For the reconstruction of the railway line between Zaprešić and Zabok stations, geotechnical investigations were conducted, and main geotechnical designs were prepared for the track alignment, bridge foundations, and excavation pit protection for the construction of underpasses at the stations.
The R201 Zaprešić – Čakovec railway line is a single-track, non-electrified line with a construction length of 100.554 km, intended for mixed rail traffic. The Zaprešić – Zabok section, with an actual length of 23,860 m, is currently the busiest part of the R201 line.
The purpose of the reconstruction and electrification is to increase speeds, reduce travel times, and standardize the line’s technical and operational characteristics (permitted infrastructure speeds of 120–160 km/h, with shorter sections limited to 80–100 km/h; maximum permitted railway vehicle mass of 20–22.5 t/axle and 8.0 t/m; electrification using a 25 kV 50 Hz single-phase AC system; platforms 55 cm high and 160–200 m long).
The reconstruction also encompasses the Zaprešić – Zabok section, which includes the stations of Zaprešić, Novi Dvori, Luka, Veliko Trgovišće, and Zabok. Reconstruction and electrification of the Zaprešić – Zabok railway section.
The railway section from Zaprešić (exclusive) to Zabok (inclusive) is divided into four subsections:
Sub-section I: Zaprešić station (exclusive) (km 0+403.12 (PS27)) – Novi Dvori station (inclusive) (km 4+691.53 (PS9))
Sub-section II: Novi Dvori station (exclusive) (km 4+691.53 (PS9)) – Luka station (inclusive) (km 13+257.80 (PS6))
Sub-section III: Luka station (exclusive) (km 13+257.80 (PS6)) – Veliko Trgovišće station (inclusive) (km 18+620.00 (PS5))
Sub-section IV: Veliko Trgovišće station (exclusive) (km 18+620.00 (PS5)) – Zabok station (inclusive) (km approx. 24+250.00)
The subgrade soil was tested in situ using geotechnical exploratory drilling, a static penetration probe (CPTU), and ground-penetrating radar. Testing on soil samples was conducted in a geotechnical laboratory. The subgrade soil in the project area is horizontally stratified and consists of a surface humus layer up to 50 cm thick, a clay layer 2 to 2.5 meters thick, and layers of sand and gravel. Based on an analysis of subgrade test results from trial pits—which determined the thickness of the ballast prism and sub-ballast layer, as well as the type, condition, and compaction of the subsoil—sections were identified where the compaction of the formation level was unsatisfactory. Analysis of geophysical survey results obtained via the GPR (Ground Penetrating Radar) method along the railway alignment identified ballast pockets and areas of mud pumping at the formation level.
Geotechnical designs for the railway alignment determined the specifications for the substructure, the requirements for subsoil reinforcement, and the conditions for widening the existing embankment. Techniques employed included subsoil improvement using gravel piles, reinforcement of the embankment and formation level with geotextiles and geogrids, and material replacement.
The geotechnical designs for the bridges specified the dimensions for reinforced concrete piles and the shoring systems for the foundation excavation pits.
The geotechnical designs for the underpasses determined the excavation support systems required for their construction at the stations. Construction methods were established to align with railway traffic regulations during the works, and all excavation support elements were sized accordingly.
For the reconstruction of the railway line between Zaprešić and Zabok stations, geotechnical investigations were conducted, and comprehensive geotechnical designs were prepared covering the route alignment, bridge foundations, and excavation support systems for the station underpasses.
The R201 Zaprešić – Čakovec railway line is a single-track, non-electrified line with a construction length of 100.554 km, intended for mixed railway traffic. The Zaprešić – Zabok section, with an actual length of 23.860 km, is currently the busiest part of the R201 line.
The purpose of the reconstruction and electrification is to increase speeds, reduce travel times, and standardize the line’s technical and operational characteristics (permitted infrastructure speeds of 120–160 km/h, with short sections limited to 80–100 km/h; maximum permissible railway vehicle mass of 20–22.5 t/axle and 8.0 t/m; electrification via a 25 kV 50 Hz single-phase AC system; and platforms 55 cm high and 160–200 m long). The reconstruction also covers the Zaprešić – Zabok railway section, which includes the Zaprešić, Novi Dvori, Luka, Veliko Trgovišće, and Zabok stations. Reconstruction and electrification of the Zaprešić – Zabok railway section. The Zaprešić (exclusive) – Zabok (inclusive) railway section is divided into four subsections:
- Sub-section I: Zaprešić station (exclusive) (km 0+403.12 (PS27)) – Novi Dvori station (inclusive) (km 4+691.53 (PS9))
- Sub-section II: Novi Dvori station (exclusive) (km 4+691.53 (PS9)) – Luka station (inclusive) (km 13+257.80 (PS6))
- Sub-section III: Luka station (exclusive) (km 13+257.80 (PS6)) – Veliko Trgovišće station (inclusive) (km 18+620.00 (PS5))
- Sub-section IV: Veliko Trgovišće station (exclusive) (km 18+620.00 (PS5)) – Zabok station (inclusive) (km approx. 24+250.00)
The subgrade soil was tested in situ using geotechnical exploratory drilling, a static penetration probe (CPTU), and ground-penetrating radar (GPR). Testing on soil samples was conducted in a geotechnical laboratory. The subgrade soil in the project area is horizontally stratified, consisting of a surface humus layer up to 50 cm thick, a clay layer 2 to 2.5 meters thick, and layers of sand and gravel. Based on an analysis of subgrade testing results from test pits—which determined the thickness of the ballast prism and sub-ballast layer, as well as the type, condition, and compaction of the subsoil—sections were identified where the compaction of the formation level was unsatisfactory. Analysis of geophysical survey results obtained via GPR (Ground Penetrating Radar) along the railway alignment identified ballast pockets and areas of mud pumping at the formation level.
Geotechnical designs for the railway alignment determined the dimensions of the substructure, the requirements for subsoil reinforcement, and the conditions for widening the existing embankment. Soil improvement techniques using gravel piles, embankment and formation reinforcement with geotextiles and geogrids, and material replacement were employed.
Geotechnical designs for bridges specified the dimensions of reinforced concrete piles and the protection measures for foundation excavation pits.
Geotechnical designs for underpasses determined the excavation protection measures required for constructing underpasses at railway stations. Construction methods were established to align with railway traffic regulations during the works, and all excavation protection elements were dimensioned accordingly.