US Bridges

Boyson Road over I-380

Good

Linn County, Iowa · 1.4 Mi. N of JCT.100 · Structure no. 000000000604740

Built
1982
43 years old
Condition
Good
inspected March 2023
Type
Stringer/Multi-beam or Girder
Prestressed Concrete
Length
248 ft
4 main spans
Daily traffic
16,284
2022 count
Owner
State
State Highway Agency

About this bridge

Boyson Road over I-380 is a prestressed concrete stringer/multi-beam or girder carrying Boyson Road over I-380 in Linn County, Iowa. It was built in 1982, so it is 43 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 16,284 vehicles a day, roughly 4% of them trucks, projected to reach 16,284 by 2043. The structure is 248 ft (75.6 m) long and 47 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

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CarriesBoyson Road
CrossesI-380
Location1.4 Mi. N of JCT.100
RouteCity Street 0
CountyLinn County
StateIowa
Coordinates42.04521, -91.68522
Functional classUrban Minor 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 inspectionMarch 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation7: Better than present minimum criteria
Deck geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Approach roadway alignment5: Somewhat better than minimum adequacy to tolerate being left in place as is
Operating rating80.6 US tons
Inventory rating38 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans4
Design loadHS 20
Structure length248 ft (75.6 m)
Longest span81 ft (24.7 m)
Deck width47 ft (14.4 m)
Roadway width44 ft (13.4 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic16,284 (2022)
Projected traffic16,284 by 2043
Trucks4%
Lanes on structure3
Traffic directionTwo-way traffic
CarriesOverpass structure at an interchange
CrossesHighway
Detour if closed1.2 mi (2 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 Boyson Road over I-380 built?

It was built in 1982, making it 43 years old in 2025.

What condition is Boyson Road over I-380 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 March 2023.

How much traffic does Boyson Road over I-380 carry?

About 16,284 vehicles per day (2022 count), of which roughly 4% are trucks.

How long is Boyson Road over I-380?

The structure is 248 ft (75.6 m) long with a longest span of 81 ft (24.7 m) and a deck 47 ft wide.

Who owns Boyson Road over I-380?

It is owned by the State Highway Agency.