Digital Engineering and Energy-Aware Management of Urban Crossings Under Growing Electrified Micromobility: Three-Year Field Evidence and a Field-Calibrated Energy Budget

Urban digitalization requires site-specific evidence to determine where intelligent sensing, edge processing, warning actuation and energy management functions are justified. This repeated cross-sectional field study quantified changes in smartphone-related behaviour and electrified micromobility at an unsignalized roundabout in Kielce, Poland, and translated them into technical requirements and an energy budget for a privacy-preserving, energy-aware crossing infrastructure. Two observers recorded 27,487 crossing-area users in 1728 arm-specific five-minute intervals during 18 standardized two-hour sessions in 2023–2025. Any phone use increased from 41.87% to 48.63% (difference 6.76 percentage points, 95% CI 5.31–8.20; Cohen’s h = 0.14), and a combined electric micromobility exposure indicator increased from 11.84% to 22.39% (h = 0.28), while bicycle prevalence remained near 8%. The phone-use trend was robust to the clustering of observations: session-clustered logistic regression, a random-intercept model and an exact stratified permutation test using the 18 sessions as independent units (p < 0.001) gave consistent results, and a composition analysis showed that the trend was not explained by the growing share of micromobility users. The effects are small in standardized terms but correspond to approximately 120 additional phone-engaged users per hour at peak volumes. The framework specifies homography-based trajectory prediction, time-to-collision conflict detection, a logistic risk score with data-driven threshold selection, k-anonymous aggregate data release and a staged validation plan with key performance indicators. A field-calibrated, state-based energy budget estimated 0.63–0.73 kWh/day for event-based operation of a four-approach edge node, 28–42% less than presence-activated and 60–65% less than continuously active operation. Transport-energy savings cannot be inferred because trip distances and displaced modes were not observed.