US Bridges

SB I-29 over Haynie Slough

Fair

Mills County, Iowa · 2.4 Mi. S of S Jct. US 34 · Structure no. 000000000036220

Built
1971
54 years old
Condition
Fair
inspected June 2024
Type
Slab
Concrete Continuous
Length
83 ft
3 main spans
Daily traffic
6,850
2022 count
Owner
State
State Highway Agency

About this bridge

SB I-29 over Haynie Slough is a concrete continuous slab carrying SB I-29 over Haynie Slough in Mills County, Iowa. It was built in 1971, so it is 54 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 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 6,850 vehicles a day, roughly 31% of them trucks, projected to reach 6,850 by 2044. The structure is 83 ft (25.3 m) long and 43 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

Open in Google Maps
CarriesSB I-29
CrossesHaynie Slough
Location2.4 Mi. S of S Jct. US 34
RouteInterstate 29
CountyMills County
StateIowa
Coordinates40.97088, -95.8
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.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure7 GoodSome minor problems.
Channel and channel protection7 GoodSome minor problems.
Last inspectionJune 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation6: Equal to present minimum criteria
Deck geometry7: Better than present minimum criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating76.2 US tons
Inventory rating45.5 US tons

Structure

Structure typeSlab
MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20
Structure length83 ft (25.3 m)
Longest span31 ft (9.4 m)
Deck width43 ft (13.2 m)
Roadway width40 ft (12.2 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic6,850 (2022)
Projected traffic6,850 by 2044
Trucks31%
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 SB I-29 over Haynie Slough built?

It was built in 1971, making it 54 years old in 2025.

What condition is SB I-29 over Haynie Slough 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 June 2024.

How much traffic does SB I-29 over Haynie Slough carry?

About 6,850 vehicles per day (2022 count), of which roughly 31% are trucks.

How long is SB I-29 over Haynie Slough?

The structure is 83 ft (25.3 m) long with a longest span of 31 ft (9.4 m) and a deck 43 ft wide.

Who owns SB I-29 over Haynie Slough?

It is owned by the State Highway Agency.