Method for regional system wide optimal signal timing for traffic control based on wireless phone networks
First Claim
1. A method for controlling and adjusting phase timings at all signalized intersections within a given geographical region with the purpose of allocating more green light time for roads with heavier traffic flows at the expense of less loaded roadways comprising the steps of:
- acquiring of dynamic traffic information from a cellular network provider or a group of cellular network providers and from GPS based technology whenever available for the purpose of monitoring movements of as many traveling vehicles in a given region as possible;
continuously or periodically obtaining location data on plurality of cell phones in the regional network in a specific real time frame;
determining for each particular cell phone whether the cell phone terminal is located in a traveling vehicle;
setting up a list of all cell phones currently identified as located in traveling vehicles;
compiling and updating a sequence of real time positions of each cell phone located in a traveling vehicle;
positioning each cell phone located in a traveling vehicle onto an appropriate road section at each particular moment according to its coordinates;
eliminating untenable cell phone positions (outlying positions) by analyzing series of recently recorded positions and relating them to nearby road sections;
making imputations for missing cell phone positions by analyzing series of recently recorded positions and relating them to nearby road sections;
calculating feasible continuous paths for all cell phones located in traveling vehicles within a given time period;
identifying multiple phones in a common vehicle and combining them into a single vehicular cluster entity based on closely located positions at corresponding time moments and common direction of movement;
calculating feasible continuous paths for vehicular clusters within a given time period; and
storing the relevant position data for each individual vehicle (vehicular cluster) traveling along a given road section in the database for the purpose of maintaining vehicle'"'"'s recent path information.
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Abstract
A method for the system wide control of signals in a traffic network in real time to provide an overall reduction in congestion is described. In the method, signals obtained from vehicular-based cellular phones provide location information on moving vehicles and are input into an Intelligent Traffic Control System to provide position information that is stored in the form of records. Mathematical models use those records together with detailed digital maps and algorithms to compute actual travel times consumed by traveling along road sections, by queuing near signalized intersections, and by making various allowed turns and go-throughs in the vicinity of signalized intersection areas. The actual travel times measured for a fixed control time period are compared to the corresponding theoretical travel times and form a basis for a mathematical optimization model. Maximization of that model allows computation of adjusted phase timings for signalized intersections within a given area to optimize vehicular flows for the next control period.
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Citations
18 Claims
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1. A method for controlling and adjusting phase timings at all signalized intersections within a given geographical region with the purpose of allocating more green light time for roads with heavier traffic flows at the expense of less loaded roadways comprising the steps of:
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acquiring of dynamic traffic information from a cellular network provider or a group of cellular network providers and from GPS based technology whenever available for the purpose of monitoring movements of as many traveling vehicles in a given region as possible;
continuously or periodically obtaining location data on plurality of cell phones in the regional network in a specific real time frame;
determining for each particular cell phone whether the cell phone terminal is located in a traveling vehicle;
setting up a list of all cell phones currently identified as located in traveling vehicles;
compiling and updating a sequence of real time positions of each cell phone located in a traveling vehicle;
positioning each cell phone located in a traveling vehicle onto an appropriate road section at each particular moment according to its coordinates;
eliminating untenable cell phone positions (outlying positions) by analyzing series of recently recorded positions and relating them to nearby road sections;
making imputations for missing cell phone positions by analyzing series of recently recorded positions and relating them to nearby road sections;
calculating feasible continuous paths for all cell phones located in traveling vehicles within a given time period;
identifying multiple phones in a common vehicle and combining them into a single vehicular cluster entity based on closely located positions at corresponding time moments and common direction of movement;
calculating feasible continuous paths for vehicular clusters within a given time period; and
storing the relevant position data for each individual vehicle (vehicular cluster) traveling along a given road section in the database for the purpose of maintaining vehicle'"'"'s recent path information. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
(k) maintaining and updating for each of the plurality of road sections a list of vehicles presently traveling along it;
(l) maintaining and updating for each of the plurality of road sections a list of vehicles that exited it within a predetermined period of time;
(m) updating the database based on the lists provided in steps (k) and (l);
(n) providing for each turn and each go-through of each controlled intersection the list of vehicles that passed there within a predetermined period of time;
(o) determining an estimated travel time for each of the plurality of road sections; and
(p) determining an estimated time for traversing each of the plurality of controlled intersections.
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3. The method according to claim 2, further comprising the steps of:
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(q) maintaining and updating lists of moving vehicles for corresponding road sections together with other relevant information;
(r) maintaining and updating lists of vehicles for corresponding road sections that exited them within a predetermined period of time together with other relevant information;
(s) maintaining and updating estimates of averaged recent travel times for road sections;
(t) maintaining and updating estimates of averaged crossing times for signalized intersections;
(u) estimating and updating the current status of the traffic situation and traffic flow at each road section;
(v) estimating and updating the current status of the traffic situation and traffic flow at each signalized intersection; and
(w) calculating estimated turning proportions of vehicles on signalized intersections.
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4. The method according to claim 2, further comprising the steps of:
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(q) maintaining and updating an estimate of averaged recent travel time for each road section; and
(r) maintaining and updating an estimate of averaged recent times for at least one of turning within and traversing through the plurality of controlled intersections.
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5. A method according to claim 1 for estimating and adjusting previously computed green light timings at all signalized intersections in a given geographical region for the next time period comprising the steps of:
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maximization (under appropriate restrictions) of a linear objective function in green light timings with the coefficients that measure time delays at all signalized intersections resulting from traffic congestion;
computing the values of green light timing variables that bring the linear objective function to its maximum; and
applying the obtained values of green light timing variables to the corresponding signalized intersections for controlling phase timings during the next time period.
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6. The method according to claim 5, wherein the plurality of controlled intersections each have a respective control signal, the method further comprising the steps of:
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(o) determining a theoretical respective traversal time for each of the controlled intersections within at least a portion of the predetermined region;
(p) determining an estimated respective traversal time for each of the controlled intersections within at least the portion of the predetermined region;
(q) determining the coefficients used in the linear objective function of step (l) in claim (3);
(r) measuring time delays as ratios of the estimated travel times of step (p) and the theoretical respective traversal times of step (o) for each one of the plurality of controlled intersections; and
(s) determining the linear objective function of step (l) in claim (3) to be maximized as a function of a timing of the control signal based on a time delay measured in step (r) at the plurality of controlled intersection.
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7. The method according to claim 1, wherein the plurality of road sections include a plurality of controlled intersections each having a respective control signal, the method further comprising the steps of:
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(k) determining a theoretical respective travel time for each of the controlled intersections within at least a portion of the predetermined region;
(l) determining an estimated respective traversal time for each of the controlled intersections within at least the portion of the predetermined region;
(m) determining the coefficients used in the linear objective function of step (l) in claim (3);
(n) measuring time delays as ratios of the estimated traversal times of step (l) and the theoretical respective traversal times of step (k) for each one of the controlled intersections; and
(o) determining the linear objective function of step (l) in claim (3) to be maximized as a function of a timing of the control signal based on a time delay measured in step (n) at the corresponding controlled intersection.
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8. A method according to claim 1 for storing and updating traffic situations at road sections and signalized intersections in a regional road system comprising the steps of:
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maintaining and updating lists of moving vehicles together with other relevant information for road sections;
maintaining and updating lists of vehicles for road sections that recently exited them together with other relevant information;
maintaining and updating estimates of averaged recent travel times for road sections;
maintaining and updating estimates of averaged crossing times for signalized intersections;
estimating and updating the current status of the traffic situation and traffic flow at each road section;
estimating and updating the current status of the traffic situation and traffic flow at each signalized intersection; and
calculating turning proportions of vehicles on signalized intersections.
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9. The method according to claim 1, wherein the plurality of road sections include a plurality of controlled intersections each having a respective control signal, the method further comprising the steps of:
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(k) collecting and storing real time road traffic data for the plurality of road sections in the predetermined geographical region;
(l) providing the data to at least one of a vehicle-based navigation system and an Internet based traffic server;
(m) collecting historical statistical traffic data for i) the plurality of road sections and ii) the plurality of controlled intersections on a periodic basis; and
(n) generating a short term prediction and a long term prediction of traffic volumes and travel times for the plurality of road sections and the plurality of controlled intersections.
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10. The method according to claim 1, wherein the traffic information is acquired from the at least one of i) road sensors, ii) mobile traffic reporting units, and iii) vehicle-tracking equipment.
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11. The method according to claim 1, further comprising the step of:
(k) interpolating for a missing observation of position for at least one of the plurality of cell phones.
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12. The method according to claim 11, wherein the interpolating step (k) is based on analyzing a series of stored positions of the corresponding cell phone and relating them to further road sections.
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13. The method according to claim 1, wherein the path constructed in step (i) is a continuous path.
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14. The method according to claim 1, wherein the combining step (h) is based on (i) distances among the multiple cell phones at consecutive times and (ii) a direction of movement of each of the multiple cell phones.
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15. The method according to claim 1, wherein the database stored in step (j) maintains recent path information for each of the plurality of vehicle clusters.
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16. The method according to claim 1, wherein the acquiring step (a) also acquires data from a satellite based positioning system.
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17. The method according to claim 1, wherein the location data is obtained within a predetermined time period.
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18. The method according to claim 1, wherein step (g) is based on an analysis of previous cell phone positions and local structure within the plurality of road sections.
Specification