Psychophysiological stress response to urban traffic: the effect of speed limits, road surface type, and greenery

• Noise annoyance increased with speed and poorer pavement conditions. • Poorer pavement conditions increased phasic SC and HF-HRV, indexing stress/displeasure. • Higher driving speeds increased stress, as captured by phasic SC and HR. • Road maintenance and low speeds can reduce stress caused by road traffic noise. The acoustic environment in urban spaces is often dominated by human-made noise sources, with road traffic noise as the most pervasive. Meanwhile, urban planning often overlooks how soundscape can impact citizens' well-being. This study combined virtual reality, biometric sensing, and questionnaires to evaluate how urban design measures targeting road traffic noise affect, beyond acoustic characteristics, psychological and physiological stress indicators. Participants ( N = 37) were immersed in a virtual urban environment with passing vehicles at different speeds (20,30, 50 km/h) over different road surface types and maintenance levels (new vs. deteriorated asphalt concrete and cobblestones) and varying green infrastructure (Green View Index: 0 %, 14 %, 26 %). Noise stimuli were captured through CPX measurements and subsequently auralized, resulting in signals with L Aeq spanning a 20 dBA range. Phasic skin conductance (SC), heart rate (HR), and high-frequency heart rate variability (HF-HRV) were recorded, while noise annoyance and cognitive performance were measured through self-report. Noise annoyance consistently increased with poorer pavement conditions and higher speeds. Speed was linked to high phasic SC and HR, while road surface type increased phasic SC and reduced HF-HRV from new to deteriorated asphalt and cobblestones, indexing heightened physiological stress impacting the autonomic nervous system regulation in response to less favourable road/speed conditions. Greenery, at the GVI levels studied, did not impact physiological responses or cognition but minimally reduced noise annoyance. These findings suggest that enforcing lower speed limits and ensuring smoother, well-maintained road surfaces in urban areas can lessen the biological alert state activation while reducing psychological stress.