US Bridges

170th Street over Grand River

Poor

Union County, Iowa · 072280703 · Structure no. 000000000325320

Built
1957
68 years old
Condition
Poor
inspected October 2023
Type
Stringer/Multi-beam or Girder
Prestressed Concrete
Length
207 ft
3 main spans
Daily traffic
46
2022 count
Owner
County
County Highway Agency

About this bridge

170th Street over Grand River is a prestressed concrete stringer/multi-beam or girder carrying 170th Street over Grand River in Union County, Iowa. It was built in 1957, so it is 68 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 46 vehicles a day, projected to reach 46 by 2043. The structure is 207 ft (63.1 m) long and 22 ft wide. If it were closed, the detour would be 3.7 mi (6 km).

Location

Open in Google Maps
Carries170th Street
CrossesGrand River
Location072280703
RouteCounty Highway 0
CountyUnion County
StateIowa
Coordinates41.0562, -94.11308
Functional classRural Local

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.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionOctober 2023
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 geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Waterway adequacy7: Better than present minimum criteria
Approach roadway alignment7: Better than present minimum criteria
Operating rating45.3 US tons
Inventory rating20 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans3
Design loadH 15
Structure length207 ft (63.1 m)
Longest span69 ft (21 m)
Deck width22 ft (6.7 m)
Roadway width20 ft (6.1 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic46 (2022)
Projected traffic46 by 2043
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 statusNot eligible for the National Register of Historic Places
Work proposedReplacement because of substandard load-carrying capacity or roadway geometry
Estimated improvement cost—
NavigationNo navigation control on waterway

Frequently asked questions

When was 170th Street over Grand River built?

It was built in 1957, making it 68 years old in 2025.

What condition is 170th Street over Grand River 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 October 2023.

How much traffic does 170th Street over Grand River carry?

About 46 vehicles per day (2022 count).

How long is 170th Street over Grand River?

The structure is 207 ft (63.1 m) long with a longest span of 69 ft (21 m) and a deck 22 ft wide.

Who owns 170th Street over Grand River?

It is owned by the County Highway Agency.