## 4 Discussion and Future Research Directions
### Future Research Directions  
* Considering various types of flooding: Further research is required to develop efficient strategies for transportation planning that can mitigate the impact of various types of flooding. With the expectation of more severe and frequent flood events, particularly intense storm surges resulting from coastal floods, it is imperative that future studies focus on identifying effective response strategies to this type of flood. Given the complexity of flood disaster modeling, utilizing the concept of a stochastic disaster scenario derived from historical flood data can be an effective approach for transportation resilience planning. * Applying a broader temporal scale: It must be taken into account that the flood time scale in most of the analyzed floods in previous research ranged from one hour to a whole day. Limited studies have considered the temporal scales of flood analysis compared to the spatial scales. This could be also attributed to the lack of necessary data for estimating the intangible and indirect impacts. Considering the frequent prediction of flood increases in the upcoming years in parallel with the urbanization and transportation network growth, the flood-affected links and the overall resilience of the traffic networks are constantly changing. Therefore, applying temporal resolution in the post-flood analysis ranging from weeks to years may potentially recognize both direct and indirect impacts of flooding on transportation networks. The findings can be used to determine what steps should be taken to improve network resilience and sustainability. * Applying combined methodologies along with the updated data: To achieve precise results in flood modeling and assessing its impacts on transportation, the most crucial requirement is accurate historical data. In local scales, such as in controlled communities, accurate data of many variables, such as precipitation and traffic data could be measured [12]. However, it is worth noting that the reliability of flood maps for  
Figure 7: Data used to parametrize the model in articles. indicating indirect impacts and cascading effects of flooding on transportation systems is subject to significant uncertainties. Population growth and rapid urbanization can lead to changes in land use and landscape alterations that compromise the accuracy of historical flood maps. As a result, flood risk assessments based solely on historical flood maps may not provide a reliable indication of the indirect impacts and cascading effects of flooding on transportation systems. Thus, incorporating updated and reliable data is critical to ensure the accuracy of flood risk assessments, particularly in areas experiencing population growth and urbanization. The use of computational and imaging programs, such as GIS and geospatial technologies, in addition to the available spatial and temporal databases, has advanced flood forecasting and modeling for flood risk assessment [65]. Data, such as precipitation, can be converted into hydrograph for flood estimation using physical methods or mathematical equations. Although researchers frequently used statistical analysis for estimating flood frequency in the past, in more recent studies they usually merge this analysis with other methods using the progress of GIS techniques. This combination leads to the development of combined methodologies that are based on integrating several tools, such as remote sensing and GIS, with several simulations, models, data, statistical analyses, and machine learning methods to assess flood impacts [65]. * Applying a whole system approach: Articles mostly have analyzed the traffic of a specific type of vehicle (passenger vehicles) by partially or fully closing roads, while including different vehicle types, such as public, freight, and passenger, can more accurately assess the increased traffic costs and analyze how they interact and affect each other. In other words, a 'whole system approach' is required.