## 3 Results
### Research Questions' Answers
#### 3.2.6. RQ5  
What Transportation Modes Are Evaluated in the Indirect Impact Analysis of Floods?  
Although this SLR covers all types of transportation vehicles, almost all of the articles examined in the review focused solely on road networks. Only two articles, authored by [PERSON] et al. [17] and [PERSON] et al. [53], discussed disruptions in rail transportation. Two other articles included considerations of pedestrian and waterway disruptions, in addition to road networks [36; 54]. Figure 6 depicts a comparison of the frequency of articles analyzed in the current SLR, based on their scale and the analyzed modes of transportation. The analysis reveals that road networks have garnered more attention than any other type of transportation network at all spatial scales. Rail networks, on the other hand, have only been analyzed in regional scales, while multimodal networks have received the least attention at all spatial scales.  
As seen in Figure 6, the articles primarily concentrated on a single mode of transportation when it comes to flooding, with a stronger emphasis on road networks, highlighting their significance in flood situations. The majority of articles focused on the movements of road vehicles, without distinguishing between different categories of vehicles. Nonetheless, a small number of articles did concentrate on specific types of vehicles. For instance, three articles examined emergency service vehicles, such as ambulances and fire trucks [21; 49; 50], while one article examined private and public road vehicles separately [36].  
The limited number of articles focusing on rail networks, or public transportation more broadly, may be due to the absence of critical databases necessary to obtain accurate results, such as traffic control systems, train movement conditions, and passenger behavior during a disruption. However, flooding on railway networks can significantly impact commuter travel and have severe economic consequences for a country, as many businesses rely on rail transportation to move goods and cargo from one location to another.  
Conversely, researchers have increasingly turned their attention to disruptions in multimodal transportation networks in recent years, as evidenced by the work of [PERSON] et al. [36] and [PERSON] et al. [54]. While these efforts have made significant contributions to the management and mitigation of natural hazards during and after floods, it is believed that further research is needed to assess the impacts of floods on multimodal transportation networks. Although general multimodal traffic is projected to increase in the coming years [12], research into the effects of flooding on multimodal traffic flow and economic analysis remain limited.  
It is worth noting that this systematic literature review (SLR) only concentrates on the indirect effects of floods on transportation. However, if a broader range of disasters,  
Figure 6: Frequency of articles evaluating indirect impacts of floods on different transportation modes.  
such as the spread of epidemics [55], or a wider context of analysis, such as network resilience [56; 57], is considered, it will be observed that more modes of transportation are included.