Culverts are vital components of earth embankments, allowing watercourses like streams and nallas to flow without disrupting the natural water movement. They play a key role in managing floodwaters on either side of the embankment, helping to reduce water levels and mitigate flood risks. Culverts are available in various shapes, including arch, slab, and box configurations, and can be constructed from materials such as masonry or reinforced concrete. Embedded within earth embankments, culverts are subjected to traffic loads similar to those on the road and must be designed to accommodate these loads. This paper focuses on the structural design and parametric analysis of RCC box culverts, with and without cushion, using STAAD-Pro. Design parameters, including size, invert level, and layout, are determined based on hydraulic requirements and site-specific conditions, with the cushion varying according to the road profile at the culvert location. The study examines various load cases, such as empty box, full box, and surcharge loads, and considers factors like effective width, load dispersion through fill, impact factor, and earth pressure coefficient, in accordance with IRC codes. It offers a comprehensive discussion on code provisions, design considerations, and justifications for the structural design of RCC box culverts, ensuring they can withstand maximum bending moments and shear forces.