For culverts retaining water or exposed to aggressive environments, crack widths are limited (e.g., 0.2mm to 0.3mm).
Walls are subjected to combined axial load (from top slab and earth fill) and bending moment (from earth pressure). This is a Beam-Column check. box culvert design calculations pdf
The walls act as retaining structures.
A proper box culvert design calculations PDF will systematically address all three domains. For culverts retaining water or exposed to aggressive