COLLISION AVOIDANCE AND TRAFFIC SIGNAL PREEMPTION SYSTEM
20170236412 · 2017-08-17
Assignee
Inventors
Cpc classification
G08G1/0965
PHYSICS
G08G1/087
PHYSICS
International classification
Abstract
A method of avoiding collisions and preempting traffic signals, including the steps of predicting a first likely travel route of a first vehicle along established roadways; predicting a second likely travel route of a second vehicle along the established roadways; preempting a normal operation of at least one traffic signal at an intersection of roadways along at least one of the first likely travel route and the second likely travel route allowing at least one of the first vehicle and the second vehicle to traverse the intersection; and determining whether both the first vehicle and the second vehicle will be at the intersection within a predefined time interval of each other.
Claims
1. A method of avoiding collisions and preempting traffic signals, comprising the steps of: predicting a first likely travel route of a first vehicle along established roadways; predicting a second likely travel route of a second vehicle along the established roadways; preempting a normal operation of at least one traffic signal at an intersection of roadways along at least one of the first likely travel route and the second likely travel route allowing at least one of the first vehicle and the second vehicle to traverse the intersection; and determining whether both the first vehicle and the second vehicle will be at the intersection within a predefined time interval of each other.
2. The method of claim 1, further comprising the step of sending information to a receiving device in at least one of the first vehicle and the second vehicle.
3. The method of claim 1, further comprising the step of sending information to a receiving device in the first vehicle and to a receiving device in the second vehicle, the information including an estimated amount of time until the first vehicle will be proximate to the second vehicle.
4. The method of claim 3, further comprising the step of providing an alert to an operator of the first vehicle if the determining step indicates that the first vehicle will be proximate to the second vehicle within the predefined time interval in the intersection.
5. The method of claim 3, further comprising the step of displaying the estimated amount of time until the first vehicle will be proximate to the second vehicle, the displaying taking place on at least one display in the first vehicle.
6. The method of claim 5, further comprising the step of overlaying a directional indicator on a map on the display of the first vehicle indicating a direction to a current position of the second vehicle.
7. The method of claim 6, further comprising the step of associating the estimated amount of time to the directional indicator on the map on the display of the first vehicle.
8. The method of claim 7, wherein the overlaying step and the associating step are carried out while the current position of the second vehicle places it beyond a boundary of the map being displayed on the display of the first vehicle.
9. The method of claim 1, further including the steps of identifying at least one of the first vehicle and an operator of the first vehicle; and arriving at what the first likely travel route is of the identified first vehicle or the identified operator dependent upon previous travel routes of the identified first vehicle or the identified operator; and executing the preempting step dependent upon the first likely travel route.
10. The method of claim 9, wherein the identifying step identifies a type of the first vehicle.
11. A collision avoidance and traffic signal preemption system, comprising: a travel route prediction device predicting a first likely travel route of a first vehicle along established roadways and a second likely travel route of a second vehicle along the established roadways; a traffic signal preemption device preempting a normal action of a traffic signal at an intersection of the roadways along at least one of the first likely travel route and the second likely travel route allowing at least one of the first vehicle and the second vehicle to traverse the intersection; and a controller to determine the information as to whether both the first vehicle and the second vehicle will be at the intersection within a predefined time interval of each other.
12. The collision avoidance and traffic signal preemption system of claim 11, further comprising a receiving device in at least one of the first vehicle and the second vehicle, the receiving device receiving the information from the controller.
13. The collision avoidance and traffic signal preemption system of claim 11, wherein the receiving device in the first vehicle receives the information including an estimated amount of time until the first vehicle will be proximate to the second vehicle.
14. The collision avoidance and traffic signal preemption system of claim 13, further comprising an alert device to provide an alert to an operator of the first vehicle if the first vehicle will be proximate to the second vehicle within the predefined time interval in the intersection.
15. The collision avoidance and traffic signal preemption system of claim 13, further comprising a display device in the first vehicle, the estimated amount of time until the first vehicle will be proximate to the second vehicle being displayed on the display in the first vehicle.
16. The collision avoidance and traffic signal preemption system of claim 15, wherein a directional indicator is overlaid on a map on the display of the first vehicle indicating a direction to a current position of the second vehicle.
17. The collision avoidance and traffic signal preemption system of claim 16, wherein the estimated amount of time is associated with the directional indicator on the map on the display of the first vehicle.
18. The collision avoidance and traffic signal preemption system of claim 17, wherein the directional indicator is pointing to the second vehicle even though the second vehicle is located such that its position is beyond a boundary of the map being displayed on the display of the first vehicle.
19. The collision avoidance and traffic signal preemption system of claim 11, further comprising: at least one identification device for identification of the first vehicle and/or a driver of the first vehicle; and a historical travel database including records of routes previously taken by the first vehicle or the driver, the travel route prediction device using the records of routes to predict the first likely travel route.
20. The collision avoidance and traffic signal preemption system of claim 19, wherein the identification device identifies a type of the first vehicle.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention will be better understood by reference to the following description of an embodiment of the invention taken in conjunction with the accompanying drawings, wherein:
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[0037] Corresponding reference characters indicate corresponding parts throughout the several views. The exemplification set out herein illustrates one embodiment of the invention and such exemplification is not to be construed as limiting the scope of the invention in any manner.
DETAILED DESCRIPTION OF THE INVENTION
[0038] Referring now to the drawings, and in particular to
[0039] The present invention puts forward the concept of “intelligent predictive preemption”, based on historical data. For the purposes of this invention, the term “preemption” can also mean transit signal priority for buses (TSP). The invention further allows the incorporation of geowindows, which are well known to those skilled in the discipline of traffic signal preemption and TSP (geowindows are disclosed in U.S. Pat. Nos. 5,986,575 and 8,912,922 among others). Geowindows may be created either by the intersection (as in U.S. Pat. No. 5,986,575), or by the vehicle (as in U.S. Pat. No. 8,912,922).
[0040] Now, additionally referring to
[0041] Now, as a second example, we will assume that vehicle V1 has been identified as specifically No. 3 ambulance of the hospital. The historical travel pattern of No. 3 is that 75% of the time it takes street SA to street S2, turns right and continues on street S2 to street SC, turns left and proceeds straight to the hospital. In this case lights L7, L4, L5, L6 and L3 are used to preempt the normal working of these lights so that vehicle V1 can reach the destination in a statistically improved amount of time.
[0042] Now, as a third example, we will assume that vehicle V1 is being driven by an identified driver, here assumed to be Sally. Sally, as recorded in the historical travel database, 90% of the time turns right at light L7, proceeds along street S3 to light L9, turns left on street SC and then travels straight to the hospital. In this case lights L7-L9, L6 and L3 are used to preempt the normal working of these lights so that vehicle V1 can reach the destination in a statistically improved amount of time.
[0043] In the above scenarios if the driver uses a turn signal that is contrary to the predicted route, then the present invention responds to the turn signal selection to preempt traffic in that indicated route, and will release those lights from preemption which will now not be effected. For example if the No. 3 ambulance uses a turn signal to turn right at light L7, then the route along street S2 will be abandoned to normal operation and if a new likely route is predicted that route will anticipate the travel of No. 3.
[0044] In the above scenarios, if Sally were to use the left turn signal at light L7, and turn left on street S3 then the prediction to the hospital is abandoned, unless reestablished by some routing of vehicle V1 back toward the hospital. Here if Sally turns left at light L7 it may be predictive of a route to another hospital and the present invention adapts and establishes a predicted route thereto, using the preemption method of the present invention.
[0045] To illustrate the advantage of the present invention it is important to understand the difference between the prior art and the inventive nature of the present invention, look now to
[0046] This problem is overcome by the approach of the present invention. For example, if an ambulance normally turns left at a given intersection 90% of the time, and the driver has forgotten to engage his left turn signal, this system will automatically begin a preemption sequence for traffic lights to the left of the intersection, just in case he does turn left, based on historical preemption data. This approach involves the storage of preemption data (including how many times the vehicle has previously turned left/right or continued straight through the intersection), retrieval of this data (including vehicle ID, driver ID, direction of travel, speed, date and time of preemption initiation and termination for each event, direction of preemption, location of intersection), the aggregation of the data, its analysis, and the additional subsequent preemption of traffic signals in anticipation of the emergency vehicle's route based on an analysis of this historical data is logged, aggregated, analyzed and put in useful form for administrative personnel to review. The logs and data generated by this methodology may additionally, for example, be useful as a training tool to show how many times a particular emergency vehicle turned right or left, while failing to properly use turn signals prior to making those turns. This could allow supervisors to identify which drivers, if any, may be in need of additional safety training regarding the proper use of turn signals.
[0047] It is also contemplated that the preemption system can detect a sequence of vehicles, such as a convoy or a funeral procession, with the detection being a vehicle that is allowed a prolonged preemption with the system detecting and tracking an ending event to the convoy/procession, such as an ending vehicle that releases the intersection from the preemption process. For example, in
[0048] It is further contemplated that the traffic signal preemption of the present invention will also take into account the historical travel patterns relative to the time of day, the day of the week and other historical events, such as holidays and community events (such as sporting events). For example, if a driver typically takes one route in the morning to the destination and another in the afternoon to the destination, the present invention will weigh such behavior in the decision to preempt the normal function of the traffic systems accordingly. This advantageously allows the present invention to take advantage of the historical data that may be related to driving habits that may be based on otherwise uncontemplated routine occurrences. These uncontemplated occurrences may be simply the solar incidence in the morning along one route versus another route that causes the driver to take a certain route in the morning and a different route in the afternoon.
[0049] Now, additionally referring to
[0050] At step 104 traffic preemption takes place dependent upon the use of a turn signal and method 100 continues to be available to assist in the preemption of a predicted pathway. Step 104 effectively overrides a contrary pathway prediction. However, if the left turn signal is in concert with the predicted path then the signal lights along that path are already in the mode of preempting their normal operation and the turn signal reinforces the already predicted travel path. As a result of arriving at step 104 lights L10, L12 and L13 will be preempted as vehicle V1 travels, see
[0051] At step 106, database 18 is queried by device 16 to see what the identified type of vehicle, the identified specific vehicle and/or the driver of the vehicle generally does at upcoming intersections. At step 108 that follows, if vehicle V1 historically turns left at an intersection more than a predetermined percentage of the time then method 100 proceeds to step 112 and if not then to step 110. The method then repeats.
[0052] At step 110, if vehicle V1 is as shown in
[0053] At step 112, lights L10-L13 are all selected for preemption since there is a reasonably high probability that vehicle V1 will turn left. The preemption of both the straight forward direction as well as the left turn is to accommodate the two likely travel paths of vehicle V1.
[0054] Now, reviewing a method 200, illustrated in
[0055] At step 202 it is determined if the right turn signal is activated in vehicle V1, which can be in the form of a signal from a turn signal indicator or sensor, and if activated method 200 proceeds to step 204, otherwise method 200 proceeds to step 206.
[0056] At step 204 traffic preemption takes place dependent upon the use of a turn signal and method 200 continues to be available to assist in the preemption of a predicted pathway. Step 204 effectively overrides a contrary pathway prediction. However, if the right turn signal is in concert with the predicted path then the signal lights along that path are already in the mode of preempting their normal operation and the turn signal reinforces the already predicted travel path. As a result of arriving at step 204 lights L15, L14 and L11 will be preempted as vehicle V1 travels right at the next intersection, see
[0057] At step 206, database 18 is queried by device 16 to see what the identified type of vehicle, the identified specific vehicle and/or the driver of the vehicle generally does at upcoming intersections. At step 208 that follows, if vehicle V1 historically turns right at an intersection more than a predetermined percentage of the time then method 200 proceeds to step 212 and if not then to step 210. The method then repeats.
[0058] At step 210, if vehicle V1 is as shown in
[0059] At step 212, lights L15, L16, L 14 and L11 are all selected for preemption since there is a reasonably high probability that vehicle V1 will turn right. The preemption of both the straight forward direction as well as the right turn is to accommodate the two likely travel paths of vehicle V1 in this scenario.
[0060] Now, reviewing a method 300, illustrated in
[0061] At step 302 it is determined if either the right or left turn signal is activated in vehicle V1, which can be in the form of a signal from a turn signal indicator or sensor, and if activated method 300 proceeds to step 304, otherwise method 300 proceeds to step 306.
[0062] At step 304 traffic preemption takes place dependent upon the use of the turn signal and method 300 continues to be available to assist in the preemption of a predicted pathway. Step 304 effectively overrides a contrary pathway prediction. However, if the turn signal is in concert with the predicted path then the signal lights along that path are already in the mode of preempting their normal operation and the turn signal reinforces the already predicted travel path. As a result of arriving at step 304 lights in the selected direction will be preempted as vehicle V1 travels right at the next intersection, see
[0063] At step 306, database 18 is queried by device 16 to see what the identified type of vehicle, the identified specific vehicle and/or the driver of the vehicle generally does at upcoming intersections. At step 308 that follows, if vehicle V1 historically turns at an upcoming intersection more than a predetermined percentage of the time then method 300 proceeds to the appropriate step 312L or 312R and if not then to step 310. The method then repeats.
[0064] At step 310, vehicle V1 is presumed to be heading in a straight direction and the lights in the straight direction are selected for preemption, since the historically right or left turn percentages are below the predetermined amount. Of course if vehicle V1 turns at the upcoming intersection then system 12 seeks to determine a new predicted pathway.
[0065] At step 312L, lights to the left as well as those in a straight path are all selected for preemption since there is a reasonably high probability that vehicle V1 will turn left. The preemption of both the straight forward direction as well as the left turn is to accommodate the two likely travel paths of vehicle V1 in this scenario.
[0066] At step 312R, lights to the right as well as those in a straight path are all selected for preemption since there is a reasonably high probability that vehicle V1 will turn right, in spite of the lack of use of the turn signal. The preemption of both the straight forward direction as well as the right turn is to accommodate the two likely travel paths of vehicle V1 in this scenario.
[0067] Now additionally referring to
[0068] The situation of emergency vehicles being proximate to each other particularly at an intersection where the normal function of a traffic signal is being preempted for an emergency vehicle can lead to an assumption that the intersection is cleared for them and can lead to a collision of the emergency vehicles. To avoid such situations the present invention identifies when emergency vehicles are likely to be proximate to each other at traffic signals that are about to or are having their normal functions preempted, and provide indications of potential conflicts at an intersection so that the drivers can adjust accordingly. In the situation shown in
[0069] Additionally there is shown in
[0070] A display of a configuration screen 400A is shown in
[0071]
[0072] In
[0073] In
[0074] In
[0075] Screens 400F and 400G illustrate the establishing of geo windows that may take place either in system 600 or system 700, to define the latitude and longitude of the geo windows, for use by the present invention.
[0076] In
[0077] In
[0078] System portion 700, is implemented in each vehicle and controller 702 interfaces with vehicle information 704, a driver ID reader 706, a turn signal detector 708, a light bar detector 710, a GPS system 712, a parking brake detector 714, a door ajar detector 716, a temperature detector 718, a road condition detector 720, and any other sensors that may be a part of an emergency vehicle.
[0079] The advanced notifications of potentially impending collisions of the present invention is a useful tool for the emergency vehicle driver. The following outlines the method and programming of the collision avoidance system 12 for emergency vehicles which also preempts traffics signals.
[0080] This is merely one method of programming and using a graphic user interface (GUI) to facilitate and more easily control the programming and function of a GPS 712 based emergency vehicle traffic signal preemption and collision avoidance system 12.
[0081] Vehicle System
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[0083] Touching the words “Collision Avoidance Distance” takes you to a screen shown in
[0084] In
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[0086] Touching the screen in
[0087] Touching the screen in
[0088] Again the (red) arrows 418, 420, 422 and 424 near the edge of the screen in
[0089] Icons on the upper left side of the screen in
[0090] In one mode of operation (referred to above as “smart mode”) the system 600/700 will automatically preempt traffic signals without any user intervention required. In smart mode, the vehicle will automatically begin preempting traffic signals when the following conditions are satisfied: [0091] 1. The vehicle is determined to be within range to begin turning a traffic signal green in favor of the vehicle's direction of travel. [0092] 2. The light bar is engaged. [0093] 3. None of the doors on the vehicle are opened. [0094] 4. The parking brake is not applied. [0095] 5. The vehicle's transmission is in “Drive”.
[0096] When any of the above conditions are NOT satisfied (while in smart mode), preemption is deactivated. Also, “Off” mode manually deactivates preemption, and “On” mode is the same as “smart” mode, except that the light bar does not need to be activated for preemptions to occur. “On” mode may be useful, for example, by a police vehicle that does not wish to announce its presence with the use of its light bar, but still wishes the use of the preemption feature.
[0097] The upper right hand quadrant of buttons depicted in
[0098] The GUI of the present invention can also show the status of nearby traffic signals. In
[0099] Traffic Signal System
[0100] The traffic signal system is such that it does not require a GPS antenna to know its location. This can save considerably in the manufacturing cost of the Traffic Signal System. Each traffic signal intersection can be programmed using Google Earth, for example, to “know” where it is located, using conventional coordinates for latitude/longitude. Additionally, the traffic signals are programmed to work on “geo windows” (drawing a polygon surrounding the intersection to determine when preemption will be activated) or ETA (preempting based on estimated time of arrival at the intersection). One method of programming a traffic signal follows.
TABLE-US-00001 Step Description 1) If Google Earth is not installed, navigate to https://www.google.com/intl/en/earth/download/ge/agree.html to download Google Earth Select [Agree and Download] Open your download folder and execute the ‘GoogleEarthSetup.exe’ file Follow instructions to install Google Earth Make a copy of the “TrafficLightDefinition.rtf” file template (Fig 17), and name it to reflect the name of the intersection you are programming (Fig 18). 2) In the [Search] text field, enter the address or the latitude/longitude of the intersection of interest Select the [Search] button Confirm the map is at the location of interest 3) Select the [Thumb Tac] button shown on the left Place the [Thumb Tac] at the center of the intersection Enter [Name:] for the placemark dialog and select [OK] Go to “Tools” then “Options” then 3D view then Under “Show Lat/Lon” check “Decimal Degrees”. Add the Lat and Lon of center point to the *.RTF file 4) Select the [Ruler] Select the center of the Thumb Tac on the map and draw a line down the intersection Enter the heading for your first intersect angle definition in the open Traffic Light Definition RTF Save it in a word document. Repeat this step for at least four intersect angles or upwards of eight if necessary (Fig. 18) 5) If defining GEO windows, select the icon to the left On the map, select the four points that represent the GEO window. NOTE: Only define four points Enter [Name:] for the new path dialog Repeat this for at least four GEO window definitions (Fig. 18). 6) From the [Places] control select the GEO window definition from step 5 Right-click [the Place] and select [Copy] Open Notepad and select [Paste] Copy the latitude/longitude definitions that exist within the <coordinates> </coordinates> tag Paste the values into the RTF GEO window definition. Ensure no spaces exist at the beginning/end or between the latitude/longitude definitions. Eliminate any ‘0’ that exist between the latitude/longitude definition Only four point definitions should exist for a GEO window definition Repeat this step for the remaining GEO window definitions 7) Note: If utilizing GEO windows, you must define both intersect angles (0- 3) and GEO windows (0-3) for the device to work properly. The utilization of GEO windows occurs by setting the ‘StaticDevice.IsETA=false’. Specify the following information in the file from a traffic definition RTF: #Utilized if the MAC address cannot be determined: Device.SerialNumber=000000000000000 #Value=Latitude; Longitude (degrees) StaticDevice.Location=41.043716;−85.235665 StaticDevice.StreetInfo=Engle Road #true for intersect angles, false for intersect angles and GEO windows StaticDevice.IsETA=true #Value=Integer number in feet StaticDevice.MinPreemptionDistanceFeet=300 #Value=Integer as seconds StaticDevice.ETAThresholdSeconds=25 #Value=Angle From North (degrees) StaticDevice.IntersectAngle0=35.68 StaticDevice.IntersectAngle1=215.57 StaticDevice.IntersectAngle2=123.96 StaticDevice.IntersectAngle3=286.98 StaticDevice.IntersectAngle4=NOT_SET StaticDevice.IntersectAngle5=NOT_SET StaticDevice.IntersectAngle6=NOT_SET StaticDevice.IntersectAngle7=NOT_SET #Value=StartLatitude;StartLongitude;EndLatitude;EndLongitude;Width (feet) decimal form StaticDevice.GeoWindow0=41.044485;−85.235609;41.043614;− 85.235856;41.043559;−85.235643;41.04439;−85.235308 StaticDevice.GeoWindow1=41.043614;−85.235856;41.042813;− 85.232958;41.043284;−85.232878;41.043831;−85.235736 StaticDevice.GeoWindow2=41.043831;−85.235736;41.043186;− 85.236082;41.043158;−85.235882;41.043559;−85.235643 StaticDevice.GeoWindow3=41.044413;−85.237539;41.043559;− 85.235643;41.043755;−85.235439;41.044669;−85.237217 StaticDevice.GeoWindow4=NOT_SET StaticDevice.GeoWindow5=NOT_SET StaticDevice.GeoWindow6=NOT_SET StaticDevice.GeoWindow7=NOT_SET COPY File To Static Unit 8) Change directory to the CCC System BIN directory: cd /home/pi/CCC System/config 9) Copy the PROPERTIES file from the thumb drive to the configuration directory: sudo cp [Media Drive Location]/*.properties. Validate the Settings 10) Change directory to the CCC System BIN directory: cd /home/pi/CCC System/bin 11) Execute the diagnostic command: sudo ./cccStartup.sh static_hw_tech 12) Test executes validating the properties file and then reports via STDOUT the status of the attached supporting hardware. Any errors will report as an EXCEPTION. Correct as necessary and re-execute this procedure. 13) Reassemble, reboot the device, or power off when completed
[0101] The steps of a method of avoiding collisions and preempting traffic signals, include predicting a first likely travel route of a first vehicle 402 along established roadways; predicting a second likely travel route of a second vehicle 410 along the established roadways; preempting a normal operation of at least one traffic signal at an intersection of roadways along at least one of the first likely travel route and the second likely travel route allowing at least one of the first vehicle and the second vehicle to traverse the intersection; and determining whether both the first vehicle 402 and the second vehicle 410 will be at the intersection within a predefined time interval of each other.
[0102] The sending information to a receiving device 702 is depicted in
[0103] An alert is provided to an operator of the first vehicle 402 if the determining step indicates that the first vehicle 402 will be proximate to the second vehicle 410 within the predefined time interval in the intersection. The alert can be visual, audible or mechanical, such as a vibration in a portion of the driver's seat.
[0104] The estimated amount of time, such as 2 seconds depicted in
[0105] The method of avoiding collisions and preempting traffic signals, further including the steps of identifying the first vehicle 402 or an operator of the first vehicle 402; and arriving at what the first likely travel route is of the identified first vehicle 402 or the identified operator dependent upon previous travel routes of the identified first vehicle 402 or the identified operator; and executing the preempting of the normal operation of a traffic signal dependent upon the first likely travel route. The identifying step can also identify a type of the first vehicle 402, such as it being an ambulance, which will influence the like route determination if the ambulance is going in a general direction toward a hospital.
[0106] The collision avoidance and traffic signal preemption system 12 has a travel route prediction device 600 predicting a first likely travel route of a first vehicle 402 along established roadways and a second likely travel route of a second vehicle 410 along the established roadways. A traffic signal preemption device 610 preempting a normal action of a traffic signal at an intersection of the roadways along at least one of the first likely travel route and the second likely travel route allowing at least one of the first vehicle 402 and the second vehicle 410 to traverse the intersection. Controller 602 determines the information as to whether both the first vehicle 402 and the second vehicle 410 will be at the intersection within a predefined time interval of each other.
[0107] Receiving device 702 in the first vehicle 402 and/or the second vehicle 410, receives the information from the controller 602. The information includes an estimated amount of time until the first vehicle 402 will be proximate to the second vehicle 410. An alert device (display 400) provides an alert to an operator of the first vehicle 402 if the first vehicle 402 will be proximate to the second vehicle 410 within the predefined time interval in the intersection. Display device 400 in the first vehicle 402 displays the estimated amount of time until the first vehicle 402 will be proximate to the second vehicle 410.
[0108] The collision avoidance and traffic signal preemption system 12 also includes at least one identification device 608 for identification of the first vehicle 402 and/or a driver of the first vehicle 402; and a historical travel database including records of routes previously taken by the first vehicle 402 or the driver, the travel route prediction device 602 using the records of routes to predict the first likely travel route.
[0109] While a system for collision avoidance and directional control and the flow of traffic has been described with respect to at least one embodiment, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.