US Bridges

I 380 SB over San Marnan DR

Fair

Black Hawk County, Iowa · 1.0 Mi. N of N Jct. 20 · Structure no. 000000000605300

Built
1983
42 years old
Condition
Fair
inspected August 2023
Type
Stringer/Multi-beam or Girder
Prestressed Concrete
Length
181 ft
3 main spans
Daily traffic
9,050
2022 count
Owner
State
State Highway Agency

About this bridge

I 380 SB over San Marnan DR is a prestressed concrete stringer/multi-beam or girder carrying I 380 SB over San Marnan DR in Black Hawk County, Iowa. It was built in 1983, so it is 42 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 6 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 9,050 vehicles a day, roughly 14% of them trucks, projected to reach 9,050 by 2043. The structure is 181 ft (55.2 m) long and 55 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

CarriesI 380 SB
CrossesSan Marnan DR
Location1.0 Mi. N of N Jct. 20
RouteInterstate 380
StateIowa
Coordinates42.46897, -92.31885
Functional classUrban Principal Arterial - Interstate

Condition and inspection

Fair

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

ComponentRatingMeaning
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure8 Very GoodNo problems noted.
Substructure7 GoodSome minor problems.
Last inspectionAugust 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 alignment8: Equal to present desirable criteria
Operating rating92 US tons
Inventory rating62.4 US tons

Structure

MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20
Structure length181 ft (55.2 m)
Longest span96 ft (29.3 m)
Deck width55 ft (16.8 m)
Roadway width52 ft (15.9 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic9,050 (2022)
Projected traffic9,050 by 2043
Trucks14%
Lanes on structure3
Traffic directionOne-way traffic
CarriesOverpass structure at an interchange
CrossesHighway
Detour if closed1.2 mi (2 km)
TollOn a free road
National Highway SystemYes
Strategic Highway NetworkInterstate STRAHNET route

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 I 380 SB over San Marnan DR built?

It was built in 1983, making it 42 years old in 2025.

What condition is I 380 SB over San Marnan DR 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 2023.

How much traffic does I 380 SB over San Marnan DR carry?

About 9,050 vehicles per day (2022 count), of which roughly 14% are trucks.

How long is I 380 SB over San Marnan DR?

The structure is 181 ft (55.2 m) long with a longest span of 96 ft (29.3 m) and a deck 55 ft wide.

Who owns I 380 SB over San Marnan DR?

It is owned by the State Highway Agency.