Assessment of road accessibility to medical demand points under the influence of specific speed reduction parameter settings

OBJECTIVE: To address the dual constraints of icy-snowy conditions in winter and traffic congestion on expressway medical rescue efficiency, this study constructs an accessibility assessment model integrating multiple road condition scenarios. It reveals the spatiotemporal accessibility characteristics of rescue services along expressways in cold regions, providing a basis for optimizing resource allocation and improving emergency response time. METHODS: ) is introduced to quantify the impact of varying icy-snowy road conditions on vehicle speed, enabling multiscenario simulation by coupling normal congestion with icy-snowy conditions. RESULTS: The overall accessibility of expressway medical services in Shenyang is 45.51%, rated as "medium." As icy-snowy conditions worsen (decrease from 1.0 to 0.6), accessibility drops to 28.83%, average travel time increases from 1,618 s to 2,351 s, and speed decreases from 16.46 m/s to 11.33 m/s. Accessibility shows a spatial pattern of "high in the center, low in the periphery." Under icy-snowy conditions, accessibility during evening rush hours, in mountainous areas, and along provincial boundary sections deteriorates sharply, with most sections failing to meet the golden rescue time when λ ≤ 0.8. CONCLUSIONS: Icy-snowy road conditions significantly weaken expressway medical rescue accessibility in cold regions, and existing resource allocation struggles to meet emergency needs under combined congestion and icy-snowy conditions. This indicates inadequate expressway medical rescue services in China's cold regions, with emergency response capabilities compromised by seasonal icy-snowy weather. This study elucidates the spatiotemporal evolution of accessibility under the joint influence of traffic congestion and icy-snowy conditions, providing insights for proactive resource allocation and optimized scheduling.