Baseline case (2 km, A₀ = 100 m², 350 km/h): exterior pressure histories (a) at a fixed mid-tunnel probe and (b) at a probe moving with the train. The inset resolves the wave front: the dispersive overshoot is a numerical feature and is excluded from every reported wave amplitude, whereas the dotted line is the physical post-front amplitude, taken as the median over 0.2–0.7 s after arrival; the slow rise that follows it is the quasi-steady field of the approaching train, not part of the front. The smaller ringing after each reflected front is the same dispersive feature. The successive steps in both panels are portal reflections, that is, physical wave arrivals, not numerical noise. Source: Author's own work