US Bridges

SB I-29 over Allen Creek

Fair

Harrison County, Iowa · 1.9 Mi. N of Jct. US 30 · Structure no. 000000000028160

Built
1967
58 years old
Condition
Fair
inspected June 2024
Type
Stringer/Multi-beam or Girder
Steel Continuous
Length
161 ft
3 main spans
Daily traffic
7,750
2022 count
Owner
State
State Highway Agency

About this bridge

SB I-29 over Allen Creek is a steel continuous stringer/multi-beam or girder carrying SB I-29 over Allen Creek in Harrison County, Iowa. It was built in 1967, so it is 58 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 7,750 vehicles a day, roughly 31% of them trucks, projected to reach 7,750 by 2044. The structure is 161 ft (49.1 m) long and 42 ft wide.

Location

Open in Google Maps
CarriesSB I-29
CrossesAllen Creek
Location1.9 Mi. N of Jct. US 30
RouteInterstate 29
CountyHarrison County
StateIowa
Coordinates41.57404, -95.92852
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 geometry6: Equal to present minimum criteria
Waterway adequacy6: Equal to present minimum criteria
Approach roadway alignment7: Better than present minimum criteria
Operating rating70 US tons
Inventory rating42 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel Continuous
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20
Structure length161 ft (49.1 m)
Longest span61 ft (18.6 m)
Deck width42 ft (12.9 m)
Roadway width39 ft (11.9 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic7,750 (2022)
Projected traffic7,750 by 2044
Trucks31%
Lanes on structure2
Traffic directionOne-way traffic
CarriesHighway
CrossesWaterway
Detour if closed—
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 Allen Creek built?

It was built in 1967, making it 58 years old in 2025.

What condition is SB I-29 over Allen Creek 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 Allen Creek carry?

About 7,750 vehicles per day (2022 count), of which roughly 31% are trucks.

How long is SB I-29 over Allen Creek?

The structure is 161 ft (49.1 m) long with a longest span of 61 ft (18.6 m) and a deck 42 ft wide.

Who owns SB I-29 over Allen Creek?

It is owned by the State Highway Agency.