Mapping fiber optic cables with GPR

Summary

Ground Penetrating Radar (GPR) was used to locate and identify fiber optic cables installed in a road. Pre-excavation studies like this are important to avoid damages in critical infrastructure and prevent accidents on site.

PROJECT

Method: GPR
Solution: MALÅ Easy Locator Core
Measurement: Time window 46 ns. Trace interval 2.5 cm
Software for processing and interpretation: MALÅ Vision Web

Challenge

The European Commission has established standards requiring all European households to have a minimum internet connection speed of 100 MB/s by 2025. As part of this initiative, the rollout and installation of fiber optic networks have been designated as high priority. Installing fiber optics involves excavating congested subsurface areas with safety and efficiency considerations. Additionally, previously installed fiber optic cables need to be identified and, in some cases, replaced with new ones.

This urgent requirement has led to numerous accidents across Europe, resulting in rising associated costs. Ground Penetrating Radar (GPR) has been employed in the past to locate fiber optics. However, due to their small size and depth, it has been challenging for GPR to accurately detect the cables and for operators to understand the nature of the target.

Advancements in GPR technology, along with the installation of fiber optics in ducts, have made it easier to locate and map fiber optic networks today.

A common way to map utilities is to work in parallel profiles. The separation depends on the geological surroundings and the size of the utility. It can be wider if you are mapping larger utilities in homogenous ground and denser if looking for smaller and several utilities. A suitable spacing is often 0.5 or 1 meter

Solution

Fiber optic cable mapping often requires working on streets, which may involve navigating pavements, parked cars, confined spaces, and other obstacles. The MALÅ Easy Locator Core solution is a small, lightweight GPR equipment developed for utility mapping. The MALÅ Easy Locator Core provides real-time interpretation support through MALÅ AI, wireless data collection using mobile devices, cloud storage, post-processing, and on-site reporting using MALÅ Vision.

MALÅ Easy Locator Core can be positioned with both internal or external GNSS, and if needed, also run without any positioning, e.g., along marked lines.

MALÅ Easy Locator Core looking for fiber optics. Data is directly displayed, so the system can efficiently also be used for direct marking.

Results & Conclusions

Data was collected in single 2D lines with a spacing of 1 meter. The maximum investigation depth was set to 2 meters, the most common depth range for fiber optics.

During data collection with MALÅ Controller App, gain and other filters can be applied for high visibility already in the field. Data was flawlessly exported to MALÅ Vision, the cloud-based postprocessing software, for filtering, interpretation of objects, and export to a suitable format, as e.g., dxf.

The data revealed fiber optic ducts, telecommunication cables and water pipes all within short distance.

The fiber optic duct is clearly seen in the middle of the resulting radargram, marked in yellow

A water pipe is marked in red, and a telecommunication set of cables in yellow