US Bridges

I-75 SB over Alafia River

Fair

Hillsborough County, Florida · 0.3 MI N of Gibsonton DR · Structure no. 100358

Built
1981
44 years old
Condition
Fair
inspected September 2023
Type
Stringer/Multi-beam or Girder
Prestressed Concrete
Length
1,555 ft
21 main spans
Daily traffic
157,000
2023 count
Owner
State
State Highway Agency

About this bridge

I-75 SB over Alafia River is a prestressed concrete stringer/multi-beam or girder carrying I-75 SB over Alafia River in Hillsborough County, Florida. It was built in 1981, so it is 44 years old, older than the Florida average of 41.3 years.

The most recent inspection reported to the Federal Highway Administration rates it in fair condition with a lowest component rating of 5 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 157,000 vehicles a day, roughly 9% of them trucks, projected to reach 272,395 by 2042. The structure is 1,555 ft (474 m) long and 72 ft wide. If it were closed, the detour would be 0.6 mi (1 km).

Location

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CarriesI-75 SB
CrossesAlafia River
Location0.3 MI N of Gibsonton DR
RouteInterstate 75
CountyHillsborough County
StateFlorida
Coordinates27.85736, -82.347
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
Deck5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Superstructure7 GoodSome minor problems.
Substructure7 GoodSome minor problems.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionSeptember 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation7: Better than present minimum criteria
Deck geometry7: Better than present minimum criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating66 US tons
Inventory rating57 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete
DeckConcrete, precast panels
Main spans21
Design loadHS 20 + Mod
Structure length1,555 ft (474 m)
Longest span90 ft (27.5 m)
Deck width72 ft (21.8 m)
Roadway width69 ft (20.9 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic157,000 (2023)
Projected traffic272,395 by 2042
Trucks9%
Lanes on structure4
Traffic directionOne-way traffic
CarriesHighway
CrossesWaterway
Detour if closed0.6 mi (1 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 proposedOther structural work, including hydraulic replacements
Estimated improvement cost$426,000
NavigationNavigation control on waterway (bridge permit required)

Frequently asked questions

When was I-75 SB over Alafia River built?

It was built in 1981, making it 44 years old in 2025.

What condition is I-75 SB over Alafia River 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 September 2023.

How much traffic does I-75 SB over Alafia River carry?

About 157,000 vehicles per day (2023 count), of which roughly 9% are trucks.

How long is I-75 SB over Alafia River?

The structure is 1,555 ft (474 m) long with a longest span of 90 ft (27.5 m) and a deck 72 ft wide.

Who owns I-75 SB over Alafia River?

It is owned by the State Highway Agency.