US3783446A

US3783446A - Traffic control system

Info

Publication number: US3783446A
Application number: US00206274A
Authority: US
Inventors: J Mcgimpsey
Original assignee: Individual
Current assignee: Individual
Priority date: 1971-12-09
Filing date: 1971-12-09
Publication date: 1974-01-01
Anticipated expiration: 1991-01-01

Abstract

A traffic control and warning system for the control of traffic characterized by a series of traffic lights selectively operated through relays which are operated by switches located in the roadway and which switches are tripped by the wheels of a vehicle. Provision is made for warning drivers when a vehicle stalls in the roadway.

Description

United States Patent [191 McGimpsey 1 TRAFFIC CONTROL SYSTEM [76] Inventor: John W. McGimpsey, 83 Oakdene Ave, Teaneck, NJ. 07666 [22] Filed: Dec. 9, 1971 [21] Appl. No.: 206,274

[52] US. Cl 340/31 R [51] Int. Cl G08g l/02 [58] Field of Search 340/31 R, 38 R, 35, 340/41, 22,31 A, 38 L [56] References Cited UNITED STATES PATENTS 3,618,003 11/1971 Marshall 340/31 R 3,593,262

7/1971 Spencer .7 340/36 1 Jan. 1, 1974 6/1971 Davin 340/31 R 9/1966 Barker 340/31 R Primary Examiner-Kathleen H. Claffy Assistant Examiner-Randall P. Myers Atl0rneyReno A. Del Ben [57] ABSTRACT A traffic control and warning system for the control of traffic characterized by a series of traffic lights selectively operated through relays which are operated by switches located in the roadway and which switches are tripped by the wheels of a vehicle. Provision is made for warning drivers when a vehicle stalls in the roadway.

4 C aims 5 Qrewingfi PAIENIEDJAH 1 m4 SHEET 2 BF 3 Eu mm mm um vw INVENTOR W MCGIMPSEY V ATTORNEY PATENIEB 3, 783.446

SHEET 3 OF INVENTOR JOHN W. MCGIMPSEY ATTORNEY TRAFFIC ,CONTROL SYSTEM This invention dealswith traffic control devices, and in particular with switching mechanisms for controlling traffic and the speed of traffic along various portions of a route, with particular emphasis on the control of traffic where vision is obscured, such ,as by.heavy fog.

In the past, it has frequently been necessary on highspeed roads, such asturnpike s, to close said roads or take other drastic. action.-to;prevent accidents and multiple-car collisions. Various attemptshave been made to alleviate the fog-conditions, whichattempts have gone so far as to theinstallation of fans in attempts to blow-off the fog fromthe roadway. The methods which have'been tried havegenerally been ineffective and costly.

The present invention .attempts a solution, of this problem by providing a traffic signal system operated by pads or contact bars: installed in the roadway along those sections of the roadway persistently troubled by fog problems or other problems of obscured vision, whereby a driver may be warned when a car is either immediately in front of the driver or else has stalled on the roadway.

One of the objects of this invention is to provide a warning signal system for fogbound roadways whereby traffic can be effectively. and easily controlled.

Another object of this invention is to providea signal system which will let a driver known what to do without actually seeing what is ahead of him.

Still another object of this inventionis to provide a signal system which will automatically alert adriver to expect an emergency situation ahead of him so that the driver can take appropriate action in advance.

Another object of the inventionis to prevent vehicles from riding too close together andwarning vehicles when a vehicle is stopped by reason of a malfunction on fog bound roads.

These and other objects of the invention will appear from time to time as these specifications proceed and with reference to the accompanying drawings, wherein:

F IG. 1 is a view of a typical road interchange, showing a portion of the invention in place.

FIG. 2 is a plan view of a contact bar assembly, part of the invention.

FIG. 3 is a cross-sectional view. of the contact bar assembly of FIG. 2, taken on the plane 3-3 ofFIG. 2.

F IG. .4 is a schematic diagram of a portion of the wiring circuitry of the invention; indicating. the various relays of the invention andthe connections thereto.

FIG. 4A is a schematic diagram of a. portion of the wiring circuitry of the invention, and is an extension of the schematic diagramof FlG.,4, linesnumbered 11 through 37 of FIG. 4A 1 being continuations respectively, of lines numbered ll through 37 ofsFlG...4, and indicating the connections of the various relays to stop lights and road contact bars.

Referring to the drawings in-which the same numerals are used for the identical or similar parts in the various drawings:

Generally the inventionisdesigned primarily to provide a warning signal system for fogbound turnpikes and thruways, and for this purpose contact bar assemblies, 100, are installedin the roadway and include electrical contacts for controlling relays which control spotlights.

The contact bar assemblies, designated generally by the numeral 100, typically comprise a contact bar,.l01,

which installed substantially level with a roadway, springs, 102, installedin a cavity .103 in the roadbed under the contact bar 101 and which support the contact bar, mating rigid supportsil04 provided on the contact bar 101 and in the cavity .103, which will support the contact bar 101 whenthe springs 102 have been depressed a predetermined distance and at least one momentary contact switch installed in the cavity 103 and operated by the depression of the contact bar 101. There are two types of momentary contact switches 105 a momentary open, normally closed momentary contact switch, 109, anda momentary close, normally open momentary contact switch, 110. A momentary close, normally open momentary contact switch, 110, comprises at leasttwo electrical contacts .106 installed in the cavity 103 and attached by suitable .less than the mating portions of the rigid supports 104 so that depressing the contact bar 101 will cause the bus bar 107 to make contact .with the electrical contacts 106, closing one and opening the other circuit between the electrical contacts 106. A momentary open, normally closed momentary contact switch, 109, comprises at least two electrical contacts 111 installed in the cavity 103 and attached by suitable leads to the various relays of the invention and a bus bar 107 supported on springs 108. The ends of the electrical contacts 111 are formed so that they extend above. the bus bar 107 and make contact with same wherethe contact bar 101 is not depressed. The bus bar 107 is supported in such a manner that. it will break contact with the electrical contacts 111 when the contact bar 101 is depressed.

In the various drawings, specific contact bar assemblies and their various parts are designated by the

numerals

117, 118, 119, 120, 121,122, 123, and 124.

cle, a momentary contact switch in the contact bar assembly is closed and energizes a relay which puts on a red light at the station associated with this contact. bar

assembly and at the same time breaking contactfor a red light at the previous station and putting on a green light at this previous station. These stations can be spaced apart according to the best safety rules.

The only way a red light willgo off .is by a vehicle depressing a contact bar on the road at the next station ahead of this red light. When this happens this red light changes to a green light allowing traffic to move to the next station.

According to this system, all .vehicles would be spaced equally far apart unless a vehicle would choose to go past a red light. If all vehicles travel at the same speed each light will go, green asthe various vehicles reach contact bars. If, on the otherhand, the speeds are different, the red lights will-stop traffic, being controlled by the speed of thevehiclle that is ahead. The system can be turned on when fogappears, and can be shut off during periods of normal visibility. An audible signal can be installed in conjunction with the visible signals.

When a light does not change from red to green within a specified period of time such as would occur when a vehicle became disabled, a time delay switch which is incorporated in the circuitry changes the red light to a blinker light, thereby allowing traffic to proceed while warning of a possible obstruction ahead. A manual reset is provided to put the system back into normal operation when the obstruction has been eliminated.

At a section of roadway which includes an intersection a contact bar assembly No. 118 is installed at a predetermined distance from a side road entry and when a vehicle on the main road depresses the contact bar 101 of contact bar assembly No. 118 in the main road the side road red light is put on, stopping side road traffic.

When a vehicle on the main road hits the contact bar 101 of contact bar assembly No. 119 at the intersection, it will cancel this red light 168 and put a green light 162 on the preceding station and a red light 168 on the side road, and it also puts red light 164 on.

When a vehicle approaches the main road from the side road it will depress the contact bar 101 of contact bar assembly No. 122, energizing by-pass relay No. 61, and will prevent the main road red light No. 164 from going off due to a vehicle on the main road depressing contact bar 101 of contact bar assembly No. 120. At the same time the side road red light 168 will go off and the side road green light 170 will go on, allowing the vehicle on the side road to enter the main road. The side road vehicle then passes over the stop line, which is located between contact bar assemblies No. 122 and No. 123, and will depress bar 101 of contact bar assembly 123, and in so doing cuts the power to coil of bypass relay No. 61. The vehicle entering then proceeds to contact bar assembly No. 124 which, when its contact bar 101 is depressed, will put on

red light

164 and 168.

When the vehicle leaves the main road to get off on side road it will depress the contact bar 101 of contact bar assembly 121 on the side road which will cancel red light 160 and put on green light 162 at the preceding station.

Referring now to FIGS. 4 and 4A, switch No. 52 and No. 62 are time delay relay switches. Switches No. 56 and No. 66 are normally closed push-button switches which can be momentarily opened to reset certain relays, as hereinafter indicated.

Relays No. 51, 57, 58, 59, 60, and 61 are double pole double throw relays, having respectively,

terminals

511 and 512, 571, and 572, 581 and 582, 591 and 592, 601 and 602, 611 and 612 connected to the opposite sides of their respective coils. The contact bar, 150, of each respective relay is in the position where the conductors of the respective contact 'bar makes contact, respectively with

terminals

513 and 514, 573 and 574, 583 and 584, 593 and 594, 603 and 604, and 613 and 614, of the respective relay with which the contact bar is associated when the respective coil is not energized.

Relays N0. 53, 54, 63 and 64 are double pole-single throw relays of the normally closed circuit type, having, respectively,

terminals

531 and 532, 541 and 542, 631 and 632, and 641 and 642 connected to opposite sides of their respective coils. The contact bars, 150, of the relays are positioned so that they make contact, respectively, with

terminals

533 and 534, 543 and 544, 633 and 634, and 643 and 644 when the coil is not energized.

Relays No. 55 and 65 are double-pole single throw relays of the normally open circuit type, having, respectively,

terminals

551 and 552, and 651 and 652 connected to opposite sides of their respective coils. The contact bars, 150, of the relays are positioned so that they do not make contact, respectively, with

terminals

555 and 556, and 655 and 656, when the coil is not energized.

Lines designated L1 and L2 are opposite sides of a source of electrical power, the side designated L1 being preferably the ground side, while the side designated L2 is preferably the hot side.

The operation of the relays is as follows:

When the contact bar 101 of the contact bar assembly No. 117 in the main road is depressed by the weight of a vehicle the normally open momentary contact switch 109 of contact bar assembly 117 is closed allowing current to flow from power line L2 to the normally closed momentary contact switch 109 in contact bar assembly 121 and then to one of the normally closed momentary contact switch 109 in contact bar assembly 119 and then to the normally closed push button station 56 and then through to one side of relay 5] energizing the coil of relay 51. The movable contact bar of the relay of which the two poles are connected to power lines 61 and 62 respectively through

terminals

515 and 516, are put in contact by the energized coil with the two

terminals

517 and 518 allowing current to flow in the red light and allowing current to flow in time delay relay 52. In the event that the vehicle does not reach contact bar assembly 119 due to a malfunction, at a set time the time delay relay 52 will energize the coil of relay 53 causing the cancellation of the main road red light 160 and cancelling relay 54. When relay 54 is not energized the time delay switch puts current into the blinker light flasher 163 which in turn causes the yellow light 161 to flash continuously. The blinker light flasher 163 will stay on until cancelled by opening the normally closed push button switch 56, which will also cause the red and green lights to operate in a normal mode. Relay 55 which is also energized by time delay relay 52 by-passes normally closed momentary contact switch 109 of the Contact bar assembly 119 preventing the opening of this circuit and putting on green light 162 while the blinker light flasher is in service.

When the vehicle does not have a malfunction it will continue on to contact bar assembly 118 closing switch 110 of bar assembly 118. Current from power line L2 will go through said switch 110 of contact bar assembly 118 and then through the normally closed momentary contact switch 109 of contact bar assembly 119 to terminal 572 of relay 57 energizing the coil and putting on side road red light 168. When the vehicle depresses bar 101 of contact bar assembly 119 it will open momentary contact switch 109 coming from the contact bar assembly 118 circuit, cancelling current relay 57 and cutting off power to side road red light 168. The normally closed momentary contact switch 109 of contact bar assembly 119 coming from the contact bar assembly 121 circuit will open, cancelling current to terminal 512 of the coil of relay 51 which relay 51 will cancel red light 160 at contact bar assembly 117, cutting power to time delay relay 52 which cancels relay 53, relay 54 and relay 55. Green light 162 will be on at bar 117 when relay 51 is not energized.

The normally open momentary contact switch 110 of contact bar assembly 119 when depressed will close, allowing current to flow through the normally closed momentary contact switch 109 of contact bar assembly 120 to

terminals

642 and 646 of relay 64 to terminal 602 of relay 60, putting on side road red light 168, to terminal 582 of relay 58, putting contact bar 150 of relay 58 in contact with the terminals of relay 58 which puts on red light at bar 119 and puts time delay relay 62 in service. This circuit from normally open momentary contact switch 110 of contact bar assembly 119 also permits current to flow through the L2 line side of relay 59 which cancels side road green light 170. Relays 53 and 55 which are maintaining circuits are supplied power by time delay relay 52. Relays 63, 64, and 65 are supplied power bytime delay relay 62. When a vehicle reaches contact bar assembly 120 a normally closed momentary contact switch 109 will open, cutting power to relays 58, 59, and 60, putting on green lights 166 on main road and 170 on side road entry. When a vehicle coming from side road entry depresses bar 101 of contact bar assembly 122 the normally open momentary contact switch 110 closes allowing current to flow through the normally closed momentary contact switch 109 of contact bar assembly 123 to terminal 612 of relay 61, which bypasses normally closed momentary contact switch 109 at contact bar assembly 120 preventing opening of circuit when contact bar 101 of contact bar assembly 120 is depressed, so that red light 164 and green light 170 will remain on allowing side road vehicle to proceed on to main road. If a vehicle fails to reach contact bar assembly 120 due to malfunction the time delay relay 62 at a set time will allow current to flow into terminal 652 of relay 65 permitting bypassing of the normally closed momentary contact switch 109 of contact bar assembly 120 preventing

green lights

166 and 170 from coming on. At the same time relay 62 will allow current to flow into terminals 632 of relay 63 energizingthe coil. Relay 62 when energized will open the circuit to the main road red light 164 and open circuit to relay 64 putting on blinker

light flashers

167 and 171 which will cause

yellow lights

165 and 169 respectively to flash continuously. When the disabled vehicle is removed, a nor mally closed push button 66 is provided which can be pushed, cancelling blinker

light flashers

167 and 171 and putting red and green light system into normal ser vice again.

When a vehicle chooses to exit at a side road it will depress a contact bar in the exit road such as contact bar 101 of contract bar assembly 121, which will open circuit from switch 110 of contract bar assembly 117 to switch 109 of contact bar assembly 119 cancelling current to relay 51 and putting on green light 162 at contact bar assembly 117.

The switch 110 of contact bar assembly 120 is connected to the subsequent contact bar assembly which is identical to contact bar assembly 117. The switch 109 of contact bar assembly 117 is connected to a switch similar to switch .110 of contact bar assembly 120, in the preceding contact bar assembly. In this i and so on to the other preceding stations, putting all these stations on blinker lights assuming that all these stations are on red lights. If any are on green lights there is no problem. To avoid this the time setting can be arranged so that there would be a difference of a few seconds between each station. This could be done in groups of five or ten stations so that there would not be too long a time delay between a large group of stations.

The time delay relays may be wired to a monitored centrally located indicator panel, wired in parallel with the various yellow lights, to aid authorities in determining the location of possible problems in traffic.

Considering now the operation of the system during its different phases:

When there is no traffic in a typical stage or approaching the stage from the immediately preceding stage, the coils of the various relays are not energized, and electrical current flows from line L2 to terminal 516, thence to terminal 514, along line 17 to green light 162, illuminating same, thence along line 14 to terminal 513, thence to terminal 515 which is grounded to line L1. At the same time electrical current flows from line L2 to terminal 596, thence to terminal 594, then along line 21 to green light 170, illuminating same, thence along line 27 to terminal 573 thence to terminal 575 thence to terminal 593, thence to terminal 595 which is grounded to line L1. At the same time electrical current flows from line L2 to terminal 586 thence to terminal 584 thence along line 29 to green light 166, illuminating same, thence along line 22 to terminal 582 thence to terminal 585 which is grounded to line Ll, thus all traffic lights are green in the particular stage.

When a car approaches the stage, it passes over contact bar assembly 117 causing switch of contact bar assembly 117 to momentarily close, resulting in electrical power from line L2 flowing from terminal 516 along line 16, through switch 110 of contact bar assembly 117 to switch 109 of contact bar assembly 121, thence to switch 109 of contact bar assembly 119, thence along line 19 to terminal 553 thence to switch 56 thence to terminal 512, energizing the coil of relay 51, thence to terminal 542 and terminal 546. At the same time power flows from terminal 553 to terminal 555 and along line 18 to switch 109 of contact bar assembly 121, resulting in the coil of relay 5] being kept energized. The energizing of relay 51 starts the timer 52, since electrical power now flows from terminal 516 to terminal 518 and then to timer 52. The power flowing out of terminal 518 also flows to terminal 534, thence to terminal 536 and to red light 160, energizing same immediately behind the car passing over contact bar assembly 117, thence to terminal 517, thence to terminal 515 which is groundedto line L1. At the same time relay 54 is energized, since terminal 541 is grounded through terminals 533, 534, and 517. If the car does not proceed to one of the next contact bar assemblies, the timer will, after a predetermined time interval, energize the coils of relays 53 and 54, breaking the connections to red light 160, and de-energizing relay 54, causing electrical powerfrom terminal 546 to flow to terminal 544, thence along line 15 to blinker flasher 163, which will send intermittent power to yellow light 161, energizing same, which blinker flasher 163 and yellow light 161 are grounded by means of line 11, and

terminals

543, 517, and 51:5 to line L1.

If the car exits at the ramp, it will pass over contact bar 121, breaking the electrical connection through switch 109 of contact bar 121, which will result in the breaking of the electrical connection to the coil of relay 51, causing electrical power to flow from line L2 through terminal 516, thence to terminal 514, then along line 17 to green light 162, energizing same, thence along line 14 to terminal 513, thence to terminal 515 which is grounded to line L1, and at the same time de-energizing either light 160 or light 161, whichever was energized in the manner previously indicated.

If, instead of exiting, the car continues to contact bar assembly 118, it will momentarily close switch 110 of contact bar assembly 118. This will cause electrical power to flow from line L2, through switch 110 of contact bar assembly 118, through switch 109 of contact bar assembly 119 which is connected to switch 110 of contact bar assembly 118, along line 26 to terminal 572, energizing the coil of relay 57 and causing electrical power to flow from line L2 along line 31 to red light 168, illuminating same, thence along line 30 to terminal 577, thence to terminal 575 which is connected to terminal 593 and which is grounded to line Ll through terminal 595, at the same time stopping the flow of electrical power to green light 170. As the car continues, it will pass over contact bar assembly 119, momentarily opening switch 109 and closing switch 110, allowing electrical power to flow from line L2 along line 20, through switch 110 of contact bar assembly 119, along line 28 and line 35 to switch 109 of contact bar assembly 120, along line 37 to

terminals

602 and 582, energizing the coils of

relays

60 and 58. This allows electrical power to flow from line L2 through terminal 606, through terminal 608 to terminal 634 to red light 164, illuminating same directly behind the car, then along line 24 to terminal 636 which is not connected electrically to terminal 634, then to terminal 608 which is grounded through terminal 606 to line L2. At the same time electrical power flows from line L2, along line 31 to red light 168, illuminating same, then along line 30 to terminal 607 which is now connected electrically to grounded terminal 605. At the same time the flow of electrical power to

green lights

166 and 170 is interrupted. Meanwhile the electrical power which had been flowing through switch 109 of contact bar assembly 119 has been momentarily interrupted, causing the coil of relay 51 to be de-energized, resulting in the flow of electrical power from line L2 through terminal 516, then to terminal 514, along line 17 to green light 162, illuminating same, then along line 14 through terminal 513, to grounded terminal 515, at the same time interrupting the flow of electrical power to red light 160. As the car continues it will pass over contact bar assembly 120, momentarily opening switch 109 of contact bar assembly 120. This interrupts the flow of electrical power which comes from line L2 through terminals 596, then through terminal 598, through push button switch 66 to contact bar assembly 120, and thus de-energizing the coils of

relays

58 and 59, resulting in electrical power flowing from line L2 through terminal 586, then through terminal 584, along line 29 to green light 166, illuminating same, then along line 22, through terminal 582, then through terminal 585 to ground line Ll, while at the same time electrical power flows from line L2 by way of terminal 596, then terminal 594, then line 21 to green light 170, illuminating same, then along line 27, then terminal 573, then terminal 575, then terminal 593 to terminal 595 which is grounded, and at the same time the flow of electrical power to

red lights

164 and 168 is interrupted.

If a car approaches the main highway from the entry ramp, it will first pass over contact bar assembly 122,

momentarily closing switch of contact bar assembly 122. This will cause electrical power to flow momentarily from line L2 along line 20 through switch 110 of contact bar assembly 122 to switch 109 of contact bar assembly 123 and along line 33 to terminal 612 energizing the coil of relay 61 and causing contacts 615 and 617 to be electrically connected and contacts 616 and 618 to be electrically connected through the bus bar of relay 61 and locked in place by the flow of electrical power from line L2 through terminal 616, then through terminal 618, along line 32 through switch 109 of contact bar assembly 123, along line 33 to terminal 612 of the coil of relay 61, the other terminal 611 of the coil of relay 61 being grounded to line Ll. When the car reaches contact bar assembly 123, switch 109 of contact bar assembly 123 is momentarily opened breaking the circuit through the coil of relay 61 and de-energizing same. When the car reaches contact bar assembly 124 it momentarily closes switch 110 of contact bar assembly 124 causing a circuit to be made from line L2 through switch 110 of contact bar assembly 124, along line 28, through switch 66, through terminal 598, to terminal 596, and back to line L2, and causes electrical power to flow from said circuit at switch 66, along line 35 through switch 109 of contact bar assembly to terminals 582 and 592, energizing the coils of

relays

58 and 59, and causing electrical current to flow from line L2-through terminal 586, through terminal 588, through time delay switch 62 to terminal 632, energizing the coil of relay 63, back through the ground side of time delay switch 62, to terminal 587 and then to terminal 585, which is grounded. This allows electrical current to flow from line L2 through red light 168, illuminating same directly behind the car, along line 30 to terminal 577, then to terminal 593, then to terminal 595, and then to ground line L1. At the same time electrical current flows from line L2 through terminal 596, through terminal 598, through terminal 634, through terminal 636 to red light 164, illuminating same, then back to ground along line 25, terminal 587 and terminal 585. Simultaneously, electrical power to green lights 166 and is interrupted.

When the vehicle reaches contact bar assembly 120,

red lights

164 and 168 are extinguished and

green lights

166 and 170 are illuminated as previously indicated.

The foregoing is a typical illustration of the flow of electricity through different portions of the circuits during various phases of operation of the invention.

1 claim:

1. A traffic control system, for use in controlling traffic traveling along a uni-directional roadway having separate entrances and exits, comprising a series of traffic control zones, each of said zones comprising:

at least one entering detector for sensing the entrance of a vehicle into the zone; at least one exiting detector for sensing the exiting of a vehicle from the zone;

at least one traffic signal installed at the entrance to said zone and at each entrance to the said roadway to control traffic travelling along said roadway and entering onto said roadway; each of said traffic signals being provided with a plurality of differently colored lights;

light controlling switch means operated by said entering and exiting detectors to control the lighting of said differently colored lights, said entering and exiting detectors being connected to said light controlling switch means in such a manner as to control the lighting of the various lights located at the entrances to the zone and to the preceding zone, so that when a vehicle is detected entering the zone by an entering detector, its presence within the zone is indicated at the entrances to the zone, and when the vehicle is detected leaving the zone by an exiting detector, itsabsence from the zone is indicated at each entrance to the zone; and

timing means operating in conjunction with said light controlling switch means to activate lights at each entrance to a zone 'to indicate when a possible obstruction in the form of a stopped vehicle may be expected in the zone, said timing means being adapted to transmit a signal to activate warning lights at the entrances to a zone when a vehicle in the zone fails to pass from an entering detector to an exiting detector of the zone within a predetermined interval of time; and

an entering detector being provided at each entrance to the roadway to sense the approach of a vehicle at an entrance to the roadway and the traffic control system being adapted to control the same entry of the vehicle onto the roadway and to cause the lights at the entrances to the zone to indicate that the entering vehicle is in the zone associated with the roadway entrance.

2. A traffic control system as claimed in claim 1 wherein the entering detectors and the exiting detectors comprise pressure operated switching means which comprise a plurality of contact bar assemblies installed in cavities in said roadway and at the entrances and exits to said roadway, each of said contact bar assemblies comprising a contact bar mounted substantially level with the surface of the roadway and perpendicularly movable with respect to said surface of the roadway, rigid supports for limiting said perpendicular movement of said contact bar, spring means for supporting said contact bar substantially level with the roadway when there is no stress placed on said contact bar, and momentary contact switch means operated by the said perpendicular movement of said contact bar.

3. A traffic control system as; claimed in claim 1 wherein the light controlling switch means to control the delivery of electrical power to said lights comprises

Claims

1. A traffic control system, for use in controlling traffic traveling along a uni-directional roadway having separate entrances and exits, comprising a series of traffic control zones, each of said zones comprising: at least one entering detector for sensing the entrance of a vehicle into the zone; at least one exiting detector for sensing the exiting of a vehicle from the zone; at least one traffic signal installed at the entrance to said zone and at each entrance to the said roadway to control traffic travelling along said roadway and entering onto said roadway; each of said traffic signals being provided with a plurality of differently colored lights; light controlling switch means operated by said entering and exiting detectors to control the lighting of said differently colored lights, said entering and exiting detectors being connected to said light controlling switch means in such a manner as to control the lighting of the various lights located at the entrances to the zone and to the preceding zone, so that when a vehicle is detected entering the zone by an entering detector, its presence within the zone is indicated at the entrances to the zone, and when the vehicle is detected leaving the zone by an exiting detector, its absence from the zone is indicated at each entrance to the zone; and timing means operating in conjunction with said light controlling switch means to activate lights at each entrance to a zone to indicate when a possible obstruction in the form of a stopped vehicle may be expected in the zone, said timing means being adapted to transmit a signal to activate warning lights at the entrances to a zone when a vehicle in the zone fails to pass from an entering detector to an exiting detector of the zone within a predetermined interval of time; and an entering detector being provided at each entrance to the roadway to sense the approach of a vehicle at an entrance to the roadway and the traffic control system being adapted to control the same entry of the vehicle onto the roadway and to cause the lights at the entrances to the zone to indicate that the entering vehicle is in the zone associated with the roadway entrance.

3. A traffic control system as claimed in claim 1 wherein the light controlling switch means to control the delivery of electrical power to said lights comprises a plurality of relays wired to said entering and exiting detectors.

4. A traffic control system as claimed in claim 1 wherein a flasher is provided which is operated by said timing means, which flasher provides electrical power to intermittently operate the lights used to warn about a possible obstruction, and manually operated reset means are provided which are adapted to by-pass the said timing means and to terminate the operation of the said warning lights.