US Bridges

Interstate 15 NB over National Ave

Good

San Diego County, California · 11-SD-015-R0.21R-SD · Structure no. 57 0742R

Built
1978
47 years old
Condition
Good
inspected March 2023
Type
Box Beam or Girders - Single or Spread
Prestressed Concrete
Length
138 ft
1 main span
Daily traffic
48,000
2019 count
Owner
State
State Highway Agency

About this bridge

Interstate 15 NB over National Ave is a prestressed concrete box beam or girders - single or spread carrying Interstate 15 NB over National Ave in San Diego County, California. It was built in 1978, so it is 47 years old, younger than the California average of 54.8 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 48,000 vehicles a day, roughly 2% of them trucks, projected to reach 64,343 by 2041. The structure is 138 ft (42.1 m) long and 49 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

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CarriesInterstate 15 NB
CrossesNational Ave
Location11-SD-015-R0.21R-SD
RouteState Highway 15
CountySan Diego County
StateCalifornia
Coordinates32.69582, -117.12038
Functional classUrban Principal Arterial - Other Freeway or Expressway

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.
Superstructure7 GoodSome minor problems.
Substructure7 GoodSome minor problems.
Last inspectionMarch 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation6: Equal to present minimum criteria
Deck geometry9: Superior to present desirable criteria
Approach roadway alignment5: Somewhat better than minimum adequacy to tolerate being left in place as is
Operating rating64.6 US tons
Inventory rating28.5 US tons

Structure

Structure typeBox Beam or Girders - Single or Spread
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans1
Design loadHS 20
Structure length138 ft (42.1 m)
Longest span136 ft (41.5 m)
Deck width49 ft (14.9 m)
Roadway width46 ft (13.9 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic48,000 (2019)
Projected traffic64,343 by 2041
Trucks2%
Lanes on structure2
Traffic directionOne-way traffic
CarriesHighway
CrossesHighway
Detour if closed1.2 mi (2 km)
TollOn a free road
National Highway SystemYes

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 Interstate 15 NB over National Ave built?

It was built in 1978, making it 47 years old in 2025.

What condition is Interstate 15 NB over National Ave 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 Interstate 15 NB over National Ave carry?

About 48,000 vehicles per day (2019 count), of which roughly 2% are trucks.

How long is Interstate 15 NB over National Ave?

The structure is 138 ft (42.1 m) long with a longest span of 136 ft (41.5 m) and a deck 49 ft wide.

Who owns Interstate 15 NB over National Ave?

It is owned by the State Highway Agency.