US Bridges

Mn 21 over Cannon River

Fair

Rice County, Minnesota · 0.6 MI N of JCT TH 60 · Structure no. 6640

Built
1954
71 years old
Condition
Fair
inspected August 2023
Type
Girder and Floorbeam System
Concrete
Length
146 ft
2 main spans
Daily traffic
15,200
2016 count
Owner
State
State Highway Agency

About this bridge

Mn 21 over Cannon River is a concrete girder and floorbeam system carrying Mn 21 over Cannon River in Rice County, Minnesota. It was built in 1954, so it is 71 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 6 out of 9. The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.

It carries about 15,200 vehicles a day, roughly 4% of them trucks, projected to reach 15,200 by 2036. The structure is 146 ft (44.5 m) long and 73 ft wide. If it were closed, the detour would be 3.7 mi (6 km).

Location

Open in Google Maps
CarriesMn 21
CrossesCannon River
Location0.6 MI N of JCT TH 60
RouteState Highway 21
CountyRice County
StateMinnesota
Coordinates44.30281, -93.29012
Functional classUrban Minor Arterial

Condition and inspection

Fair

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

ComponentRatingMeaning
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection7 GoodSome minor problems.
Last inspectionAugust 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourScour critical; foundations unstable for calculated scour conditions
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry4: Meets minimum tolerable limits to be left in place as is
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating44.1 US tons
Inventory rating26.6 US tons

Structure

Structure typeGirder and Floorbeam System
MaterialConcrete
DeckConcrete, cast-in-place
Main spans2
Design loadHS 20
Structure length146 ft (44.5 m)
Longest span53 ft (16.2 m)
Deck width73 ft (22.1 m)
Roadway width54 ft (16.5 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic15,200 (2016)
Projected traffic15,200 by 2036
Trucks4%
Lanes on structure4
Traffic directionTwo-way traffic
CarriesHighway and pedestrian
CrossesWaterway
Detour if closed3.7 mi (6 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerState Highway Agency
Maintained byState Highway Agency
Historic statusNot eligible for the National Register of Historic Places
Work proposedNone recorded
Estimated improvement cost$184 million
NavigationNo navigation control on waterway

Frequently asked questions

When was Mn 21 over Cannon River built?

It was built in 1954, making it 71 years old in 2025.

What condition is Mn 21 over Cannon River 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 August 2023.

How much traffic does Mn 21 over Cannon River carry?

About 15,200 vehicles per day (2016 count), of which roughly 4% are trucks.

How long is Mn 21 over Cannon River?

The structure is 146 ft (44.5 m) long with a longest span of 53 ft (16.2 m) and a deck 73 ft wide.

Who owns Mn 21 over Cannon River?

It is owned by the State Highway Agency.