US Bridges

I-78 WB over Nj Route 173

Fair

Hunterdon County, New Jersey · 0.43 MI E of Rt 632 · Structure no. 1014151

Built
1959
66 years old
Condition
Fair
inspected April 2023
Type
Stringer/Multi-beam or Girder
Steel
Length
93 ft
1 main span
Daily traffic
51,321
2023 count
Owner
State
State Highway Agency

About this bridge

I-78 WB over Nj Route 173 is a steel stringer/multi-beam or girder carrying I-78 WB over Nj Route 173 in Hunterdon County, New Jersey. It was built in 1959, so it is 66 years old, older than the New Jersey average of 58.5 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 51,321 vehicles a day, roughly 9% of them trucks, projected to reach 62,602 by 2043. The structure is 93 ft (28.3 m) long and 58 ft wide. If it were closed, the detour would be 1.9 mi (3 km).

Location

Open in Google Maps
CarriesI-78 WB
CrossesNj Route 173
Location0.43 MI E of Rt 632
RouteInterstate 78
CountyHunterdon County
StateNew Jersey
Coordinates40.66022, -75.07004
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.
Superstructure7 GoodSome minor problems.
Substructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Last inspectionApril 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 geometry2: Basically intolerable, requiring high priority of replacement
Approach roadway alignment8: Equal to present desirable criteria
Operating rating110.1 US tons
Inventory rating63.1 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckConcrete, cast-in-place
Main spans1
Design loadHS 20
Structure length93 ft (28.3 m)
Longest span89 ft (27.1 m)
Deck width58 ft (17.8 m)
Roadway width51 ft (15.5 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic51,321 (2023)
Projected traffic62,602 by 2043
Trucks9%
Lanes on structure4
Traffic directionOne-way traffic
CarriesHighway
CrossesHighway
Detour if closed1.9 mi (3 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 statusHistorical significance not determinable at this time
Work proposedWidening with deck rehabilitation or replacement
Estimated improvement cost$767,000 (2023 estimate)
NavigationNot applicable (no waterway)

Frequently asked questions

When was I-78 WB over Nj Route 173 built?

It was built in 1959, making it 66 years old in 2025.

What condition is I-78 WB over Nj Route 173 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 April 2023.

How much traffic does I-78 WB over Nj Route 173 carry?

About 51,321 vehicles per day (2023 count), of which roughly 9% are trucks.

How long is I-78 WB over Nj Route 173?

The structure is 93 ft (28.3 m) long with a longest span of 89 ft (27.1 m) and a deck 58 ft wide.

Who owns I-78 WB over Nj Route 173?

It is owned by the State Highway Agency.