Portable traffic control system

[57] ABSTRACT

A portable traffic control system for use along a stretch of road where normal traffic movement must be altered for one reason or another. The system includes a pair of remotely and independently radiocontrolled lamp-containing signal-display units which may be placed at opposite ends of the road stretch, and controlled by an operator from a remote handheld transmitter. Optical systems are provided in these units which enable the operator to monitor from the back sides of the units the lighted conditions of the lamps therein.

Claims, 3 Drawing Figures

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PATENTED mi 81975

3,867.718

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3,867,718

PORTABLE TRAFFIC CONTROL SYSTEM

BACKGROUND AND SUMMAARY OF THE INVENTION

This invention pertains to a portable traffic control system. More particularly, it pertains to such a system which may be used along a stretch of road where, because of construction or some other reason, normal traffic movement must temporarily be altered.

As is well known, there are many situations where normal traffic flow must be modified somewhat along a stretch of road to accommodate construction work, or sonjething else, which extends into the road. For example, there may be a stretch of road extending along a construction work zone where slow moving construction equipment may periodically enter for short periods of time. In such a situation, it may be desired to allow normal two-way traffic along the road stretch except at those times when equipment must enter the road—at which times traffic in both directions should temporarily be stopped. As another example, it is often the case that one of the lanes in a two-lane road must be blocked for an extended period of time, with alternate one-way traffic permitted along the other lane.

The present invention contemplates a novel portable traffic control system which may easily be set up for handling these and other similar circumstances for satisfactorily controlling traffic movement.

More specifically, the invention features a system comprising at least a pair of lamp-containing signaldisplay units which may be placed adjacent opposite ends of a road stretch where normal traffic movement must be altered. Radio-frequency remote control is employed in the system for controlling the lighted conditions of lamps in these units, with selective and independent control provided for the lamps in each of the units. With such selective and independent control provided, it is a simple matter for an operator of the system to adjust the lighted conditions of the lamps as desired to handle the particular traffic situation. In other words, the operator is provided a considerable amount of flexibility by the proposed system.

Another important feature of the invention is that means are provided in the signal-display units for indicating on the back sides thereof (i.e., those sides which face into a work zone), the particular lighted conditions then existing in the lamps in the units. With such a feature, it is a simple matter for an operator inside a work zone, i.e., between units, to know at all times exactly what the signal conditions are in the units. Such a feature is extremely important for reliable and safe control of traffic movement.

DESCRIPTION OF THE DRAWINGS

These and other objects and advantages attained by the invention will become more fully apparent as the description which follows is read in conjunction with the accompanying drawings, wherein:

FIG. 1 is a simplified side elevation illustrating a system as contemplated herein set up for controlling traffic movement along a stretch of road;

FIG. 2 is an enlarged fragmentary cross-sectional view, taken generally along the line 2—2 in FIG. 1, illustrating details of construction in one of the signaldisplay units in the system of FIG. 1; and

FIG. 3. is a diagram illustrating a circuit employed in the system of FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

Turning now to the drawings, and referring first to FIG. 1, indicated generally at 10 is an elongated stretch of read which extends along a construction work zone 12, in which zone is employed a portable traffic control system 14 constructed according to the present invention. System 14 herein includes a pair of signal-display units 16, 18, and a signal-display actuating means including a pair of radio-frequency receivers 20, 22 and a radiofrequency transmitter, or remote control device, 24. Receivers 20, 22 are associated with units 16, 18, respectively. Units 16, 18 are supported on stands 26, 28, respectively, along road 10 adjacent opposite ends of zone 12. Transmitter 24 is a hand-held unit which, in FIG. 1 is held by an operator 30 located in zone 12 between the signal-display units.

Further describing the two signal-display units, which are substantially identical in construction, and considering FIGS. 1 and 2 together, unit 16 includes a housing 32 inside of which are suitably mounted three vertically spaced electrical lamps, or signal-display elements, 34, 36, 38. Mounted on the front side of housing 32 directly in front of lamps 34,36,38 are three front lenses, or optical systems, 40, 42, 44, respectively. Lens 40 is red, lens 42 amber, and lens 44 green. Suitably mounted inside housing 32, for each of the three lamps therein, are reflecting mirrors such as mirror 46 (see FIG. 2) provided for lamp 38. These three mirrors reflect light from lamps 34, 36, 38, through rear lenses 48, 50, 52, respectively, which are mounted on the back side of housing 32. Lens 48 is red, lens 50 amber, and lens 52 green. Each such associated mirror-lens pair is referred to herein also as an optical system for its associated lamp. As can be seen clearly in FIG. 2, lenses 44, 52, which are associated with lamp 38, are constructed to project light therefrom outwardly in opposite directions from housing 32 along offset, nointersecting, substantially parallel and horizontal axes 55, 57, respectively. The reason for such an arrangement will be more fully explained later.

The optical systems just mentioned are also referred to herein as monitoring enabling means; and these optical systems, together with their associated lamps, constitute signal-display means.

As was mentioned earlier, unit 18 is substantially the same in construction as unit 16. Thus, unit 18 includes lamps 54,56,58 corresponding to lamps 34,36,38, respectively; front lenses 60, 62, 64 corresponding to front lenses 40, 42, 44, respectively; and reaar lenses 66, 68, 70 corresponding to rear lenses 48, 50, 52, respectively. As can be seen in FIG. 1, the signal-display units are positioned with their front lenses facing away from zone 12, and their rear lenses facing into the zone.

Provided for powering receivers 20, 22, and also the lamps in units 16,18, are batteries 72, 74, respectively. A cable 76 extends to unit 16, and a similar cable 78 extends to unit 18.

The transmitter and receivers employed in system 14 are conventional radio-control devices which communicate by way bf an amplitude-modulated radiofrequency wave. The particular transmitter employed herein is provided with two signaling buttons indicated at 24α, 24b. With the transmitter energized, on the operator operating button 24α, the carrier frequency of the transmitter is modulated at one preselected audio rate to which receiver 20 is tuned. Thus, operation of

3,867,718 transmitter button 24α causes a control signal to be transmitted to receiver 20. Such a control signal, however, is not responded to by receiver 22 which is tuned to respond to another audio-modulating rate which results with operation of transmitter button 24b. As a consequence of this arrangement, it will be apparent that the radio-frequency communication system provided enables selective and independent transmission of control signals to the two receivers associated with the two signal-display units.

But for the fact that rece ivers 20,22 are tuned, as just mentioned, to respond to different control signals coming from transmitter 24, the receivers are otherwise substantially identical in construction. In particular, and referring now to FIG. 3, each receiver, such as receiver 20, includes an output terminal, such as terminal 20α, on which a positive voltage pulse is produced on the receiver receiving and responding to a control signal from transmitter 24.

Explaining now further what is show in FIG. 3, indicated at 80, 82,84 are three relays which are employed in conjunction with receiver 20 and control unit 16. Relay 80 is a conventional stepping relay including a coil 80α, and three contacts 80b, 80c, 80d. Also included in this stepping relay is a rotary wiper 80e. Relay 82 is a conventional time-delay relay including a coil 82α, and a normally open contact 82b. On coil 82α being energized herein, a delay of about 6 seconds occurs before closure of contact 82b. Relay 84 includes a coil 84α and a normally open contact 84b.

The positive output terminal of battery 72 is connected to a conductor 86 which interconnects wiper 80e and the positive voltage supply terminal of receiver 20. The negative terminal of the battery is connected to a conductor 88 which extends both through cable 76 ³⁵ coil 84α, whereupon contact 84b again closes. And, to one set of sides of lamps 34, 36, 38, and also to the ..... negative supply terminal of receiver 20. Contacts 80b, 80c, 80d in relay 80 are connected through conductors 90, 92, 94, respectively, (which are contained in cable 76) to the other sides of lamps 34, 36, 38, respectively. One side of coil 80α in relay 80 is connected through a conductor 96 to one side of relay contact 84b. The other side of coil 80α is connected to a conductor 98 which interconnects conductor 86 and one side of relay . contact 82b.

The lower end of coil 82α in FIG. 3 is connected to conductor 88 through a conductor 100, and the upper end of this coil in the Figure is connected through a conductor 102 to conductor 92.

The other side of relay contact 82b is connected through a conductor 104 to a conductor 106 which interconnects the upper end of relay coil 84α and output terminal 20α in receiver 20. A conductor 108 connects the lower end of coil 84α and conductor 88. A conductor 110 connects conductor 108 to the other side of relay contact 84b.

A circuit similar to that just described in FIG. 3 interconnects unit 18, receiver 22 and battery 74.

Explaining now how the system described herein may be used, and considering, for example, the controlling of signal displays presented by unit 16, let us refer for this purpose to FIG. 3 in the drawings. Under the circumstances illustrated in this figure, the coils in relays 80, 82, 84 are deenergized, and lamp 34 is lit (i.e., is in a signaling state). As a consequence, beams of red light are projected from the lamp—forwardly through lens 40 and rearwardly through lens 48. This, of course, signals traffic approaching zone 12 from the left in FIG. 1 to stop.

When it is desired to change this condition to indicate that traffic from this direction can move through the work zone, button 24α in transmitter 24 is operated to send a control signal to receiver 20. On this occurring, the receiver produces a shortduration positive voltage pulse on its output terminal 20α, which pulse momentarily energizes coil 84α. With energizing of this coil, contact 84b closes momentarily to energize coil 80α whereupon, wiper 80e moves out of contact with contact 80b, and into contact with contact 80zZ. On such a change occurring, lamp 34 turns off (i.e., is placed in a nonsignaling state), and lamp 38 turns on. ' With lighting of lamp 38, beams of green light are projected therefrom—forwardly through lens 44 and rearwardly through lens 52. This situation remains until further operation of transmitter button 24α.

When it is desired to return to a condition with lamp ¹ 34 lit, transmitter button 24α is again operated to send another control signal to receiver 20. Receiver 20 then again supplies a momentary positive voltage pulse to its output terminal which causes momentary energizing of coil 84α and closing of contact 84b. Such action again results in momentary energizing of relay coil 80α, which energizing results in movement of wiper 80e into contact with relay contact 80c. With closure of wiper 80e and contact 80c, lamp 36 lights, causing beams of amber light to be projected from the lamp forwardly through lens 42 and rearwardly through lens 50.

In addition, relay coil 82α becomes energized, and about 6 seconds later, as mentioned earlier, closes its associated contact 82b. With closure of contact 82b, positive voltage from battery 72 is supplied to energize such action results in relay coil 80α again energizing, with the result that wiper 80e closes upon contact with 80b. Thus, lamp 36 turns off, and lamp 34 again lights up.

It will thus be apparent that successive operations of transmitter button 24α result, in one instance, in unit 16 changing from a condition displaying a red light to a condition displaying a green light, and in the next instance from a condition displaying a green light, through a condition temporarily displaying an amber light, and finally to a condition again displaying a red light. Such operation results without any change necessarily occurring in the lighted conditions of lamps in display unit 18.

Similar operation is, of course, producible with respect to the lamps in display unit 18 with successive operations of transmitter button 24b.

It will be apparent, therefore, that only a single operator is required to control the operations of the signal display units. This operator may be one who is located in the work zone, and who may perform therein tasks other than simply operating transmitter 24.

Because of the fact that the lighted conditions of the lamps inside the display units are monitorable from the rear sides of the units, i.e., within the work zone between them, an operator in the zone will always be able to tell exactly what the lighted condition of each display unit is.

With the lenses provided for each lamp in a display unit axially offset, and constructed to project light beams along offset nonintersecting axes, spurious light transmission directly from one lens to another is not

3,867,718 possible. Such transmission is, of course, undesirable, since it might result in a confusing indication as to the lighted condition in a display unit.

It should be noted that while a particular system has been described herein as having a particular arrangement of lamps and lenses, and as using only two signaldisplay units, modifications are possible. For example, there might be applications where a flashing amber light might be desired instead of a steady green light. Also, there might be situations where more than two independent signal-display units are wanted.

Thus, while an embodiment of the invention has been described herein, it is appreciated that various modifications may be made within the scope of the invention to take care of particular situations.