Vicinity map for the Little Tonsina Bridge
The Alaska Department of Transportation and Public Facilities (DOT&PF) in partnership with the Copper River Watershed Project is working to replace the existing Little Tonsina River culverts with a new bridge; Little Tonsina River Bridge #568, on Burma Pit Road near MP 74.2 of the Richardson Highway. The existing gravel access road is used by the Alyeska Pipeline Corporation to access the pipeline, by DOT&PF to access a material pit, and by homeowners in the area.
The purpose of this project is to remove the two existing culverts and replace with a new bridge.
The existing culverts have been determined to be a barrier to fish passage by the Alaska Department of Fish and Game. A hydraulic analysis of the site suggests that before the Richardson Highway was constructed, the junction of the Little Tonsina with the main fork of the Tonsina River was 1.5 miles to the North. The highway construction likely cut off approximately 1 mile of the river length, straightening the river and causing erosion. The existing culverts are frequently over topped with high stream flows during break-up and heavy rain fall, and also frequently get plugged up with debris. Major flooding occurred in the area in 2006 and required an emergency repair contract to make necessary repairs.
The new bridge will be slightly to the north of the existing culverts and will be a concrete deck bulb tee single span bridge, 103 feet long by 27 feet wide. The new bridge will allow for better fish passage, better flood mitigation, and form a more natural stream.
An illustration of the proposed realignment and Little Tonsina bridge location.
Work on this project includes:
Construction on this project began in July 2022 and is anticipated to be complete by the end of July 2023.
This project is being developed and funded in cooperation with the Copper River Watershed Project and USFWS, NOAA, NRCS, BLM, and the Alaska Sustainable Salmon Fund.
Staff lower new bridge girders into place, October 2022. DOT&PF photo.