US Bridges

Ia 175 over I-29

Poor

Monona County, Iowa · At JCT I-29 · Structure no. 000000000036830

Built
1959
66 years old
Condition
Poor
inspected September 2024
Type
Stringer/Multi-beam or Girder
Steel Continuous
Length
248 ft
4 main spans
Daily traffic
4,090
2022 count
Owner
State
State Highway Agency

About this bridge

Ia 175 over I-29 is a steel continuous stringer/multi-beam or girder carrying Ia 175 over I-29 in Monona County, Iowa. It was built in 1959, so it is 66 years old, older than the Iowa average of 45.5 years.

The most recent inspection reported to the Federal Highway Administration rates it in poor condition with a lowest component rating of 4 out of 9. The lowest-rated primary component is rated 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions.

It carries about 4,090 vehicles a day, roughly 17% of them trucks, projected to reach 4,090 by 2044. The structure is 248 ft (75.6 m) long and 36 ft wide. If it were closed, the detour would be 11.8 mi (19 km).

Location

Open in Google Maps
CarriesIa 175
CrossesI-29
LocationAt JCT I-29
RouteState Highway 175
CountyMonona County
StateIowa
Coordinates42.02698, -96.13303
Functional classRural Minor Arterial

Condition and inspection

Poor

The lowest-rated primary component is rated 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions.

ComponentRatingMeaning
Deck4 PoorAdvanced section loss, deterioration, spalling or scour.
Superstructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionSeptember 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
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
Approach roadway alignment6: Equal to present minimum criteria
Operating rating43.3 US tons
Inventory rating26 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel Continuous
DeckConcrete, cast-in-place
Main spans4
Design loadHS 20
Structure length248 ft (75.6 m)
Longest span72 ft (21.9 m)
Deck width36 ft (11 m)
Roadway width30 ft (9.1 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic4,090 (2022)
Projected traffic4,090 by 2044
Trucks17%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesOverpass structure at an interchange
CrossesHighway
Detour if closed11.8 mi (19 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—
NavigationNot applicable (no waterway)

Frequently asked questions

When was Ia 175 over I-29 built?

It was built in 1959, making it 66 years old in 2025.

What condition is Ia 175 over I-29 in?

The National Bridge Inventory rates it in poor condition. The lowest-rated primary component is rated 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions. The last reported inspection was in September 2024.

How much traffic does Ia 175 over I-29 carry?

About 4,090 vehicles per day (2022 count), of which roughly 17% are trucks.

How long is Ia 175 over I-29?

The structure is 248 ft (75.6 m) long with a longest span of 72 ft (21.9 m) and a deck 36 ft wide.

Who owns Ia 175 over I-29?

It is owned by the State Highway Agency.