About

Urban tracks are often embedded in roadways, with the track structure covered up to the top of the rail. In such tracks, visual inspection of all components is impossible, and effective drainage is difficult to ensure, resulting in water retention within the track structure. This leads to aggressive corrosion processes that cannot be detected visually. The problem has become particularly pronounced in recent years, with increasingly intense rainfall often causing flooding in urban areas.

Previous research has shown that, under aggressive corrosive conditions such as those frequently encountered within track structures, corrosion can reduce the service life of track components to just a few years and compromise traffic safety. Since this type of deterioration cannot be observed in embedded tracks, the aim of this project is to develop a method for identifying areas of increased corrosion risk using non-destructive testing methods—ground penetrating radar (GPR) and infrared thermography.

The research methodology combines ground penetrating radar (GPR) surveys and infrared (IR) imaging to identify zones of elevated moisture within embedded track structures, which will serve as indicators of increased corrosion risk. This approach will enable fully non-destructive, rapid and efficient testing, improving rail infrastructure inspection practices and supporting more effective maintenance and targeted corrosion protection.

The project activities are organised into four work packages.

The main objective of the project is to develop a non-destructive method for detecting zones of increased risk of corrosion and stray current occurrence in embedded urban track structures, enabling appropriate protective measures and maintenance strategies to be planned in a timely manner.

To achieve the main objective, the following additional objectives have been defined:

1. Conducting tests on a track specimen

   • Collecting data using ground penetrating radar (GPR) and an infrared (IR) camera.

   • Measuring moisture levels, corrosion rates and electrical resistance within the track specimen.

2. Analysing the collected data

   • Correlating the moisture levels recorded within the track specimen with data obtained using GPR and the IR camera.

   • Analysing the data recorded within the track specimen to establish relationships between the measured parameters, particularly the influence of moisture levels on corrosion rates and electrical resistance values. Electrical resistance will serve as an indicator of stray current occurrence in the track.

3. Testing the developed method for detecting moisture within track structures on several tramway track sections in the City of Zagreb

   • Conducting measurements using GPR and an IR camera.

   • Given the sensitivity of IR imaging data to environmental conditions, unmanned aerial vehicles equipped with IR cameras are planned to be used to minimise the survey duration and enable data collection while meteorological conditions remain unchanged.

4. Analysing the characteristics of locations with elevated moisture levels in track infrastructure

   • Examining the type of track structure, traffic loading, drainage arrangements and type of road pavement structure.

   • Identifying the parameters that determine where water accumulates within the track structure.