WO2013003096A1

WO2013003096A1 - Double advance notice traffic light with signs

Info

Publication number: WO2013003096A1
Application number: PCT/US2012/042971
Authority: WO
Inventors: Daniel Kunau
Original assignee: Individual
Current assignee: Individual
Priority date: 2011-06-28
Filing date: 2012-06-18
Publication date: 2013-01-03
Anticipated expiration: 2013-12-28

Abstract

A traffic light provides advance warning of a change from green to red by adding two additional periods to the standard red, green, amber light cycle. The two additional periods may each be active for about the same amount of time as the amber light cycle. Warning signs may be included that are placed a points along the road where a car travelling at the posted speed limit may pass as the state of the traffic light changes.

Description

Double Advance Notice Traffic Light with Signs by

Daniel Kunau

Background

Technical Field

The present subject matter relates to traffic control signals. More specifically, the present subject matter relates to an improved traffic light cycle that operates with signs to provide predictable advance notice of light changes.

Description of Related Art Traffic lights with red, amber and green colored lights visible to approaching traffic have been in common use for many years. It is commonly known to drivers that if the red light is illuminated, the driver should stop at the intersection and if the green light is illuminated, the driver may have the right-of-way to proceed through the intersection. A yellow light is commonly understood to mean that the traffic light is about to change to red and that the driver should either stop or proceed with caution, depending on their distance from the intersection and their speed. So a standard traffic light cycle in use today in many parts of the world may consist of a relatively long period of green, followed by a short period of amber, followed by a relatively long period of red, before switching back to green.

Even though the standard traffic light cycle described above is very well known to drivers, many people are still injured each year in traffic accidents at intersections controlled by traffic lights. One problem with the standard traffic light cycle is that the length of time that the amber light is illuminated may vary from intersection to

intersection depending on various factors including the type of road (minor collector, major collector, highway, and the like), the surrounding neighborhood (residential, urban, rural, and the like), and speed limit. The time that the amber is illuminated may typically be 3, 4 or 5 seconds, although in some installations other times may be used. This variability, may contribute to an uncertainty in a driver's mind as to whether a yellow light should be interpreted as an indication to stop.

Summary

According to various embodiments, traffic may be controlled at an intersection using various articles of manufacture, systems and methods by using a traffic light having a red light, an amber light, and a green light that are simultaneously visible to traffic approaching the intersection from a particular direction and not easily visible to traffic approaching the intersection from other directions. The traffic light may utilize a cycle having a period of illuminating only the red light, followed by a period of

illuminating only green the light, followed by a period of illuminating the green light and the amber light, followed by another period of illuminating only the green light, followed by a period of only illuminating the amber light before illuminating the red light again. Some embodiments may also include additional warning signs.

Brief Description of the Drawings The accompanying drawings, which are incorporated in and constitute part of the specification, illustrate various embodiments of the invention. Together with the general description, the drawings serve to explain the principles of the invention. They should not, however, be taken to limit the invention to the specific embodiment(s) described, but are for explanation and understanding only. In the drawings:

FIG. 1 shows a perspective view of an embodiment of a system for controlling traffic at an intersection;

FIG. 2 is a state diagram of an embodiment of a method for controlling traffic at an intersection using a traffic light;

FIG. 3 shows an overhead view of a system for controlling traffic at an

intersection superimposed with an abstract view of the traffic light cycle; and

FIG. 4 shows a block diagram of an embodiment of a traffic light controller suitable for various embodiments. Detailed Description

The present inventor recognized a problem with conventional traffic light cycles. Namely, conventional traffic light cycles give very little advance warning of a change from green to red. In many cases, a driver may not have enough time to safely stop his or her vehicle in the amount of time of the amber light. This may be especially true for heavily loaded trucks and/or speeding vehicles. And if a driver does not happen to notice the exact instant that the light changes from green to amber, additional precious time may be lost before the driver is aware that a stop may be required.

The present inventor has created an improvement to conventional traffic light cycles by providing additional warning periods indicating that the traffic light is about to change from green to red, without changing the traffic light signaling mechanism of a red light, an amber light, and a green light. The herein described improvement adds two additional warning periods between the standard green light and the standard amber light. The first additional warning period turns on both of green and amber lights and the second additional warning period has only the green light illuminated. While the second warning period of green only may look similar to the standard green light, the fact that the period is short and it is bracketed by periods where the amber light is on can be noticed by the driver as a warning period. Both additional warning periods may have about the same duration as the standard amber period.

To help the driver even further, warning signs, that may be traditional signs on the side of or above the road, or may be indications such as lines painted on the road surface, may be placed at distances from the intersection where a driver may pass as the warning indications are presented by the traffic light. The distances from the intersection may be calculated by multiplying the time before red that the light changes by the expected speed of a vehicle. While drivers may not fully interpret the information being presented at first, they will quickly be able to learn that by using the additional warning periods from the traffic light in conjunction with the warning signs as they approach an intersection, they will be able to very accurately predict how much time they have before the traffic light turns red. This information can be used by the driver to make the best decision as to whether to proceed through the intersection or stop for the red light. It also provides enough advance notice for even the heaviest trucks and speeding vehicles to stop safely before the traffic light turns red. Drivers are given much 3 times more advance notice of an impending red light as compared to a conventional traffic light cycle, as well as three changes of the light pattern that may be more readily noticed than the conventional single change. Some of the greatest beneficiaries of the improved cycle may include drivers of heavy trucks, the elderly and impaired, speeding drivers, and distracted drivers. Some of the advantages of the improved traffic light cycle may include reduced traffic fatalities and injuries, fuel savings and reduced brake wear, reduced stress for drivers, easier enforcement of speed limits, ease of implementation and low implementation cost.

In the following detailed description, numerous specific details are set forth by way of examples in order to provide a thorough understanding of the relevant teachings. However, it should be apparent to those skilled in the art that the present teachings may be practiced without such details. In other instances, well known methods, procedures and components have been described at a relatively high-level, without detail, in order to avoid unnecessarily obscuring aspects of the present concepts. A number of descriptive terms and phrases are used in describing the various embodiments of this disclosure. These descriptive terms and phrases are used to convey a generally agreed upon meaning to those skilled in the art unless a different definition is given in this specification. Some descriptive terms and phrases are presented in the following paragraphs for clarity. Reference now is made in detail to the examples illustrated in the accompanying drawings and discussed below.

FIG. 1 shows a perspective view of an embodiment of a system 100 for controlling traffic at an intersection 101 . A traffic light 1 10 may be mounted near the intersection 101 so that the red light 1 1 1 , amber light 1 12 and green light 1 13 of the traffic light may be readily visible to traffic approaching the intersection from a given direction along a road 102. In most embodiments the lights may not be readily visible to traffic approaching the intersection 101 from other directions. The traffic light may be mounted on a post or other support at the intersection 101 beside the road 102 on the right or left, depending on local custom, above the road 102, above the intersection 101 , or other locations or in multiple locations. The road 102 approaching the intersection 101 may have a stop line 130 painted on the roadway showing where a vehicle should stop if signaled to by the traffic light 1 10. As with conventional traffic light cycles, a vehicle is expected to stop behind the stop line 130 if the red light 1 1 1 is illuminated by the time the vehicle is at the intersection 101 . In most embodiments, the lights may be mounted in a vertical column with the red light 1 1 1 on the top, the amber light 1 12 in the middle and the green light 1 13 on the bottom, although some embodiments may position the lights side-by-side. In at least one embodiment the lights 1 1 1 , 1 12, 1 13 may use white incandescent lights covered with a colored lens and in at least one other embodiment, the lights 1 1 1 , 1 12, 1 13 may use light emitting diodes (LEDs) to generate the desired color of light. The color of the red light 1 1 1 may be any shade, hue, or saturation of red and may include additional colors of light other than red such as orange or yellow. The color of the amber light 1 12 may be any shade, hue, or saturation of yellow, orange, or amber and the color of the green light 1 13 may be any shade, hue, or saturation of green and may include additional colors of light other than green such as blue. The spectrum of each light may have a single spike at the appropriate wavelength for that color (e.g. -575 nanometers for yellow) or may be a mix of different colors that the human eye may perceive as a single color (such as red and green to create a perceived yellow color). Each of the colors may be created by using a lighting element that generates light at the appropriate wavelength, by placing a colored filter or lens in front of a white light or some other colored light, by using a light that emits one color of visible or invisible light (such as ultraviolet light) to excite a phosphor to emit the desired color of light, or any other method using any type of lighting technology and the three different lights may use different methods of generating the desired color of light.

The traffic light 1 10 may include a traffic light controller 400 (not visible in FIG. 1 , but shown in more detail in FIG. 4) that is capable of turning each of the lights in the traffic light 1 10 on and off. In some embodiments the traffic light controller 400 may be integrated into the traffic light 1 10 but in many embodiments, the traffic light controller 400 may be placed remotely to the traffic light 1 10 and may control multiple traffic lights such as all the traffic lights for a single intersection. In some embodiments, the traffic light controller 400 may be located in a central facility and control a large number of traffic lights in a neighborhood, city, or region, allowing the traffic lights to be

coordinated for improved traffic flow.

The traffic light controller 400 may include two additional warning periods in its cycle, in addition to the standard green, amber and red periods. These additional warning periods may be inserted between the conventional green and amber periods. The first warning period may turn on the amber light 1 12 in addition to the green light 1 13. The second warning period may extinguish the amber light 1 12 and leave the green light 1 13 on before switching to the standard amber warning period where only the amber light 1 12 is illuminated. Each of the additional two warning periods may be about the same length as the standard amber warning period. The additional warning periods provide up to three times as much advance warning to approaching drivers that the traffic light 1 10 will be turning red. This additional time may be valuable to provide enough advance notice for drivers to stop and the additional granularity of having three separate warning periods may help drivers to make the best decision about whether to stop at the stop light 1 10 even if no additional warning signs are included.

In some embodiments, however, warning indications may be placed near the road that may be noticed by drivers of vehicles approaching the intersection 101 on the road 102. The warning indications may be signs posted near a side of the road, signs posted above the road, signs painted on the road, rumble strips on the road, or at least one line painted on the road. The warning indications, or signs, may be positioned anywhere that they may be noticed by drivers as they pass a spot in the road. The distance of the warning signs from the intersection 101 may be determined by the length of the warning periods as well as the expected speed of traffic on the road 102, which may typically be the posted speed limit as shown on the speed limit sign 125. A warning distance 129 may be calculated by multiplying the expected speed of vehicles by the length of the warning periods. As an example, if the posted speed is 35 miles per hour (mph) and the warning periods are each 3 seconds long, the warning distance 129 may be calculated by multiplying the speed of 35 mph by a conversion factor of

5280/3600 feet-hour/mile-second and the warning period of 3 seconds to give a warning distance of 154 feet.

Because vehicle speed may vary greatly, the actual distance used for the warning distance need not be exact and may vary as much as 25% or more from what might be calculated using the posted speed limit. Other factors, such as the location of driveways or other impediments on the side of the road 102 may also impact the exact placement of the warning signs. Some embodiments may use a warning distance 129 that is shorter than what would be calculated using the posted speed limit to ensure that drivers actually have more time before the traffic light turns red than is indicated by the warning signs. In some installations, the posted speed limit may change within the distance between the third warning sign 123/133 and the intersection 101 and the locations of the warning signs may be changed to accommodate this. Some embodiments may also use different lengths of time for the three different warning periods and the warning sign placement can be changed to accommodate this as well. It should also be noted that the nomenclature of the first, second and third warning signs is denoted using distance from the intersection 101 so that a driver approaching the intersection will encounter the third warning sign 123/133 first, followed by the second warning sign 122/132 then the first warning sign 121/131 .

A first warning sign 121 may be placed beside the road 102 and/or a warning sign 131 painted on the road at about the warning distance 129 from the stop line 130 at the intersection 101 . The intent of the first warning sign 121/131 is to alert an

approaching driver as to the point where he or she should see the traffic light 1 10 turn amber if they are driving at the speed limit. In some embodiments a single warning sign 121/131 may be used with a conventional traffic light to improve the safety of an intersection 101 . If a driver approaching the intersection 101 sees the traffic light 1 10 turn amber before they reach the first warning sign 121/131 , they know that the traffic light 1 10 will turn red before the reach the intersection 101 and they know that they should stop at the stop line 130. If the driver sees the traffic light 1 10 turn amber after they have passed the first warning sign 121/131 , they can utilize the information of how far they have gone past the first warning sign 121/131 to help determine if they can proceed through the intersection safely or if they should stop.

A second warning sign 122 may be placed beside the road 102 and/or a warning sign 132 painted on the road at about two times the warning distance 129 from the stop line 130 at the intersection 101 . The intent of the second warning sign 122/132 is to alert an approaching driver as to the point where he or she should see the traffic light 1 10 turn from green and amber to green only if they are driving at the speed limit. If a driver approaching the intersection 101 sees the traffic light 1 10 turn from green and amber to green only before they reach the second warning sign 122/132, they know that the traffic light 1 10 will turn red before the reach the intersection 101 and they should stop at the stop line 130. If the driver sees the traffic light 1 10 turn green only from green and amber after they have passed the second warning sign 122/132, they can utilize the information of how far they have gone past the second warning sign 122/132 to help determine if they can proceed through the intersection safely or if they should stop. A third warning sign 123 may be placed beside the road 102 and/or a warning sign 133 painted on the road at about three times the warning distance 129 from the stop line 130 at the intersection 101 . The intent of the second warning sign 122/132 is to alert an approaching driver as to the point where he or she should see the traffic light 1 10 turn from green to amber and green if they are driving at the speed limit. If a driver approaching the intersection 101 sees the traffic light 1 10 turn from green to amber and green before they reach the third warning sign 123/133, they know that the traffic light 1 10 will turn red before the reach the intersection 101 and they should stop at the stop line 130. If the driver sees the traffic light 1 10 turn green and amber from green after they have passed the third warning sign 123/133, they can utilize the information of how far they have gone past the third warning sign 123/133 to help determine if they can proceed through the intersection safely or if they should stop.

The design of the warning signs may vary between embodiments but in at least one embodiment the first warning sign 121 may be a single solid yellow circle and the second warning sign 122 may be two solid yellow circles stacked vertically. The third warning sign 123 may be three solid yellow circles stacked vertically in one embodiment but in other embodiments may be a picture of a traffic light with red, yellow and green lights or a conventional "traffic light ahead" sign. In some embodiments a warning sign 121 , 122, and/or 123 may be combined on a single post with other traffic signs such as shown for the third warning sign 123 and the speed limit sign 125, or multiple functions, including one of the warning signs 121/122/123, may be integrated onto a single sign.

As mentioned above, in some embodiments, warning signs may be painted on the road 102 in place of, or in addition to, the warning signs on the side of the road. In at least one embodiment, the first warning sign 131 may be a single strip of paint and the second warning sign 132 may be two strips of paint arranged as a dashes across the road as shown or parallel to each other like an "equals" sign. The third warning sign 133 may be three strips of paint arranged horizontally as a single broken line as shown in FIG. 1 or as three parallel lines. The color of the lines may be white in some

embodiments although other colors may be used, such as yellow, in other

embodiments. Other embodiments may use different painted warning signs on the road 102 such as words or other indications.

In some jurisdictions, police may use the warning signs as timing marks to determine whether or not a vehicle may be exceeding the posted speed limit if the warning signs are positioned so that a vehicle travelling at the speed limit will travel the distance between signs in the warning period time of the traffic light 1 10. So by simply timing the vehicle as it travels between two warning signs, such as the third warning sign 123/133 and the second warning sign 122/132, a vehicle may be determined to be exceeding the speed limit if the timed travel is shorter than the warning period. So as long as the police officer knows what the warning period is for a particular traffic light 1 10, the officer can accurately determine which vehicles are speeding. In some cases, the officer may even be able to use the light cycle itself to provide the timing basis, so that if a vehicle passes the third warning sign 123/133 while the traffic light 1 10 has the green light 1 13 and amber light 1 12 illuminated, and those two lights are still illuminated as the vehicle passes the second warning sign 122/132, the officer can determine that the vehicle is speeding.

In some embodiments, traffic cameras may be included to perform automatic speed limit enforcement. Two cameras may be included with one camera aimed at the point in the road where traffic would pass the third warning sign 123/133 and a second camera aimed at the point in the road where traffic would pass the second warning sign 122/132. Alternative embodiments may have cameras aimed at the road near the second warning sign 122/132 and the first warning sign 121/131 or all three warning signs. In some embodiments, the camera(s) may take a still picture based on the vehicle passing the warning sign(s) using a sensor such as an in-road inductive sensor, a light beam crossing the road, a pressure strip across the road, or an ultrasonic motion detector or other sensor. In other embodiments, the camera(s) may be video cameras capturing a stream of video. The cameras may be connected to a computer system capable of recognizing vehicles by their license plates or other characteristics. The computer system may then use the known distance between the warning signs and the time that it takes for a vehicle to pass from one sign to another sign to determine the speed of a vehicle. If the computer determines that a vehicle is speeding, a report may be issued allowing the vehicle/driver to be cited. In some embodiments, the computer may issue the citation without further human intervention.

FIG. 2 is a state diagram 200 of an embodiment of a method for controlling traffic at an intersection using a traffic light 1 10. The state diagram 200 may also be referred to as a flowchart. In some embodiments, the method may start in any state and may repeat until power is lost or some other event occurs to interrupt the cycle. Some embodiments may include additional states such as states allowing for a protected left turn. In other embodiments additional inputs may be received that may modify the cycle shown, such as a traffic sensor that may affect the various time periods or an

emergency vehicle approach sensor that may modify proceed quickly to a state to allow the emergency vehicle to pass, or other modifications of the cycle shown.

Starting at the red light state 201 for convenience, the red light 1 1 1 is illuminated for a period of time that will be referred to as 'R' seconds. The value of 'R' may be any number of seconds, depending on the characteristics of the intersection where the traffic light 1 10 is installed and the goals for traffic flow through the intersection, but may typically be between 20 and 180 seconds. After 'R' seconds have elapsed, the red light 1 1 1 is turned off and the green light 1 13 turned on in state 203. The green light 1 13 is illuminated for a period of time that will be referred to as 'G' seconds. The value of 'G' may be any number of seconds, depending on the characteristics of the intersection where the traffic light 1 10 is installed and the goals for traffic flow through the

intersection, but may typically be between 15 and 175 seconds.

After 'G' seconds have elapsed the amber light 1 12 is illuminated in state 205 without turning off the green light 1 13 so that both the amber light 1 12 and the green light 1 13 are turned on for a period of time referred to as 'A' seconds in state 205. The value of 'A' may be any number of seconds depending on the characteristics of the intersection where the traffic light 1 10 is installed and the goals for traffic flow through the intersection, but may typically be between 3 and 5 seconds. After 'A' seconds have elapsed, the amber light 1 12 is turned off, leaving the green light 1 13 illuminated in state 207.

After another 'A' seconds have elapsed, the amber light 1 12 is illuminated again and the green light 1 13 is turned off so that only the amber light 1 12 is on during state 209. The amber light 1 12 remains on for another 'A' seconds before the amber light 1 12 is extinguished and the red light 1 1 1 is illuminated again back in state 201 to start the cycle over.

At basic 4-way intersections 101 where both crossing roads having comparable construction and traffic flow, the values of 'R' may be equal to the value of 'G' plus 3 times 'A' plus a safety margin. This timing may allow the traffic in one direction to be stopped by the red light 1 1 1 for the entire time that the crossing traffic is allowed to cross through the intersection 101 during states 203, 205, 207 and 209. The safety margin is a time when the red light 1 1 1 in both directions may be illuminated to allow any traffic that is in the intersection 101 to pass through the intersection 101 before the crossing traffic is allowed to proceed.

Depending on the embodiment, the exact length of the time period 'A' may vary somewhat for the three different state transitions where it is used. While some variation in the time period may be acceptable, the ability of a driver to use the duration of one state to help predict the duration of one of the following states that use the time period 'A' is at least a part of the value offered by various embodiments. For the purposes of this disclosure and associated claims, the various time periods labeled 'A' in the state diagram 200 may be considered to be about the same length of time if there is no more than a 2:1 ratio between the longest 'A' and the shortest Ά'.

FIG. 3 shows an overhead view of a system 100 for controlling traffic at an intersection 101 superimposed with an abstract view of the traffic light cycle 300. The traffic light cycle 300 is shown as the lights of the traffic light 1 10 that are illuminated as seen by a vehicle travelling at the expected rate of speed for the road 102, for that position on the road 102, if the vehicle would pass the stop line 130 just as the traffic light 1 10 turns red. If the traffic light 1 10 would implement a conventional cycle, the driver of the vehicle would have no indication that the traffic light 1 10 was going to turn red until the location of the first warning sign 121/131 . In many cases, such as a heavily loaded truck or a speeding vehicle, this may not provide enough time for the driver to safely stop the vehicle.

But with the improved traffic light cycle with two additional warning periods, the driver is given three times as much advance warning of the traffic light 1 10 turning red. As a vehicle approaches the intersection 101 from the bottom of FIG. 3 on road 102 the traffic light 1 10 may have the green light 1 13 illuminated as the traffic light 1 10 may be in state 203. As the vehicle approaches the third warning sign 124/133, which is a different type of sign than sign 123 shown in FIG. 1 , the traffic light 1 10 may switch to state 205 and turn on both the green light 1 13 and the amber light 1 12. If the driver passes the third warning sign 124/133 with the traffic light 1 10 still illuminating only the green light 1 13, the driver knows that he can legally pass through the intersection 101 by travelling at the expected speed, or posted speed limit because the third warning sign 124/133 is located at a distance of three times the warning distance 129 which has been calculated to allow a vehicle to traverse the warning distance 129 in the 'A' time period as described in FIG. 2. If the driver sees that the amber light 1 12 has been illuminated at some point before he passes the third warning sign 124/133, he or she knows that they should stop at the intersection 101 because there is not enough time for them to make it through the intersection travelling at the posted speed limit before the traffic light 1 10 turns red. This gives a driver as much as three times as much time and distance to safely stop the vehicle as compared to a conventional traffic light cycle.

Similarly, if the traffic light 1 10 has only the green light 1 13 illuminated in state 207 before the driver passes the second warning sign 122/133, the driver knows that they must stop at the intersection 101 . While some drivers may miss state 205 where both the green light 1 13 and amber light 1 12 are illuminated, and only look up during state 207 when just the green light 1 12 is illuminated, they are in no worse shape than they would have been given a conventional traffic light cycle. Many drivers may be observant enough to notice that the traffic light went from amber and green to green only and may interpret that to provide additional notice that the traffic light 1 10 is about to turn red. As long as they have already passed the second warning sign 122/132 by the time the traffic light 1 10 changes from green and amber to green only, they should have enough time to pass through the intersection 101 legally while travelling at the posted speed limit. If, however, they see the traffic light 1 10 change from green and amber to green only before they pass the second warning sign 122/132, they know that they should stop at the intersection 101 .

If a driver approaches the first warning sign 121/131 with either a conventional traffic light cycle or the improved traffic light cycle described herein, and the traffic light 1 10 is still green, the driver knows that they should have enough time to pass through the intersection legally. The addition of the first warning sign 121/131 provides valuable information above and beyond what a conventional traffic system provides to allow the driver to make this determination. With the improved traffic light cycle described herein, the driver has already had two warning periods, and should be much more prepared for the traffic light 1 10 to turn red. So if the traffic light 1 10 changes to state 209, turning off the green light 1 13 and turning on the amber light 1 12, before the driver passes the first warning sign 121/131 , he or she knows that they should stop at the intersection 101 as the traffic light 1 10 will switch to state 201 and illuminate the red light 1 1 1 before they can enter the intersection 101 . FIG. 4 shows a block diagram of one possible embodiment of a traffic light controller 400. The traffic light controller 400 may have a processor 41 1 capable of executing computer instructions implementing computer programs having various functions. The processor 41 1 is coupled to light control circuitry 413 by a

communications connection 412, allowing the processor 41 1 to control the light control circuitry 413. The light control circuitry 413 in some embodiments may be capable of directly providing power to the red, amber and green lights of one or more traffic lights over connection 432. In other embodiments, the light control circuitry 413 may provide individual low-voltage control lines that are coupled to additional circuitry associated with the red, amber and green lights in one or more traffic lights as connection 432. The light control circuitry 413 of some embodiments may implement a network connection over connection 432 suitable for communicating over the network to the red, amber and green lights of one or more traffic lights. Such a network over connection 432 may be configured to support any type of computer or telephony network, including wired networks, radio frequency networks, power line communication networks, and optical networks. Wired networks that could be used include, but are not limited to, various speeds and configurations of IEEE 802.3 ethernet networking, infiniband, Multimedia over Coax Alliance (MoCA), or other standard and/or proprietary protocols. Radio frequency networks that could be used include, but are not limited to, various versions of IEEE 802.1 1 Wi-Fi, wireless mesh networks such as IEEE 802.15.4 ZigBee or Z- Wave, Global Systems for Mobile Communications (GSM), Code Division Multiple Access 2000 (CDMA2000), other third generation (3G) or fourth generation (4G) mobile telephony standards, IEEE 802.16 WiMax and other "wireless" networks, standards based or proprietary, utilizing radio frequency communication. Power line

communication networks that could be used include, but are not limited to, protocols published by the HomePlug Powerline Alliance, the Universal Powerline Association, the HD-PLC Alliance, the ITU-T, or other standards based or proprietary powerline communication protocols. In some embodiments, the traffic light controller 400 may have more than one network interface and network connection, allowing it to

communicate over multiple networks that may implement the same or different protocols or types of networking.

The traffic light controller 400 may also include memory 415 and/or other non- transitory computer readable storage medium coupled to the processor 41 1 with a communications connection 416. In some embodiments, the processor 41 1 and the memory 415 may integrated into a single semiconductor die and/or a single package. The memory 415 may be implemented using dynamic random access memory (DRAM) chips, synchronous dynamic random access memory (SDRAM), double data rate random access memory (DDR), NOR or NAND type flash memory chips, static random access memory (SRAM), electrically erasable programmable read only memory

(EEPROM), read only memory (ROM), programmable read only memory (PROM), hard disk, CD ROM, DVD ROM, or any other computer readable storage medium, volatile or non-volatile. The memory 415 may hold computer program code 417 that is readable and executable by the processor 41 1 . The computer program code 417 may be configured to implement various methods such as the method shown in state diagram 200 in FIG. 2.

Any combination of one or more computer readable storage medium(s) may be utilized. A computer readable storage medium may be embodied as, for example, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or other like storage devices known to those of ordinary skill in the art, or any suitable combination of computer readable storage mediums described herein. In the context of this document, a computer readable storage medium may be any tangible medium that can contain, or store a program and/or data for use by or in connection with an instruction execution system, apparatus, or device.

Computer program code for carrying out operations for aspects of various embodiments may be written in any combination of one or more programming

languages, including an object oriented programming language such as Java, Smalltalk, C++, or the like, and conventional procedural programming languages, such as the "C" programming language or similar programming languages. In accordance with various implementations, the program code may execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer or server. In the latter scenario, the remote computer may be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or the connection may be made to an external computer (for example, through the Internet using an Internet Service Provider). Aspects of various embodiments are described with reference to flowchart, state diagram illustrations and/or block diagrams of methods, apparatus, systems, and computer program products according to various embodiments disclosed herein. It will be understood that various blocks or combinations of blocks in figures may be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions/acts specified in the flowchart, state diagram, and/or block diagram block or blocks.

These computer program instructions may also be stored in a computer readable medium that can direct a computer, other programmable data processing apparatus, or other devices to function in a particular manner, such that the instructions stored in the computer readable medium produce an article of manufacture including instructions which implement the function/act specified in the flowchart, state diagram, and/or block diagram block or blocks. The computer program instructions may also be loaded onto a computer, other programmable data processing apparatus, or other devices to cause a series of operational steps to be performed on the computer, other programmable apparatus or other devices to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide processes for implementing the functions/acts specified in the flowchart, state diagram and/or block diagram block or blocks.

The various figures help to illustrate the architecture, functionality, and operation of possible implementations of systems, methods and computer program products of various embodiments. In this regard, each block in the figures may represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). It will also be noted that each block or combinations of blocks in the figures, may be implemented by special purpose hardware-based systems that perform the specified functions or acts, or combinations of special purpose hardware and computer instructions.

So in some embodiments, the traffic light controller 400 may be implemented without a processor using electronic circuitry to implement a finite state machine for the method shown in state diagram 200 in FIG. 2. In other embodiments, relay logic may be used in the traffic light controller 400. In other embodiments the traffic light controller 400 may be implemented on a general purpose computer or server executing computer program instructions that may be retrieved from a non-transitory computer readable memory. The traffic light controller 400 may be implemented using any suitable method that may include electronic circuitry, mechanical elements, computer program

instructions on a non-transitory computer readable medium, a processor, or any combination of the forenamed elements and/or any other suitable elements.

As used in this specification and the appended claims, the singular forms "a", "an", and "the" include plural referents unless the content clearly dictates otherwise. Thus, for example, reference to an element described as "a device" may refer to a single device, two devices or any other number of devices. As used in this specification and the appended claims, the term "or" is generally employed in its sense including "and/or" unless the content clearly dictates otherwise.

As used herein, the term "coupled" includes direct and indirect connections.

Moreover, where first and second devices are coupled, intervening devices including active devices may be located there between.

Any element in a claim that does not explicitly state "means for" performing a specified function, or "step for" performing a specified function, is not to be interpreted as a "means" or "step" clause as specified in 35 U.S.C. § 1 12, If 6. In particular the use of "step of in the claims is not intended to invoke the provision of 35 U.S.C. § 1 12, If 6.

The description of the various embodiments provided above is illustrative in nature and is not intended to limit the invention, its application, or uses. Thus, variations that do not depart from the gist of the invention are intended to be within the scope of the embodiments of the present invention. Such variations are not to be regarded as a departure from the intended scope of the present invention.

Claims

What is claimed is:

1 . A method for controlling traffic at an intersection, the method comprising:

illuminating a red light while not illuminating a green light and an amber light for a first period of time;

illuminating the green light while not illuminating the red light and the amber light for a second period of time following the first period of time;

illuminating the green light and the amber light while not illuminating the red light for a third period of time following the second period of time;

illuminating the green light while not illuminating the red light and the amber light for a fourth period of time following the third period of time;

illuminating the amber light while not illuminating the red light and the green light for a fifth period of time following the third period of time; and

illuminating the red light while not illuminating the green light and the amber light for a sixth period of time following the fifth period of time;

wherein the red light, the green light and the amber light are simultaneously visible to traffic approaching the intersection from a particular direction and not easily visible to traffic approaching the intersection from other directions.

2. The method of claim 1 , further comprising:

positioning a first warning indication at a first calculated distance from the intersection near the road in the particular direction;

wherein the first calculated distance is based on the fifth period of time and an expected speed of a vehicle between the first warning indication and the intersection.

3. The method of claim 2, further comprising:

positioning a second warning indication at a second calculated distance from the intersection near the road in the particular direction; and

positioning a third warning indication at a third calculated distance from the intersection near the road in the particular direction;

wherein the second calculated distance is based on the fourth period of time, the fifth period of time, and an expected speed of a vehicle between the second warning indication and the intersection; and the third calculated distance is based on the third period of time, the fourth period of time, the fifth period of time, and an expected speed of a vehicle between the third warning indication and the intersection.

4. The method of claim 2, wherein the first warning indication is selected from a group consisting of a sign posted near a side of the road, a sign posted above the road, a sign painted on the road, rumble strips on the road, and at least one line painted on the road.

5. The method of claim 1 , wherein the third, fourth and fifth periods of time vary by no more than 50% from one another.

6. The method of claim 1 , wherein the third, fourth and fifth periods of time vary by no more than one second from one another.

7. The method of claim 1 , wherein the first and second periods of time are both greater than about 20 seconds, and the third, fourth and fifth periods of time are each between about 3 seconds and about 5 seconds.

8. The method of claim 1 , wherein the first and second periods of time vary based on traffic conditions at the intersection.

9. A system for controlling traffic at an intersection comprising:

a traffic light controller capable to:

illuminate a red light while not illuminating a green light and an amber light for a first period of time;

illuminate the green light while not illuminating the red light and the amber light for a second period of time following the first period of time;

illuminate the green light and the amber light while not illuminating the red light for a third period of time following the second period of time;

illuminate the green light while not illuminating the red light and the amber light for a fourth period of time following the third period of time;

illuminate the amber light while not illuminating the red light and the green light for a fifth period of time following the third period of time; and illuminate the red light while not illuminating the green light and the amber light for a sixth period of time following the fifth period of time.

10. The system of claim 9, wherein the third, fourth and fifth periods of time vary by no more than one second from one another.

1 1 . The system of claim 9, further comprising:

a traffic light including the red light, the amber light and the green light;

wherein the red light, the amber light and the green light are directionally oriented to be visible from the same direction.

12. The system of claim 1 1 , further comprising:

at least a first warning sign.

13. The system of claim 1 1 , wherein

the traffic light is positioned near an intersection and oriented so that the red light, the amber light, and the green light are visible to traffic approaching the

intersection from a particular direction;

a first warning indication is positioned on or near the road at a first calculated distance from the intersection in the particular direction;

a second warning indication is positioned on or near the road at a second calculated distance from the intersection in the particular direction; and

the third warning indication is positioned on or near the road at a third calculated distance from the intersection in the particular direction;

wherein the first calculated distance is based on the distance travelled during the third period of time by the traffic travelling at a speed limit for the road between the first warning indication and the intersection;

the second calculated distance is based on the distance travelled during the third and the fourth periods of time by the traffic travelling at the speed limit for the road between the second warning indication and the intersection;

the second calculated distance is based on the distance travelled during the third and the fourth periods of time by the traffic travelling at the speed limit for the road between the second warning indication and the intersection.

14. The system of claim 13, wherein the first warning indication, the second warning indication, and the third warning indication, are selected from a group consisting of a sign posted near a side of the road, a sign posted above the road, a sign painted on the road, rumble strips on the road, and at least one line painted on the road.

15. The system of claim 9, wherein the first and second periods of time are both greater than about 20 seconds, and the third, fourth and fifth periods of time are each between about 3 seconds and about 5 seconds.

16. The system of claim 9, further comprising:

a sensor, coupled to the traffic light controller, to provide information about traffic conditions near the intersection; wherein the first and second periods of time are dependent on based on the information from the sensor.

17. An article of manufacture comprising a non-transitory computer readable storage medium having instructions stored thereon that, if executed by a processor, result in: illuminating a red light while not illuminating a green light and an amber light for a first period of time;

illuminating the red light while not illuminating the green light and the amber light for a sixth period of time following the fifth period of time.

18. The article of manufacture as claimed in claim 17, wherein the third, fourth and fifth periods of time vary by no more than one second from one another.

19. The article of manufacture as claimed in claim 17, wherein the first and second periods of time are both greater than 19 seconds, and the third, fourth and fifth periods of time are each between about 3 seconds and about 5 seconds.

20. The article of manufacture as claimed in claim 17, wherein the first and second periods of time vary based on traffic conditions at the intersection.