Explainable Traffic Flow Prediction with Large Language Models

Traffic flow prediction provides essential future views in the intelligent transportation system. Explainable predictions offer valuable insights into the factors influencing traffic patterns, which help urban planners, traffic engineers, and policymakers make informed decisions about infrastructure development, traffic management strategies, and public transportation planning. Despite their widespread popularity and commendable accuracy, prediction methods grounded in deep learning frequently disappoint in terms of transparency and interpretability. Recently, the availability of large-scale spatio-temporal data and the development of large language models (LLMs) have opened up new opportunities for urban traffic prediction. With the popularity of LLMs, people witnessed the potential reasoning and generating ability of foundation models in various tasks. Considering text as input and output, LLMs have advantages in generating more intuitive and interpretable predictions. Hence, this work introduces TP-LLM, an explainable foundation-model-based method for traffic prediction, aiming at more direct and reasonable forecasting. TP-LLM presents a framework to unify multi-modality factors as language-based inputs, TP-LLM avoids complex spatial-temporal data programming and outperforms state-of-art baselines merely under fine-tuning foundation models. Also, TP-LLM can generate input-dependency explanations for more confident prediction and can be easily generalized to different city dynamics for zero-shot prediction with a similar framework. These findings demonstrate the potential of LLMs for explainable traffic prediction.