EÜ Innere Kanalstraße — wireless bridge monitoring

Three units, 2 channels each, 125 Hz. Overview shows a 1 s min–max envelope; zooming below ~10 minutes automatically loads the raw 125 Hz signal. Conversion to mm: displacement = scale × (V − zero). Default scale comes from the on-site step calibration of 19 Aug 2026 (assuming a 40 mm step — to be confirmed); zero can be set from a chart window (Analyse button), empty zero = display relative to the first sample. Signals are despiked with a 5-sample median filter (removes periodic electrical spikes of the ADC — see the noise panel in Dynamic analysis below); original CSV samples are unchanged.

Two units, 500 Hz, burst recording (files of ~60 s). The first chart shows the peak-to-peak amplitude in every second; dots mark detected events. Zooming below ~10 minutes loads the raw 500 Hz signal. The FFT button computes the spectrum and natural frequencies from the current window.

Automatic detection from the dynamic (DynaSense) measurements. Vibration events: contiguous seconds with peak-to-peak acceleration ≥ 15 mg. Displacement events: short-term deviation of a dilatometer channel from its rolling baseline (≥ 6× noise level, min. ~0.25 mm). Detection starts after the installation was completed (19 Aug 2026, 20:00 local). Events within 30 s of each other share a crossing group number. Click a row to zoom the charts above to that event (raw signal loads automatically); tick rows and press Compare to overlay their responses below.

Applies the SRIMS methodology (STATOTEST + CTU Prague, project TM05000045): mid-span deflection is estimated from the sum of the longitudinal bearing displacements at both ends of the span as u_z = k · u_x · l / h; train load then follows linearly from deflection after calibration on known trains. Crossings are detected on the raw 125 Hz dilatometer signals (Savitzky–Golay smoothing, threshold ≥ max(6× noise, 0.8 mV ≈ 0.03 mm)) and require a coincident response on at least two units (axes 30 and 40 within 3 s) plus a confirmation: either coincident vibration on the accelerometers (≥ 15 mg — the accelerometer acts as the train trigger, as in the SRIMS concept) or, when no accelerometer was recording, a position outside the :00/:30 phase of the periodic electronics bumps. For the instrumented span 30–40: u_x = |axis 30 longitudinal (DIL 3 ch2)| + |axis 40 longitudinal (mean of DIL 4/5 ch2)|. Caveat: the methodology was validated on simply supported spans — this bridge is a continuous curved girder. The default k = 0.36 is an ESTIMATED value (showcase project): computed from a continuous three-span line model of this bridge (constant EI, lever arm h/2), giving k ≈ 0.35–0.38 depending on the load position (the simple-span table value would be 0.32); it has not been calibrated by an FEM model or a load test yet, so the deflections below are indicative. Values prefixed ≥ are partial: DIL 3 (axis 30) was not recording during the crossing, so u_x contains only the axis 40 contribution (lower bound) — for full SRIMS evaluation the three dilatometer units should record simultaneously (align their recording schedules in the firmware). Click a row to zoom the charts above to the crossing.

Response trends: each dot is the peak response of one detected event — a stable response to comparable trains indicates unchanged structural behaviour, a long-term increase may indicate a developing problem (bearing friction, stiffness change). Event comparison: select events in the table above and press Compare — their responses overlay here on a common time axis. Spectra and noise diagnostics below. (The FFT tool for natural frequencies is on the axis charts above.)

Two stations, DEV_1596 (axis 30) and DEV_1597 (axis 40), period ~10 min: X/Y inclination (ADXL355), two dilatometers SOP-KPM-R-50 on a 24-bit ADC (longitudinal displacement of the left/right bearing), internal temperature (TMP112) and an external probe (DS18B20). DEV_1596 additionally provides a liquid inclinometer (ready-made ° values, data type Unit) and a hygrometer.

The dominant driver of static quantities is temperature. The scatter charts show each measurement against the structure temperature (external probe) with a fitted linear thermal response — a stable slope and a narrow band indicate normal behaviour. The residual chart removes the fitted thermal component: what remains should stay near zero; a persistent drift or a step indicates a non-thermal change (bearing restraint, settlement, sensor problem).

Public DB timetable for station Köln Geldernstr./Parkgürtel — the bridge sits between Köln-Nippes and this station (~500 m south of it), so every train serving the station crosses the bridge (single-track line 2620, S6 and S11 in both directions; S6 short-turns terminating at Nippes never reach the bridge and are automatically excluded). Sources: IRIS planned timetable + live departure board with real delays; the logger polls every 5 minutes. Public sources only expose the schedule a few hours back, so the log grows from the moment it was started (28 Aug 2026) — earlier measured crossings cannot be matched retroactively. Freight and empty-stock runs are not in the public passenger timetable: a measured crossing without a matched train (typically at night) is most likely one of those. Each train is paired with the dynamic measurement (detected crossing → estimated deflection u_z, vibration) and with the static measurement (structure temperature and Chester bearing displacement at the time of passage). Click a row with a measured crossing to open it in the Dynamic tab.