Hybrid topic modelling and network analysis for urban traffic research using TF‑IDF and NMF


Abstract

Urban traffic systems generate vast amounts of research data, reflecting evolving challenges and innovations in mobility. To uncover latent themes and their interconnections in the urban traffic literature, this study proposes a hybrid text-mining approach that combines topic modelling and network analysis. We analyze 88 traffic-related research papers published from 2016 to 2025, focusing on titles, abstracts, and author keywords. A Term Frequency–Inverse Document Frequency (TF‑IDF) vectorization with Non-Negative Matrix Factorization (NMF) identifies five salient topics, which are interpreted to represent key research themes (e.g., traffic flow prediction, smart mobility analytics, trajectory and travel behaviour analysis, congestion and network management, and graph-based machine learning for transport). Each document is assigned a dominant topic, and the distribution of documents across these topics is visualized. We further construct a keyword co-occurrence network to elucidate how author-provided keywords cluster into thematic groups and interlink across publications. Temporal analysis reveals how topic prevalence has shifted annually from 2016 to 2025, highlighting emerging and declining research trends. Our findings indicate a growing prominence of data-driven and AI-powered methods in recent years, alongside enduring interest in traffic flow and congestion issues. The proposed hybrid approach yields a comprehensive landscape of urban traffic research, integrating quantitative topic modelling with network-based insights. We highlight three primary contributions: (1) a methodological framework that fuses TF‑IDF, NMF topic modelling, and co-occurrence network analysis for urban research text mining, (2) an application of topic modelling to illuminate evolving themes in urban traffic literature, and (3) visualization-driven, network-based insights that reveal thematic clusters and keyword interlinkages in the field. These contributions demonstrate how combining text analytics with network science can support urban computing research by mapping knowledge domains and guiding future studies.
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