US Bridges

CR 161 over Bay of Thunder Lake

FairPosted for load

Cass County, Minnesota · 1.1 MI N of JCT TH 6 · Structure no. 1660

Built
1915
110 years old
Condition
Fair
inspected September 2024
Type
Stringer/Multi-beam or Girder
Steel
Length
25 ft
1 main span
Daily traffic
44
2022 count
Owner
County
County Highway Agency

About this bridge

CR 161 over Bay of Thunder Lake is a steel stringer/multi-beam or girder carrying CR 161 over Bay of Thunder Lake in Cass County, Minnesota. It was built in 1915, so it is 110 years old, older than the Minnesota average of 38.5 years.

The most recent inspection reported to the Federal Highway Administration rates it in fair condition with a lowest component rating of 5 out of 9. The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound. Its operating status is: posted for load restriction.

It carries about 44 vehicles a day, projected to reach 100 by 2042. The structure is 25 ft (7.6 m) long and 18 ft wide. If it were closed, the detour would be 1.9 mi (3 km).

Location

Open in Google Maps
CarriesCR 161
CrossesBay of Thunder Lake
Location1.1 MI N of JCT TH 6
RouteCounty Highway 161
CountyCass County
StateMinnesota
Coordinates46.96529, -93.94215
Functional classRural Local

Condition and inspection

Fair

The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.

ComponentRatingMeaning
Deck5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Superstructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Substructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Channel and channel protection5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Last inspectionSeptember 2024
Inspection intervalevery 24 months
Operating statusPosted for load restriction
ScourFoundations stable; scour above top of footing
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry3: Basically intolerable, requiring high priority of corrective action
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment5: Somewhat better than minimum adequacy to tolerate being left in place as is
Operating rating33.8 US tons
Inventory rating20.2 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckConcrete, cast-in-place
Main spans1
Design loadUnknown
Structure length25 ft (7.6 m)
Longest span23 ft (6.9 m)
Deck width18 ft (5.6 m)
Roadway width17 ft (5.2 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic44 (2022)
Projected traffic100 by 2042
Trucks—
Lanes on structure1
Traffic directionOne-lane bridge for two-way traffic
CarriesHighway
CrossesWaterway
Detour if closed1.9 mi (3 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerCounty Highway Agency
Maintained byCounty Highway Agency
Historic statusNot eligible for the National Register of Historic Places
Work proposedNone recorded
Estimated improvement cost$58 million
NavigationNo navigation control on waterway

Frequently asked questions

When was CR 161 over Bay of Thunder Lake built?

It was built in 1915, making it 110 years old in 2025.

What condition is CR 161 over Bay of Thunder Lake in?

The National Bridge Inventory rates it in fair condition. The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound. The last reported inspection was in September 2024.

How much traffic does CR 161 over Bay of Thunder Lake carry?

About 44 vehicles per day (2022 count).

How long is CR 161 over Bay of Thunder Lake?

The structure is 25 ft (7.6 m) long with a longest span of 23 ft (6.9 m) and a deck 18 ft wide.

Who owns CR 161 over Bay of Thunder Lake?

It is owned by the County Highway Agency.