US Bridges

120th ST over Hardin-Story Dd 1

Good

Story County, Iowa · .46 MI E of NW Cor. · Structure no. 000000000315751

Built
2018
7 years old
Condition
Good
inspected November 2022
Type
Slab
Concrete Continuous
Length
71 ft
3 main spans
Daily traffic
11
2022 count
Owner
County
County Highway Agency

About this bridge

120th ST over Hardin-Story Dd 1 is a concrete continuous slab carrying 120th ST over Hardin-Story Dd 1 in Story County, Iowa. It was built in 2018, so it is 7 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 8 out of 9. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

It carries about 11 vehicles a day, projected to reach 11 by 2043. The structure is 71 ft (21.6 m) long and 33 ft wide.

Location

Open in Google Maps
Carries120th ST
CrossesHardin-Story Dd 1
Location.46 MI E of NW Cor.
RouteCounty Highway 0
CountyStory County
StateIowa
Coordinates42.18036, -93.24219
Functional classRural Local

Condition and inspection

Good

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

ComponentRatingMeaning
Deck8 Very GoodNo problems noted.
Superstructure8 Very GoodNo problems noted.
Substructure8 Very GoodNo problems noted.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionNovember 2022
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation8: Equal to present desirable criteria
Deck geometry7: Better than present minimum criteria
Waterway adequacy9: Superior to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating76.8 US tons
Inventory rating46 US tons

Structure

Structure typeSlab
MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans3
Design loadHL 93
Structure length71 ft (21.6 m)
Longest span28 ft (8.5 m)
Deck width33 ft (10.1 m)
Roadway width31 ft (9.3 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic11 (2022)
Projected traffic11 by 2043
Trucks0%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed—
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 proposedNone recorded
Estimated improvement cost—
NavigationNo navigation control on waterway

Frequently asked questions

When was 120th ST over Hardin-Story Dd 1 built?

It was built in 2018, making it 7 years old in 2025.

What condition is 120th ST over Hardin-Story Dd 1 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 November 2022.

How much traffic does 120th ST over Hardin-Story Dd 1 carry?

About 11 vehicles per day (2022 count).

How long is 120th ST over Hardin-Story Dd 1?

The structure is 71 ft (21.6 m) long with a longest span of 28 ft (8.5 m) and a deck 33 ft wide.

Who owns 120th ST over Hardin-Story Dd 1?

It is owned by the County Highway Agency.