Answer:

Introduction:
When planning the construction of a highway, it is important to consider the potential risks and challenges posed by natural disasters such as flooding. In areas where there is a passage of flood water, the highway should be built on an embankment. This choice is made to ensure the safety and functionality of the road during flood events. Let's explore the reasons behind this decision.

Reasons for building the highway on an embankment:

1. Flood protection: An embankment acts as a barrier between the highway and floodwaters, protecting the road from damage caused by inundation. It prevents floodwater from directly reaching the road, reducing the risk of erosion, subsidence, and structural damage.

2. Elevation: By constructing the highway on an embankment, its elevation is raised above the floodplain level. This elevation helps to keep the road surface above the water level during flood events, ensuring that it remains passable and functional.

3. Drainage: Embankments are designed to include proper drainage systems, such as culverts or ditches, which allow water to flow away from the road efficiently. These drainage measures help to prevent waterlogging or ponding on the highway, maintaining its usability even during heavy rainfall or flooding.

4. Stability: Embankments are engineered to provide stability and strength to the highway. They are constructed using suitable materials, compacted in layers to withstand the weight of the road and the forces exerted by floodwaters. This ensures that the highway remains intact and safe for vehicles to travel on, even in challenging flood conditions.

5. Cost-effectiveness: Building a highway on an embankment is often a more cost-effective solution compared to other alternatives such as constructing subways, overpasses, or underpasses. Embankments require less complex construction methods and materials, resulting in lower construction costs and reduced maintenance expenses.

Conclusion:
Constructing a highway on an embankment in areas prone to flooding is the most suitable option due to its flood protection capabilities, elevation advantages, efficient drainage systems, stability, and cost-effectiveness. By considering these factors, a properly designed and constructed embankment can ensure the safety, functionality, and longevity of the highway in flood-prone regions.