The aging State Highway 21 bridge over the South Fork of the Payette River in Lowman will soon be replaced with a modern structure that improves safety for both drivers and pedestrians. Traffic control for this multi-season project begins setting up next week.
In the initial phase, crews will begin reconstructing the roadway adjacent to the existing bridge. Starting July 2025, demolition of the bridge’s north half will begin. From July through November 2025, traffic will be reduced to a single alternating lane, controlled by a temporary traffic signal, as construction on the north portion of the new bridge gets underway.
To minimize environmental impact—especially on critical bull trout spawning habitat—and to keep traffic moving, construction will take place over two seasons. Full completion is anticipated in spring 2027. Once finished, the new Lowman Bridge will offer improved travel conditions and enhanced safety.
The site has a rich history of moving Idahoans safely across the river: the original late 1800s timber truss bridge was replaced in 1925 with a newer timber truss bridge, which featured a timber center pier and two concrete piers. That bridge was declared unsafe in 1946 and replaced shortly thereafter with the current steel girder bridge.
Delays are expected during construction. Motorists are encouraged to check their route at 511.idaho.gov before heading to the area.