Lupoglav – Raša Study
The existing L213 Lupoglav – Raša railway line extends approximately 53 km and is a significant infrastructural connection in the region. Built in 1948 and opened for traffic in 1952, the railway was closed on 26 December 2008, due to geotechnical issues, primarily the activation of a landslide known as the “drunk railway”.
The railway route passes through several administrative units, including the municipalities of Lupoglav, Kršan, Pićan, Sveta Nedelja, and Raša. Along the route are four official railway locations: Raša station, Lupoglav marshaling yard, and Učka and Kršan, two freight terminals.
The terrain conditions along the railway are highly diverse. The initial section, from Lupoglav to Kršan, extends 32,3 km through a hilly area composed of flysch and limestone, featuring high and steep embankments, cuts, and long culverts for torrential watercourses. This section includes four active landslides along with the mentioned critical area. The remaining 20,7 km of the railway crosses the lower terrain with gentler cuts and embankments.
Our task was to develop the geotechnical part of the feasibility study to provide a detailed analysis of the geological, engineering geological, and geotechnical characteristics of the terrain. The study assessed the suitability of the location for railway remediation, its impact on the surrounding structures, as well as the identification of potential geotechnical risks affecting infrastructure stability and future traffic safety.
The geotechnical study proposed two conceptual solutions for railway remediation. Variant 1 involves remediation only of critical sections, while Variant 2 includes complete railway reconstruction. The variants are described in more detail below.
Varijanta 1 – remediation critical sections
Variant 1 primarily focuses on the remediation and reconstruction of only those sections identified as critical. This includes interventions on structural and geotechnical elements such as landslides, embankments, cuts, bridges, tunnels, culverts, hydrotechnical structures, and crossings. Additionally, this variant includes a complete renewal of the railway superstructure and modernization of the substructure equipment.
In this approach, slope stabilization along the cuts and excavations does not involve additional excavation into existing slopes. The slope protection system is standardized and identical in both variants. A field survey was conducted to assess the overall condition and classify the materials, with particular attention to rock cuts and excavations, determining the average Geological Strength Index (GSI).
For slopes lower than 2,50 m, no additional treatment will be required unless instabilities are detected that could endanger the railway line. Variant 1 also includes the remediation of four landslides along the route and the widening of embankments that do not meet the required geometric standards for the railway ballast prism.
Variant 2 – complete railway reconstruction
Variant 2 includes all measures outlined in Variant 1 while additionally addressing non-critical embankment and slope instabilities to ensure the long-term stability of the route.
This variant provides rock slopes protection, regardless of their height. If instabilities are detected on slopes lower than 2,50 m, which could cause a risk to railway safety, re-profiling to an appropriate slope angle will be necessary.
Moreover, Variant 2 includes a comprehensive reconstruction of the railway substructure. Instead of focusing only on critical points, as in Variant 1, this variant proposes the remediation of all embankments along the railway route that fail to meet the geometric and functional requirements of the track bed, including drainage, width, and other technical parameters.
Conclusion
Through the geotechnical study, we analyzed the geological, engineering-geological, and geotechnical characteristics of the terrain, collecting key data for assessing geotechnical risks and proposing optimal technical solutions for the remediation of the L213 railway line. Additionally, the report provided a preliminary estimate of the necessary financial investments.
A more detailed analysis will be possible only after geotechnical investigation and testing, which will provide precise information on the composition and mechanical properties of the soil. These investigations are planned for the next project phase and have been outlined according to the variant solutions proposed in the geotechnical study.
