Large-scale environmental noise modelling beyond END regulatory coverage: evidence from the Region of Murcia (Spain)

Abstract

Environmental noise assessments in Europe are mostly based on the infrastructure categories prescribed by the Environmental Noise Directive (END), which may not represent the full exposure conditions experienced by populations and ecosystems. This study quantifies how that strategic scope affects exposure estimates by comparing END-restricted road traffic noise simulations with a complementary modelling configuration that includes all road categories. A regionally validated noise model was implemented over the Region of Murcia (Spain) using high-resolution acoustic propagation and large-scale parallel computation. Results show that END-based assessments capture only a fraction of the affected territory and population: the area where noise exceeds moderate levels expands by more than a factor of three when all roads are included, and the number of residents exposed above relevant health-based thresholds nearly doubles. Protected areas also display substantial additional exposure, revealing diffuse noise propagation into ecological sites that remains undetected under the regulatory scope. These findings show that END-based indicators, while appropriate for strategic reporting, capture only part of the broader exposure field because large portions of the transport network remain outside the mapped domain. The results therefore support the use of complementary full-network modelling when the objective extends beyond END reporting to exposure assessment, health-oriented analysis or environmental planning, and indicate that such simulations are tractable with current high-performance computing infrastructures.