WO2010103504A1

WO2010103504A1 - System and method for controlling traffic by coordination of intersection approaching flows

Info

Publication number: WO2010103504A1
Application number: PCT/IL2009/000705
Authority: WO
Inventors: Yehuda Gore
Original assignee: Yehuda Gore
Priority date: 2009-03-08
Filing date: 2009-07-19
Publication date: 2010-09-16

Abstract

A method and system for coordinating traffic at an intersection having a plurality of multi-lane entry routes are provided. The method includes selecting a sub-set of entry routes out of the plurality of entry routes and order of entry from the sub-set of entry routes into said intersection. At each of the sub-set of entry routes, velocity of a group of cruising vehicle platoons is adjusted upon arrival to a predetermined distance from the intersection. The duration of permission to cross the intersection for each of the sub-set of entry routes is calculated based on the adjusted velocity and length of the group of cruising vehicle platoons after crossing the predetermined distance. The length of the group of cruising vehicle platoons goes through affine transformation of translation and scaling when crossing the predetermined distance due to the velocity adjustment. Additionally, a method and system for coordination between intersections are provided.

Description

SYSTEM AND METHOD FOR CONTROLLING TRAFFIC BY COORDINATION OF

INTERSECTION APPROACHING FLOWS

BACKGROUND OF THE INVENTION

[001] Existing traffic control systems usually try to solve the conflict between the demands for green light on entry routes to an intersection by the "Divide and Rule" principle. The conflict between the demands for green light between flows on entry routes into an intersection may serve as input for the intersection controller and the time plan for green light division between the entry routes may be based on a search space and various search methods for dividing the green light periods over a given time horizon to achieve a selected measure of effectiveness. [002] There are two basic approaches for solving the control problem: the centralized approach and the decentralized approach. One of the features of the centralized approach is to achieve coordination between consecutive intersections, mainly on arterials under saturation or oversaturation conditions, and especially at peak hours, to ensure unidimensional green wave, mainly in the main direction of traffic. The closer the consecutive intersections, the higher the chance to get a longer green light wave. Nevertheless, due to the various flows on the different entry routes that the intersection controllers use as inputs, and the random fluctuations in flows whose location, strength and duration are hard to predict, it is difficult to maintain the planned offset values and in many cases this interrupts the planned continuity of the green waves. [003] According to the decentralized approach, each intersection handles in separate all flows toward the intersection, that serve as input for the control system, and the intersection controller looks for an optimal green light division for the various entries, independent of the condition of flows in adjacent intersections, and the time plans these intersection controllers build. [004] According to the two approaches, the typical difficulties, mainly under saturation and oversaturation conditions, result from insufficiently accurate predictions of the flows, a high volume of flow data on the entry routes and the high processing loads, mainly as a function of the search space over the defined time horizon, and the optimization methods implemented by the controller.

[005] The higher the demands for green light under saturation and oversaturation conditions, the lower the gap between the common control strategy performance from fixed time up to responsive adaptive, and the lower the efficiency of the control system performance.

[006] A report of an expert committee nominated by the American Senate dated 2008 suggests that without a breakthrough solution for the growing problem of traffic congestion, until 2025 a total gridlock is expected in about 500 of the major urban centers in the USA. i [007] Therefore, a solution is needed for the growing problem of traffic congestion which may overcome the deficiencies of the existing approaches.

BRIEF DESCRIPTION OF THE DRAWINGS

[008] The subject matter regarded as embodiments of the invention is particularly pointed out and distinctly claimed in the concluding portion of the specification. The invention, however, both as to organization and method of operation, together with objects, features, and advantages thereof, may best be understood by reference to the following detailed description when read with the accompanying drawings in which:

[009] Fig. 1 is a schematic illustration of a system for controlling traffic, according to embodiments of the present invention;

[0010] Fig. 2 is a schematic illustration of a multi-lane entry route into an intersection which may be coordinated with other entry route, according to embodiments of the present invention;

[0011] Fig. 3 is a schematic illustration of a road system the traffic in which may be coordinated according to embodiments of the present invention; and

[0012] Fig. 4 is a flow chart illustrating a method for controlling traffic in an intersection according to embodiments of the present invention.

[0013] It will be appreciated that for simplicity and clarity of illustration, elements shown in the figures have not necessarily been drawn to scale. For example, the dimensions of some of the elements may be exaggerated relative to other elements for clarity. Further, where considered appropriate, reference numerals may be repeated among the figures to indicate corresponding or analogous elements.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

[0014] In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be understood by those skilled in the art that the present invention may be practiced without these specific details. In other instances, well-known methods, procedures, and components have not been described in detail so as not to obscure the present invention.

[0015] Embodiments of the present invention may overcome the inherent limitations of the existing control systems. In embodiments of the present invention, the decision making process may be implemented by an intersection controller to divide the green light between the various entry routes into the intersection. [0016] The intersection controller according to embodiments of the present invention may force cooperation between platoons of vehicles approaching the intersection, for example, from several multi-lane entry routes, as described in detail below with reference to the Figures. In the description herein below, the terms "platoon", "vehicle platoon" refer to a group of vehicles traveling one after the other, or a series of vehicles. As described herein below, the intersection controller may, for example, cause intentional reduction of the velocities of the leading edges of cruising platoon groups, for example, at a predetermined distance from the intersection. This may cause shock waves, forcing gradual reduction of the velocity through the platoons, from the leading edges to the lagging edges of the cruising platoons. By controlling the velocity of the cruising platoons on each entry route, the intersection controller may ensure coordination in the order of entry into the intersection from the different entry routes.

[0017] As described in detail herein below, the shock waves, which may be caused by the change in velocity of the leading edges of the platoons, may result in affine transformation of translation and scaling of the lengths of the vehicle platoons. The intersection controller may estimate the location of the leading and lagging edges of each platoon at the end of the transformation based on the velocities and locations of the leading and lagging edges of the platoon before the transformation and the velocity of the platoon at the end of the transformation, for example, by assuming that the order of traffic on a lane does not change. The location and velocity of the leading and lagging edges of each platoon at the end of the transformation may be used by the intersection controller in order to set the duration of the permission to cross the intersection (green light duration) necessary for cruisers approaching the intersection from the different entry routes to cross the intersection at the velocities set by the controller.

[0018] Accordingly, embodiments of the present invention usually may not require information regarding internal vehicles within the vehicle platoons. The intersection controller described herein may coordinate the intersection entry routes as described herein below, for example, by using location and velocity information regarding the leading and lagging edges of the vehicle platoons approaching the intersection.

[0019] Reference is now made to Fig. 1, which is a schematic illustration of a system 100 for controlling traffic according to embodiments of the present invention. System 100 may include, for example, an intersection controller 110, traffic lights 120 and velocity regulators 130, for example, at an intersection 140. Intersection 140 may have, for example, various entry routes 142, 144, 146 and 148. Although Fig. 1 shows four entry routes to intersection 140, embodiments of the present invention may be applicable for substantially any number of entry routes to intersection 140 Cruising vehicle platoons 12 and/or decelerating/waiting vehicle platoons 10 may be about to cross intersection 140. The present invention may be applied on various kinds of intersections and situations of the platoons within the intersection. In the exemplary situation illustrated in Fig. 1, entry route 142, for example, includes one platoon 10 decelerating towards the intersection and one cruising platoon 12. Entry route 144 may have, for example, permission to cross the intersection ("green light") and thus, for example, may include two cruising platoons 12 which may be about to cross the intersection. Additionally in the exemplary situation illustrated in Fig. 1, entry routes 146 and 148, for example, include waiting platoons 10 and cruising platoons 12.

[0020] Intersection controller 110 may control velocity regulators 130 and traffic lights 120 in order to control the traffic in intersection 140. According to embodiments of the present invention, Intersection controller 110 may calculate and/or determine time plans for rounds of entry into the intersection from the various entry routes 142, 144, 146 and 148. In each round, intersection controller 110 may determine the number of entry routes participating in the round and order of entry into intersection 140. Intersection controller 110 may also determine the duration of each round and the duration of permission to cross the intersection ("green light") for each of entry routes 142, 144, 146 and 148.

[0021] System 100 may also include velocity/location sensors 150 which may detect location and/or velocity of vehicles. Velocity/location sensors 150 may be installed at predefined location/s along entry routes 142, 144, 146 and 148 and/or in the vehicles. For example, sensors 150 may be cellular and/or GPS-based, loop detectors and/or video sensors and/or any other suitable velocity/location sensor.

[0022] Intersection controller 110 may control the traffic at intersection 140 by forcing cooperation between entry routes 142, 144, 146 and 148. Intersection controller 110 may control ^' velocity regulators 130. In some embodiments of the present invention, velocity regulators 130 may instruct drivers, for example, which have a manual speed control, for example, by visual and/or vocal indication, to drive at a certain velocity. Velocity regulators 130 may include, for example, Variable-Message Signs (VMS) which may instruct drivers to drive vehicles at a required velocity. Alternatively or additionally, velocity regulators 130 may directly control the velocity of vehicles. In one embodiment of the present invention, velocity regulators 130 may include transmitters, for example, transmitters located at the intersection or/and at the road margins, which may transmit velocity signals to receivers installed in the vehicles, for example, in automatic speed control systems installed in the vehicles, in order to cause the vehicle to go at a desired velocity. This may facilitate a more accurate and effective coordination of the intersection by intersection controller 110.

[0023] Intersection controller 110 may cause, for example, by velocity regulators 130, intentional shock waves to vehicle platoons 10, 12 on entry routes 142, 144, 146 and 148, e.g. by reduction of the velocities of the leading edges of the vehicle platoons upon entering a predetermined coordination distance 132 in each entry route. The velocity at each of entry routes 142, 144, 146 and 148 may be reduced, for example, according to the order of entry from the different entry routes to the intersection. The sequential reduction may be set by controller 110, and thus, for example, ensuring coordination in the order of flows between all entry routes 142, 144, 146 and 148 as they approach the intersection. For example, upon arrival of a vehicle platoon/platoons 10, 12 on one of entry routes 142, 144, 146 or 148 to predetermined coordination distance 132, intersection controller 110 may reduce the velocity of the leading edges of the vehicle platoon, so that the leading edge of the vehicle platoon may not cross the intersection before the lagging edge of the previous entry route in the order of entry set by controller 110 crosses the intersection. [0024] The coordination by intersection controller 110 may prevent, or at least minimize dramatically the conflict between the demands for green light on various entry routes 142, 144, 146 and 148 at conflicting periods of time, and force cooperation between traffic flows from entry routes 142, 144, 146 and 148, for example, to ensure that the order of entry into the intersection set by intersection controller 110 is met and thus, for example, achieving virtual free flow at intersection 140.

[0025] Intersection controller 110 may control traffic lights 120, for example, to adjust the green light duration for each of entry of routes 142, 144, 146 or 148, for example, in order to coordinate the traffic flows from entry routes 142, 144, 146 and 148. In determining the green light duration, intersection controller 110 may take into account the time required for waiting/decelerating vehicle platoons 10 to cross the intersection and the time required for cruising vehicle platoons 12 in a determined range to cross the intersection. The range of cruising vehicle platoons 12 allowed to cross the intersection in a certain round may be determined by intersection controller 110, for example according to a measure of efficiency describe herein below.

[0026] According to some embodiments of the present invention, intersection controller 110 may receive from sensors 150 location and/or velocity data of leading edges and lagging edges of vehicle platoons 10, 12, for example, and may use this data in order to establish a time plan for the next round of entry into intersection 140. [0027] Reference is now made to Fig. 2, which is a schematic illustration of a multi-lane entry route 242 into an intersection 240 which may be coordinated according to embodiments of the present invention. Intersection 240 may include traffic lights 220. Intersection 240 may have M entry routes (not shown). Entry route 242 may be the n entry route of m entry routes to intersection 240 which participate in a round of entry to intersection 240 determined by intersection controller 110, wherein m may be smaller or equal to M. Intersection controller 110

may have M_T options for selecting m entry routes out of M, wherein M_τ = V M -

[0028] Intersection controller 110 (described above with reference to Fig. 1) may determine a leading edge 60 and a lagging edge 50 of a group 215 of cruising vehicle platoons 210, for example, by receiving location and velocity data from sensors 150 (shown in Fig. 1). Once leading edge 60 reaches a determined coordination distance 232 having length CD at a velocity Vn, intersection controller 110 may set to leading edge 60 a new velocity V*n for crossing coordination distance 232, for example, in order that leading edge 60 may not cross intersection 240 before the lagging edge of a group of cruising vehicle platoons at the entry route previously allowed to cross intersection 240 (not shown) has finished crossing intersection 240. In order to meet this condition, the maximum value of V*n may be sequentially determined according to the equation:

wherein t _{n n}_γ ≡ t_n - t_n_ι , wherein t_n is the time of arrival of leading edge 60 on route n to coordination distance 232 and wherein T_Cjn is the duration of green light for cruising vehicle platoons 210 on route n.

[0029] In preferred embodiments of the present invention, intersection controller 110 may.adjust the velocity of leading edge 60 to V*n according to equation (1), preferably only in cases where the maximum value of V*n calculated according to equation (1) is smaller or equal to Vn. In cases where maximum value of V*n calculated according to equation (1) is bigger then Vn, intersection controller 110 may choose another order of the entry routes, which does not result in V*n bigger than Vn . In accordance with equation (1), in cases where t_n,_n-i is equal to Tc,n, the maximum value of V*n may be equal to V*_n-i. In cases where t_n>n-i is equal to zero, the maximum value of

V*n may be equal to r^ • Generally, when t_n._n-i is between 0 to Tc,n the maximum

¹ CD ^c'-^x value of V*n may be in the range j-²^ < F_n ^* < F_nI₁ . When t_n.n-i is greater thanTc,n, the

1 + V_n, T

CD ^c'"^'] velocity V*n may be greater than the velocity V*_n-1. However, intersection controller 110 may determine that at any case V*n will not be greater than Vn.

[0030] Accordingly, the velocity V*m of leading edge 60 on the m'^h entry route in the round determined by intersection controller 110, may be set by:

r m > 2 .

[0031] In some embodiments of the present invention, intersection controller 110 may determine the velocity V*i of leading edge 60 on the first entry route in the round when crossing coordination distance 232 according to pre-decided parameters, for example efficiency and/or the continuousness of the traffic flow. In preferred embodiments of the present invention, intersection controller 110 may determine the velocity V*_! to be equal to the velocity V₁ of leading edge 60 before reaching coordination distance 232.

[0032] Intersection controller 110 may determine the velocities V* i ... V*_m for each possible order of entry to intersection 240 from m entry routes, for example, according to equation (2). In preferred embodiments of the present invention, in case a given entry order of m routes obtains F_n ^* > F_n for a certain entry route n, intersection controller may reject this order option of the m entry routes.

[0033] For each round of crossing intersection 240, intersection controller 110 may choose m entry routes which may participate in the round out of the M entry routes to intersection 240, and/or the order of entry into intersection 240 of the m entry routes. Intersection controller 110 may choose the m routes and the order of the routes based on optimization of measures of efficiency/effectiveness such as, for example, total travel time of the round, total delay time of vehicles, number of stops of vehicles and/or by optimization of any other suitable measure of effectiveness. Additionally or alternatively, intersection controller 110 may compute a measure of

∑ c m effectiveness E_n, = ^! for each option of m routes and their order wherein

Σ + Σ

∑ _{c m} is the sum of lengths of cruising vehicle platoons 12 crossing the intersection during green light periods from all m routes and X _{s m} is the sum of lengths of waiting/decelerating vehicle platoons 10 crossing the intersection during green light periods from all m routes. Intersection controller 110 may choose the m entry routes and their order which provides the maximal and/or optimal measure of effectiveness E_m, i.e. the m entry routes and their order for which the percent of the sum of lengths ∑ _{c m} of cruising platoons 12 out of the sum of lengths ∑ _{s m} + ∑ _{c m} of decelerating/waiting platoons 10 and cruising platoons 12 crossing the intersection during a single green light period from all m routes is maximal and/or optimal By maximizing E_n,, the coordination process according to this invention may create two-dimensional "green waves", e.g., sequence of green lights at sequential intersections.

[0034] Intersection controller 110 may determine, for example based on optimization of a measure of efficiency, an adjusted lagging edge 52 of a group of vehicle platoons allowed to cross intersection 240 on a given entry route 242 having K lanes. Based on the adjusted lagging edge 52, intersection controller 110 may determine the duration of green light period needed for a given entry route 242 at a certain round. The measure of efficiency p for determining the relative location of adjusted lagging edge 52 may be computed by

(3) P =

wherein ∑ _c ^ is the sum of lengths of cruising vehicle platoons 210 on lane k between adjusted lagging edge 52 and leading edge 60, and wherein Δ_c is the difference between adjusted lagging edge 52 leading edge 60. The length L_Ck of each cruising vehicle platoon 210 on lane k, the distances of lagging edge 50, adjusted edge 52 and leading edge 60 from intersection 240 may be determined by intersection controller 110, for example, according to data received from sensors

150. Accordingly, Intersection controller may compute Δ_c which is the absolute length of the group of cruising vehicle platoons at route n which may be allowed to cross the intersection during green light.

[0035] Intersection controller 110 may set adjusted lagging edge 52 for which p is maximal and/or optimal. Intersection controller 110 may determine the duration of green light period for a given entry route 242 at a certain round so that, for example, the vehicles on route 242 between leading edge 60 and adjusted lagging edge 52 may be allowed to cross the intersection. In some cases, for example, a rear portion of one or of several of vehicle platoons 210 may be left behind adjusted lagging edge 52 and thus, for example, stopped at the red light. [0036] In order to determine adjusted lagging edge 52, intersection controller 110 may apply a sliding window, e.g. starting from calculating p for adjusted edge 52 located at lagging edge 50, and then gradually reducing the window, e.g. bringing adjusted lagging edge 52 closer to leading edge 60 by selecting adjusted lagging edge 52 closer to leading edge 60 and calculating p until finding adjusted edge 52 for which p is maximal and/or optimal, i.e. indicating maximal and/or optimal amount of cruising vehicle platoons for a given length of group of cruising vehicle platoons. Intersection controller 110 may also run other suitable calculations and/or perform other suitable procedures in order to find the location of adjusted edge 52 for which p is maximal and/or optimal.

[0037] Intersection controller 110 may determine the duration of green light for each of the m entry routes, for example, of routes 142, 144, 146 and 148, based on, for example, the calculated velocities V* _\ ... V*_m and based on the adjusted edge 52, calculated for each entry route, for which p is maximal. The duration T_n of green light for entry route n may include the duration Ts,n required for waiting/decelerating vehicle platoons 10 to cross intersection 240 and the duration Tc,n required for cruising vehicle platoons 12 (Fig. 1) to cross intersection 240. As discussed above, cruising vehicle platoons 12 sequentially change their velocity when entering to coordination distance 232. Substantially from the moment the leading edge of a cruising platoon 12 changes its velocity from V_n to V*_n, a shock wave goes through the platoon, causing, for example, a progressive change in velocity through the platoon. During the progressive change in the velocity, the length of each of platoons 12 may go through an affine transformation and thus, for example, may change upon entering to coordination distance 232. Therefore, the length Δ_c , which is defined above with reference to equation (3), may go through affine transformation of translation and scaling and thus, for example, gradually change to Δ c upon entering to coordination distance 232. Therefore, intersection controller may compute Tc,n based on the length Δ c and the velocity V*n.

[0038] Intersection controller 110 may set a maximum green light duration T_n,_max as a high limit of the duration Tn. However, T_n,maχ may be changeable according to some considerations, for example, the need to let more cruising vehicles to cross intersection 240, for example, in order to prevent great accumulation of vehicles waiting to cross intersection 240. As mentioned above, The duration T_n of green light for entry route n may include the duration Ts,n required for waiting/decelerating vehicle platoons 10 to cross intersection 240 and the duration Tc,n required for cruising vehicle platoons 12 (Fig. 1) to cross intersection 240. Accordingly,

T < T - T

¹C₅Ii - ^A n,max ¹S^ ^•

[0039] The moment τ_n at which the green light is switched on for route n may be calculated by intersection controller 110 according to the equation:

CD

(4) τ_n = t_n + — T- ^Ts,n

V_n

Wherein T_Sin is the duration of green light for waiting/decelerating platoons on route n and V*n, CD and t_n are as defined above. Accordingly, if X_n is greater than t_n the green light on lane n should be switched on after leading edge 60 crosses coordination distance 232, whereas if t_n is smaller than t_n the green light on lane n should be switched on before leading edge 60 crosses coordination distance 232.

[0040] Reference is now made to Fig. 3, which is a schematic illustration of a road system 300 the traffic in which may be coordinated according to embodiments of the present invention, for example, in recurrent or non-recurrent saturated or oversaturated events, especially at peak hours. Road system 300 may include an arterial road 350 and secondary roads 352 which may lead to arterial road 350. Arterial road 350 may have a main direction A in which most of the vehicles may travel at peak hours. Road system 300 may include Primary Intersections (PI) 320 (annotated in Fig. 3 by X) and Secondary Intersections (SI) 322 (annotated in Fig. 3 by O). Between every two consecutive PIs 320, there may be several SIs 322. PIs 320 may endure and/or coordinate the flow of vehicles at the entries to arterial road 350 and the flows on arterial road 350 in main direction A, for example, by intersection controllers 310 similar to controllers 110 described above with reference to Figs. 1 and 2. Entrance to arterial road 350 in main direction A and exit from arterial road 350 in main direction A may be feasible exclusively from PIs 320. SIs 322 may endure and/or coordinate, for example, by controllers 310, the flow of vehicles at the entries to arterial road 350 in the direction opposite to the main direction as well as the flows for crossing arterial road 350. Entrance to arterial road 350 in a direction opposite to main direction A and crossing of arterial road 350 may be feasible exclusively from SIs 322.

[0041] Intersection controllers 310 may control SIs 322 to function according to the traffic needs through PIs 320. For example, SIs 322 may be controlled so that, for example, priority may be given to entry to arterial road 350 and/or to travelers in main direction A through PIs 320. As long as PIs 320 are at green light for entry to arterial road 350 or for travel in main direction A, the relevant SIs 322 between the PIs 320 may be at green light in main direction A and in roads 352 in the directions leading to arterial road 350. When PIs 320 are at red light for entry to arterial road 350 or for travel in main direction A, SIs 322 may be at green light for crossing arterial road 350 and/or for crossing roads 352.

[0042] According to some embodiments of the present invention, intersection controllers 310 of PIs 320 may provide permission to intersection controllers 310 of SIs 322 to allow crossing of SIs 322 in main direction A and in directions leading to arterial road 350 when PIs 320 permit entry to arterial road 350 or traveling in main direction A. Additionally, intersection controllers 310 of PIs 320 may provide permission to intersection controllers 310 of SIs 322 to allow crossing of SIs 322 in a direction crossing arterial road 350 when PIs 320 forbids entry to arterial road 350 or traveling in main direction A.

[0043] Intersection controllers 310 may control PIs 320 and SIs 322 as described above with reference to Figs. 1 and 2, for example under the constraints described above, in each of intersections 320 and 322, intersection controllers 310 may apply the coordination process described above between the flows of cruising vehicle platoons 12 (shown in Fig.l) from the various entry routes, for example, routes 142, 144, 146 and 148 described with reference to Fig. 1. Intersection controllers 310 may conduct the optimization process described above to select the number of entry routes and the order of entry, under limitation of priority to main direction A and/or the constraints of SIs 322 described above.

[0044] The division into PIs 320 and SIs 322 may serve as a filter for separation between vehicles driving on arterial road 350 in main direction A and all other vehicles, and may result in an increased traffic capacity of arterial road 350 in main direction A, for example, at peak hours. [0045] Reference is now made to Fig. 4, which is a flow chart illustrating a method for controlling traffic in an intersection according to embodiments of the present invention. As indicated in block 410, the method may include determining the leading and lagging edges of the group of cruising vehicle platoons to enter the intersection from a respective entry route. The determining may include receiving location data from location sensors. The determining may include computing a measure of efficiency to determine the lagging edge, the measure of efficiency may indicate the amount of cruising vehicle platoons for a given length of the group of cruising vehicle platoons, and wherein the lagging edge may be determined by maximizing the measure of efficiency.

[0046] As indicated in block 420, the method may include selecting a sub-set of entry routes out of a plurality of entry routes and order of entry from the sub-set of entry routes into the intersection. The selection may include computing a measure of effectiveness Em for selecting the sub-set of entry routes and the order of entry routes, the measure of effectiveness may indicate the percent of the total length of cruising vehicle platoons crossing the intersection during a green light from the sub-set of entry routes out of the total length of decelerating/waiting platoons and cruising platoons crossing the intersection during a green light from the sub-set of entry routes, and wherein the selection may be performed by maximizing and/or optimizing the measure of efficiency.

[0047] As indicated in block 430, the method may include calculating predicted time of arrival of the leading edge to a predetermined distance from the intersection.

[0048] As indicated in block 440, the method may include, at each of the sub-set of entry routes, adjusting velocity of a group of cruising vehicle platoons upon arrival to the predetermined distance from the intersection so that a leading edge of said group of cruising vehicle platoons may not cross the intersection before a lagging edge of the previous entry route crosses intersection, wherein the adjusting may be based on predicted time of arrival to the predetermined distance and adjusted velocity of the previous entry route group of cruising vehicle platoons. [0049] As indicated in block 450, the method may include calculating duration of green light for each of the sub-set of entry routes, based on the adjusted velocity and length of the group of cruising vehicle platoons after crossing the predetermined distance.

[0050] While certain features of the invention have been illustrated and described herein, many modifications, substitutions, changes, and equivalents will now occur to those of ordinary skill in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention.

Claims

CLAIMS[0051] What is claimed is:

1. A method for coordinating traffic at an intersection having a plurality of multi-lane entry routes, the method comprising the steps of: selecting a sub-set of entry routes out of said plurality of entry routes and order of entry from said sub-set of entry routes into said intersection; at each of said sub-set of entry routes, adjusting velocity of a group of cruising vehicle platoons upon arrival to a predetermined distance from the intersection, so that a leading edge of vehicle platoons in a first entry route may not cross the intersection before a lagging edge of a group of cruising vehicle platoons of a second entry route crosses the intersection, said second entry route being previous to said first entry route in said selected order; and calculating duration of permission to cross the intersection for each of the sub-set of entry routes, based on said adjusted velocity and length of said group of cruising "vehicle platoons after crossing said predetermined distance.

2. A method according to claim 1, further comprising the steps of: determining the leading and lagging edges of said group of cruising vehicle platoons to enter the intersection from a respective entry route; and calculating predicted time of arrival of the leading edge to said predetermined distance from the intersection, wherein said adjusting is based on a predicted time of arrival to said predetermined distance and adjusted velocity of a group of cruising vehicles of the previous entry route.

3. A method according to claim 1, wherein said determining the leading and lagging edges comprises receiving location data from location sensors.

4. A method according to claim 1, wherein said determining the leading and lagging edges comprises computing a measure of efficiency to determine the lagging edge, the measure of efficiency indicates the amount of cruising vehicle platoons for a given length of the group of cruising vehicle platoons, and wherein the lagging edge is determined by optimizing the measure of efficiency.

5. A method according to claim 1, wherein said selecting comprising computing a measure of effectiveness for selecting the sub-set of entry routes and the order of entry routes, the measure of effectiveness indicates the percent of the total length of cruising vehicle platoons crossing the intersection during a green light from said sub-set of entry routes out of the total length of decelerating/waiting platoons and cruising platoons crossing the intersection during a green light from said sub-set of entry routes, and wherein said selecting is by optimizing the measure of effectiveness.

6. A method according to claim 1, further comprising the step of determining an adjustable maximum duration of permission to cross the intersection.

7. A method according to claim 1, further comprising the step of calculating said length of said group of cruising vehicle platoons after crossing said predetermined distance based on locations and velocities of said leading and lagging edges before crossing the said predetermined distance and said adjusted velocity.

8. A method according to claim 1, wherein length of said group of cruising vehicle platoons goes through affine transformation of translation and scaling when crossing said predetermined distance due to the velocity adjustment.

9. A system for coordinating traffic at an intersection, the system comprising: an intersection controller to control order of entry to an intersection from various entry routes, to adjust velocity of vehicle platoons when reaching a predetermined distance from the intersection so that a leading edge of said group of cruising vehicle platoons may not cross the intersection before a lagging edge of a group of cruising vehicles of the previous entry route crosses intersection, and determining duration of green light for each entry route.

10. A system according to claim 9, further comprising: velocity regulators, controlled by said intersection controller, to regulate velocity of cruising vehicle platoons when reaching a predetermined distance from the intersection; location sensors to transmit location data of vehicles to said intersection controller; and traffic lights controlled by said intersection controller.

11. A method for coordination between intersections, the method comprising: allowing entrance to an arterial road in a certain direction and exit from said arterial road in said certain direction exclusively from a first kind of intersections; allowing entrance to said arterial road in a direction opposite to said certain direction and crossing of said arterial road exclusively from a second kind of intersections; providing permission to cross said second kind of intersections in said certain direction and in directions leading to said arterial road when said first kind of intersections permit entry to said arterial road or traveling in said certain direction; and providing permission to cross said second kind of intersections in a direction crossing said arterial road when said first kind of intersections forbids entry to said arterial road or traveling in said certain direction.

12. A system for coordination between intersections, the system comprising: first intersection controllers of a first kind of intersections, wherein entrance to an arterial road in a certain direction and exit from said arterial road in said certain direction is allowed exclusively from said first kind of intersections; second intersection controllers of a second kind of intersections, wherein entrance to said arterial road in a direction opposite to said certain direction and crossing of said arterial road is allowed exclusively from said second kind of intersections; wherein said first intersection controllers provides permission to said second intersection controllers to allow crossing of said second kind of intersections in said certain direction and in directions leading to said arterial road when said first kind of intersections permit entry to said arterial road or traveling in said certain direction; and wherein said first intersection controllers provides permission to said second intersection controllers to allow crossing of said second kind of intersections in a direction crossing said arterial road when said first kind of intersections forbids entry to said arterial road or traveling in said certain direction.