PUTTING THREE-SIDED STRUCTURES IN CONTEXT

Context sensitive design (CSD) is a collaborative approach where scenic, historic, aesthetic, environmental resources are preserved, and safety and mobility are maintained, in the development of a transportation facility or structure. This article describes two different bridge projects where CSD was employed through the use of precast three-sided structures in replacing deficient bridges. The Coton Bridge, a 446-ft-long bridge commemorating an 18th century local plantation, involved the placement of precast three-sided arch elements on cast-in-place piers and abutments. The approach reduced construction time, minimized stream disruption, and led to a bridge design that featured an arch shape similar to other historical structures in the area. The second project, which also involved using precast, three-sided bridge elements, featured the reconstruction of the historic Animal Bridge at Jackson Park in Chicago. Numerous design challenges faced the project, such as the requirements that the bridge needed to be widened, realigned, and moved 20 feet north from its original location to improve local traffic and accommodate safer traffic lanes and pathways for pedestrians and bicyclists. The precast pieces were produced offsite, while the refurbished facade pieces were placed after the placement of the bridge units. Both projects were successful in satisfying the six goals of CSD.