Traffic Signal Transition Time Prediction Using Mobile Probe Data
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Solution Overview
Problem
Existing methods for determining traffic control signal operation information rely heavily on fixed infrastructure, which is inflexible and costly, and may provide inaccurate data due to clock inaccuracies in traffic signal timing.
Innovation Solution
Using positional data from mobile devices to determine transition times of traffic control signals, allowing for flexible and accurate prediction of future transition times without the need for additional infrastructure, by analyzing the actual movement of vehicles relative to the signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fixed infrastructure (sensors, traffic signal data collection systems) is used to obtain traffic control signal operation data, then data availability is improved, but implementation cost and system complexity increase significantly
Solution Approach 1:
The patent uses mobile devices (smartphones, GPS units) as portable copies of fixed sensors to collect traffic signal data. Instead of deploying expensive fixed infrastructure, the system leverages the positioning and timing capabilities of widely available mobile devices to capture vehicle position, speed, and traffic signal state information, thereby reducing infrastructure requirements while maintaining data collection reliability
Solution Approach 2:
The system utilizes the existing sensors and processing capabilities of mobile devices themselves to collect traffic data. The mobile devices' built-in GPS, accelerometers, and gyroscopes are employed to detect vehicle motion and infer traffic signal states without requiring external fixed infrastructure, allowing the system to serve itself using readily available resources
2Ease of manufacture
If third party data sources are used to obtain traffic control signal information, then implementation cost is reduced, but data accuracy deteriorates due to clock inaccuracies and data collection limitations
Solution Approach 1:
The system continuously monitors vehicle position, speed, and acceleration data from mobile devices and uses this feedback to detect changes in traffic signal states. By analyzing patterns in vehicle motion (such as sudden deceleration indicating red light, or acceleration indicating green light), the system infers transition times with higher accuracy than static third-party data sources that rely on imprecise clock synchronization
Solution Approach 2:
Instead of directly measuring traffic signal transition times using fixed sensors near the signals (which suffer from clock inaccuracies), the patent inverts the approach by inferring signal states from vehicle response data. The system observes how vehicles react to signal changes and works backward to determine transition times, thereby avoiding the clock synchronization problems inherent in direct measurement approaches
3Measurement precision
If fixed sensors are deployed near traffic control signals to collect operation data, then transition time measurement precision is improved, but adaptability to different traffic signals and locations deteriorates
Solution Approach 1:
The patent creates a universal data collection system where mobile devices can collect traffic signal data from any location without requiring location-specific fixed infrastructure. The same software algorithm running on mobile devices can adapt to measure transition times at different traffic signals, intersections, and locations, providing both precision through vehicle response analysis and versatility across multiple signals simultaneously
Solution Approach 2:
The system transitions from static fixed sensors to dynamic mobile measurement points. Mobile devices move through different locations, allowing the system to adaptively collect data from various traffic signals as vehicles naturally traverse them. This dynamic approach enables the system to measure transition times at multiple locations over time without deploying fixed infrastructure at each site
Data Source
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AI summary
A method of obtaining data relating to the timing of a transition between phases of a traffic control signal. The method involves obtaining live probe data relating to the travel of vehicles in the region of the traffic control signal, and using the data to determine times at which a given transition of the signal has occurred. This is carried out by consideration of the distance from the traffic signal at which a vehicle waits when stopped at the signal, and a time of passing the signal, as determined using the probe data. Different transition time pairs are analysed to obtain time differences between the transition times. A cycle time which best fits the time difference data is determined, and used with the transition time data to predict future transition times of the traffic control signal.