**3. Case Study Example**

#### *3.1. Description of the Case Study Area*

The railway network in Croatia consists of more than 2600 km of lines, with the majority forming parts of European railway transport corridors (Figure 5). Given the general age of the railway infrastructure and deterioration including the impact of war conflicts [39], a number of sections have traffic speed restrictions with maximum speeds of only 20 km/h on some sections.

To validate the categorization procedure proposed in this paper, a case study was chosen which included 181 km of railway embankments in Croatia along 18 different railway lines. For each investigated line, a categorization procedure was conducted. The investigated lines were chosen by railway managers from eight Supervision Centers (SC) of the Croatian Railway Infrastructure: SC Ogulin (three investigated lines), SC Osijek (three investigated lines), SC Pula (one investigated line), SC Rijeka (one investigated line), SC Slavonski Brod (two investigated lines), SC Varaždin (four investigated lines), SC Vinkovci (one investigated line), and SC Zagreb (three investigated lines).

**Figure 5.** Railway network in Croatia, scale 1:6,000,000, from [40].
