Like many large cities, many of Chicago's area roadways run below grade with long retaining walls along the expressway and at entrance and exit ramps.
In the fall of 2018, Illinois Department of Transportation inspectors noticed something unusual at the Lawrence Ave entrance ramp to I-90. Four of the many 60' retaining panels were out of alignment. They had tilted a couple inches outward from the top.
In late winter, one of panels suddenly rotated a few feet outward. Its collapse was certain if immediate action was not taken. Contractors quickly stabilized the huge 60' panel with supporting braces. It took ingenuity to keep the heavy wall from falling and keep the braces from sliding into traffic.
Upon excavation, IDOT determined that water had built up behind the wall. They believe it happened during a polar vortex when the water in the soil turned to ice. As it froze, it expanded outward putting more stress on the wall.
IDOT had used Maintainable Weep Hole Filters on other projects. They knew the filters were a quick and cost effective solution to re-establish drainage on an existing wall. Four inch open-end units were installed on all of the 60' panels holding up the entrance and exit ramps.