Specifications include, but are not limited to: Reinforced Concrete Box Culverts (RCBCs) are the preferred structure when practical. This is primarily due to RCBCs being typically less expensive than a bridge, less complicated to design, and easier to construct and maintain. RCBCs are either cast-in-place or precast and both have circumstances in which their construction type is optimum. However, there are many circumstances when choosing the best RCBC option is not clear. Factors such as site conditions, long-term performance, costs, and speed of construction can impact the final selection. The normal practice for SDDOT is to provide plans for cast-in-place RCBC installations and include a precast option when certain design criteria are met. Guidelines in the SDDOT Bridge Design Manual specify that if the proposed RCBC has a skew of more than 10 degrees, flared wing walls, slope-tapered aprons, side-tapered inlets, or water control structures, a precast option is not offered. Refining these guidelines by presenting the optimum RCBC construction type, rather than presenting options, would reduce selection and design time. Also, with the continual advancements in precast manufacturing processes, design software, and materials science, the development of refined guidelines may reveal innovative options addressing previous limitations regarding the use of precast RCBC.
