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TECHNICAL FIELD

This disclosure is in the field of traffic engineering and pertains to pertains to methods, systems and software to derive traffic signal timing plans from connected vehicle trajectory data.

BACKGROUND OF THE INVENTION

In many places, especially larger cities, smooth flow of vehicular traffic (and often, pedestrian or cyclist safety) depends on electric traffic control signals—for example, those that display the common green-yellow-red sequence of lights. Traffic signals generally operate according to a timing plan. There may be different timing plans for time of day (say, rush hours), days of the week, holidays, etc.

Our U.S. Pat. No. 9,396,657 (Bauer, et al.) teaches methods and apparatus for prediction of traffic signal state changes. That patent discloses a computer software emulator to emulate operation of a field traffic signal controller (FSC) at a given location, utilizing its associated timing parameters, to predict state changes. Traffic signals run on scheduled timing plans at different times, by time of day, day of week, and holidays or special events. These timing plans and schedules are obtainable from local or regional agencies' central computers, databases, or hardcopy file archives that are used to enter the traffic signal controllers.

Determining a fixed-time timing plan for a signalized intersection can be accomplished by real-time monitoring of the traffic controller, and more specifically acquiring signal state data from the controller. Traffic control signal state data can be obtained in real time by interfacing to individual traffic signal controllers (often housed in a metal box on a street corner), and or interfacing to a central traffic control server. In either case, permission and cooperation of the local traffic control authority is needed, and the cost and delay of developing and deploying such interfaces is substantial.

Improved performance, scalability and lower cost can be obtained if timing plans could be determined without relying on interfacing with the signal control system. The present disclosure addresses this and other challenges.

SUMMARY OF THE INVENTION

The following is a summary of the invention in order to provide a basic understanding of some aspects of the invention. This summary is not intended to identify key/critical elements of the invention or to delineate the scope of the invention. Its sole purpose is to present some concepts of the invention in a simplified form as a prelude to the more detailed description that is presented later.

The present disclosure obviates reliance on live state data from traffic signal controllers or related infrastructure, and it does not require access to local control signal timing plans. Thus it avoids the costs and delays associated with interfacing to those resources. Instead, according to this disclosure, we generate fixed-time signal timing plans without the need for agency approval or interfacing with traffic control equipment.

In one embodiment, a process consistent with this disclosure may include the following:

provisioning a computer server and software executable in the server to cause the server to carry out the steps of—

receive user input to select a subject intersection, wherein the subject intersection is a physical intersection controlled by electric traffic signals based on at least one timing plan;

acquire vehicle trajectory data from a first datastore, the vehicle trajectory data archived over a sampling period of time, and each instance of the trajectory data including a date/time stamp, GPS location, and speed vector of the corresponding vehicle;

access a second datastore to acquire MAP data that defines detailed geometries of the subject intersection;

filter the acquired vehicle trajectory data to form a trajectory dataset of vehicle journeys near the subject intersection;

apply clock drift adjustments to the date/time stamps of the raw trajectory dataset to form a corrected trajectory dataset wherein the data is temporally aligned to actual state changes of the traffic signals at the subject intersection;

analyze the vehicle journeys based on the MAP data to identify stopline crossings at the subject intersection during the sampling period, the stopline crossing datapoints (“crossings”) including their respective timestamps; and

based on the stop line crossings and the MAP data, determine a first timing plan of the subject intersection.

The innovation generally must be implemented in a combination of hardware and software (i.e., stored, machine-readable instructions) for execution in one or more processors. The volume and complexity of operations involved preclude any manual or “pencil and paper” solution as impracticable. In one preferred embodiment, an implementation of the invention may be provided as a service, for example, over a network such as the internet.

Additional aspects and advantages of this invention will be apparent from the following detailed description of preferred embodiments, which proceeds with reference to the accompanying drawings.

