Under-construction bridge collapses in Oconomowoc following falsework failure

An under-construction bridge in Oconomowoc, Wisconsin, partially collapsed after a series of construction-stage failures, prompting renewed scrutiny of temporary support systems and site safety measures.

The Lapham Street bridge, which was being rebuilt to replace an aging single-lane structure, partially collapsed into the Oconomowoc River while work was ongoing at the site. The incident occurred days after an earlier failure involving temporary support elements during a concrete pour. In that earlier event, a falsework beam supporting fresh concrete failed, causing material to spill but not resulting in a full collapse.

Following the initial incident, crews allowed the concrete to cure before beginning removal work. During those operations, part of the structure gave way, sending debris into the river. No injuries were reported in either event.

The failure underscores the importance of properly designed and inspected temporary works during bridge construction. Falsework and related support systems must be able to carry construction-stage loads, including wet concrete and loads generated during placement, curing, and removal operations. Officials have since announced enhanced inspections, additional support measures, and an environmental cleanup plan.

The bridge project is part of a wider upgrade intended to improve capacity and safety by replacing the old one-lane crossing with a two-lane structure that includes shoulders and raised sidewalks. Authorities are continuing to assess the incident, while the City of Oconomowoc and WisDOT have said the full bridge construction remains scheduled for completion in early September.