Adaptive Traffic Signal Control Using Semi-Markov Decision Process
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Solution Overview
Problem
Conventional traffic control systems are inadequate in adapting to unanticipated traffic flow patterns and fail to optimize traffic signal control at intersections, leading to prolonged waiting times and inefficiencies.
Innovation Solution
A method and system that utilize traffic data to calculate the current traffic state and rate of change, applying a semi-Markov Decision Process to optimize traffic signal control by switching signals based on continuous decision-making processes that maximize rewards for traffic conditions such as fuel consumption, pollution, and waiting time, using sensors like loop detectors and cameras.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional time-based traffic control systems are used with manually developed switching plans, then the system structure is simple and easy to operate, but the system cannot adapt to unanticipated traffic flow patterns and leads to prolonged waiting times
Solution Approach 1:
The patent implements dynamic traffic signal control by transitioning from fixed time-based switching plans to a real-time adaptive system that continuously monitors traffic flow using loop detectors and adjusts signal phases and durations dynamically. The system evaluates traffic states and makes real-time decisions to optimize signal control, enabling adaptation to unanticipated traffic patterns while reducing vehicle waiting times through continuous optimization.
2Adaptability or versatility
If adaptive phase control systems like SCOOT and SCATS are implemented, then real-time adjustments can be made based on traffic flow measurements, but the systems are limited to switching between a limited number of phases in a predetermined order and cannot provide greater flexibility
Solution Approach 1:
The patent segments the traffic signal control into independent signal groups that can be controlled individually rather than being constrained to predetermined phase sequences. Each signal group can be optimized independently based on real-time traffic conditions, allowing flexible reconfiguration of signal patterns without being limited by fixed phase structures, thereby increasing system flexibility while managing complexity through modular control.
3Speed
If gap detection and saturation balancing techniques are used to estimate end-of-queue time and green light time, then the control system can respond to traffic conditions, but the techniques are sensitive to variations and unable to respond quickly to high rates of traffic flow changes
Solution Approach 1:
The patent implements a feedback mechanism using loop detectors that continuously monitor traffic flow and provide real-time data to the control system. The system uses this feedback to dynamically adjust signal control decisions, enabling rapid response to traffic flow changes while filtering out measurement variations through continuous monitoring and adaptive algorithms, thus improving both response speed and reliability simultaneously.
Data Source
AI summary
A method of controlling traffic signals at a road intersection, which has a plurality of signal groups, each of which controls at least one direction of traffic within the intersection. The method comprises the steps of obtaining and utilizing traffic data to calculate a current traffic state and the rate of change in the traffic state. The method further comprises formulating at least one action and the duration of the action in response to these calculations. Each action comprises switching at least one traffic signal. One or more policies based on the calculations and the action are resolved. A continuous decision making process is applied to evaluate a reward for the policies resolved and a policy that maximizes the reward is selected.