PSI - Issue 84

Michela Briganti Botta et al. / Procedia Structural Integrity 84 (2026) 344–351

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The viaduct has a width of approximately 8.90 m, originally sufficient for double-track operation. Today, however, this width is inadequate to perform routine inspection and maintenance operations safely. Moreover, the massive seaward-side masonry parapet reduces the usable platform width to about 7.9 m (current railway deck standards exceed 12 m). Thus, RFI requires the installation of steel walkways to allow inspection and maintenance activities while respecting track safety clearances. • Origin and Historical Background The structure is located along the Postojna–Trieste section of the Southern Railway (the “Carso Railway”), completed in 1857 and close to the Aurisina junction, from where the line to Venice departs—opened on 1 October 1860. The junction station (then called Nabresina, the name of the settlement it served) played a significant sorting role for passengers travelling between the Kingdom of Italy and the Austro-Hungarian Empire. Here, coaches arriving from Vienna were separated: those bound for Trieste were detached from those continuing toward Venice.

This viaduct, like others of the era, was built following the Empire’s typical railway bridge construction standards. With its 42 arches—at the time the second-longest in Europe—it has considerable historical significance, to the extent that it appears on the coat of arms of the municipality of Aurisina. While the context has changed over the years, the viaduct did not sustain major damage during the World Wars and remains fully functional today, with the only limitation of insufficient width for standard inspection/maintenance operations without significantly disrupting service. The proposed pedestrian walkways aim to minimize operational impacts while preserving the structure’s historical value.

Fig. 4. Coat of arms of the municipality of Aurisina

2.3. Sablice • Overview and Characteristics

The intervention concerns a masonry bridge along the Venice–Trieste railway line, between Monfalcone station and the Aurisina Junction (approx. km 120). This section of the line is the result of various projects developed for different political and strategic purposes and was built by the Austro-Hungarian Empire in the mid-1800s, opening to service in October 1860. Here the line coincides with the Udine–Trieste railway, making the structure an important node for connections to Trieste and to Austria and Slovenia. The viaduct, built with masonry arches, is 110 m long (from abutment to abutment), divided into six spans with an 18-m spacing. Dating from 1850–1860, it features construction techniques typical of the period—squared limestone blocks with architectural projections at the arch’s springers and parapet bases.

Fig. 5. Sablice – Valley-side view 1