Traffic signal with integrated sensors

[0001] 1. Technical Field

[0002] The present invention relates generally to traffic signals and public lamps. Still more particularly, the present invention relates to a traffic signal and public lamps having one or more sensors integrated with a housing.

[0003] 2. Description of Related Art

[0004] Traffic signals for directing traffic at road intersections are ubiquitous and have been known for decades. More recently, traffic signal cabinets have been equipped with communications equipment that allows local law enforcement, fire departments, and various government agencies to better optimize the control of traffic signals. In addition, cameras and microphones have been located at various points at intersections to monitor traffic, detect violations of traffic laws, and generally monitor intersections for criminal activity. As used herein, the term “traffic signals” includes both traditional traffic signals, pedestrian crossing signals, railroad crossing signals, boating signals, and other signals useful for controlling the flow of vehicles and pedestrians.

[0005] Various government agencies responsible for maintaining intersections and traffic signals are interested in further increasing the ability to monitor intersections. For example, agencies responsible for civil defense are interested in adding nuclear, biological, or chemical sensors at intersections because the communications infrastructure required to coordinate so many of these sensors is likely to already be in place. However, the cost of many of these sensors can be high, especially because the sensors must be resistant to weather, vandalism, and other dangers. Thus, it would be advantageous to have an improved apparatus for providing a variety of sensors at traffic intersections.

[0006] The present invention provides an apparatus for integrating sensors with a traffic signal. The traffic signal includes a housing, a light source disposed within the housing, and a door operably attached to the housing. The door is configured such that photons generated by the light source may be sensed outside the housing. The traffic signal also includes a sensor attached to one of the door and the housing.

[0018] The description of the preferred embodiment of the present invention has been presented for purposes of illustration and description, but is not intended to be exhaustive or limited to the invention in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art. The embodiment was chosen and described in order to best explain the principles of the invention the practical application to enable others of ordinary skill in the art to understand the invention for various embodiments with various modifications as are suited to the particular use contemplated.

[0019] With reference now to the figures, FIG. 1 shows traffic signal 100 in accordance with an illustrative embodiment of the present invention. Traffic signal 100 includes three signal cases, such as signal cases 102, 104, and 106. These signal cases are connected to each other via rod 108. Rod 108 is attached to a traffic signal pole, wire, or other support, not shown, such that drivers can see traffic signal 100. Wires, cables, or other means for transferring power and data signals are attached to signal cases 102, 104, and 106, with wires or cables possibly routed through rod 108.

[0020] Each signal case includes a lens, such as lenses 110, 112, and 114, through which light is emitted. Each lens is provided with an appropriate color, such as red, yellow, and green, respectively, and possibly a mask, such as an arrow.

[0021] Traffic signal 100 may take a variety of forms. For example, more or fewer signal cases may be provided. Even one signal case may be utilized as a traffic signal. One or more signal cases, such as signal cases 102, 104, and 106, may be placed inside of a traffic light casing, as opposed to being connected together via rod 108. In addition, each signal case may be provided and deployed separately, such that a traffic light casing or rod is not required. Thus, the mechanism of the present invention may be provided in a wide variety of traffic light arrangements other than those shown. The particular arrangement of signal cases 102, 104, and 106 is present for purposes of illustration and not meant to imply architectural limitations as to the number or arrangement of different signal cases.

[0022] FIG. 2 shows a signal case for use in the traffic signal shown in FIG. 1 in accordance with an illustrative embodiment of the present invention. In this example, signal case 200 includes housing 202 and door 204. Door 204 also may be referred to as a lid, top, or cap. Although door 204 is connected to housing 202 via hinges 206, door 204 may be connected to housing 202 via any suitable method. For example, door 204 may be rotatably attached to housing 202, slidably attached to housing 202, screwed to housing 202, bolted to housing 202, adhered to housing 202, twistably attached to housing 202, and may be otherwise removably attachable to housing 202. In addition, one or more latches, brackets, screws, bolts, or other attachment means, not shown, may be used to secure door 204 to housing 202.

[0023] In the illustrative examples, door 204 is operably attached to housing 202 to allow access to the interior of housing 202. By being operably attached to housing 202, door 204 may be opened or otherwise removed to reveal the interior of housing 202. In another illustrative example, door 204 may instead be permanently attached to housing 202 such that door 204 becomes one of the sides of housing 202. Slot 208 is optionally provided, should signal case 200 take the form of one of the signal cases shown in FIG. 1.

[0024] Signal case 200 also includes light source module 210, which contains a light source. In an illustrative example, the light source is a solid-state light emitting diode array, such as that shown in Hutchison, Modular Upgradable Solid State Light Source for Traffic Control, U.S. Pat. No. 6,426,704 (Jul. 30, 2002). However, the light source may be an incandescent bulb or any other suitable light source. Photons emitted by the light source travel through lens 212 and thereafter may be sensed. In the depicted examples, door 204 is configured such that photons generated by the light source may be sensed outside housing 202. Thus, a driver can see light emitted through lens 212. As described above, lens 212 may be a variety of colors, such as red, yellow, green, and may be provided with a mask or silhouette, such as an arrow for indicating direction of traffic flow.

[0025] In FIG. 3, a diagram of an inside view of a door from FIG. 2 is depicted in accordance with an illustrative embodiment of the present invention. Door 300 shows the inside portion of door 204 in FIG. 2. In this example, door 300 is rotatably attached to housing 302 via hinges 304. Similarly, light source module 306 is attached to door 300, with a light source, not shown, disposed on the opposite side of light source module surface 308.

[0026] In addition, tab 310 is attached to door 300. Sensor 312 is attached to tab 310, though sensor 312 may be disposed elsewhere on door 300, within housing 302, or may be disposed outside signal case 330, such as in a separate housing attached to housing 302. Depending on the type of sensor used, aperture 314 may be placed in door 300 in any suitable manner that sensor 312 may be used. For example, if sensor 312 is a camera, then aperture 314 is configured such that light may travel from outside door 300 into the camera. In another example, if sensor 312 is a microphone, then aperture 314 may instead take the form of a cluster of small apertures instead of a single large aperture, as shown. The cluster of small apertures allows the microphone to more easily detect or sense sound waves from sources outside signal case 330, while protecting the microphone. In another example, if sensor 312 is a biological sensor, then aperture 314 may be a cluster of small apertures, a mesh, or a filter. Furthermore, a small fan may be attached to door 300, or otherwise provided in signal case 330, to draw outside air through door 300 and into the biological sensor. On the other hand, if sensor 312 is a nuclear sensor designed to detect or sense gamma rays, then aperture is not needed when housing 302 is made of plastic. Hence, at least one of housing 302 or door 300 may be adapted to allow the sensor to sense a parameter outside the housing. The term “sense” as used herein means to detect, sense, measure, or record a parameter. The parameter may be anything that can be detected, measured, or recorded by a sensor, such as light color or intensity, or any other kind of parameter in the case of different kinds of sensors, such as a radiation count or other parameters.

[0027] In this illustrative example, sensor 312 is disposed such that sensor 312 is located wholly inside housing 302 when door 300 is shut to provide maximum protection to sensor 312. However, a portion of sensor 312 may extend through aperture 314, if necessary or desirable for operation of sensor 312.

[0028] In addition to sensor 312, control board 316 may be provided to control operation of sensor 312. Control board 316 is operably connected to sensor 312 by any suitable means, such as via wires connected to pins 318, via a wireless connection, or by any other suitable method. By being operably connected to sensor 312, control board 316 is connected to sensor 312 in such a way that control board 316 may control the operation of sensor 312. Control board 316 may be a circuit board, computer card, or any suitable hardware and software for controlling sensor 312.

[0029] In turn, control board 316 is attached to backboard 320. Backboard 320 is attached to door 300. In this manner, control board 316 is attached to door 300 through its attachment to backboard 320. In these examples, backboard 320 provides a convenient surface to mount control board 316. However, control board 316 may be otherwise attached to other components in other locations, such as door 300, light source module 306, housing 302, or within housing 302 of signal case 330. In other illustrative examples, control board 316 may be placed in a separate protective housing disposed outside housing 302.

[0030] One or more of control board 316 and sensor 312 may be connected to a communications center and a power source via wired or wireless communications methods. The communications center allows a user to remotely control sensor 312 and to remotely gather data from sensor 312. Thus, for example, a user may monitor video or pictures from sensor 312 in the form of a camera. In another illustrative example, control board 316 may include one or more forms of non-volatile memory for storing data. Thus, pictures or other data may be stored in signal case 330 for later retrieval. Data may be retrieved directly by directly connecting to the non-volatile memory, or remotely via the communications center.

[0031] In addition, multiple sensors and tabs may be provided. For example, second tab 324 may be attached to door 300 and second sensor 326 may be attached to second tab 324. Second aperture 328 may also be provided, if necessary or desirable for the operation of second sensor 326. Second tab 324 and second sensor 326 may be sized, dimensioned, arranged, and may otherwise operate as described with respect to tab 310 and sensor 312.

[0032] In these illustrative examples, frame 322 is present. Tab 310, and optionally backboard 320, control board 316, second tab 324, and second sensor 326 may be attached to or otherwise be a part of frame 322. Frame 322 allows existing signal cases to be easily fitted with one or more sensors. Thus, in an existing signal case without sensors, door 300 may be opened, frame 322 attached to door 300 or housing 302 using screws, adhesives or other suitable methods, and apertures 314 and 328 drilled. Frame 322 may be removably attachable to door 300 or housing 302 such that frame 322 may be easily replaced.

[0033] Frame 322 may have a variety of shapes and dimensions, depending on the number and type of sensors used and the desired location of sensors within signal case 330. Frame 322 may extend over light source module 306 and may completely cover light source module 306. In this case, frame 322 may provide multiple tabs and may provide multiple mounting surfaces for multiple sensors and multiple control boards. In another illustrative example, frame 322 may be adjustable or one or more portions of frame 322 may be adjustable to allow easier access to sensors or control boards. As used herein, the term adjustable means flexible, movable, moldable, or otherwise capable of being adjusted such that a user may manipulate the frame or tab.

[0034] In other illustrative examples, one or more sensors may be attached to door 300 or housing 302 using tabs or other means, with control functions for the sensors provided at the communications center. Thus, control board 316 is optional. Likewise, tab 310 is optional if some other means is used to mount sensor 312 to door 300 or housing 302.

[0035] FIG. 4 shows a camera attached to a tab that is, itself, attached to the door of the signal case shown in FIG. 2 in accordance with an illustrative example of the present invention. Tab 400 is attached to door 402. Sensor 404 is attached to tab 400 opposite aperture 406. Light source module 408, hinge 410, and housing 412 are shown for reference.

[0036] Tab 400 may take a variety of shapes and forms and may be disposed on door 402 in any suitable manner. For example, tab 400 may be an L-shaped bracket integrally formed with door 402, as shown in FIG. 4. In this case, the base of sensor 404 is attached to the seat of the L-shaped bracket so that sensor 404 faces aperture 406. Therefore, tab 400 is a mounting surface for sensor 404. Tab 400 may be adjustable such that a person may manipulate tab 400 to provide access to sensor 404. Thus, tab 400 may be flexible such that a person may bend tab 400 to gain easy access to sensor 404. In another example, tab 400 may be manufactured separately and attached to door 402 in the manner shown. In another example, tab 400 may have a different shape that accommodates a particular type or shape of sensor 404. In yet another example, tab 400 is part of a frame, such as frame 322 in FIG. 3, to which the sensor control board may also be attached. Thus, in signal cases that do not already have tabs or control boards, a frame may be quickly and easily attached to door 402. The frame includes tab 400, sensor 404, and a control board, and may include additional tabs and additional sensors.

[0037] In addition, sensor 404 may be a variety of sensors. For example, sensor 404 may be a nuclear sensor, a chemical sensor, a bacteriological sensor, an audio sensor, a motion sensor, a thermometer, or a moisture sensor. In each case, any suitable sub-type of sensor may be used. For example, a nuclear sensor can be used to detect or sense alpha particles, beta particles, or high energy photons. A chemical sensor can be designed to detect or sense chemical weapons, such as sarin, soman, or VX gas, or to detect or sense other compounds, such as nitrates, TNT, or other explosives. A bacteriological sensor can be utilized to detect or sense various bacteria, such as anthrax, staff, or other bacteria. An audio sensor may be a microphone and may be a directional microphone. A motion sensor may sense the motion of cars or pedestrians. A thermometer may track the temperature of the surrounding area. A moisture sensor can sense the humidity or even rainfall levels in the area of the sensor.

[0038] In addition, any other sensor may be used to implement sensor 404, so long as the particular sensor is sized and dimensioned to fit within signal case 414 and is sufficiently durable to survive conditions inside signal case 414. Furthermore, multiple sensors may be provided. Thus, signal case 414 may include one or more arrays of different kinds of sensors. Each sensor may be disposed on a tab, or may be otherwise attached to door 402, light source module 408, or housing 412.

[0039] FIG. 5 shows the inside portion of the housing of the signal case shown in FIG. 2 in accordance with an illustrative embodiment of the present invention. As with signal case 200 shown in FIG. 2, signal case 500 includes housing 502, door 504, hinges 506, slot 508, and lens 510 arranged as described with respect to FIG. 1 and FIG. 2. In addition, frame 512 is shown inside housing 502. Portions of frame 512 are shown in phantom to show its position inside housing 502. Frame 512 rests inside housing 502, though frame 512 may be mounted or attached to housing 502 using any suitable method, such as screws, latches, or adhesives. In this illustrative example, frame 512 includes tabs 514 that rest against or are attached to mounts 516 provided within housing 502.

[0040] One or more sensors 518 are mounted on tabs 514. Each sensor in sensors 518 may be one of a variety of types of sensors and may operate as described with respect to FIG. 3 and FIG. 4. One or more apertures 520 may be provided to allow for the operation of sensors 518, as described with respect to FIG. 3 and FIG. 4. In addition, one or more control boards, such as control board 522, may be provided to control sensors 518. Control board 522 is attached to frame 512 via any suitable method, such as via welding, latches, screws, or an adhesive.

[0041] Frame 512 may be fashioned from a variety of materials, such as metal or plastic, and may be formed from a group of interconnecting rods or bars. Frame 512 is sized and dimensioned to accommodate the size and dimensions of a light source module attached to a door, such as light source module 306 in FIG. 3, and to accommodate the size and dimensions of the door and housing. Frame 512 may be attached directly to door 504 or may be attached to or otherwise disposed in housing 502.

[0042] In this illustrative example, frame 512 is adjustable and sized and dimensioned to fit snugly within housing 502. In these illustrative examples, frame 512 is flexible. Thus, frame 512 may be bent slightly, inserted into housing 502, and then allowed to rebound into its original shape such that frame 512 fits snugly inside housing 502. Hence, frame 512 allows sensors 518 and one or more control boards to be quickly and easily inserted into housing 502.

[0043] FIG. 6 shows the inside portion of the door of a signal case in accordance with an illustrative embodiment of the present invention. As with the illustrative example shown in FIG. 3, signal case 600 includes housing 602, door 604 connected to housing 602 via hinges 606, and light source module 608.

[0044] As shown in this illustrative example, tabs 610 may be directly attached to or integrally formed with light source module 608. One or more sensors 612 may depend from tabs 610 opposite apertures 614. Control board 616 is directly attached to light source module 608, though control board 616 may be disposed within light source module 608 or on the opposite side of light source module 608. Sensors 612, control board 616, and apertures 614 operate in a manner similar to that described with respect to FIG. 3 and FIG. 4.

[0045] FIG. 7 shows an exploded view of a signal case in accordance with an illustrative example of the present invention. Signal case 700 includes door 702 attached to housing 704 via hinges 706 and hinge pins 708. Tab 710 is attached to door 702 and sensor 712 is attached to tab 710 opposite aperture 714 in door 702. Backboard 716 is attached to door 702 and control board 718 is attached to backboard 716.

[0046] In addition, light source module 720 is attached to lens 722 in door 702. When door 702 is shut, light source module 720 is disposed within housing 704. Light source module 720 includes light source 724, which, as shown, is a light emitting diode array. Of course, other types of light sources may be used in place of or in addition to light emitting diode array 724. Slot 726 is provided in housing 704 for use in connecting multiple signal cases together, as described in FIG. 1. Mounts 728 are provided in housing 704 to facilitate insertion of a frame, such as frame 512 in FIG. 5.

[0047] In use, signal case 700 is operated as a traffic light. Sensor 712 is used to sense some desired parameter while the traffic light is operating, or, if desired, when the traffic light is not operating. For example, sensor 712 may be a camera that takes pictures or video of object or events within the field of view of the camera.

[0048] FIG. 8 shows the outside portion of the door of a signal case in accordance with an illustrative embodiment of the present invention. Traffic signal 800 includes sensor 802 disposed within door 804. Traffic signal window 806 is disposed within door 804 to allow light to shine out of traffic signal 800.

[0049] As shown, sensor 802 is oriented outwardly from door 804 and is attached to the outside surface of door 804. Sensor 802 can be any sensor, as described above with respect to FIG. 4 through FIG. 7. Although sensor 802 is shown in the bottom left portion of door 804, sensor 802 can be disposed in or on any portion of door 804. Although not preferred in most applications, sensor 802 could be disposed within traffic signal window 806.

[0050] Sensor 802 can also be attached to any other portion of the traffic signal. For example, sensor 802 can be attached to a surface of the traffic signal on the portion of the housing that is opposite traffic signal window 806. Sensor 802 can be attached to or disposed through the top of the housing, the bottom of the housing, or one or more sides of the housing. Sensor 802 can be mounted at a variety of different angles with respect to the housing or the traffic signal. Multiple sensors can be disposed inside, on, or around the traffic signal. Thus, multiple sensors, such as sensor 802, can survey multiple parameters in multiple directions around the traffic signal. Thus, either door 804 or the housing of the traffic signal is configured such that the sensor can sense a parameter outside the housing. To protect the sensor, the sensor can be at least partially inside the housing.

[0051] Sensor 802 can be attached to door 804 or any other part of the housing of the traffic signal in a variety of ways. For example, sensor 802 can be provided with screw threads such that the sensor itself is screwed into door 804 or the housing of the traffic signal. Sensor 802 can also be directly mounted to door 804 or other portion of the housing of the traffic signal using screws, nails, glue, hook-and-loop fastener or any other suitable method. In this way, sensor 802 can be attached to any pre-existing traffic signal. As used herein, the term “pre-existing” means that the traffic signal or other object did not include sensor 802 when originally constructed or deployed. The term “pre-existing” also includes the specific example of a traffic signal or other object that was constructed without any intent to mount or deploy a sensor on or in the traffic signal or other object.

[0052] Sensor 802 can be provided with a power source, such as a rechargeable battery, a solar panel, or other power source to allow sensor 802 to operate independently. Sensor 802 can also be adapted to receive power from existing systems designed to power the traffic signal.

[0053] Attached to sensor 802 is optional cover 808. Optional cover 808 covers sensor 802 and protects sensor 802 from water, dust, flying debris, or other hazards. Also optionally, sensor 802 and cover 808 are of the same color as door 804 and of the housing of the traffic signal. In an illustrative example, the color is black, though any color or group of colors, such as camouflage, may be used. In this way, sensor 802 and cover 808 will be difficult to detect visually from a distance. Sensor 802 or cover 808 can also be provided with window 810 to further protect sensor 802. Window 810 is disposed in front of the sensor to protect the sensor. Together, window 810 and cover 808 thereby are disposed to protect window 810.

[0054] Although sensor 802 is shown as attached to a traffic signal, because sensor 802 can be attached to a pre-existing traffic signal sensor 802 can be attached to other objects. For example, sensor 802 can be attached to a public lamp. A public lamp is a light source attached to an object such that the light source can illuminate a public area. A public area is any area designated for public use, such as a street, road, walkway, parking lot, or other public area. The object can be any suitable object. In the case of a street or road the object is usually a pole. Together, the pole and public lamp are commonly referred to as street lights or street lamps. However, the term public lamp is not limited to street lights. For example, the term public lamp, as defined above, also includes traffic signals. The public lamp to which sensor 802 is attached can be a pre-existing public lamp. The public lamp to which sensor 802 is attached can also be specifically modified to allow sensor 802 to be easily mounted to the public lamp.

[0055] Attaching sensor 802 to a public lamp, particularly a public lamp near a traffic intersection, as a number of advantages. Public lamps are generally taller than traffic signals. Thus, a camera or other sensor 802 located on or near the top of a public lamp has a wider or longer field of view down roads leading to the traffic intersection. Additionally, mounting a camera or other sensor 802 to a public lamp will provide lighting for viewing an area to be surveyed by the camera or other sensor 802. Either or both of these advantages provide for the ability to perform “advanced detection,” which is tracking vehicles far down roads leading to an intersection in order to take actions described above—such as changing the timing of traffic signals or turning a public lamp on or off.

[0056] Additionally, another action that can be taken is to implement a technique that can be referred to as “red light holding.” In the red light holding technique, the velocity and distance of vehicles approaching an intersection is monitored as a light changes to red. Normally, when a traffic signal light turns red, all the lights in the intersection for red for a short time, usually between about 1 to 2 seconds. In red light holding, this short time can be extended to 3 seconds or more if vehicles moving at beyond a predetermined speed are predicted to enter an intersection in violation of a red light. Red light holding “holds” the red light at all directions of an intersection. Because no one else enters the intersection when all lights are read, an accident can be prevented.

[0057] In another example, sensor 802 can be attached or mounted to a wall, door, building, awning, or any other object that has a view of a public area. Sensor 802 can also be used to sense parameters within private areas, though permission from the private owner should be obtained in this case.

[0058] As described above, sensor 802 can be used to sense a parameter, where the parameter could be a great many physical properties of interest. An action can be taken in response to detecting a parameter. Usually, the action is implemented by a processor, such as processor 1000 shown in FIG. 10, though the action could be implemented by some other circuit or manually by a user.

[0059] For example, sensor 802 can be a camera used to detect visibility. If visibility falls below a pre-defined threshold, such as in the case that a fog arises in the vicinity of sensor 802, then a processor or circuit to which sensor 802 is attached takes an action. In this case, exemplary actions include increasing the brightness of the traffic signal, changing the intensity or color of a public lamp or some other light, causing the traffic lights to flash, extending the length of a color of a traffic light (red, yellow, or green), transmitting an alert to a control center, or taking some other action. As used herein a control center can be any type of human or computer-controlled system for controlling traffic signals, controlling other objects or systems, or monitoring data from one or more sensors. Examples of control centers include emergency 911 dispatchers, traffic control centers maintained by public transportation departments, military command outposts, disaster relief or control centers, data collection center, any centralized command and control facility, server farms, or any other suitable area for receiving data from one or more sensors. The action taken by the processor upon detecting this parameter can be one of these actions or a combination of these actions.

[0060] In another example, sensor 802 can be a microphone used to detect sound waves. If sound waves characteristic of an explosion, accident, gun shot, or other potentially urgent situation are detected, then a processor or circuit to which sensor 802 is attached takes an action. Exemplary actions include alerting a 911 dispatcher or alerting a traffic control operation center to prompt a human to directly monitor the output of sensor 802. If multiple sensors are used around an intersection or in various locations throughout an area, then the location of the gunshot, accident, explosion, or other incident can be determined via triangulation and/or by correlating the intensity of sound waves at different locations. The action taken by the processor upon detecting this parameter can be one of these actions or a combination of these actions.

[0061] In another example, sensor 802 can be a camera that is disposed to monitor traffic approaching an intersection. As vehicles approach, a processor uses output from sensor 802 to determine the speed of vehicles approaching an intersection and/or the distance of vehicles approaching an intersection. The processor can then, by executing computer-usable program code, determine whether the length of a yellow light is appropriate for a given “dilemma zone.” A dilemma zone is an area extending from an intersection along a street or road in which drivers traveling at about the speed limit must make a split-second decision whether to stop for a yellow light or to continue through the intersection. The time to make this decision can be estimated. This time is multiplied by chosen speed, usually the speed limit, to calculate the length of the dilemma zone.

[0062] Because the dilemma zone depends on the speed of the vehicles approaching the intersection, sensor 802 can be used to take action in case the overall average speed of vehicles change within a pre-determined time period. For example, if the sensor or sensors sense an overall average speed of vehicles increases within a pre-determined time period, then the processor takes an action to increase the length of time a yellow light is activated or to change the duration of a red or green light. The length of time a yellow light or other light is on can be similarly shortened if the overall average speed of vehicles changes within a particular time. Additionally, the processor can cause an alert to be transmitted to a control center so that a human or a computer program can monitor the situation. The action taken by the processor upon detecting this parameter can be one of these actions or a combination of these actions.

[0063] Additionally, the dilemma zone depends on the ability of vehicles approaching the intersection to stop. Thus, for example, if sensor 802 or some other sensor sense rain, ice, or other dangerous conditions on the road, then the processor can take action to cause the traffic light to display yellow for a longer period of time.

[0064] In other examples, sensor 802 or one or more additional sensors can detect additional parameters and take correspondingly appropriate actions. For example, if one or more sensors detect radiation, such as beta radiation, alpha radiation, or high energy photons, over a pre-determined amount of background radiation, then the processor can take an action to alert a control center, notify police or other emergency personnel, sound an audible or visible alarm in the vicinity of the sensor, or take some other action. If one or more sensors detect biological hazards, such as bacteriological like anthrax or viral agents like smallpox, then similar action can be taken. If one or more sensors detect chemical hazards, such as toxins like pre-determined high levels of gasoline or chemical weapons like sarin, soman, or VX, then similar action can be taken. The action taken by the processor upon detecting this parameter can be one of these actions or a combination of these actions.

[0065] The examples of uses for sensor 802 given above are not exhaustive. Many other uses for sensor 802 exist, such as traffic law enforcement, criminal investigation, traffic flow control, and others. For example, if sensor 802 detects a vehicle violating a red light or detects excessive speed in a vehicle, then the processor can take action to, using known methods, cause a traffic citation to be automatically generated and mailed to the owner of the offending vehicle. In another example, if sensor 802 detects more than a predetermined number of cars at a particular portion of an intersection, then the processor can take action to lengthen or shorten the duration of green or red lights facing particular directions to change dynamically how a group of traffic signals operate at an intersection.

[0066] FIG. 9 shows a sensor attached to a gimbal in accordance with an illustrative embodiment of the present invention. Sensor 900 is attached to door or housing 902 in the exemplary embodiment of FIG. 9 via screw threads 904. Sensor 900 can be any of the sensors described with respect to FIG. 3 through FIG. 8 and can be operated to perform any of the functions described vis-à-vis those figures.

[0067] In the example shown in FIG. 9, sensor 900 includes camera 906. Camera 906 is attached to gimbal 908. A gimbal is a mechanical device that allows the rotation of an object in two or three dimensions. A gimbal includes two or three pairs of pivots, mounted on axes at right angles. A three-axis gimbal may allow an object mounted on it to remain in a horizontal plane regardless of the motion of its support. In the example shown in FIG. 9, gimbal 908 is a three-axis gimbal, though gimbal 908 can be any type of gimbal. Thus, sensor 900 can turn or rotate as desired or needed to monitor different areas of an intersection. Additionally, when sensor 900 is a camera, gimbal 908 allows sensor 900 to view further down a road leading to an intersection. In other illustrative examples, sensor 900 can be provided with multiple gimbals of different sensitivity to modify how sensor 900 is rotated or moved.

[0068] Other portions of sensor 900 are shown in FIG. 9 for reference. For example, cover 910 is shown extending from the outside of door or housing 902. O-ring 912 seals the area inside door or housing 902 from the external environment, thereby protecting any electronics or components inside door or housing 902. Window 914 can be disposed outside door or housing 902 to further protect camera 906. Window 914 corresponds to window 810 in FIG. 8. Additionally, mount 916 may optionally be provided.

[0069] FIG. 10 is a block diagram of a processing unit in accordance with an illustrative embodiment of the present invention. Processing unit 1000 may be any suitable data processing system, such as a personal computer, personal digital assistant, a mobile computer, a stand-alone processing unit, or any suitable processor or data processing system for operating computer-usable code in a recordable-type medium. Processing unit 1000 can be an existing processor used to control a traffic signal, or can be an additional processor used to control a sensor attached to a traffic light or a public lamp. Processing unit 1000 could also be in electrical communication with a sensor attached to a traffic light or a public lamp. In any case, processing unit 1000 can execute computer-usable code to perform an action in response to the sensor sensing a parameter, as described elsewhere herein. The action can be any number of actions and the parameter can be any number of parameters, as described above with respect to FIG. 8 or elsewhere herein.

[0070] Processing unit 1000 includes bus 1002 which allows various other components of processing unit 1000 to communicate with each other. In particular, bus 1002 is in communication with processor 1004, which executes computer usable program code for producing a slice or a model of an object. An example of a processor is an Intel Pentium IV® processor, though many different processors may be used.

[0071] Bus 1002 is also in communication with input/output device 1006. Input/output device 1006 allows processing unit 1000 to communicate with various external devices, such as a control center, as described in FIG. 8. Examples of input/output devices include an Ethernet port and a wireless communication device, though many different input/output devices may be used.

[0072] Bus 1002 is also in communication with memory 1008. Memory 1008 includes computer usable program code for performing an action in response to the sensor sensing a parameter. Bus 1002 is also in communication with persistent storage 1010. Persistent storage 1010 can also contain computer usable program code as described above. Persistent storage 1010 can also contain data collected by a sensor.

[0073] The aspects of the present invention have several advantages over currently available traffic signals. For example, by including sensors within the signal case itself, the sensor is protected from the elements and from vandals. In addition, the chance of a person noticing the sensors is reduced. For this reason, the sensor or sensors are more likely to capture criminal activity. By attaching the sensors to a frame, the sensors may be quickly and cost effectively added to existing signal cases or other types of traffic signals.

[0074] The description of the different aspects of the present invention have been presented for purposes of illustration and description, and is not intended to be exhaustive or limited to the invention in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art. The embodiment was chosen and described in order to best explain the principles of the invention, the practical application, and to enable others of ordinary skill in the art to understand the invention for various embodiments with various modifications as are suited to the particular use contemplated.