FairTP: A Prolonged Fairness Framework for Traffic Prediction

Traffic prediction is pivotal in intelligent transportation systems. Existing works mainly focus on improving the overall accuracy, overlooking a crucial problem of whether prediction results will lead to biased decisions by transportation authorities. In practice, the uneven deployment of traffic sensors in different urban areas produces imbalanced data, making the traffic prediction model fail in some areas and leading to unfair regional decision-making that eventually severely affects equity and quality of residents' life. Additionally, existing fairness machine learning models fail to preserve fair traffic prediction for a prolonged time. Although they can achieve fairness at certain time points, such static fairness will be broken as the traffic conditions change. To fill this research gap, we investigate prolonged fair traffic prediction, introduce two novel fairness definitions tailored to dynamic traffic scenarios, and propose a prolonged fairness traffic prediction framework, namely FairTP. We argue that fairness in traffic scenarios changes dynamically over time and across areas. Each traffic sensor or city area has state that alternates between "sacrifice" and "benefit" based on its prediction accuracy (high accuracy indicates "benefit" state). Prolonged fairness is achieved when the overall states of sensors similar within a given period.Accordingly, we first define region-based static fairness and sensor-based dynamic fairness. Next, we designed a state identification module in FairTP to discriminate between states of "sacrifice" or "benefit" to enable prolonged fairness-aware traffic predictions. Lastly, a state-guided balanced sampling strategy is designed to select training examples to promote prediction fairness further, mitigating the performance disparities among regions with imbalanced traffic sensors. Extensive experiments in two real-world datasets show that FairTP significantly improves prediction fairness without causing much accuracy degradation.