Crack Sensor Live
For crack movements that take seconds: with the Crack Sensor Live, up to four displacement transducers are connected to the live gateway and measure at 1 to 10 Hz with 0.001 mm resolution. The gateway transmits live to the platform via LTE, stores in parallel on USB, and every reading is checked against your thresholds immediately.
- 0.001 mm resolution
- 1 to 10 Hz
- Up to four transducers per gateway
- Cloud and USB in parallel
Why live
Crack movements that last only seconds
Some crack movements happen within the seconds of a lorry crossing or a construction operation and disappear in hourly values. The Crack Sensor Live makes them visible.
Up to 10 readings per second
The measuring rate can be set from 1 to 10 Hz. A crossing, a construction operation or a load test shows up in the second-by-second signal, not only in the hourly mean.
0.001 mm resolution
The displacement transducers resolve changes in crack width down to 0.001 mm. Temperature is measured as well, so that load and temperature effects can be separated.
One gateway, up to four transducers
Up to four displacement transducers connect to one live gateway via IP68 connectors, each with up to 50 m of cable. One gateway can therefore cover several cracks.
Cloud and USB in parallel
The readings go live to the platform via LTE and are stored on a USB stick at the same time, as a backup even without mobile reception.
Power as available on site
The live gateway runs on a solar module, mains power or a buffer battery. It fits on a bridge as well as inside a box girder.
From live to long-term without remounting
After the live phase, the same displacement transducers are plugged into the long-term gateway. Long-term monitoring continues without remounting.
Technical data
Specifications at a glance
- Measured quantities
- Change in crack width (relative to the zero point), temperature
- Measuring range
- 0–10, 0–25 or 0–50 mm (depending on the transducer)
- Resolution
- 0.001 mm
- Sampling rate
- 1 to 10 Hz, adjustable
- Expandability
- up to four displacement transducers per live gateway, IP68 connectors
- Cabling
- Cable to the live gateway, up to 50 m
- Data transmission
- LTE, live to the data platform
- Memory
- USB stick on the gateway, in parallel with the cloud
- Alerting
- Warning and alarm threshold per transducer
- Power source
- Live gateway with solar module, mains power or buffer battery
- Mounting
- screwed, with counter bracket
- Reusable
- switch to the long-term gateway without remounting
How the system works
From the crack to the platform
Displacement transducer, live gateway and platform form an unbroken chain. What happens at the crack appears seconds later as a trend on the platform, where it is checked.
- 01
Measure
The displacement transducer bridges the crack and records the change in crack width at 1 to 10 Hz, plus temperature.
- 02
Transmit
The readings go by cable to the live gateway, from there via LTE to the data platform and in parallel to the USB stick.
- 03
Check and alert
Every reading is checked against the warning and alarm threshold of its transducer. If a threshold is exceeded, the system reports immediately.
Live or long-term
Two crack sensors, two tasks
Which variant fits depends on how quickly the crack movement develops. The two can be combined: live first, then long-term.
Long-term
Crack Sensor
Measures 1 to 480 times a day, transmits via NB-IoT and runs on solar power, a long-life battery or mains power. The right choice for crack movements over weeks, months and years.
To the Crack Sensor
Application
Crack monitoring
How cracks are monitored, which variant fits when and how thresholds are set.
To crack monitoringFrom practice
Client: Die Autobahn GmbH des Bundes
Prestressed concrete motorway bridge: load and temperature in the second-by-second signal
Following a special inspection, crack movements on the bottom slab inside the box girder of a prestressed concrete bridge from the 1960s were to be measured. Four displacement transducers ran at 1 Hz on the live gateway for just over five weeks, stored locally on USB and in parallel in the cloud.
Every lorry crossing was visible as a step in the second-by-second signal. The number of events per day followed the lorry toll data; on Sundays, when lorries are banned, it was around a tenth. The daily crack movement followed the air temperature with a lag of four to five hours. For long-term monitoring, the same displacement transducers are plugged into the long-term gateway without remounting.
Structure not named at the client’s request.
To the motorway bridge reference- live data at 1 Hz, late June to early August 2026
- 898 h
- load events detected, step of at least 10 µm/s at three or more measuring points
- 264,960
- daily number of events against lorry toll data
- r = 0.98
- daily fluctuation of the crack width (median)
- 83 µm
Analyses
What the live data reveal about the crack
The second-by-second signal allows analyses that hourly values cannot provide. These four come from the live project for Die Autobahn GmbH.
Load events in the second-by-second signal
When a heavy lorry crosses the structure, the crack opens for a few seconds. In the 1 Hz signal, every event is visible at all measuring points at the same time. In the project, a load event was defined as a step of at least 10 µm/s at three or more measuring points.
Temperature cycle and lag
Over the day, the crack width follows the air temperature, in the project with a lag of four to five hours and 3.9 to 5.9 µm per degree. Knowing this share makes it possible to tell temperature effects from damage.
Events against lorry traffic
The number of load events per day is compared with lorry toll data. In the project, the correlation was r = 0.98; on Sundays, when lorries are banned, the number fell to around a tenth. This shows that the events come from heavy traffic.
Trend after temperature correction
Removing the temperature and load components leaves the trend: the change the structure itself shows. It is the basis for thresholds and for the long-term monitoring that then continues at hourly intervals.
Schematic illustration, not measured values.
Related solutions
The sensor as part of a solution
Crack monitoring
Monitor cracks continuously, in the long-term or the live variant.
Learn more
Traffic load monitoring
Record load events from traffic and assess their effect on the structure.
Learn more
Monitoring & Alerting
Warning and alarm thresholds, alarm chain by email and SMS, around the clock.
Learn moreInfrasolute platform
Live readings on the platform
The readings of the Crack Sensor Live appear on the Infrasolute platform seconds after measurement, are checked against the thresholds and can be analysed together with temperature and traffic data.
Platform modules
Want to know what happens at the crack within seconds?
Describe the structure, the crack pattern and the reason to us. We recommend measuring points, measuring rate, thresholds and the right power supply for the live gateway.
Christian Steffes 
Frequently asked questions about the Crack Sensor Live
How does the Crack Sensor Live differ from the Crack Sensor?
How many displacement transducers can be connected to one live gateway?
What happens if there is no mobile reception?
How is the live gateway powered?
Can measurement continue long-term after the live phase?
Project inquiry
Enquire about the Crack Sensor Live
Tell us about the structure, the crack pattern and the period. We recommend the number and position of the displacement transducers, the measuring rate, the thresholds and the power supply for the live gateway, and get back to you promptly.
+49 6742 8599600 DE +41 41 670 00 11 CH [email protected]