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ID-21, Lowman Bridge Replacement

The old bridge is at the end of its life cycle and will be rebuilt

The Idaho Highway 21 Bridge over the Southfork of the Payette River in Lowman will be replaced with a new structure designed to blend in to the natural surroundings, while safely accommodating vehicle and pedestrian traffic. Construction is currently scheduled for spring-fall, 2024 and 2025.

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Background

The original late 1800’s timber truss bridge at this location was replaced by a new timber truss bridge in 1925. This bridge used a timber crib center pier and two concrete piers, both still in use today, to support the deck. The truss bridge was determined unsafe in 1946 and soon replaced with the existing steel girder bridge.

The new weathering steel girder bridge will feature 11-foot travel lanes and seven-foot shoulders, with red-toned, three-tube galvanized steel railings.

Construction Timeline

To protect critical bull trout spawning habitat and avoid winter weather delays, construction will span two season.

Beginning Spring 2024, crews will reconstruct the roadway adjacent to the bridge followed by demolition of the north half of the current bridge in July. Traffic will alternate using one lane of the existing bridge and a traffic signal through November, while the new north section of bridge is constructed.

November 2024 through June 2025, both lanes will be open. Southbound traffic will use the new structure and northbound traffic will use the old structure.

Between July and November 2025, traffic will shift to one alternating lane on the new bridge with signal control, while crews demolish the remaining old bridge and construct the south half of the new structure.

The new bridge is scheduled for completion in fall 2025. Anticipated schedule below.

Spring - Fall 2024
Crews to reconstruct the roadway adjacent to the bridge and start demolition of the current bridge.
November 2024 - June 2025
Two way lanes will be opened to the public.
July - November 2025
Crews to demolish remaining bridge and new structure to start construction.
Fall 2025
Completion of the new bridge.

1925

Original Timber Truss Bridge

The original late 1800's timber truss bridge was replaced by a new timber truss bridge.

1946

Truss Bridge Considered "Unsafe"

The 1925 truss bridge was deemed unsafe and soon replaced with the existing steel girder bridge.

Late 1940's

Current steel girder bridge constructed.

2021

Design begins of the replacement bridge.

Project
Updates

The history of this bridge is long and rich. Navigate through the timeline of the bridge from when it was first built to its current state.

Be sure to click the link below to receive updates on the upcoming reconstruction project!

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