US Bridges

Ia 946 NB over Valley ST

Good

Dubuque County, Iowa · 0.5 Mi. S. of Jct. US 20 · Structure no. 000000000606115

Built
1990
35 years old
Condition
Good
inspected October 2023
Type
Stringer/Multi-beam or Girder
Prestressed Concrete
Length
146 ft
3 main spans
Daily traffic
3,400
2022 count
Owner
State
State Highway Agency

About this bridge

Ia 946 NB over Valley ST is a prestressed concrete stringer/multi-beam or girder carrying Ia 946 NB over Valley ST in Dubuque County, Iowa. It was built in 1990, so it is 35 years old, younger than the Iowa average of 45.5 years.

The most recent inspection reported to the Federal Highway Administration rates it in good condition with a lowest component rating of 7 out of 9. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

It carries about 3,400 vehicles a day, roughly 8% of them trucks, projected to reach 3,400 by 2043. The structure is 146 ft (44.5 m) long and 29 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

Open in Google Maps
CarriesIa 946 NB
CrossesValley ST
Location0.5 Mi. S. of Jct. US 20
RouteState Highway 946
CountyDubuque County
StateIowa
Coordinates42.48511, -90.66337
Functional classUrban Other Principal Arterial

Condition and inspection

Good

All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

ComponentRatingMeaning
Deck7 GoodSome minor problems.
Superstructure8 Very GoodNo problems noted.
Substructure7 GoodSome minor problems.
Last inspectionOctober 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation7: Better than present minimum criteria
Deck geometry8: Equal to present desirable criteria
Approach roadway alignment5: Somewhat better than minimum adequacy to tolerate being left in place as is
Operating rating65.8 US tons
Inventory rating39.6 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20
Structure length146 ft (44.5 m)
Longest span59 ft (18 m)
Deck width29 ft (8.9 m)
Roadway width26 ft (7.9 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic3,400 (2022)
Projected traffic3,400 by 2043
Trucks8%
Lanes on structure1
Traffic directionOne-way traffic
CarriesHighway
CrossesHighway
Detour if closed1.2 mi (2 km)
TollOn a free road
National Highway SystemYes

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 946 NB over Valley ST built?

It was built in 1990, making it 35 years old in 2025.

What condition is Ia 946 NB over Valley ST in?

The National Bridge Inventory rates it in good condition. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted. The last reported inspection was in October 2023.

How much traffic does Ia 946 NB over Valley ST carry?

About 3,400 vehicles per day (2022 count), of which roughly 8% are trucks.

How long is Ia 946 NB over Valley ST?

The structure is 146 ft (44.5 m) long with a longest span of 59 ft (18 m) and a deck 29 ft wide.

Who owns Ia 946 NB over Valley ST?

It is owned by the State Highway Agency.