Project Images Illinois 104 over Illinois River at Meredosia Project Summary Hanson assisted Halverson Construction Co. Inc. with construction engineering for a new, 2,128-foot-long bridge carrying Illinois 104 over the Illinois River in Meredosia. The new structure, which has two 12-foot lanes and 10-foot shoulders on each side, replaces a narrower, two-lane bridge that was built in 1936. For the 590-foot-long tied-arch main span, Hanson performed a construction-stage analysis for each stage and prepared a construction sequence for the contractor to follow while erecting the structural steel. Hanson designed 160-foot-tall temporary towers and cable stays that supported the tied-arch bridge during erection and designed a tie-jacking system used to pull the tied-arch bridge together with eight 430-ton jacks after the last tie girders were in place. Hanson designed rigging to lift structural steel members during erection and checked the stability of these members during lifting. Hanson provided on-call engineering to review the as-built geometry of the bridge during erection and prepared recommended adjustments to the temporary towers and stays during the bridge erection. Hanson also designed temporary crane platforms within the river that supported construction equipment used to build the piers. Hanson’s responsibilities also included designing cofferdams for six river piers, bracing excavations for two in-ground facilities and preparing demolition plans for removing the existing truss spans.