Bridge monitoring

What is bridge monitoring? 

Bridge monitoring is the continuous, automated measurement of a bridge's structural condition and traffic loads. Sensors attached directly to the structure and its surroundings record physical responses and environmental conditions in real time, 24 hours a day – giving bridge owners and operators the data needed to ensure safety and plan maintenance.

Bridge monitoring complements, but does not replace, expert visual inspections. While inspections provide a periodic qualitative picture, monitoring delivers continuous, quantitative data that makes it possible to detect gradual changes and emerging issues between inspection cycles.

Why is bridge monitoring necessary? 

Many bridges were designed and built decades ago, under traffic assumptions that no longer reflect reality. Traffic volumes have increased significantly, and heavy vehicle loads have grown. Aging structures carry greater stress than originally planned for, yet their internal condition is not visible from the outside. Consequently, structural failure can occur abruptly. 

Monitoring provides the objective, ongoing evidence that bridge owners need to understand real structural behavior, prioritize maintenance budgets, and intervene before a minor issue becomes critical. 

Two core technologies in bridge monitoring

Modern bridge monitoring combines two complementary systems. Each addresses a different part of the problem: one measures how the bridge responds, the other measures what is causing those responses. When SHM and WIM data are synchronized, engineers can directly link a structural response to the vehicle load that caused it – making capacity assessments and fatigue analysis far more accurate than code-based assumptions alone.

Bridge protection

Bridge protection goes one step further: a Weigh In Motion system installed before the bridge detects overloaded vehicles at free-flow speeds and triggers toll enforcement or rerouting before they ever reach it  stopping the most damaging loads at the source. Monitoring and protection are two sides of the same coin: one measures, the other prevents.

What parameters are measured in bridge monitoring?

Sensors capture both the structural responses of the bridge and the external conditions that influence them. To obtain a holistic view of the bridge's health, these different datasets are typically correlated. The following table provides an overview of typical parameters measured in bridge monitoring. Depending on the bridge type, location, and specific requirements, additional parameters  may also be included.

• Real-time insight into bridge health – Continuous, data-driven insights into structural behavior, rather than just momentary snapshots from visual inspections 
• Understanding real traffic impact – Measurement of actual traffic loads (axle loads, gross vehicle weight, speed) via Weigh-in-Motion (WIM) to better understand bridge fatigue
• Early warning of emerging issues – Early detection of anomalies such as cracks, corrosion, or loss of stiffness before critical damage occurs
• Safer, longer-lasting infrastructure – Targeted, condition-based maintenance instead of reactive repairs extends service life and improves safety
• Automated enforcement of overloaded vehicles – Vehicles exceeding legal weight or speed limits can be automatically identified and penalized
• Scalable & robust solution – Modular, digital sensor system with edge processing that flexibly adapts to any bridge and is designed for harsh environments