Willett, Hofmann & Associates, Inc. was hired to perform a “Structural Assessment Reports for Contractor’s Means and Methods” (SARS) analysis for two structures at the I-70/I-57 Interchange in Effingham, IL. One structure involved developing a 3-sided temporary soil retention system (50’x27’ in plan) to resist lateral earth forces for a 24’-maximum-depth cut to construct cast-in-place culvert extensions adjacent to the US Route 45 underpass beneath I-70/I-57. The 3-sided system consisted of a single-level waler/kicker system to resist the lateral-reaction forces adding up to 10,000 lbs. per-foot of wall length. Usage of specific engineered sloping cuts resulted in development of “passive toe soil wedges” to resist the unbalanced forces of a 3-sided cut; these “soil wedges” were verified using PileBuck and RISA-2D to resist all the anticipated earth forces to allow safe demolition/construction of the existing/proposed culvert ends.

The other structure involved removal/replacement of the existing 5-span reinforced concrete deck dual bridge structure carrying I-70/I-57 over US Route 45. Due to the high existing bridge skew (31.5°), and since the design plans required staged removal and staged construction to keep existing traffic open to the public, the associated temporary soil retention system at the existing abutments required geometric compatibility and structural capacity to accommodate up to 12’-deep cuts with minimal access for walers and connection options. Lateral-reaction forces of up to 2,000 lbs. per-foot of wall length were resisted using 37’-long steel HP sections as walers for excavations as long as 42’. Stage I wale-end-reactions were resisted using plates anchored into the existing concrete abutments while Stage II wale-end-reactions were taken up through threaded rods inserted into the already-proposed bar splicers in the final bridge deck.

The remaining items pertaining to the SARS requirements included a comprehensive demolition plan to prove that the contractor’s proposed equipment, with cranes of up to 175,000 pounds in weight, did not exceed the operating rating of the existing structure. Similar calculations were provided in the steel erection plan for the proposed structure to show that the contractor’s 110 Ton crane and the contractor’s concrete-pump-trucks would not overstress the Stage I constructed elements of the bridge. Willett, Hofmann & Associates, Inc. also provided all drawings (using Microstation V8i) and calculations to assist the contractor in construction of the required temporary shielding and pier cap formwork plans for the proposed bridge.