desired by the lighting of an amber globe as outlined above.

It will also be appreciated that the arrangements may be either as described in which the signals are automatically changed to a non-discriminatory condition at times of light traflic or this method of working may only be brought about in response to the operation of a switch 49 which may be manually or otherwise controlled, the signals continuing to display right-of-way to one trafiic route at other times even in the absence of trafiic. This latter arrangement might be employed if it were considered desirable to have the signals always in operation during the daytime and to change over say at midnight so that they were only called into operation when actually required. The invention is not of course limited to the use of electric lamps for giving the required signals.

In accordance with' the invention, therefore, a traffic signalling system has been devised in which in times of light trafiic there is normally no dis crimination as regardsthe diiTerent trafiic routes, that is to say, the signals may be of one colour, e, g. red, or they may be extinguished entirely or their presence may merely be indicated by'an amber or other special light so that traffic is not incited to excessive speed by receiving right of way when it is a considerable distance from the crossing. When the trafl-lc nears the crossing, however, the detectors serve to bring the signals into action and if there is any danger of conflict, the signals determine in the usual manner which road shall receive priority.

From the foregoing it will be understood that a system is. provided in which, among others, the several objects of the invention as specifically afore noted are achieved. As aforebrought out, the nondiscriminating condition may, for example, embrace an indication of interruption to right of way to the traific lanes, may include an energization of cautionary indicationindividual orcommon to the lanes; may embrace total absence of signal indication to the lanes, or any other non-discriminating condition which may seem best suited to the particular needs of the installation. Likewise, the intersection at which the signal is provided might include any number of lanes, and in this case or in the case of merely two intersecting lanes, trafiic actuated controls might-except where otherwise indicated in the claimsbe included in merely one lane. Obviously, many other changes of construction and rearrangement of the apparatus might be resorted to without departing from the'spirit of the invention as defined by the claims.

1. A traffic control system for an intersection of a plurality of traific lanes including in combination signalling means for according and interrupting right of way in each of the lanes, traffic actuated means in each of the lanes, and a timer connected to the signalling means. and to the trafiic actuated means and adapted to cause the signalling means to interrupt and transfer right of way between the lanes in accordance with actuations of the traffic actuated means, means forming a part of said timer and operable to cause said signalling means to interrupt right of way in all lanes within a predetermined period after the last actuation on any lane and until further actuation, and means forming a part of said timer and operable to cause the interruption of right of way in all lanes to be maintained for a shorter predetermined period after the next actuation and before according right of way in the event that such next actuation occurs on a lane different from the lane of such last actuation.

2. A traflic control system for the intersection of a plurality of trafiic lanes including in combination signalling means for according and interrupting right of way in each of the lines, traffic actuated means in each of the lanes, and a timer connected to the signalling means and the trafiic actuated means, and adapted to control the former in response to operation of the latter, said timer including means operable normally in the absence of any traffic actuation to cause interruption of right of way in all lanes, means operable upon actuation only in one lane occurring after a period of absence of all actuation to accord right of way to said one lane, means operable a predetermined time after the last actuation in said one lane of any actuations occurring while right of way is accorded to said one lane and in the absence of actuation in any other lane to restore the normal indications, means operable upon actuation in a second lane while right of way is accorded to said one lane to cause interruption of right of way in said one lane a shorter predetermined time after the last actuation in said one lane and thereupon to transfer right of way to the second lane before right of way is again accorded to said one lane.

3. A traflic control system for an intersection of a plurality of traflic lanes including in combination signalling means for according and interrupting right of way in each of the lanes, traffic actuated means in each of the lanes, and a timer connected to the signalling means and to the trafiic actuated means and adapted to cause the signalling means to interrupt and transfer right of way between the lanes in accordance with actuations of the trafiio actuated means, means forming a part of said timer and operable normally in the absence of any traffic actuation to cause interruption of right of Way in all lanes by indications of said signalling means, further means operable upon actuation in one lane to accord right of way to said lane for a predetermined period and then cause restoration of the normal indications, means operable upon actuation in a second lane before said restoration of normal indications to cause transfer of right of way to said second lane after an intervening period of such normal indications and means operable upon actuation in the first lane during said intervening period to extend said intervening period.

4. A traflic control system for the intersection of a plurality of trafiic lanes, including in combination signalling means displayable for interrupting right of way in each of the lanes, traffic actuated means in each of the lanes, a timer connected to the signalling means and to the traflic actuated means and adapted to cause the signalling means to be displayed to all except one of said lanes to provide right of way for such one lane and to transfer such right of way for one lane at a time to the several lanes successively in accordance with actuations of the respective traffic actuated means, means forming a part of the timer and operable in response to the first actuation of one of said trafiic actuated means to cause interruption of right of way solely in the lanes of the other traffic actuated means for a predetermined period, means operable upon actuation in the same lane during said predetermined period to extend said period, means operable upon successive actuations in said lane continuing during said extended period and upon actuation in a second lane during said extended period to cause transfer of right of way to said second lane after a predetermined maximum period by display of said signal in said same lane and cessation of such display in said second lane, a cautionary signal forming a part of said signalling means and means operable only upon such transfer of right of way at said predetermined maximum period to cause display of said cautionary signal.

5. A traffic control system for the intersection of a plurality of trailic lanes, signalling means for displaying stop indications in each of the lanes, a trafi'ic actuated means in one of said lanes, timing means connected to said signalling means and to said traffic actuated means and operable for normally causing display of stop indications in all lanes in the absence of actuation of said traffic actuated means and upon actuation of the latter to cause the former to extinguish the stop indication solely in the said one lane for a predetermined period and thereupon restore normal stop indications in all lanes, said timer comprising a condenser, means connected to said condenser to charge the same upon actuation of the traffic actuated means in said one lane, means including charge responsive means and connected to said condenser and operable upon said condenser reaching a predetermined charge to cause termination of said period of extinguished stop indication in said one lane and restore the normal indications, and means operable upon actuation during said period to discharge said condenser to delay such charging action and thus to prolong said period, a second traflic actuated means in a second lane, means operable upon actuation of said second trafiic actuated means during said period for preventing after a predetermined period begin ning with such actuation of said second trafiic actuated means further discharge of said condenser by said first traflic actuated means during said period of extinguished stop indication in said one lane.

6. A traffic control system for the intersection of a plurality of trafiic lanes including in combination signalling means for displaying stop indications to each of the lanes, trafiic actuated means in each of the lanes, a timer connected to said signalling means and trailic actuated means and adapted to cause the former to extinguish the stop indication solely in any one of the lanes for a predetermined period in response to actuation in said one lane, and thereafter in the absence of further actuation cause display of stop indications in all lanes, means forming a part of said timer to cause successive extinguishment of stop indication solely in a first and then solely in a second lane upon successive actuations within a predetermined period in the said first and second lanes so as to cause transfer of right of way from the first to the second lane, said timer including a condenser, means for charging the condenser and connected to the same upon extinguishment of stop indication in the first lane, a charge responsive means connected to said condenser upon actuation in the second lane while the stop indication is extinguished in the first lane and operable upon the condenser reaching a predetermined charge to cause said transfer of right of way to the second lane, a second charge responsive means connected to said condenser while the stop indication is so extinguished in the first lane and operable upon the condenser reaching a predetermined charge higher than that of the first mentioned charge responsive means in the absence of such actuation on the second lane to cause restoration of the stop indication in said first lane whereby said signalling means will display such indication in all lanes in the absence of further actuation.

"7. A I traffic control system for intersecting traffic lanes including signalling means for according and interrupting right of way in such lanes, traffic actuated means in one of said lanes, a timer connected to said signalling means and traffic actuated means and operating, to cause the signalling means in response to actuation of the traffic actuated means to accord right of way to the lane of the latter for at least a minimum period of time and normally to terminate right of way in such lane at the end of said period, means cooperating with said timer and acting in response to each further traffic actuation while right of way is accorded to said one lane to continue the right of way accordation for an extension period after each such actuation, maximum timing means acting after a predetermined period of right of way in said one lane to render said last named means unresponsive to further actuation ofthe traffic actuated means whereby right of way on said one lane will be terminated after completion of the last said extension period in spite of further actuations, and means functioning upon said maximum timing means so acting and during the remainder of the last said extension period to give indication to said one lane that right of way is about to be terminated therein.

8. In a traflic control system for intersecting traffic lanes having signalling means for displaying stop indications to each of said lanes, a trafiic actuatable device for each lane, and a timer for operating said signalling means to stop traffic alternately in each of said lanes so as to permit traffic to proceed in the other lane in response 'to actuation of said devices in said lanes by traffic, the provision in said timer of a rotary switching mechanism having a plurality of contact positions including one for normally displaying the stop indication on the first of said lanes only to permit traffic to proceed in the second, a second position for normally displaying the stop indication on the second of said lanes only to permit traffic to proceed on the firstpa timing means operated by said switching means in its first position to cause at the end of a time period and in event of actuation of said device on said first lane the shift of said mechanism to its second position, and means cooperating with said timing means and operating while said mechanism is in said first position at the end of a time period longer than that first mentioned and in the absence of actuation on said lanes to cause the display of a stop indication in said second lane whereby stop indications will thereafter be displayed in both lanes.

9. In a traffic control system for intersecting trafiic lanes having signalling means for displaying stop indications to each of said lanes, a trafiic actuatable device for each lane, and a timer for operating said signalling means to stop trafiic alternately in each of said lanes so as to permit traffic to proceed in the other lane in response to actuation of said devices in said lanes by traffic, the provision in said timer of a rotary switching mechanism having a plurality of contact positions including one for normally displaying the stop indication on the first of said lanes only to permit traffic to proceed in the second, a second position for normally displaying the stop indication on the second of said lanes only to permit traffic to proceed on the first, a timing means operated by said switching means in its first position to cause at the end of a time period'and in event of actuation of said device on said first lane the shift of said mechanism to its second position, means cooperating with said timing means and operating while said mechanism is in said first position at the end of a time period longer than that first mentioned and in the absence of actuation on saidlanes to cause the display of a stop indicationin said second lane whereby stop indications will thereupon be displayed in both lanes, and means acting while stop indications are so displayed in both lanes and in response to traffic actuation on said second lane to extinguish the stop signal on said second lane only and to reset said timing means to retime the periods mentioned whereby traflic may proceed on such lane for a further period.

' 10. In a trafiic control system for intersecting traffic lanes having signalling means for displaying stop indications to each of said lanes, a traffic actuatable device for each lane, and a timer for operating said signalling means to stop trafiic alternately in each of said lanes so as to permit traffic to proceed in the other lane in response to actuation of said devices in said lanes by trafiic, the provision in said timer of a rotary switching mechanism having a plurality of contact positions including one for normally displaying the stop indication on the first of said lanes only to permit traffic to proceed in the second, a second position for normally displaying the stop indication on the second of said lanes only to permit traffic to proceed on the first, a timing means operated by said switching means in its first position to cause at the end of a time period and inievent of actuation of said device on said first lane the shift of said mechanism to its second position, ,means cooperating with said timing means and opertaing while said mechanism is in said first position at the end of a time period longer than that first mentioned and in the absence of actuation on said lanes to cause the display of a stop indication in said second lane whereby stop indications will thereafter be displayed in both lanes, and means acting in response to traffic actuation in said second lane before the end of said longer time period to reset said timing means to retime the periods mentioned so as to delay the display of the stop signal in said second lane.

11. A traflic control system for the intersection of a plurality of traffic lanes, signalling means for displaying stop indications in each of the lanes, trafiic actuated means in each of the lanes, switching means for operating said signalling means and operating to assume one switching position to extinguish the stop indications solely in one lane in response to traific actuation therein and a second position to extinguish the stop indications solely in a second lane in response to actuation in the lane, and to cause display of stop indications in all lanes in continued absence of all actuation, a condenser, means connected to said condenser insaid first position of said switching means to vary the charge on said condenser from an initial value toward a predetermined value over a time period, means operating upon traffic actuation in said one lane while the stop indication is extinguished therein to vary the charge on said condenser back toward said initial value, means operated by actuation in said second lane while the stop indication is so extinguished in said one lane and responsive to the charge on said condenser exceeding a certain value between said absence of such actuation in said one lane to cause operation of said switching means into said second position, and further means responsive to the charge on said condenser reaching said predetermined value in the absence of such actuation on said second lane and in the continued absence of actuation on all lanes while said switching means is in said first position to cause the display of said stop indication in said one lane so as to provide stop indications in all lanes after a time period of absence of actuations.

12. A traflic control system for intersecting trafiic lanes having signalling means for displaying green, red and amber signals to each lane for indicating respectively accord of right of way, interruption of right of way and change of right of way to traffic proceeding in the lanes, trafiic actuated means in said lanes, a timing mechanism connected to said signalling means and operating to cause the signalling means to accord the green signal to one of the lanes at a time while according the red signal to the other lane in response to actuation of the traffic actuated means, timing means in said mechanism for timing a minimum period of display of the green signal to one of the lanes in response to traffic actuation to cause said mechanism to terminate said green signal display in such lane normally at the end of said period, means cooperating with said timing means and acting in response to each further traffic actuation in the lane to which the green signal is displayed to continue the display of the green signal for an extension period after each such actuation, maximum timing means initiated into operation by actuation in the lane having the red signal and acting after a predetermined period of display of the green signal to said one lane to render said last named means non-responsive to further actuation of the traffic actuated means whereby the green signal will be accorded to the other lane after completion of the last said extension period on said one lane in spite of further actuations thereon, means including a relay operating upon said maximum timing means so acting, and means including contacts on said relay to cause the signalling means to terminate display of the green signal and to display said amber signal to said one lane in lieu thereof until the end of such last extension period.

" 13. In a trafiic control system for intersecting trafiic lanes having signalling means for displaying Stop indications to each of said lanes, a traffic actuatable device for each lane, and a timer for operating said signalling means to stop traffic alternately in each of said lanes so as to permit traffic to proceed in the other lane in response to actuation of said devices in said lanes by traffic, the provision in said timer of a rotary switching mechanism having a plurality of contact positions, a circuit for said signalling means completed in one of such positions for normally displaying a Stop indication on the first of said lanes only to permit traflic to proceed in the second, a second circuit completed in a second of such positions for normally displaying the Stop indication on the second of said lanes only to permit traific to proceed on the first, a timing means operated by said switching means in its first position to cause at the end of a time period and in event of actuation of said device on said first lane the shift of said means to its second position, means including a relay and operating while said mechanism is in said first position at the end of a time period longer than that first mentioned and In the absence of actuation on said lanes, and contact means operated upon operation of said relay to cause said second circuit to display a Stop indication in said second lane whereby Stop indications will be thereafter displayed in both lanes as long as absence of traffic actuation persists.

14. In a traffic control system for interfering trafi'lc lanes having signalling means for displaying green and red signals to each lane for indicating respectively accord of right of way and interruption of right of way to trafiic proceeding in the lanes, trafiic actuated devices in the lanes, and a timer for operating the signalling means to accord the green signal to one of the lanes at a time while according the red signal to the other lane in response to actuation of said devices in said lanes by trafiic, the provision in said timer of a rotary switching mechanism having a plurality of contact positions for operating said signalling means and including one for normally displaying a red signal to one of the lanes and a green signal to the second lane to accord right of way to traffic in the second, a second position for normally displaying a red signal to the second of said lanes and a green signal to the first to accord right of way to trafiic in the first, a timing means operated by said switching means in its first position to cause at the end of a time period and in event of actuation of said device on said first lane the shift of said mechanism to its second position, and means cooperating with said timing means and operating while said mechanism is in said first position at the end of a time period longer than that first mentioned and in the absence of actuation on said lanes to extinguish the display of the green signal to said second lane and to cause the display of the red signal to said second lane whereby the red signals will thereafter be displayed to both lanes as long as such absence of traffic actuation persists.

15. In a trafiic control system for interfering trafiic lanes having signalling means for displaying green and red signals to each lane for indi- 'cating respectively accord of right of way and interruption of right of way to traffic proceeding in the lanes, traflic actuated devices in the lanes, and a timer for operating the signalling means to accord the green signal to one of the lanes at a time while according the red signal to the other lane in response to actuation of said device in said lanes by traffic, the provision in said timer of a rotary switching mechanism having a plurality of contact positions, circuits for said signalling means and completed in one of such positions for normally displaying a red signal to one of said lanes and a green signal to the second lane to accord right of way to traffic in the second, other circuits completed in a second of such positions for normally displaying a red signal to the second of said lanes and a green signal to the first to accord right of way to trafiic in the first, a timing means operated by said switching means in said first position to cause at the end of a time period and in the event of actuation in said device on said first lane the shift of said mechanism to its second position, means including a relay and operating while said means is in said first position at the end of a time period longer than that first mentioned and in the absence of traffic actuation on said lanes, contact means operated upon operation of said relay to break the circuit for displaying the green signal to said second lane and to complete the circuit for displaying the red signal to said sec- 0nd lane whereby red signals will thereafter be displayed in both lanes as long as such absence of traffic actuation persists.

16. In a traffic control system for interfering traflic lanes having signalling means for displaying green and red signals to each lane for indicating respectively accord of right of way and interruption of right of way to traffic proceeding in the lanes, traffic actuated devices in the lanes, and a timer for operating the signalling means to accord the green signal to one of the lanes at a time while according the red signal to the other lane in response to actuation of said device in said lanes by traific, the provision in said timer of a rotary switching mechanism having a plurality of contact positions, circuits for said signalling means and completed in one of such positions for normally displaying .a red signal to one of said lanes and a green signal to the second lane to accord right of way to traflic in the second, other circuits completed in a second of such positions for normally displaying a red signal to the second of said lanes and a green signal to the first to accord right of way to traffic in the first, a timing means operated by said switching means in said first position to cause at the end of a time period and in the event of actuation of said device on said first lane the shift of said mechanism to its second position, means including a relay and operating while said means is in said first position at the end of a time period longer than that first mentioned and in the absence of traific actuation on said lanes, and contact means on said relay operated upon operation of said relay to interrupt all said signal circuits whereby no signal will be displayed until the next actuation of one of the traffic actuated devices occurs.

17. In a trafiic control system for interfering traffic lanes having signalling means for displaying green and red signals to each lane for indicating respectively accord of right of way and interruption of right of way to traffic proceeding in the lanes, trafiic actuated devices in the lanes, and a timer for operating the signalling means to accord the green signal to one of the lanes at a time while according the red signal to the other lane in response to actuation of said device in said lanes by traffic, the provision in said timer ofa rotary switching mechanism having a plurality of contact positions, circuits for said signalling means completed in one of such positions for normally displaying a red signal to one of said lanes and a green signal to the second lane to accord right of way to traffic in the second, other circuits completed in a second of such positions for normally displaying a red signal to the second of said lanes and a green signal to the first to accord right of way to traflic in the first, a timing means operated by said switching means in said first position to cause at the end of a time period and in the event of actuation of said device on said first lane the shift of said mechanism to its second position, means including a relay and operating while said means is in said first position at the end of a time period longer than that first mentioned and in the absence of traflic actuation on said lanes, a non-discriminatory signal for displaying a cautionary indication to all the lanes and a circuit for operating such signal when said circuit is completed, and contact means on said relay for interrupting all said green and red signal circuits upon operation of said relay and completing the circuit for operating said nondiscriminatory signal.

PERCY BAILEY RENSHAW.