US Bridges

I-15 (SR-15) Nbl over 100 South Street

Fair

Washington County, Utah · 1150 E.100 S.In St.George · Structure no. 1F 289

Built
1972
53 years old, rebuilt 1990
Condition
Fair
inspected January 2023
Type
Stringer/Multi-beam or Girder
Prestressed Concrete
Length
98 ft
1 main span
Daily traffic
51,695
2021 count
Owner
State
State Highway Agency

About this bridge

I-15 (SR-15) Nbl over 100 South Street is a prestressed concrete stringer/multi-beam or girder carrying I-15 (SR-15) Nbl over 100 South Street in Washington County, Utah. It was built in 1972 and reconstructed in 1990, so it is 53 years old, older than the Utah average of 40.1 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 51,695 vehicles a day, roughly 30% of them trucks, projected to reach 62,034 by 2041. The structure is 98 ft (30 m) long and 56 ft wide. If it were closed, the detour would be 0.6 mi (1 km).

Location

Open in Google Maps
CarriesI-15 (SR-15) Nbl
Crosses100 South Street
Location1150 E.100 S.In St.George
RouteInterstate 15
CountyWashington County
StateUtah
Coordinates37.10622, -113.55921
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
Deck7 GoodSome minor problems.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionJanuary 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry6: Equal to present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating41.1 US tons
Inventory rating25.4 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans1
Design loadHS 20 + Mod
Structure length98 ft (30 m)
Longest span94 ft (28.7 m)
Deck width56 ft (17.2 m)
Roadway width53 ft (16.3 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic51,695 (2021)
Projected traffic62,034 by 2041
Trucks30%
Lanes on structure3
Traffic directionOne-way traffic
CarriesHighway
CrossesHighway
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 proposedNone recorded
Estimated improvement cost—
NavigationNot applicable (no waterway)

Frequently asked questions

When was I-15 (SR-15) Nbl over 100 South Street built?

It was built in 1972, making it 53 years old in 2025. It was reconstructed in 1990.

What condition is I-15 (SR-15) Nbl over 100 South Street 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 January 2023.

How much traffic does I-15 (SR-15) Nbl over 100 South Street carry?

About 51,695 vehicles per day (2021 count), of which roughly 30% are trucks.

How long is I-15 (SR-15) Nbl over 100 South Street?

The structure is 98 ft (30 m) long with a longest span of 94 ft (28.7 m) and a deck 56 ft wide.

Who owns I-15 (SR-15) Nbl over 100 South Street?

It is owned by the State Highway Agency.