Lost Lake Road Bridge
CSAH-108 St. Louis River Highway Crossing
Biwabik, MN

Lost Lake Road Bridge

• Structure ID: NBI: 69555
• Location: River Mile 144.8
• River Elevation: 1,334 Feet
• Highways: CSAH-108
• Daily Traffic Count: 250 (2003)
• Bridge Type: Prestressed Concrete Girder, Concrete Deck
• Bridge Length: 147 Feet, 49 Foot Longest Span
• Bridge Width: 34 Feet, 2 Lanes
• Navigation Channel Width: Non-Navigable
• Height Above Water: 16 Feet
• Date Built: 1989
Upstream of this location, the St. Louis River falls rapidly from nearly 1,700 feet in elevation down to about 1,350 feet. From here to the Forbes Dam, the river drops very gradually. The water is slow moving, and appears to be almost still at times. You can see right to the bottom when you look over either edge of the CSAH-108 bridge.

The bridge is the typical prestressed concrete girder structure. It has wide shoulders and modern guardrails, a nice luxury for a bridge that is so lightly used. The river crossing is divided into three equal length spans of 49 feet each. The mid-span joints are supported by two sets of piers. The piers are constructed by driving steel pipes into the riverbed, and topping off the pipes with a reinforced concrete pier cap. The steel pipes on the outside end of each pier is set at an angle to give the pier side to side strength. This allows a rather light structure to support the required highway load weights.


Lost Lake Road Bridge
Lost Lake Road Bridge
Lost Lake Road Bridge
Lost Lake Road Bridge
Lost Lake Road Bridge

Home  Return To St. Louis River Structures Home Page
Photo and text by John A. Weeks III, Copyright © 2008, all rights reserved.
For further information, contact: john@johnweeks.com