Reconstruction of the route and characterization of the El Habel tunnel of the Toudja roman aqueduct (Algeria) using 3D laser scanning technology

Nowadays, new data acquisition and representation techniques enable the creation of new fields of intervention and investigation for heritage specialists as well as architectural and archaeology disciplines, whether in conservation, research, or project studies. These innovative digitization techniques are critical for preserving and transmitting our heritage. The Toudja aqueduct, which supplied the Roman city of Saldae, now known as Bejaia, has deteriorated significantly over time. The El Habel tunnel preserves its history and didactic value as a technical and heritage asset, and it deserves further investigation. A 3D lasergrammetry survey method was used to reconstruct the tunnel trajectory in a plane, visualize its internal properties, including excavation error, model its components (shafts 1 and 2), and extract plans and profiles. The findings represent an improvement over previous research using conventional methods. The digitized and processed acquisitions show the tunnel's current route, geolocation, morphological, structural, and dimensional characteristics of its gallery, as well as the state of its surfaces. This study aims to incorporate this information into cultural and archaeological heritage maps to ensure its preservation. Furthermore, detecting visible disorders on the inner walls will enable more thorough examinations for potential tunnel rehabilitation.