Overview
Horner & Shifrin provided engineering design services for drainage, roadway, bridge, and hydraulics for MoDOT’s $270M I-270 North Design-Build Project. H&S led all drainage design for the 7-mile corridor along I-270 in St. Louis County from Lindbergh (Route 67) to Bellefontaine Road. The complex design accounted for widening of I-270, interchange improvements, 1-way outer road conversions, and new outer roads. Drainage design was closely coordinated with MoDOT and MSD. Detention basins were provided at many locations to account for increases in runoff. The basin design required coordination and approval by MSD.
Additionally, H&S designed geometric improvements to the Lindbergh (Route 67) interchange which included conversion of an existing diamond and loop ramp configuration to a modern design of a “squareabout”, one-way crossroads with collector-distributor connections, as well as an outer road extension and shared-use path connections. H&S was responsible for horizontal and vertical alignments, 3D modeling of the interchange, intersection warpings, grading, and cross-sections.
Bridge design included replacement of I-270 structures over Coldwater Creek. Detailed coordination was required with traffic staging operations and outer road construction. Coldwater Creek is an environmentally-sensitive stream so care was taken to minimize disturbance to the existing stream bank. H&S also obtained floodplain development permits and no-rise certificates at Coldwater Creek and four other crossings along the I-270 corridor.
