Laser-based mobile railway measurement systems: an overview

The railway infrastructure is essential for meeting the transportation needs of both freight and passengers. The increasing traffic load, heavier axles and vehicles, higher speeds, and more frequent extreme weather events place continuous and growing strain on the infrastructure. Given its vital role in transporting people and goods, it is under constant monitoring to assess its condition. This monitoring is crucial for the effective planning of maintenance activities and ensuring safe, reliable operations. Furthermore, as demands on infrastructure grow and technologies evolve, maintaining and upgrading the systems becomes increasingly complex. To facilitate this, various measurement systems have been developed, which must be precise, fast, and durable under challenging conditions. Whether used on mobile platforms or installed stationary, these systems must perform well across a range of temperatures, harsh environmental factors, and different degrees of reflectivity of the object surfaces. Despite these challenges, railway operators require accurate measurement data, high data density even at high speeds, and clear, user-friendly results. Light-based measurement techniques such as photogrammetry and laser scanning are widely used to capture the railway infrastructure - such as overhead line systems, clearance profiles, and track layouts - with great precision. A new approach utilizing active 3D multispectral data (LiDAR) is being explored to evaluate the stability of trees near infrastructure assets. This method has the potential to provide valuable data for maintaining the safety and reliability of the railway network. This article provides an overview of both traditional and modern laser-based data collection methods, as well as the use of artificial intelligence for data analysis, highlighting their respective benefits and drawbacks.