US Bridges

NB I-35 over Grand River

Fair

Decatur County, Iowa · 3.1 Mi. N of Jct. US 69 · Structure no. 000000000022920

Built
1970
55 years old
Condition
Fair
inspected July 2024
Type
Stringer/Multi-beam or Girder
Steel Continuous
Length
365 ft
3 main spans
Daily traffic
7,550
2022 count
Owner
State
State Highway Agency

About this bridge

NB I-35 over Grand River is a steel continuous stringer/multi-beam or girder carrying NB I-35 over Grand River in Decatur County, Iowa. It was built in 1970, so it is 55 years old, older than the Iowa average of 45.5 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.

It carries about 7,550 vehicles a day, roughly 37% of them trucks, projected to reach 7,550 by 2044. The structure is 365 ft (111.3 m) long and 43 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

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CarriesNB I-35
CrossesGrand River
Location3.1 Mi. N of Jct. US 69
RouteInterstate 35
CountyDecatur County
StateIowa
Coordinates40.65888, -93.85602
Functional classRural Principal Arterial - Interstate

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.
Superstructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Substructure7 GoodSome minor problems.
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionJuly 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry7: Better than present minimum criteria
Waterway adequacy6: Equal to present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating54.7 US tons
Inventory rating32.8 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel Continuous
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20
Structure length365 ft (111.3 m)
Longest span140 ft (42.7 m)
Deck width43 ft (13.2 m)
Roadway width40 ft (12.2 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic7,550 (2022)
Projected traffic7,550 by 2044
Trucks37%
Lanes on structure2
Traffic directionOne-way traffic
CarriesHighway
CrossesWaterway
Detour if closed1.2 mi (2 km)
TollOn a free road
National Highway SystemYes
Strategic Highway NetworkInterstate STRAHNET route

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—
NavigationNo navigation control on waterway

Frequently asked questions

When was NB I-35 over Grand River built?

It was built in 1970, making it 55 years old in 2025.

What condition is NB I-35 over Grand 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 July 2024.

How much traffic does NB I-35 over Grand River carry?

About 7,550 vehicles per day (2022 count), of which roughly 37% are trucks.

How long is NB I-35 over Grand River?

The structure is 365 ft (111.3 m) long with a longest span of 140 ft (42.7 m) and a deck 43 ft wide.

Who owns NB I-35 over Grand River?

It is owned by the State Highway Agency.