Hancock was involved in developing the initial design of precast concrete Box Culverts for use in the State of Minnesota and manufactured the first concrete box installed in Minnesota in 1974. Hancock was also instrumental in the development of the skewed box end sections, which allows the end sections to blend into the fill slope on skewed installations.

With superior strength and durability, precast Box Culverts provide a versatile and economical alternative to the cast-in-place concrete bridge. They are available in a multitude of sizes and can be installed in single or multi-line configurations. This gives the designer an extremely large range of options from which to choose. Compared to cast-in-place culverts or bridges, precast Box Culverts are much quicker to install usually requiring no more than 3 or 4 days from start to finish.