Advantages of low-cost LiDAR sensors in surveying underground utility networks

Abstract

Accurate knowledge of underground utility networks’ placement facilitates various tasks, such as urban development. The most accurate data can be acquired via geodetic surveys using total stations during construction while the trench has yet to be backfilled. However, the period between networks’ instalment and trench backfilling is often short, meaning that surveyors may arrive at construction sites after backfilling, making geodetic surveys impossible. A solution to this problem could be for contractors to measure the networks themselves right after the installation has been finalised. Accordingly, this study proposes an alternative surveying approach to conventional geodetic surveys. The recent emergence of low-cost LiDAR sensors provides novel data collection possibilities, making point cloud surveys accessible to many new users like construction contractors; this study evaluates the suitability of an Apple LiDAR sensor. In addition to a controlled office experiment for apprising different surveying approaches, surveys were conducted at three construction sites. Accuracy estimates generally in the range of 2…5 cm were obtained. Furthermore, the outer diameters of over 200 mm pipes and slopes of gravity flow pipelines could also be determined relatively reliably. Compared to conventional total station surveys or terrestrial laser scanning, which is employed for validation, the low-cost LiDAR surveys are also significantly faster, taking only a few minutes when utility networks span up to 100 m2. It is concluded that Apple LiDAR sensors could mitigate problems associated with fast-paced construction schedules that typically hinder underground utility networks’ surveys by allowing quick and operational data collection before trench backfilling. Practical tests demonstrate that contractors can conduct such surveys independently after training.