Abstract: A method for parking detection and identification of moveable apparatus, comprising following steps of: generating a magnetic field signal containing an unique identifier for identifying the moveable apparatus by a magnetic field generator disposed in the moveable apparatus; measuring magnetic field respectively by two magnetic field sensors of a magnetic field sensing apparatus disposed in a moveable-apparatus parking place or its peripheral area, wherein a first and a second magnetic field measurements are measured; and calculating a magnetic field measurement difference for obtaining the unique identifier, wherein the magnetic field measurement difference is a magnitude of a difference of the first and the second magnetic field measurements, or a magnitude of a difference of a first magnetic field component of the first magnetic field measurement along a characteristic direction and a second magnetic field component of the second magnetic field measurement along the characteristic direction.

Abstract: The embodiments of the present disclosure provide a method and a system for controlling intelligent street lamps in a smart city based on an Internet of Things, the method is realized by a system for controlling intelligent street lamps in a smart city based on the Internet of Things, the system for controlling intelligent street lamps in a smart city includes a user platform, a service platform, a management platform, a sensor network platform and an object platform, the method is executed by the management platform, comprising: receiving road information acquired by the object platform through the sensor network platform, the road information including ambient light intensities and road images, and the object platform including a first sensor; determining road environment information based on the road images; and determining irradiation intensities of the street lamps on a road based on the ambient light intensities and the road environment information.

Abstract: A system to identify incidents associated with streetlight fixtures based on sensor data from one or more smart sensor devices. Each smart sensor device is coupled to a respective streetlight fixture and captures data from one or more sensors. The data from a single smart sensor device or a plurality of smart sensor devices is aggregated to generate a current data signature of the one or more smart sensor devices. The current data signature is compared to a plurality of known signatures to determine if an incident associated with a streetlight fixture has occurred. Such incidents can include a failed light source, a failing light source, a weather incident, a geologic incident, etc. Depending on the type of incident an instruction is sent to the one or more smart sensor devices to perform one or more responsive actions.

Abstract: An autonomous driving method of a vehicle using V2X communication includes acquiring signal information about a plurality of traffic lights installed at an intersection, determining a signal error in at least one of the plurality of traffic lights by comparing signal information about at least two traffic lights intersecting or facing each other among the acquired signal information, and resetting a driving path of a host vehicle depending on a result of the determination.

Abstract: Embodiments of the disclosure provide systems and methods for optimizing a traffic control plan. The system may include at least one storage device configured to store instructions and at least one processor configured to execute the instructions to perform operations. The operations may include receiving traffic system log data and parsing the traffic system log data to obtain a first set of traffic performance parameters. The operations may also include receiving trajectory data relating to a plurality of vehicle movements and parsing the trajectory data to obtain a second set of traffic performance parameters. The operations may further include determining relationships between vehicle delays and degrees of saturation based on the first and second sets of traffic performance parameters. In addition, the operations may include optimizing the traffic control plan based on the relationships.

Abstract: Embodiments describe new mechanisms for signalized intersection control. Embodiments expand inputs beyond traditional traffic control methods to include awareness of agency policies for signalized control, industry standardized calculations for traffic control parameters, geometric awareness of the roadway and/or intersection, and/or input of vehicle trajectory data relative to this intersection geometry. In certain embodiments, these new inputs facilitate a real-time, future-state trajectory modeling of the phase timing and sequencing options for signalized intersection control. Phase selection and timing can be improved or otherwise optimized based upon modeling the signal's future state impact on arriving vehicle trajectories. This improvement or optimization can be performed to reduce or minimize the cost basis of a user definable objective function.

Abstract: A system and method is provided to optimize traffic light activity and minimize traffic congestion. Traffic conditions are monitored by sensors and the algorithm dynamically controls the green light time to account for traffic conditions and enhance the traffic flow across two or more traffic lights.

Abstract: An object recognition apparatus learns an axis displacement amount of a reference axis of first object detecting means, combines and integrates, as information belonging to a same object, a plurality of pieces of information present within a first combining area and a second combining area, when a positional relationship between the first combining area and the second combining area meets a predetermined combinable condition. The first combining area is set as an area in which pieces of information related to the object acquired by the first object detecting means are combined. The second combining area is set as an area in which pieces of information related to the object acquired by second object detecting means are combined. The object recognition apparatus variably sets sizes of the first combining area and the second combining area based on a learning state of the axis displacement amount of the reference axis.

Abstract: A method for controlling an electronic device includes receiving first location information of a vehicle through a location information module, capturing an image through a camera while the vehicle is driven, extracting characteristic points from the captured image and converting the captured image into a 3-D image, obtaining second location information by correcting the first location information based on a moving displacement and orientation direction of the camera installed on the vehicle, extracting an aerial view from the 3-D image based on the moving displacement and orientation direction of the camera, estimating a moving path of the vehicle using locations of traffic lanes included in the aerial view and the second location information, and displaying the captured image and the moving path of the vehicle in augmented reality by combining the captured image and the moving path.

Abstract: An imaging apparatus includes: an image sensor; a signal processing unit repeatedly performing processing different from each other in a given number of sequential frames to imaging signals obtained by the image sensor to thereby obtain image data of respective frame; and an image data output unit sequentially outputting the image data of respective frames.

Abstract: In accordance with an embodiment, a method for processing information associated with vehicular traffic includes generating an input signal that contains information associated with vehicular traffic and transmitting the information to a cloud-based server system. A control signal is generated in response to the information. In accordance with another embodiment, a traffic monitoring system has a data aggregator coupled to a malfunction management unit and to a traffic signal controller coupled to the data aggravator.

Abstract: Embodiments describe new mechanisms for signalized intersection control. Embodiments expand inputs beyond traditional traffic control methods to include awareness of agency policies for signalized control, industry standardized calculations for traffic control parameters, geometric awareness of the roadway and/or intersection, and/or input of vehicle trajectory data relative to this intersection geometry. In certain embodiments, these new inputs facilitate a real-time, future-state trajectory modeling of the phase timing and sequencing options for signalized intersection control. Phase selection and timing can be improved or otherwise optimized based upon modeling the signal's future state impact on arriving vehicle trajectories. This improvement or optimization can be performed to reduce or minimize the cost basis of a user definable objective function.

Abstract: A traffic control system includes a detector and controller-circuits. The detector is configured to detect a traffic-state characterized as inhibiting traffic-flow. A first-controller-circuit is configured to communicate with the detector and a traffic-signal. The traffic-signal is configured to control traffic-flow through an intersection, wherein the first-controller-circuit sends a request to the traffic-signal to operate to a signal-state that changes the traffic-state.

Abstract: A method and apparatus for providing a proximity alert to the operator of a vehicle, such as a vehicle approaching a pedestrian crosswalk. A fixed or mobile controller (beacon) component when activated transmits a signal relating to a potential hazard, and a software application (“app”) installed on a smartphone or other device provides the receiver/notification component. The app delivers an audible, visual, and/or tactile alert to drivers via their smartphones, tablet computers, or mobile devices installed in their vehicles that they are approaching an “activated” pedestrian crosswalk, intersection, railroad crossing, road hazard or work zone, emergency vehicle, or even a bicyclist when they are equipped with a beacon.

Abstract: The invention includes a vehicular sensor node, circuit apparatus and their operations. Power from power source is controlled for delivery to radio transceiver and magnetic sensor, based upon a task trigger and task identifier. The radio transceiver and the magnetic sensor are operated based upon the task identifier, when the task trigger is active. The power source, radio transceiver, magnetic sensor, and circuit apparatus are enclosed in vehicular sensor node, placed upon pavement and operating for at least five years without replacing the power source components. Magnetic sensor preferably uses the magnetic resistive effect to create magnetic sensor state. Radio transceiver preferably implements version of a wireless communications protocol. The circuit apparatus may further include light emitting structure to visibly communicate during installation and/or testing, and second light emitting structure used to visibly communicate with vehicle operators.

Abstract: Systems and methods are provided for systematically penalizing drivers who fail to stop at crosswalk on different circumstances. The system and method generally employ a sensor to detect a vehicle approaching the cross walk and ambient conditions. The sensor may collect information about the speed and any changes in speed of the vehicle approaching. An image capture device may be used to identify any passengers waiting to cross or actively crossing within the crosswalk. The analyzer processes the information and determines if a fine should be levied upon the vehicle approaching the cross walk. The analyzer may also determine the magnitude of the fine that is to be issued. An additional camera for sensing vehicle speed may be placed at the cross walk to obtain further information to properly assess a fine.

Abstract: Disclosed is a camera image compensating apparatus for a vehicle, including a detecting unit which detects a base line and a vehicle body contour line; a coordinate storing unit which stores a first reference image coordinate value and a second reference image coordinate value; a first coordinate calculating unit which calculates a first base line image coordinate value and calculates a first vehicle body contour line image coordinate value; a coordinate comparing unit which compares the first reference image coordinate value and the first base line image coordinate value and compares the second reference image coordinate value and the first vehicle body contour line image coordinate value; and a correcting unit which calculates angle change information of the camera, calculates correction information based on the angle change information, and corrects the camera parameter using the correction information.

Abstract: A railroad crossing barrier estimating apparatus and a vehicle that incorporates therein such a railroad crossing barrier estimating apparatus are provided. When at least one of an external object the transverse width of which increases over time and an external object having a given length at a certain height from the ground is detected, the vehicle or the railroad crossing barrier estimating apparatus estimates the detected external object as a railroad crossing barrier.

Abstract: Provided are a server and a system that are capable of generating road traffic information on traffic congestion in a more appropriate manner, considering actual road traffic conditions. If a vehicle speed V falls below a first reference speed V1 and then exceeds a second reference speed V2 (>V1), then a traffic congestion situation is estimated based on an inference that the vehicle is highly likely to have escaped from traffic congestion. To estimate a traffic congestion situation, it is required that a situation in which the vehicle speed V exceeds the second reference speed V2 continue for a second specified distance or more or for a second specified time T2 or more.

Abstract: An external adaptive control system and method control a traffic signal controller assembly. The external adaptive control system determines a non-linear schedule with one or more states corresponding to one or more individual phases with each state having a start time and a duration. The external adaptive control system generates presence data for reception by the controller assembly for each state and its associated duration.

Abstract: Devices, methods, and programs access map information including link information related to links that constitute a road, acquire a current location of a vehicle at unit time intervals, and acquire traffic information, which includes a distributed traffic congestion level of each link at predetermined time intervals. Each time the vehicle exits a link, the devices, methods, and programs sequentially store the exited link in an exited link train based on the map information. If the traffic information has been received, the devices, methods, and program store the distributed traffic congestion level included in the received traffic information as a traffic congestion level in association with a portion of the exited link train within a range from the current location at a received time point when the traffic information has been received to a location that is a predetermined distance behind the current location at the received time point.

Abstract: Approaches for issuing preemption requests. The boundaries of a geo-window are repeatedly determined based on locations and headings of a vehicle as the vehicle is traveling along a roadway. The methods and systems determine whether or not any one of a plurality of intersections is located within the boundaries of the geo-window in response to changed boundaries of the geo-window. In response to determining that one of the plurality of intersections is located within the boundaries of the geo-window, a preemption request is transmitted from the vehicle to an intersection controller at the one of the plurality of intersections.

Abstract: Provided is an apparatus and method for automatically creating stopping rates of vehicles at signal-equipped intersections. A signal-equipped intersection to be subjected to specifying of stopping rates at signal-equipped intersections is selected from a signal-equipped-intersection information storage unit as a target intersection, a pass-through-intersection extraction that extracts a signal-equipped intersection that was passed-through just before reaching the target intersection as a pass-through intersection is conducted according to a prescribed rule, driving-history data of a probe car is classified for each of the routes that start from the pass-through intersection and pass through the target intersection, and the rate at which the probe car stopped at the target intersection is specified as a stopping rate, for each of the classified routes.

Abstract: A traffic control sensor system which provides outputted signals to a receiving traffic control system to assist the traffic control system in making real-time informed green light decisions. Such signals received by the traffic control system include calls for a green light for monitored traffic lanes approaching an intersection. The traffic control sensor system employs various techniques to reduce the number of vehicles that are dropped or occluded. A vehicle is considered to be dropped or occluded whenever the traffic control sensor system first detects the vehicle entering a user defined zone within the approaching lanes to the intersection, and then fails to detect or monitor such vehicle exiting the user defined zones. Occlusion or dropping may occur whenever a sensor is malfunctioning, certain environmental conditions are present, or during any time the sensor's detection signal is interrupted such as from cross traffic entering the monitored intersection.

Abstract: A method and system for adjusting traffic lights. The method and system can dynamically divide a region according to the road congestion situation and adjust traffic lights in a resulting control region according to the control region, so as to solve the traffic congestion problem. The system for adjusting traffic lights includes: a congestion determining module, a control region determining module and a adjusting module, wherein the control region determining module is configured to determine a control region according to a dispersion demand of a first phase and a dispersal capability of a corresponding phase of an adjacent intersection, and the adjusting module is configured to adjust traffic lights of at least one corresponding phase of an adjacent intersection in the control region so as to relieve the traffic congestion situation at the first phase of the first intersection. Also described is a corresponding method for adjusting traffic lights.

Abstract: Approaches for monitoring traffic signal preemption at one or more intersections. According to one embodiment, a road map that includes a plurality of roads and intersections is displayed with a computer system. Preemption data periodically received by the computer system from at least one preemption controller at a respective intersection is used to update the road map. In response to the preemption data, the road map is updated to include a traffic signal icon at the respective intersection and a vehicle icon at a location on the map corresponding to a location of a vehicle transmitting a preemption request as indicated by the preemption data.

Abstract: A traffic management system includes a data processing unit which communicates with a road leading unit and a vehicle management unit. The road leading unit comprises a plurality of grooves and isolation railings, the grooves are formed on a road, and the isolation railings are received in the grooves and can be opened to divide the road. The data processing unit can receive vehicle identification information and driving direction information from the vehicle management unit. The data processing unit comprises a data analysis module and a control module. The data analysis module is operable to estimate road condition information and count a total traffic demand index for each road according to the vehicle identification information and the driving direction information. The control module is operable to control the isolation railings to open or retract according to the total traffic demand index.

Abstract: A system for controlling traffic for allowing passage of an emergency vehicle through an intersection controlled by traffic signals includes an intersection module for transmitting signals for preempting the traffic signals and one or more circuit cards coupled to the intersection module. Each expansion card includes a plurality of contact closures for outputting one or more of the signals for preempting the traffic signals. The intersection module selects an expansion card based on a type of output desired, and further selects one or more contact closures of the selected card for the desired output. The expansion cards allow preempt or vehicle outputs beyond the output that a single card can provide. According to another embodiment, the output expansion is achieved by emulating the communication interface between the intersection module and the traffic signal controller.

Abstract: Methods and devices for using uncertainty regarding observations of traffic intersections to modify behavior of a vehicle are disclosed. In one embodiment, an example method includes determining a state of a traffic intersection using information from one or more sensors of a vehicle. The vehicle may be configured to operate in an autonomous mode. The method may also include determining an uncertainty associated with the determined state of the traffic intersection. The method may further include controlling the vehicle in the autonomous mode based on the determined state of the traffic intersection and the determined uncertainty.

Abstract: According to a method of vehicular traffic management, a computer system receives, from devices distributed in a plurality of roadway segments of a physical roadway system, real-time traffic information individually describing vehicular traffic in each the plurality of roadway segments. The computer system determines from the real-time traffic information an advised speed for a particular roadway segment among the plurality of roadway segments. The computer system transmits, via a communication network, a speed advisory command specifying the advised speed to a device in the particular roadway segment for presentation.

Abstract: A variable speed limit sign including a controller and a display operatively coupled to the controller is provided. A traffic control system including a variable speed limit sign and methods of use thereof are also provided.

Abstract: A method of optimizing the traffic control at a traffic signal-controlled intersection in a road traffic network. The vehicle traffic in entrances to the intersection are controlled by signal groups of a traffic signal system according to associated signal times. For vehicles approaching the signal group, traffic parameters are determined from traffic data using a traffic model according to the signal times, and in order to determine optimal signal times, the traffic parameters are weighted and added up and the target function formed in such a way is optimized by varying the signal times. By individually determining the traffic parameters for each vehicle and individually weighting the traffic parameters according to the strategic relevance thereof for the implementation of a specified traffic strategy, an improved implementation of the specified traffic strategy is made possible.

Abstract: A sign (100) displays moving, still, or blank images (130). In one aspect the sign is mounted over a roadways for viewing by occupants of vehicular traffic (105) and pedestrians. In another aspect the sign is mounted on a vehicle. An associated sensor (125, 220, 221, 222) senses the motion of traffic in the vicinity of the sign. When traffic moves at less than a predetermined speed, the sign displays moving or changing information. At greater speeds the display on the sign is either still or blank, so as to avoid distracting nearby drivers. An electronic system (135) provides various aspects that augment sign operation such as GPS, reception of signage information for use in particular locations, advertiser billing information based on sign usage, and collection and reporting of demographics that aid advertisers in maximizing their impact.

Abstract: An external adaptive control system and method control a traffic signal controller assembly. The external adaptive control system determines a non-linear schedule with one or more states corresponding to one or more individual phases with each state having a start time and a duration. The external adaptive control system generates presence data for reception by the controller assembly for each state and its associated duration.

Abstract: An automotive communication method includes installing a sensor within a vehicle such that the sensor is submerged in a liquid during operation of the vehicle and/or substantially surrounded by a metallic structure during operation of the vehicle. A long wave magnetic signal is transmitted from the sensor. The signal is indicative of a condition sensed by the sensor. The signal is wirelessly received at a controller disposed within the vehicle. Receipt of the signal at the controller is responded to by adjusting a display and/or a setting within the vehicle.

Abstract: The invention relates to a device (100) for detecting the passing of individuals in the form of a mat including: a printed circuit board (104), one of the surfaces which supports a plurality of contactors designed to change state under the pressure exerted by a foot or a wheel, and at least one of the surfaces of which supports at least one electronic component (112) not subject to any pressure from said foot: and for the or each surface supporting at least one electronic component (112), a protective layer (106) attached to said surface and incompressible under the weight of individuals/trolleys, the or each electronic component (112) being recessed in a hole (110) in said incompressible protective layer (106).

Abstract: Approaches for issuing preemption requests. The boundaries of a geo-window are repeatedly determined based on locations and headings of a vehicle as the vehicle is traveling along a roadway. The methods and systems determine whether or not any one of a plurality of intersections is located within the boundaries of the geo-window in response to changed boundaries of the geo-window. In response to determining that one of the plurality of intersections is located within the boundaries of the geo-window, a preemption request is transmitted from the vehicle to an intersection controller at the one of the plurality of intersections.

Abstract: A drive assist device and method capable of preventing the confusion of a driver at a traffic signal with an arrow lamp are provided. An ECU has a section for determining whether or not it is possible to pass a signal, which determines whether or not a vehicle can pass a signal, and a signal waiting time notification control section, which determines a signal waiting time of the vehicle and displays it on a display unit when the section for determining whether or not it is possible to pass a signal determines that the vehicle cannot pass a signal. The section for determining whether or not it is possible to pass a signal determines not only a lighting time of only a red signal but also a lighting time of a red signal and an arrow lamp and a lighting time of a yellow signal subsequent thereto are determined as a no-pass time.

Abstract: A method and system for a mid-block traffic detection and traffic signal control system is provided herein that is suited to monitoring heavy commercial vehicles such as trucks is provided. The method comprises detecting a vehicle and determining at least one pre-determined parameter of the vehicle. A traffic condition is evaluated based on the at least one pre-determined parameter. In response to the evaluation of the traffic condition, a traffic signal is controlled.

Abstract: The invention may allow an in-vehicle unit of a vehicle located in a shadow portion of a large-sized vehicle and an in-vehicle unit of a vehicle at a location separated from an intersection 193 to receive traffic information. A UHF beacon unit 112 is disposed at the intersection 193, thereby distributing the traffic information using a UHF beacon signal having a diffraction characteristic. This arrangement can allow the in-vehicle unit of the vehicle located in the shadow portion of the large-sized vehicle as well to receive the traffic information. Further, since the UHF signal propagates far, this arrangement can allow the in-vehicle unit of the vehicle at the location separated from the intersection 193 as well to receive the traffic information. The UHF beacon unit 112 transmits the UHF beacon signals with the different traffic information set therein by time division and frequency division.

Abstract: A networked streetlight system associated with a central control system having control over illumination settings for a plurality of luminaires within the networked system. Particular embodiments may be used specifically with emergency vehicles to guide the vehicles to emergency destinations through the combination of knowing the location of the vehicle and its destination, and having control over the networked luminaires, each having specific illumination settings controls. Examples of illumination settings include strobe, color and intensity.

Abstract: The present lighting system adds detection capabilities to perceive the presence and measure the velocity of objects such as automobiles, trucks, pedestrian and other users, to lighting modules for transportation applications like traffic signal, pedestrian control, rails signal, street light, message board and speed monitoring board. For example, a Light Emitting Diode (LED) has the capability to be used as lighting source for illumination as a first function and also be pulsed or modulated as a source for the detection sub-system as a second function.

Abstract: A traffic information generation method for generating traffic information for each link includes a vehicle speed detection step of detecting a vehicle speed at predetermined distance intervals or at predetermined time intervals using a vehicle speed sensor; and a traffic jam degree detection step of referring to a specified speed and a specified distance prescribed in association with a traffic jam degree representing a level of a traffic jam and a connection determination distance prescribed in accordance with a road type to detect the traffic jam degree corresponding to the vehicle speed. When a link length falls within a predetermined range, information on the traffic jam degree corresponding to a fastest vehicle speed within a prescribed starting point distance from a beginning of the link is allocated to the link.

Abstract: Some embodiments disclose methods for classifying user equipment in a network, comprising: recording a first number of times a tracking area identity has changed for a user equipment device during a period of time based on messages exchanged between the user equipment device and a mobility management entity; recording a second number of times the user equipment device is paged during a second period of time; classifying the user equipment device into one of at least three categories based on the first and second recorded numbers; generating a tracking area identity list for the user equipment based device on its category; and sending the generated tracking area identity list to the user equipment device.

Abstract: A traffic control system for converting an intersection into a roundabout during periods of heavy traffic includes a mechanism for monitoring traffic flow through the intersection and about the roundabout. The system also includes a concave opening in and around the intersection and a concrete disc disposed in the cavity, a hydraulic lift is constructed and arranged to elevate the concrete disc above the level of the road and lights provided to alert motor vehicles to enter a roundabout defined by the elevated disc. The system also includes traffic lights for alerting a motor vehicle operator to drive onto the disc or around the disc to use the intersection and/or roundabout.

Abstract: A roadside equipment (RSE) system that can be used for controlling traffic signals and other equipment and corresponding method. A method includes wirelessly receiving vehicle data from an onboard equipment (OBE) system connected to a vehicle, the vehicle data including location data, time data, and vehicle identification data related to the vehicle. The method includes determining motion data for the vehicle and determining the current state of at least one traffic device. The method includes determining a roadway lane corresponding to the vehicle, based on the motion data and the current state of the at least one traffic device, and storing the vehicle and associated roadway lane.

Abstract: A wireless head for a traffic preemption system. Implementations may include one or more optical receivers adapted to identify an optical signal transmitted by an optical transmitter included in a vehicle preemption unit mounted to a vehicle and one or more head radio transceivers adapted to identify a radio signal transmitted by a vehicle radio transceiver included in the vehicle preemption unit. A head radio frequency (RF) modem may also be included adapted to transmit one or more radio signals to an intersection RF modem. The head may be mounted to a traffic support fixture. The one or more optical receivers, one or more head radio transceivers, and the head RF modem may all be operably coupled together within the wireless head. The intersection preemption unit may be adapted to change a traffic light in favor of the vehicle to which the vehicle preemption unit is mounted.

Abstract: Provided are a method for running a network for vehicle detection and a system thereof. Each vehicle detecting device is classified into a plurality of groups based on information provided from the vehicle detecting devices and control information that activates or deactivates components of the corresponding vehicle detecting devices is set for each group based on the information. Power of a signal transmitting the information is set for each vehicle detecting device.

Abstract: Device for viewing the aerial environment for aircraft, including a display, a processor and memory configured to generate and to provide a first data processing resource, the data being a graphical representation of the aerial environment composed of colored zones, each color being associated with a danger level for the aircraft, said data comprising environmental data; and a second data processing resource for cartographic data. The device further comprises a graphical mixer to overlay the graphical representation arising from the environmental data onto a representation of the cartographic data on one viewing screen, each zone of a color of the representation of environmental data having a transparency coefficient dependent on the danger level.

Abstract: Traffic light installations for producing meta information on the basis of input information about the surroundings of the traffic light installation. The traffic light installation acts as a data pool and can independently reproduce a road section using the information which it has measured or which it has obtained from adjacent vehicles. In addition, the traffic light installation can use the input information to produce meta information which is communicated to other vehicles and thus results in a constant flow of traffic.