US Bridges

SW Blackhawk Av over Miller Creek

Fair

Johnson County, Iowa · 078081904 · Structure no. 000000000203761

Built
2004
21 years old
Condition
Fair
inspected August 2024
Type
Stringer/Multi-beam or Girder
Steel
Length
66 ft
1 main span
Daily traffic
11
2022 count
Owner
County
County Highway Agency

About this bridge

SW Blackhawk Av over Miller Creek is a steel stringer/multi-beam or girder carrying SW Blackhawk Av over Miller Creek in Johnson County, Iowa. It was built in 2004, so it is 21 years old, younger 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 11 vehicles a day, projected to reach 11 by 2044. The structure is 66 ft (20.1 m) long and 24 ft wide. If it were closed, the detour would be 3.7 mi (6 km).

Location

Open in Google Maps
CarriesSW Blackhawk Av
CrossesMiller Creek
Location078081904
RouteCounty Highway 0
CountyJohnson County
StateIowa
Coordinates41.54377, -91.81434
Functional classRural Local

Condition and inspection

Fair

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

ComponentRatingMeaning
Deck5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Superstructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Substructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Channel and channel protection7 GoodSome minor problems.
Last inspectionAugust 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry6: Equal to present minimum criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating35.1 US tons
Inventory rating27.1 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckWood or timber
Main spans1
Design loadHS 20
Structure length66 ft (20.1 m)
Longest span63 ft (19.2 m)
Deck width24 ft (7.3 m)
Roadway width24 ft (7.3 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic11 (2022)
Projected traffic11 by 2044
Trucks0%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed3.7 mi (6 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerCounty Highway Agency
Maintained byCounty Highway Agency
Historic statusPossibly eligible for the National Register; requires further investigation
Work proposedWidening with deck rehabilitation or replacement
Estimated improvement cost—
NavigationNo navigation control on waterway

Frequently asked questions

When was SW Blackhawk Av over Miller Creek built?

It was built in 2004, making it 21 years old in 2025.

What condition is SW Blackhawk Av over Miller 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 August 2024.

How much traffic does SW Blackhawk Av over Miller Creek carry?

About 11 vehicles per day (2022 count).

How long is SW Blackhawk Av over Miller Creek?

The structure is 66 ft (20.1 m) long with a longest span of 63 ft (19.2 m) and a deck 24 ft wide.

Who owns SW Blackhawk Av over Miller Creek?

It is owned by the County Highway Agency.