Bridge moisture monitoring in Rhineland-Palatinate

Challenge

Early damage detection on a bridge

Moisture is one of the critical causes of damage in concrete bridges. Whether a repair lasts and the bridge waterproofing holds is hard to judge from the outside. On a small concrete bridge around 30 m long in southern Rhineland-Palatinate, the waterproofing and surfacing were renewed. The state road authority relies here on early damage detection through moisture monitoring: temperature and moisture are monitored on the structure on an ongoing basis. As there is no power on site, the monitoring has to work without a mains connection.

This bridge monitoring system serves two purposes:

• Verifying the repair: the readings show whether the repair was successful.
• Early warning for the waterproofing: moisture ingress and waterproofing damage are picked up before they lead to greater damage.

Solution

Moisture sensors in the concrete at the most critical points

The moisture sensors sit in the concrete beneath the waterproofing, where it matters most: at the low points along the drainage line, each at a water outlet. They record concrete moisture and temperature directly on the structure.

A 7 m connection runs from each sensor to its readout point. The readout points are located centrally behind the kerb, where the gateway also sits. It transmits the data and sits discreetly on the guardrail.

Monitoring does not always need large control cabinets and heavy batteries. The solar-powered gateway is self-sufficient and very energy-efficient, so no mains connection is needed. The system stays small on the structure and is barely noticeable, and installation took less than 4 hours.

Result

Condition monitoring via NB-IoT and dashboard

Temperature and moisture are read every 4 hours and transmitted automatically via NB-IoT. The readings are available online in the dashboard, and a defined alert chain by email takes effect if anything unusual occurs. This makes it possible to follow the condition of the bridge without anyone having to be on site.

As of October 2026, the sensors indicate drying out. The monitoring is planned for an indefinite period for now and makes further developments after the repair visible.

Everyone involved was very satisfied with the work. We would like to thank the state road authority and everyone involved for the smooth running of this project.

The project shows how moisture monitoring can work with very little equipment on the structure as part of bridge monitoring. You can find out more about the technology used under the concrete moisture sensor and in our overview of structural health monitoring. A comparable approach is shown in the Südbrücke Koblenz reference. Are you planning a similar project on your own structure? Tell us about it through our project inquiry.