Improving Standard Bridges with Attention to Cast-in-Place Substructure

This paper focuses on improving the efficiency and aesthetics of standard highway bridges with attention to cast-in-place substructure design. Standard short- and moderate-span bridges are predominantly functional and nondescript. Recent developments in superstructure design have led to improved efficiency of construction and material use, with a resulting slender, attractive appearance. However, typical substructure design remains a component where creativity can be played out for considerable improvements to the overall bridge appearance. A review of current cast-in-place substructure systems is presented including individual, wall, hammerhead, and multicolumn bents. Design recommendations for improving overall bridge appearance and the efficiency of the substructure are presented. Attention is given to integrating aesthetics with material and construction efficiency and with economic considerations. Recommendations include addressing structural expression, visibility through the bridge, shaping of the substructure, integration of substructure and superstructure, and enhancing substructure form with nonstructural details. Issues of coherence for large-scale projects and suggestions for standardization also are discussed. Economic implications of the design recommendations are presented.