Abstract:
An apparatus for integrating sensors with a traffic signal. A camera is operably disposed within a housing. The housing is attached to an object such that the camera can observe traffic flowing past a traffic signal. A visor is attached to the housing such that an optical aperture of the camera is covered by the visor, wherein the visor comprises a roof having an angle that slopes, relative to the housing, towards the optical aperture, wherein the visor further comprises a floor connected to the roof, and wherein the floor extends outwardly from the housing.

Description:
RELATED CASES 
       [0001]    This application is a continuation-in-part application of application Ser. No. 11/211,029 filed Aug. 24, 2005, now U.S. Patent Application Publication 2007/0052553. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Technical Field 
         [0003]    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. 
         [0004]    2. Description of Related Art 
         [0005]    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. 
         [0006]    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. 
       SUMMARY OF THE INVENTION 
       [0007]    The present invention provides an apparatus for integrating sensors with a traffic signal. A camera is operably disposed within a housing. The housing is attached to an object such that the camera can observe traffic flowing past a traffic signal. A visor is attached to the housing such that an optical aperture of the camera is covered by the visor, wherein the visor comprises a roof having an angle that slopes, relative to the housing, towards the optical aperture, wherein the visor further comprises a floor connected to the roof, and wherein the floor extends outwardly from the housing. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    The novel features believed characteristic of the invention are set forth in the appended claims. The invention itself, however, as well as a preferred mode of use, further objectives and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying drawings, wherein: 
           [0009]      FIG. 1  shows a traffic signal in accordance with an illustrative embodiment of the present invention; 
           [0010]      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; 
           [0011]      FIG. 3  is a diagram of an inside view of a door from  FIG. 2  in accordance with an illustrative embodiment of the present invention; 
           [0012]      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 embodiment of the present invention; 
           [0013]      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; 
           [0014]      FIG. 6  shows the inside portion of the door of a signal case in accordance with an illustrative embodiment of the present invention; 
           [0015]      FIG. 7  shows an exploded view of a signal case in accordance with an illustrative embodiment of the present invention; 
           [0016]      FIG. 8  shows the outside portion of the door of a signal case in accordance with an illustrative embodiment of the present invention; 
           [0017]      FIG. 9  shows a sensor attached to a gimbal in accordance with an illustrative embodiment of the present invention; and 
           [0018]      FIG. 10  is a block diagram of a processing unit in accordance with an illustrative embodiment of the present invention. 
           [0019]      FIG. 11  shows a traffic light in which illustrative embodiments may be implemented; 
           [0020]      FIG. 12  shows a traffic signal clamped between two span wires wherein the traffic signal has a camera attached thereto, in accordance with an illustrative embodiment; 
           [0021]      FIG. 13  shows a traffic signal clamped to a single span wire and a camera clamped between two span wires, in accordance with an illustrative embodiment; 
           [0022]      FIG. 14  shows a camera case and visor, in accordance with an illustrative embodiment; 
           [0023]      FIG. 15  shows a view of a camera visor, in accordance with an illustrative embodiment; 
           [0024]      FIG. 16  shows a view of a camera visor, in accordance with an illustrative embodiment; 
           [0025]      FIG. 17  shows a lens cap for a camera, in accordance with an illustrative embodiment; 
           [0026]      FIG. 18  shows a lens cap for a camera, in accordance with an illustrative embodiment; and 
           [0027]      FIG. 19  shows an intersection and placement of cameras for advanced vehicle detection, in accordance with an illustrative embodiment. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0028]    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. 
         [0029]    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 . 
         [0030]    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. 
         [0031]    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. 
         [0032]      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 . 
         [0033]    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 . 
         [0034]    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. 
         [0035]    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 . 
         [0036]    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. 
         [0037]    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 . 
         [0038]    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 . 
         [0039]    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 . 
         [0040]    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. 
         [0041]    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 . 
         [0042]    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. 
         [0043]    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. 
         [0044]    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 . 
         [0045]      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. 
         [0046]    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. 
         [0047]    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. 
         [0048]    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 . 
         [0049]      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 . 
         [0050]    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. 
         [0051]    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 . 
         [0052]    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 . 
         [0053]      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 . 
         [0054]    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 . 
         [0055]      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 . 
         [0056]    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 . 
         [0057]    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. 
         [0058]      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 . 
         [0059]    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 . 
         [0060]    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. 
         [0061]    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. 
         [0062]    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. 
         [0063]    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 . 
         [0064]    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. 
         [0065]    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. 
         [0066]    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. 
         [0067]    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. 
         [0068]    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. 
         [0069]    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. 
         [0070]    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. 
         [0071]    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. 
         [0072]    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. 
         [0073]    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. 
         [0074]    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 predetermined 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. 
         [0075]    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. 
         [0076]      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. 
         [0077]    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. 
         [0078]    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. 
         [0079]      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. 
         [0080]    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. 
         [0081]    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. 
         [0082]    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. 
         [0083]      FIG. 11  shows a traffic light in which illustrative embodiments may be implemented.  FIG. 11  shows a traffic control assembly including traffic light  1100  mounted to light post  1102 , to which is also mounted street light  1104 . Traffic light  1100  can be an existing traffic light or could be a set of traffic lights, such as those shown in  FIG. 1 . Also attached to light post  1102  is cross beam  1106 . Cross beam  1106  supports traffic light  1100 . Also attached to cross beam  1106  is traffic camera  1108 . Traffic camera  1108  represents a prior art traffic camera and a prior art system for monitoring traffic in the intersection which the traffic assembly controls. Traffic camera  1108  includes visor  1110  and cable  1112 . 
         [0084]    Traffic camera  1108  can be found throughout the United States. These cameras are typically used to monitor traffic patterns and to adjust the signal pattern displayed by traffic light  1100  according to detected traffic patterns. Traffic camera  1108  can also be used to monitor vehicle speed or to monitor for possible illegal behavior. 
         [0085]    Traffic camera  1108  is plagued with a variety of problems. One of the problems of foremost concern is an issue of dirty lens covers. Even though traffic camera  1108  is provided with visor  1110 , the lens or lens cap inside the visor often becomes covered with dirt, water condensation, or other debris. The only known method to clean the traffic camera lens is to send a work crew with a bucket truck to the intersection, cone off the lane over which the traffic camera  1108  sits, and manually clean the lens. For an intersection that typically contains between four and six cameras, the time required to perform this task can be from about one to about three hours. This task is labor intensive and expensive. 
         [0086]    An additional problem encountered by traffic camera  1108  is that traffic camera  1108  has a high-profile, not only due to the actual camera box of traffic camera  1108 , but also due to support pole  1114 . As a result, high winds can damage traffic camera  1108 , knock traffic camera  1108  out of alignment, and/or reduce the overall life expectancy of traffic camera  1108 . As a result, relatively frequent maintenance is required, particularly after a major storm. For example, in cities that are regularly hit by hurricanes, most of the traffic cameras such as those shown in  FIG. 11  have to be realigned, cleaned, and/or replaced. 
         [0087]    The third problem encountered by traffic camera  1108  is that data and power cable  1112  is exposed to the elements. This exposure further reduces the expected lifetime of traffic camera  1108  and increases the amount of maintenance required by traffic camera  1108 . Additionally, the cable connector itself is usually exposed to the elements, leading to corrosion and malfunction. Furthermore, because the connection is outside the camera housing, strain on the connector from the weight of the cable can further increase the maintenance cycle of traffic camera  1108 . 
         [0088]    In addition, the power supply for traffic camera  1108  is contained within the housing of traffic camera  1108 . As a result, the temperature within traffic camera  1108  can become very high, particularly during summer months. Temperatures as high as 175° Fahrenheit have been measured inside the housings of existing traffic cameras, such as traffic camera  1108 . 
         [0089]      FIG. 12  shows a traffic signal clamped between two span wires, wherein the traffic signal has a camera attached thereto, in accordance with an illustrative embodiment.  FIG. 12  shows traffic light  1200  attached to two spanning wires, including spanning wire  1202  and spanning wire  1204 . Traffic light  1200  is attached to spanning wire  1202  via clamp  1206  and traffic light  1200  is attached to spanning wire  1204  via clamp  1208 . 
         [0090]    In an illustrative embodiment, camera  1210  is attached to back plate  1212  of traffic light  1200 . Camera  1210  is relatively small, weighing less than half a pound, though within the range of one pound to less than a few ounces. This weight includes the weight of the camera, the weight of the camera housing, and the weight of the camera visor. Prior art traffic cameras, such as traffic camera  1108  in traffic light  1100  weigh upwards of ten to twenty pounds, or more, not including the weight of the mounting pole used to mount the prior art traffic camera to a cross beam. The low mass of camera  1210 , combined with the fact that camera  1210  has a low-profile, means that high winds are less likely to knock camera  1210  out of alignment. 
         [0091]    Camera  1210  can be disposed on areas other than back plate  1212 . For example, camera  1210  can be mounted on the visors of the actual traffic signals, such as visors  1214 ,  1216 , and/or  1218 , on the crossbeam, on the traffic light pole, on spanning wires, or in any location from which an intersection can be observed. Visors  1214 ,  1216 , and  1218  are also mounted to back plate  1212 . In most traffic signals, back plate  1212  provides a background that provides a contrast to more easily see lights  1220 ,  1222 , and  1224 . Back plate  1212  is typically about six inches wide. Back plate  1212  is itself typically mounted to the back of the traffic signal housing and not to a front cover. 
         [0092]    Camera  1210  is provided with a variety of features that solve many of the problems associated with prior art traffic cameras, such as traffic camera  1108  of  FIG. 11 . These features include use of lenses and lens covers of low specific heat material, an angled visor, relatively small optical aperture diameter, low power consumption, a non-metallic housing, a silicon dioxide coating on a lens cap, and other features. The features of the design of camera  1210  are described further with respect to  FIGS. 14 through 18 . 
         [0093]      FIG. 13  shows a traffic signal clamped to a single span wire and a camera clamped between two span wires, in accordance with an illustrative embodiment. Traffic signal  1300  is similar to traffic light  1200  shown in  FIG. 12  and could be traffic signal  100  shown in  FIG. 1 . In the illustrative embodiment shown in  FIG. 13 , traffic signal  1300  is suspended from a single span wire  1302 . 
         [0094]    Traffic signal  1300  is attached to single span wire  1302  via clamp  1304 . Traffic signal  1300  includes back plate  1306 , light visors  1308 ,  1310 , and  1312 , and corresponding lights  1314 ,  1316 , and  1318 . Unlike traffic light  1200  in  FIG. 12 , traffic signal  1300  swings from single span wire  1302  in a windy environment. Because a traffic camera should not substantially change angle in a windy environment, traffic camera  1320  is ideally not placed on traffic signal  1300 . Instead, traffic camera  1320  is mounted onto a separate, small back plate  1322 . In turn, small back plate  1322  is mounted to single span wire  1302  via clamp  1324  and to a second span wire  1326  via clamp  1328 . If second span wire  1326  is not already available, then second span wire  1326  can be strung between the two supports used to support single span wire  1302 . In this way, the direction in which traffic camera  1320  points is not substantially altered by a significant amount in a windy environment. Traffic camera  1320  has a variety of properties, such as those described with respect to  FIG. 12  and more particularly, as described with respect to  FIGS. 14 through 18 . 
         [0095]      FIG. 14  shows a camera case and visor, in accordance with an illustrative embodiment. Traffic camera  1400  can be any of traffic cameras  1320  in  FIG. 13  or camera  1210  of  FIG. 12 , or can replace camera  802  in  FIG. 8 . 
         [0096]    Traffic camera  1400  includes camera housing  1402  and visor  1404 . Additionally, a BNC (Bayonet Neill Concelman) coax connector  1406  extends from camera housing  1402 . The solid state and electronics to operate traffic camera  1400  are operably disposed within camera housing  1402 . The term “operably disposed” means that the camera is within housing  1402  and is capable of operating as a camera within housing  1402 . The camera lens is disposed within camera housing  1402  as shown by phantom line  1408 . Thus, the camera lens points out of visor  1404  as shown by arrows  1410 . Other views and features of traffic camera  1400  are shown with respect to  FIGS. 15 through 18 . 
         [0097]    In the illustrative embodiment shown in  FIG. 14 , visor  1404  is angled downwardly with respect to axis  1412  and axis  1414 . Thus, when traffic camera  1400  is mounted to a back plate visor door or other portion of a traffic signal, lens  1408  is provided with greater physical protection from dust, water, snow, ice and other contaminates. 
         [0098]    In an illustrative embodiment, power supply  1416  for traffic camera  1400  is provided in a physically separate housing. In this way, the temperature inside camera housing  1402  can be lower than temperatures that arise within the housings of traditional traffic cameras that also include a power supply. 
         [0099]    For example, traffic camera  1400  and a traditional traffic camera were placed side-by-side on the same traffic signal of a particular intersection. During the heat of the summer day, the temperature inside the housing of the traditional traffic camera was at about 175° Fahrenheit. However, at the same time, the temperature measurement inside camera housing  1402  was only about 125° Fahrenheit. This 50° temperature differential increases the longevity of the sensitive electronics that make up the camera inside camera housing  1402 . This temperature differential is achieved because, among other reasons, power supply  1416  is not inside camera housing  1402 . The temperature within camera housing  1402  can be further moderated by placing traffic camera  1400  in the lee or shadow of the traffic signal to which traffic camera  1400  is mounted. This option is not available using traditional traffic cameras because traditional traffic cameras are very large compared to traffic camera  1400  and are mounted on exposed poles. An additional technique for keeping the camera cool is to provide holes in camera housing  1402  through which air can circulate. 
         [0100]    In an illustrative embodiment, camera housing  1402  is fitted with sliders which can be made of aluminum, polycarbonate materials, Plexiglas, or other materials which are adapted to mount traffic camera  1400  on existing traffic signals. In illustrative embodiment, camera housing  1402  can be mounted on a traffic camera pole, such as pole  1114  in  FIG. 11 . Power supply  1416 , or a power regulator, can also be mounted on a traffic camera pole, such as pole  1114  in  FIG. 11 , or a cross beam or other support, such as cross beam  1106 , though power supply  1416  is physically separate from camera housing  1402 . The low weight of camera  1400  reduces the moment of inertia and the profile of the camera, thereby reducing the possibility of knocking camera  1400  out of alignment during winds. Thus, no drilling or other time consuming activities are required to mount traffic camera  1400  to any portion of a traffic signal. Note that traffic camera  1400  can be mounted to a visor of a traffic signal, to a back plate of a traffic signal, to a housing of a traffic signal, to one or more span wires to which a traffic signal is attached, to a door of a traffic signal, to the back of the traffic signal, or to a cross beam or supporting traffic signal pole. Traffic camera  1400  can also be mounted to other portions of a traffic signal system. 
         [0101]    In an illustrative embodiment, BNC coax connector  1406  is mounted inside camera housing  1402 . BNC coax connector  1406  connects the electronics of traffic camera  1400  to external computers and possibly to power. In traditional traffic cameras, such as traffic camera  1108  in  FIG. 11 , BNC coax connector  1406  is placed outside of camera housing  1402 . As a result, extra strain is placed on the connectors and, additionally, the connectors are exposed to the elements in traditional traffic cameras. For this reason, traditional traffic cameras are subject to more frequent failure. However, by placing BNC coax connector  1406  and power supply  1416  inside camera housing  1402 , such strain can be relieved and BNC coax connector  1406  can be protected from the elements. 
         [0102]    In another illustrative embodiment, traffic camera  1400  uses a relatively low amount of power. In an illustrative embodiment, the power required for traffic camera  1400  is about 12 volts direct current. Traditional traffic cameras operate at about 120 volts alternating current. This high voltage alternating current can create positive ions which attract dust. The same effect can be seen on most television screens present in the average American home. By using direct current voltage, this attraction of dust can be avoided. Additionally, because the power is lower, the temperature generated inside camera housing  1402  can be further reduced. The temperature can be further reduced by not completely sealing camera housing  1402 . Thus, some air flow can be present inside camera housing  1402  to further decrease the temperature inside camera housing  1402 . 
         [0103]    In another illustrative embodiment, a gimbal assembly can be provided inside camera housing  1402 . Camera housing  1402  protects the gimbal assembly from wind. The gimbal assembly allows the camera to point in slightly different directions. Thus, traffic camera  1400  does not necessarily have to point in exactly the same direction all the time. 
         [0104]      FIG. 15  shows a view of a camera visor, in accordance with an illustrative embodiment.  FIG. 15  shows a front view of traffic camera  1400  shown in  FIG. 14 , traffic camera  1320  in traffic camera  1320 , or camera  1210  in  FIG. 12 . 
         [0105]    In particular,  FIG. 15  shows some of the dimensions of visor  1404  in  FIG. 14 . Thus, visor  1500  corresponds to visor  1404  of  FIG. 14 . The relative scale of visor  1500  and lens cap  1502  is shown by arrows A  1504  and arrows B  1506 . In an illustrative embodiment, arrows A  1504  represent a distance of about 1.8 inches. The distance of arrows B  1506  in an illustrative embodiment represents a distance of about 1.7 inches. As shown by angle θ  1508 , a portion of visor  1500  is inclined downwardly to cover the top portion of lens cap  1502 . The angled portion of visor  1500  can be referred to as the ceiling of visor  1500 . In addition, a portion of visor  1500  shown in the general area of area  1510  extends outwardly from lens cap  1502  and/or the housing. The portion of visor  1500  in the general area of area  1510  can be referred to as the floor of the visor. Area  1510  provides additional protection to lens cap  1502 . The floor  1510  can be considered connected to the ceiling of visor  1500  via side walls. Note that the term “connected” is used for reference only; in an illustrative embodiment, the floor, walls, and ceiling are integrally formed together. 
         [0106]    In an illustrative embodiment, negative ion generator  1512  is disposed around lens cap  1502 . Although negative ion generator  1512  is shown inside visor  1500 , negative ion generator  1512  can be disposed outside of visor  1500  or on the housing of the traffic camera, such as camera housing  1402  shown in  FIG. 14 . Additionally, negative ion generator  1512  can be placed on or in the signal itself rather than on or around visor  1500 , so long as negative ion generator  1512  is near enough to visor  1500  and lens cap  1502  to be effective at helping lens cap  1502  to remain clean. When near enough to have operable effect in the vicinity of lens cap  1502 , negative ion generator  1512  is said to be adjacent to lens cap  1502 . 
         [0107]    Negative ion generator  1512  causes electrons to be added to molecules of oxygen and other trace gases in the area surrounding lens cap  1502 . This process creates negative ions. When ions collide with airborne contaminates, such as dust, mold, pollen, bacteria, ice, and other particles, a negative charge is transferred to the airborne particle. However, surrounding this newly negatively charged particle are many other particles that are positively charged. These positively charged particles are drawn to the negatively charged particle and begin to clump together. Eventually, these particles become too heavy to stay in the air and fall harmlessly to the ground. As a result, dust and other contaminates form or fall on lens cap  1502  with far less frequency than had negative ion generator  1512  not been present. 
         [0108]    Additionally, lens cap  1502  is made from a low specific heat material that repels water condensation. In an illustrative embodiment, lens cap  1502  and the lens behind lens cap  1502  can be made from a polycarbonate material, such as MAKRALON of grade AL2647. Such a material is available from Bayer Material Science, LLC. In addition to repelling water condensation, this material is scratch resistant, which further improves the transparency of lens cap  1502 . In an illustrative embodiment, a silicon dioxide coating can be added to lens cap  1502  to further repel build up of dirt, dust, and other contaminates. 
         [0109]    Taken together, all of these features provide an unexpected result of low maintenance for cameras made according to the design shown in  FIGS. 14 and 15 . In an illustrative embodiment, cameras deployed in the real world have remained clean and maintenance free for a little less than a year. Maintenance of traffic camera  1400  is at least four times less frequent than prior art traffic camera  1108  of  FIG. 11 . This result is surprising to those of skill in the art. Traditional traffic cameras, particularly in areas subject to contamination such as ocean fronts or dusty areas may need to be cleaned or maintenanced every few months, resulting in substantially increased costs. Thus, the illustrative embodiments described herein provide a quantum leap in the art of cameras for monitoring traffic. 
         [0110]      FIG. 16  shows a view of a visor for a camera in accordance with an illustrative embodiment.  FIG. 16  illustrates another view of traffic camera  1400  of  FIG. 14 , and of visor  1500  shown in  FIG. 15 . Visor  1500  of  FIG. 16  is shown as having side dimensions of proportions shown by arrows C  1600  and arrows A  1504 . Arrows A  1504  correspond to arrows A  1504  in  FIG. 15 . As with the illustrative embodiment shown in  FIG. 15 , one dimension for arrows A  1504  could be 1.8 inches, although this value may vary. In the same illustrative embodiment, an exemplary value for arrows C  1600  is 2.1 inches. 
         [0111]      FIG. 17  shows a lens cap for a camera, in accordance with an illustrative embodiment. Lens cap  1502  in  FIG. 17  corresponds to lens cap  1502  shown in  FIG. 15 . Lens cap  1502  includes cylinder  1700  and lens cap head  1702 . Lens cap head  1702  seals lens cap  1502  within visor  1500  of  FIG. 15 . In an illustrative embodiment, the size of lens cap  1502  is shown by arrows D  1704  and arrows E  1706 . In a particular illustrative embodiment, arrows D  1704  can be 0.7 inches and arrows E  1706  can be 1.5 inches. The characteristics of lens cap  1502  are described with respect to  FIG. 15 . 
         [0112]      FIG. 18  shows a lens cap for a camera, in accordance with an illustrative embodiment.  FIG. 18  shows a front view of lens cap  1502  which corresponds to lens cap  1502  of  FIG. 15  and lens cap  1502  of  FIG. 17 . As described above, arrows E  1706  represent a diameter of lens cap head  1702 . As described above, an illustrative value for the distance represented by arrows E  1706  can be 1.5 inches. The physical characteristics of lens cap  1502  are described with respect to  FIG. 15 . 
         [0113]      FIG. 19  shows an intersection and placement of cameras for advanced vehicle detection, in accordance with an illustrative embodiment.  FIG. 19  shows an exemplary intersection  1900  which has two traffic signal systems  1902  and  1904 . Traffic assembly  1902  includes mounting pole  1906 , cross beam  1908 , traffic signal  1910 , and traffic camera  1912 . Similarly, traffic assembly  1904  includes mounting pole  1914 , cross beam  1916 , traffic signal  1918 , and traffic camera  1920 . The illustrative configuration of traffic cameras shown in  FIG. 19  can be used to perform advanced detection and vehicle counts. 
         [0114]    In modern traffic control systems, video cameras are used to see beyond the stop bar of an intersection, such as, for example, stop bars  1922  and  1924 . By analyzing the number of cars lined up behind stop bars  1922  and  1924 , a traffic controller or an automatic traffic control system can determine whether and how to alter the pattern of operation of traffic signals  1910  and  1918 . Additionally, by viewing approaching cars several hundred feet away from stop bars  1922  and  1924 , traffic cameras  1912  and  1920  can be used to determine how long a time is needed for a light to be yellow in order for approaching cars to safely stop behind traffic bars  1922  and  1924 . 
         [0115]    One problem associated with performing this type of advanced detection system is how to obtain a good view with a camera. Ideally, the camera should be at a forty-five degree angle and be positioned directly above the road. In this case, the pole would be about 200 to 300 feet high to see a similar distance down the road. This solution is often not practical. One way to solve this problem is to move the camera closer towards the direction of approaching traffic. Thus, for example, traffic approaching from the left hand side of  FIG. 19  is detected using traffic camera  1920 . For this reason, traffic camera  1920  is pointed in roughly the direction shown by arrows  1926 . In other illustrative embodiments, the angle formed by arrows  1926  and a line parallel to the road is not as steep as the one shown. Similarly, traffic camera  1912  is pointed in the direction of arrows  1928 . By mounting the cameras  1912  and  1920  on the backside of traffic signals  1918  and  1910 , the camera can be placed 50 to 125 feet closer than would otherwise be possible. This orientation allows for better detection while still taking advantage of existing sensor platforms. 
         [0116]    Another advantage to orienting traffic cameras  1912  and  1920  on the back side of traffic signals  1910  and  1918  is that during vehicle counting, a more accurate count can be made. Counting cars as they approach is more difficult than counting cars as they leave. Thus, by placing cameras behind traffic signals, cars can be counted as they pass underneath the corresponding traffic signal  1910  and  1918 . 
         [0117]    An additional advantage to the orientation of traffic cameras  1912  and  1920  is that the cameras do not have to be mounted on separate poles which may result in occlusion of the cameras from other obstructing objects, such as, for example, buildings, billboards, trees, or other obstructions. Another typical occlusion is a large truck blocking view of a small car. Furthermore, cameras  1912  and  1920  can be integrated with existing electronics and wiring systems as opposed to having to provide such systems on separate mounting poles. 
         [0118]    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. Particularly, the illustrative embodiments described with respect to  FIG. 11  through  FIG. 19  are resistant to moisture, dirt, pollen, and other contaminants. 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 added quickly and cost effectively to existing signal cases or other types of traffic signals. 
         [0119]    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.