How to design box culvert?

To design a box culvert, the following steps should be followed:
1. Establishing the flow parameters, such as: hydraulic head, discharge, and watercourse friction.
2. Selecting the size and shape of the culvert based on these parameters and local regulations.
3. Determining the appropriate material for the box culvert, such as: concrete, metal, or plastic.
4. Computing the necessary structural components, such as: walls, bedding, inverts, etc.
5. Designing the appropriate constriction and inlet control features to ensure proper flow of the watercourse.
6. Calculating the necessary drainage system and other related components required.
7. Finally, constructing, testing and certifying the completed box culvert.