Geographic Information Systems in Transportation Engineering: A Critical Review of Planning, Network Operations, Accessibility, Safety, and Digital Integration

Geographic Information Systems (GIS) have evolved from digital mapping and spatial inventory tools into analytical environments that connect transport networks, land use, mobility observations, infrastructure assets, and decision-support models. This critical narrative review synthesizes the research-paper summaries supplied for this study to examine GIS applications in transportation planning, network modelling, congestion diagnosis, public transport accessibility, active mobility, operational dispatch, freight, road safety, and infrastructure management. Across the reviewed evidence, GIS contributes most strongly where spatial data integration, network topology, geocoding, route impedance, catchment analysis, and visual interpretation are linked to a clearly defined transport decision. Case evidence ranges from early integration of GIS with conventional transport models to low-cost GPS-based congestion monitoring, generalized-cost accessibility modelling, level-of-traffic-stress and energy-aware cycling analysis, passive public-transport data, and emerging AI/BIM/IoT integration. The review also identifies recurring limitations: inconsistent and outdated network data, weak interoperability, spatial and temporal aggregation, incomplete demographic representation in passive mobility data, limited external validation, and uneven capacity across regions. A decision-centred GIS-T framework is proposed, linking data governance and quality assurance with method selection, scenario analysis, uncertainty testing, independent validation, equity and privacy assessment, and operational monitoring. The synthesis suggests that the next stage of transportation GIS should prioritize reproducible multi-source data integration, multimodal and person-sensitive accessibility, transferable models, explainable GeoAI, climate resilience, and evaluation of real-world outcomes. Because the supplied source is an annotated set of studies rather than a documented database search, the paper is framed as a critical narrative review; a journal submission requiring systematic-review claims should add a reproducible search and screening protocol.