How is "drainage" defined in highway construction?

In highway construction, "drainage" refers to the process of managing water to prevent erosion and flooding. This is crucial for maintaining the integrity of the roadway and ensuring safety for vehicles and pedestrians. Effective drainage systems are designed to channel water away from the road surface, which helps to reduce the risk of water pooling, which can lead to erosion of road materials and potential structural failure. Furthermore, a proper drainage system minimizes the likelihood of flooding, which can obstruct traffic and cause hazardous driving conditions. This management of water is performed through various techniques and infrastructure, such as culverts, ditches, and stormwater systems, all aimed at controlling the flow of water in relation to roadways. Proper drainage is integral to highway design and maintenance, making it a key aspect of construction and long-term infrastructure management.