Monitoring bridges: managing infrastructure assets with IoT

Bridge monitoring is an essential preventive action for the safety of infrastructures and their users.

Currently, there are new technologies that facilitate and improve infrastructure monitoring, such as sensors, digital tools, artificial intelligence, and IoT systems. In this article, we will explore the role of Bridge Management Software in managing infrastructure assets, with particular attention to monitoring the health of bridges and the technologies used.

Bridge monitoring with a BIM IoT platform

What is bridge monitoring?

Bridge health monitoring is a process that involves observing and collecting data regarding the structural and functional conditions of a bridge. Through appropriate monitoring systems, it is possible to identify any anomalies or material degradation, ensuring the safety, efficiency, and durability of the structure over time.

How to assess the safety of existing bridges

The assessment of the safety of existing bridges is based on various parameters, including:

• age;
• material;
• type of structure;
• load;
• exposure to weather conditions.

Evaluation methodologies include:

• visual analysis;
• inspection using drones;
• use of sensors and monitoring systems;
• calculation of load-bearing capacity through mathematical models and specialized software.

Inspection and monitoring of bridges for safety assessment

Bridge health monitoring and inspection surveys are two complementary approaches to assess bridge safety. Monitoring involves collecting real-time data through sensors and monitoring systems, allowing for a continuous assessment of structural conditions. Inspection surveys, on the other hand, involve visual analysis or the use of specific technologies at predetermined times.
Visual inspections and the compilation of bridge defect sheets are fundamental processes to ensure the safety and proper maintenance of infrastructure. During these inspections, technicians and engineers examine the bridge conditions, identify any structural problems or damages, and document the results to plan for any repair or maintenance interventions. Below are described some of the main phases for visual inspection and the compilation of bridge defect sheets.

1. planning and preparation: before proceeding with the inspection, it is important to plan and prepare the activity adequately. This includes reviewing historical information about the bridge, identifying critical areas to examine, and collecting the necessary tools and equipment;
2. preliminary inspection: the inspection starts with a general visual analysis of the bridge to identify any obvious signs of damage or degradation. This may include cracks, corrosion, erosion, distortions, or other structural anomalies;
3. detailed inspection: once the areas of interest are identified, inspectors proceed with a more in-depth examination. This may include the use of specific diagnostic tools, such as test hammers, endoscopes, or ultrasonic thickness gauges, to more accurately assess the extent and severity of the detected defects;
4. documentation: during the inspection, inspectors compile defect sheets, recording all relevant details, including the location of defects, their extent and severity, and any recommendations for repair or maintenance. These sheets can be used later to determine intervention priorities and monitor progress over time;
5. data analysis and final report: once the inspections and compilation of defect sheets are completed, engineers analyze the collected data and prepare a final report summarizing the results. This report can be used to inform decisions regarding maintenance, repair, or improvement of infrastructure;
6. monitoring and maintenance: finally, it is important to continue monitoring and maintaining bridges over time, conducting periodic inspections and implementing recommendations derived from inspection reports. This will help ensure the safety and durability of the infrastructure in the long term.

The benefits of bridge monitoring include the ability to detect anomalies or degradation promptly, reducing risks and maintenance costs. However, the installation and management of monitoring systems require specific resources and expertise. Inspection surveys, on the other hand, may be more cost-effective and less complex, but offer a less detailed and continuous view of bridge conditions.

The integration of both methodologies allows for a comprehensive and accurate assessment of bridge conditions and the planning of more effective maintenance interventions.

Bridge attention class: what is it and how is it used?

The bridge attention class is a classification that takes into account various factors:

• the strategic importance of the infrastructure;
• traffic and usage;
• age;
• degree of vulnerability.

This classification allows for establishing maintenance and monitoring priorities, allocating adequate resources based on the specific needs of each bridge.
Bridge attention classes are a categorization that considers the different inspection and maintenance needs and priorities of a bridge to ensure its safety and durability. There is no universal standard classification, but some common attention classes can be identified among various countries and regulations. Below are listed four typical attention classes, with a brief description and actions to be taken for each:

Attention Class A (high priority) – concerns bridges with severe structural issues, such as damages to piers, beams, or joints, which can compromise the bridge’s safety and require immediate action. For this attention class, urgent inspections, structural assessments, and repair or strengthening interventions are necessary.
What to do:

• conduct immediate and frequent inspections to monitor the situation;
• assess the load-bearing capacity of the bridge and the possible safety implications for users.
• plan and implement repair or strengthening interventions as soon as possible.

Attention Class B (medium priority) – includes bridges with minor structural issues, such as corrosion, cracks, or erosion, which do not compromise the bridge’s safety in the short term but require maintenance interventions to prevent worsening conditions.
What to do:

• conduct regular inspections to monitor the evolution of damages;
• assess maintenance or repair options to mitigate the issue;
• schedule maintenance or repair interventions in the medium term.

Attention Class C (low priority) – concerns bridges in good structural conditions, requiring only routine maintenance and periodic inspections to ensure long-term durability and safety.
What to do:

• conduct periodic inspections to check the bridge conditions and identify any signs of degradation;
• perform routine maintenance activities, such as cleaning, lubricating joints, and replacing worn non-structural elements.

Attention Class D (monitoring) – includes bridges for which no significant structural issues have been identified, but due to their age, high traffic, or other circumstances, require continuous monitoring to prevent potential future problems.
What to do:

• install structural monitoring systems to detect early signs of degradation or overloads;
• conduct periodic inspections to check the bridge conditions and monitor the evolution of structural parameters.
• assess the impact of traffic and the surrounding environment on the bridge and implement any preventive measures, such as weight restrictions or changes to the road layout to reduce the load on the bridge;
• keep the bridge documentation up to date, including inspections, structural assessments, and maintenance actions, to ensure proper management of the infrastructure assets.

For all attention classes, it is important to follow local or national guidelines and regulations related to the design, inspection, and maintenance of bridges. Furthermore, it is essential to collaborate with engineers and professionals experienced in the infrastructure sector to ensure that the actions taken are appropriate and effective in ensuring the safety and durability of bridges.

Example of bridge monitoring: IoT and BIM

An example of a bridge monitoring system based on IoT and BIM technologies involves the use of sensors connected to a communication network to collect data on structural conditions, such as deformations, vibrations, temperature, and corrosion. This data is then integrated into the bridge’s BIM (Building Information Modeling) model, allowing for real-time visualization and analysis of information to support infrastructure management and maintenance.

The case of the Canalone viaduct

The proposed case study relates to the monitoring with innovative systems of the Canalone viaduct, located along the Naples-Salerno highway. The research project is the result of the collaboration of six Italian universities, including the Department of Structural Engineering and Architecture of the University Federico II of Naples.

Bridge monitoring | The case study of the Canalone viaduct

This is a viaduct with a structural type of upper arch, made of reinforced concrete, with a span of 120 m and 11 spans.

First of all, a 3D BIM model of the infrastructure was created, necessary to manage data coming from innovative sensors installed on the viaduct itself.

The installed sensors are:

• 48 pressure sensors (the first group installed in pairs on the bridge piers, 75 cm from the intrados of the deck beam to analyze the traveling load, the second group installed on the bridge arch with the aim of verifying the stress state and the overall unloading of the deck subject to traffic load);
• 6 triaxial accelerometers installed on the two edge beams to analyze the dynamic properties of the structure and monitor their evolution over time;
• 3 thermocouples.

The system is completed with:

• 8 nodes for managing pressure sensor data;
• 2 nodes for accelerometers;
• 1 4G router and fiber connection system.

For data processing, it was necessary to refer to a domain of standard values, useful to define whether the displacements are due to random factors or resulting from issues due to the passage of heavy vehicles. After collecting, analyzing, and processing the data, it is necessary to visualize them with the help of interoperability platforms. An interoperability platform must provide access, traceability, allow data storage related to the work, enable real-time monitoring, and provide alerts and reports.

With usBIM.IoT, it is possible to integrate BIM models and IoT systems. It is possible to upload the 3D BIM model into the platform, complete with the sensors applied to the real infrastructure. Sensors are associated with a color and a range of reference values. Upon arrival of the data detected by the sensors, the 3D model updates in real-time, showing the results detected by the on-site sensors. Verification is also visually performed with the help of colors associated with the different types of sensors.

Bridge Monitoring System

A bridge monitoring system is a set of tools and technologies used to assess and maintain the structural conditions of bridges over time. It allows detecting any problems or structural damages, providing useful information for bridge maintenance and management. A comprehensive and professional bridge monitoring system consists of the following main components:

1. sensors – sensors are devices that detect and measure various structural and environmental parameters of the bridge, which will be discussed more extensively in the following paragraphs dedicated to IoT;
2. data acquisition system (DAS) – the DAS is the component that collects and stores data from the sensors. It consists of data acquisition units, which convert the analog signal into digital and store the data for further processing;
3. communication system – this system allows data transmission between sensors, DAS, and the control center. It can use different technologies, such as cables, wireless networks, or fiber optics, depending on the specific project requirements;
4. control and monitoring center – this is the station where operators and engineers analyze the data collected by the monitoring system. The control center is equipped with software and hardware dedicated to data processing and visualization, allowing easy interpretation of the collected information;
5. analysis and diagnostic software – these programs are used to process and analyze the collected data to identify any anomalies or trends that may indicate structural problems. The software may include machine learning algorithms, numerical models, and statistical analysis techniques to improve the reliability and accuracy of diagnoses;
6. alarm and notification system – in case of detection of critical or potentially dangerous conditions, the monitoring system can automatically generate alarms and notifications to alert the responsible operators and engineers. This allows timely intervention to prevent major damages or hazardous situations.

In summary, a professional and detailed bridge monitoring system consists of a series of sensors, a data acquisition system, a communication system, a control and monitoring center, analysis and diagnostic software, and an alarm and notification system.

Types of Bridges, Most Common Pathologies, and Corresponding Types of Monitoring

The main types of bridges include arch bridges, beam bridges, cantilever bridges, cable-stayed bridges, and suspension bridges. Each type of bridge can present specific pathologies, such as corrosion, cracks, settlements, or deformations. The appropriate monitoring varies according to the type and existing pathologies and may include methods such as deformation monitoring, vibration monitoring, temperature monitoring, or corrosion monitoring.

Types of bridge monitoring can be divided into:

• static;
• dynamic;
• environmental.

Visualization of infrastructure information

Static Bridge Monitoring

Static bridge monitoring is a methodology specialized in detecting deformations and permanent loads affecting the structure over time. This approach focuses on the analysis of specific parameters, such as displacements, inclinations, stresses, and the widening or narrowing of any existing bridge lesions.

Among the fundamental tools used for static monitoring are:

• Displacement and inclination sensors: These devices are extremely sensitive and can measure variations on the order of hundredths of a millimeter. These sensors are crucial for detecting even the smallest movements that could indicate changes in the structure.
• Strain gauges: Positioned at the site of the lesions, these sensors monitor the evolution of cracks, providing data on the extent and progression of movements. This is essential for understanding the severity and evolution of damage over time.

The data collected by the sensors are then processed and analyzed to obtain a detailed overview of the structure’s health. This allows for the timely identification of any structural problems and intervention before they can compromise the bridge’s safety.

In addition to sensor monitoring, static monitoring is often integrated with periodic experimental analyses on the materials used in the bridge construction. These analyses may include laboratory tests on samples extracted from the structure to evaluate the mechanical and chemical properties of the materials and verify any deterioration.

Static monitoring represents an essential component of an integrated structural monitoring system. This system should also include dynamic monitoring, which analyzes the structure’s responses to dynamic loads, and geo-environmental monitoring, which assesses the surrounding environmental conditions and their impact on the structure.

Together with constant and planned maintenance, static monitoring allows for the adoption of a preventive maintenance strategy based on the actual condition of the structure. This proactive approach helps extend the bridge’s service life, ensuring its safety and operational efficiency.

Dynamic Bridge Monitoring

Dynamic bridge monitoring is an advanced methodology for evaluating the structural condition over time. This method is based on the analysis of the bridge’s dynamic responses, including natural frequencies, vibration modes, and damping coefficients, in relation to various traffic loads that the bridge must withstand (traffic, wind, and seismic events).

To implement dynamic monitoring, various sensors are installed directly on the bridge, such as accelerometers, strain gauges, and temperature detection devices. These sensors record real-time data on the bridge’s structural response, which is then processed to identify possible variations or damages in the structure. This approach allows engineers to intervene promptly to ensure the safety and integrity of the bridge over time.

Unlike static monitoring, which primarily focuses on cracks and deformations, dynamic monitoring provides a more in-depth assessment of the bridge’s health, identifying changes in dynamic behavior that could signal potential emerging structural issues.

This type of approach is particularly crucial for bridges that have undergone natural aging or are subject to high traffic loads, as it allows for early detection of issues and targeted maintenance planning. This helps prevent potential catastrophic incidents and extend the bridge’s service life in accordance with public safety.

Environmental Bridge Monitoring

Environmental monitoring of bridges is a fundamental element of an integrated structural monitoring system. This approach focuses on detecting environmental parameters that can affect the durability and safety of the structure. The main monitored factors include:

• Temperature: Temperature variations cause expansions and contractions in the bridge materials, affecting its stability. Accurate temperature control allows for predicting and mitigating thermal effects on the structure.
• Humidity: High humidity levels can accelerate corrosion processes, especially in steel bridges. Monitoring humidity is essential to prevent material degradation.
• Wind: Dynamic stresses caused by wind can induce vibrations and structural fatigue. Detecting wind speed and direction helps understand and mitigate these effects.
• Precipitation: Rain, snow, and ice can compromise the structure and its components. Monitoring precipitation allows for effectively managing water accumulation and ice formation.
• Corrosion: Environmental factors such as pollution and salinity accelerate corrosive processes. Specific corrosion sensors help identify critical areas and plan maintenance interventions.

The data collected by environmental sensors installed on the bridge are integrated and analyzed together with data from static and dynamic monitoring. This synergy of information provides a comprehensive and detailed view of the structure’s health, allowing for the timely identification of problems caused by environmental factors.

Environmental monitoring is essential for ensuring the safety and durability of bridges, especially in adverse climatic conditions or particularly aggressive environments. When combined with static and dynamic monitoring, environmental monitoring represents an integrated and proactive approach to infrastructure management. This advanced method allows for adopting preventive maintenance strategies, improving safety, and extending the service life of bridges.

Design and Installation of a Monitoring System

Designing and installing a bridge monitoring system requires a thorough analysis of the specific infrastructure needs, the selection of the most suitable monitoring devices and methods, and the definition of a communication network for data transmission. It is also important to plan maintenance and calibration procedures for the devices, as well as to provide training for the personnel involved in managing the system.

What is IoT and How Can It Be Used for Bridge Monitoring

The Internet of Things (IoT) is a set of interconnected devices that communicate with each other over the internet. These devices can include sensors, actuators, and data processing systems. IoT can be used to monitor various parameters of bridges, such as vibrations, deformations, temperature, and traffic, enabling real-time monitoring and more efficient maintenance.

Currently, it is also possible to use BIM IoT platforms to manage IoT devices directly from the BIM model. In practice, data collected by sensors are sent to the application that acquires and displays them in real-time on the 3D BIM model in IFC format.

Enriching the BIM model with information from the IoT ecosystem also facilitates the management of large IoT ecosystems.

IoT for monitoring the health of bridges

IoT Technologies for Bridge Monitoring

Vibration and Deformation Sensors

Vibration and deformation sensors are IoT devices that detect structural variations in bridges, providing valuable information on their integrity. These sensors can identify anomalies and report any issues before they become severe, allowing for timely interventions.

Temperature and Humidity Sensors

Temperature and humidity variations can affect the lifespan of materials used in bridges. IoT sensors monitoring these parameters help identify issues such as corrosion and material wear, facilitating preventive maintenance planning.

Traffic Monitoring Sensors

IoT traffic sensors can detect vehicle flow and weight, providing useful data for traffic management and assessing the impact of traffic on infrastructure. This data can be used to implement measures aimed at reducing the load on bridges, improving their lifespan.

Data Analysis and Alarm Systems for Data Management

Data collected by IoT sensors need to be analyzed and managed to extract useful information. Analysis and alarm systems can process data in real-time and generate notifications in case of anomalies or potentially dangerous situations, allowing for swift and targeted interventions.

Benefits of Bridge Monitoring with IoT

Risk Prevention and Reduction

The use of IoT in bridge monitoring allows for greater risk prevention and better emergency management. Thanks to real-time data collection, it is possible to identify and resolve issues before they become critical, ensuring a higher level of safety.

Maintenance Efficiency

Real-time monitoring of bridges through IoT helps optimize maintenance processes by intervening only when and where necessary. This reduces intervention times and minimizes traffic disruptions.

Cost Reduction

Implementing IoT in monitoring bridge health can lead to a reduction in maintenance costs by enabling the identification and resolution of problems promptly, avoiding more expensive and costly interventions later on.

Challenges in IoT Implementation

Despite the numerous benefits, adopting IoT in bridge monitoring poses significant challenges, such as cybersecurity, data privacy, and the need for initial investments in device installation and integration. However, considering the long-term benefits in terms of safety, efficiency, and cost reduction, experts believe that implementing IoT in infrastructure is a worthwhile and sustainable investment.

The Future of Infrastructure Monitoring with IoT

The future of infrastructure monitoring with IoT is promising, with new technologies and solutions constantly evolving. Artificial intelligence and machine learning could be integrated into monitoring systems to further improve data analysis and issue prediction. Furthermore, the advent of 5G technology could enhance data connectivity and transmission speed, making monitoring even more effective and timely.

To learn more, read also: Bridge construction: 10 stages to manage the entire process