US Bridges

Nj 31 NB over 78 & RMP[31 SB to 78 Eb]

Fair

Hunterdon County, New Jersey · I-78 & 31 NB Junction · Structure no. 1017158

Built
1967
58 years old, rebuilt 1994
Condition
Fair
inspected March 2023
Type
Stringer/Multi-beam or Girder
Steel
Length
213 ft
2 main spans
Daily traffic
17,320
2023 count
Owner
State
State Highway Agency

About this bridge

Nj 31 NB over 78 & RMP[31 SB to 78 Eb] is a steel stringer/multi-beam or girder carrying Nj 31 NB over 78 & RMP[31 SB to 78 Eb] in Hunterdon County, New Jersey. It was built in 1967 and reconstructed in 1994, so it is 58 years old, younger 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 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 17,320 vehicles a day, roughly 4% of them trucks, projected to reach 21,132 by 2043. The structure is 213 ft (64.9 m) long and 47 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

CarriesNj 31 NB
Crosses78 & RMP[31 SB to 78 Eb]
LocationI-78 & 31 NB Junction
RouteState Highway 31
Coordinates40.6378, -74.88731
Functional classUrban Other Principal Arterial

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.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionMarch 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation6: Equal to present minimum criteria
Deck geometry6: Equal to present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating60 US tons
Inventory rating36 US tons

Structure

MaterialSteel
DeckConcrete, cast-in-place
Main spans2
Design loadHS 20
Structure length213 ft (64.9 m)
Longest span112 ft (34.1 m)
Deck width47 ft (14.3 m)
Roadway width37 ft (11.3 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic17,320 (2023)
Projected traffic21,132 by 2043
Trucks4%
Lanes on structure2
Traffic directionOne-way traffic
CarriesHighway and pedestrian
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 statusHistorical significance not determinable at this time
Work proposedNone recorded
Estimated improvement cost—
NavigationNot applicable (no waterway)

Frequently asked questions

When was Nj 31 NB over 78 & RMP[31 SB to 78 Eb] built?

It was built in 1967, making it 58 years old in 2025. It was reconstructed in 1994.

What condition is Nj 31 NB over 78 & RMP[31 SB to 78 Eb] 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 March 2023.

How much traffic does Nj 31 NB over 78 & RMP[31 SB to 78 Eb] carry?

About 17,320 vehicles per day (2023 count), of which roughly 4% are trucks.

How long is Nj 31 NB over 78 & RMP[31 SB to 78 Eb]?

The structure is 213 ft (64.9 m) long with a longest span of 112 ft (34.1 m) and a deck 47 ft wide.

Who owns Nj 31 NB over 78 & RMP[31 SB to 78 Eb]?

It is owned by the State Highway Agency.