What is an important factor in the design of highway drainage systems?

An important factor in the design of highway drainage systems is ensuring adequate slope and capacity to facilitate proper water drainage. This aspect is crucial because the primary function of a drainage system is to manage surface water runoff effectively. Proper slope ensures that water flows away from the roadway and prevents pooling, which can lead to hazardous driving conditions and potential damage to the road structure.

Additionally, the design must account for the volume of water that the drainage system may need to handle during heavy rain or storms. This involves calculating the drainage capacity, which must be sufficient to manage the expected water flow without overflow. By prioritizing slope and capacity, engineers can significantly reduce the risk of flooding and improve the overall safety and longevity of the roadway.