With over 70,000 bridges in Australia and New Zealand, drones and sensors enhance safety during inspections but cannot fully replace the hands-on assessments needed to confirm structural integrity.

Australia alone racks up a hefty $100 million annual bill for bridge maintenance, with the cost of replacing faulty bridges estimated in the billions. Bridge maintenance itself needs maintenance.

Austroads has introduced new guidelines to improve bridge management and encourage technology integration with expert engineering. This balanced, evidence-based approach, aligned with international standards, ensures bridges remain safe, efficient, and well-maintained.

Types of inspections

Bridges require a variety of inspections, most of which are visual, to ensure their safety and structural integrity:

• Routine inspections: monitor overall condition and changes.
• Fracture-critical inspections: focus on components where failure could lead to collapse.
• Underwater inspections: conducted by specialised divers or Remotely Operated Vehicles (ROVs) to assess submerged structures.
• Damage inspections: evaluate the cause and extent of suspected issues.
• Acoustic inspections: detect material separations through sound changes.
• Thermal inspections: use infrared data to spot temperature fluctuations that signal degradation.
• Ground Penetrating Radar (GPR): uses electromagnetic radiation to visualise subsurface conditions.

Global comparisons

The UK manages around 100,000 highway bridges, from ancient masonry arches to modern structures. Surprisingly, many twentieth-century bridges, built for a 120-year lifespan, already show signs of wear after just 50 years due to design flaws and poor construction. A recent study found that 2,928 of the 73,208 road bridges in England, Scotland, and Wales are substandard – about 4% of the total.

With tight budgets and a shortage of experienced bridge managers, ensuring effective maintenance is an ongoing challenge.

Highway Bridge Management is a UK guide compiled by industry veterans that provides practical advice on inspections, assessments, and risk management, helping to prepare the next generation of bridge managers.

The US also grapples with a bridge crisis from ageing infrastructure and insufficient maintenance resources, highlighting the need for improved management strategies.

In the US, over 617,000 bridges face a similar crisis, with 42% at least 50 years old. A staggering 7.5%, or 46,154 bridges, are considered structurally deficient, underscoring the urgent need for better management strategies.

Assessing the current state of Australia’s bridges is difficult, as State road authorities release limited information on bridge conditions or maintenance budgets. In addition, legal weight limits for trucks have risen by about 10% each decade since the 1950s.

Computer vision

Computer Vision (CV) is machine learning that allows computers and systems to comprehend and interpret visual information as humans do. For bridge inspections, CV faces challenges like limited open-source datasets, sensitivity to hardware and environment, and computational limits for real-time defect detection.

While robots and sensors exist for surface inspections, more cost-effective solutions are needed. Vibration and displacement measurements lack accuracy, and vehicle monitoring covers single parameters. Future systems must integrate bridge and vehicle monitoring for better structural health management.

Tech trends in bridge management

Innovative technologies are revolutionising bridge management, enhancing safety, boosting efficiency, and promoting sustainable infrastructure maintenance.

Bridge Management Systems (BMSs) offer cutting-edge solutions, utilising data, sensors, and advanced modelling to optimise repairs and predict deterioration. These systems empower bridge owners to prioritise maintenance, assess vulnerability to extreme events, and accurately forecast costs, ensuring long-term safety and efficiency.

By increasing automation and innovative materials, like non-corroding reinforcement and fibre-reinforced composites, we can facilitate proactive, cost-effective maintenance that extends bridge lifespans while minimising disruption.

Drones

Upfront costs are offset by long-term savings as drones reduce the need for manual labour and traditional equipment. They can easily access hard-to-reach or hazardous areas, capture high-resolution data without traffic disruption, and generate real-time imagery and 3D models to assess deterioration patterns, enhancing safety and efficiency. By cutting time and costs, drones streamline inspection and produce detailed reports for better project management.

Despite their benefits, drones have limitations, including weather sensitivity, limited battery life, and the need for skilled operators. However, they’re proving invaluable for improving bridge safety and longevity. For instance, Transport for NSW has been trialling AI-equipped drones to enhance inspections on major infrastructure like the Sydney Harbour Bridge.

Sensors and IoT

Sensors are game-changers for tracking strain, corrosion, vibration, and temperature changes in real-time. Constant monitoring allows engineers to catch issues early and plan proactive maintenance to prevent costly structural failures. The data gathered provides valuable insights into a long-term bridge performance, making future upkeep more predictable.

However, while sensors are becoming smaller, cheaper, and more reliable, installing them can still be challenging, and regular maintenance adds to costs. Interpreting data is complex, and false positives can complicate identifying real issues, so using sensors alongside traditional inspections is crucial.

IoT integration with BIM models is another advancement that allows remote monitoring through digital twins. There are hurdles like cybersecurity risks, data privacy, and high initial costs, but the long-term safety, efficiency, and cost benefits make IoT a smart investment for bridge management.

Digital Twin

This tech is revolutionising bridge inspections by making structural monitoring safer and more efficient. Agencies like the Minnesota Department of Transportation (MnDOT) use drones and advanced software to create dynamic digital models that track changes over time.

By integrating data from drones, photogrammetry, and sensors, these models provide a comprehensive view of bridge health, reducing the need for frequent on-site visits. While emerging, digital twins are already boosting safety, cutting costs, and enhancing decision-making while paving the way for greater adoption of augmented reality and remote collaboration in bridge management.

Laser scanning

Three-dimensional (3D) laser scanning is a non-contact tool that quickly collects surface topography data, providing precise x, y, and z coordinates with attributes like laser intensity. These systems are widely used in building maintenance and categorised based on location, such as aerial, mobile, or terrestrial.

Terrestrial laser scanning (TLS) is gaining popularity for inspection tasks due to its rapid speed, submillimeter accuracy, and cost-effectiveness compared to traditional methods. While extensive research on TLS exists, little review exists on its application in bridge engineering, inspection, and maintenance.

3D modelling

Turning raw topographic point cloud data into usable 3D models for bridge engineering is complex, requiring precision and reliable data. Scanning errors and the intricate geometry of bridges make accurate data collection challenging.

Engineers are refining scanning techniques and using advanced filters to clean and organise data. Segmentation methods help transform point clouds into geometric shapes, forming the foundation for detailed 3D CAD models.

These models, created through preprocessing and segmentation, enable better assessment, maintenance, and long-term management of bridge structures.

Complementary approaches

The collapse of the Ponte Morandi in Genoa highlights the critical need to advance bridge maintenance strategies. Regular inspections by qualified engineers, supported by drone surveys, structural health monitoring, and predictive analytics, help overcome challenges like limited funding and ageing infrastructure.

Combining traditional methods with data-driven decision-making enables managers to prioritise repairs and implement proactive strategies. Embracing innovative repair techniques and sustainable practices extends bridge lifespan and reduces environmental impact. A balanced approach that blends hands-on expertise with modern technology is essential for ensuring long-term bridge safety and functionality.

Future-proof bridge maintenance

Emerging technologies offer valuable tools for bridge inspections but are not an isolated solution. A balanced approach combining traditional physical inspections with the latest technological advancements is essential to ensure the safety and integrity of our bridges. To see how we integrate these practices into our work – check out our bridge projects. For expert assistance – chat with our team.