US Bridges

Stone Sign Post RD over Plum Brook

Fair

Hunterdon County, New Jersey · 0.6 MI West of CR 579 · Structure no. 100D390

Built
1903
122 years old, rebuilt 2003
Condition
Fair
inspected April 2023
Type
Stringer/Multi-beam or Girder
Steel
Length
30 ft
1 main span
Daily traffic
133
2023 count
Owner
County
County Highway Agency

About this bridge

Stone Sign Post RD over Plum Brook is a steel stringer/multi-beam or girder carrying Stone Sign Post RD over Plum Brook in Hunterdon County, New Jersey. It was built in 1903 and reconstructed in 2003, so it is 122 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 133 vehicles a day, roughly 3% of them trucks, projected to reach 160 by 2043. The structure is 30 ft (9.1 m) long and 16 ft wide. If it were closed, the detour would be 1.9 mi (3 km).

Location

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CarriesStone Sign Post RD
CrossesPlum Brook
Location0.6 MI West of CR 579
CountyHunterdon County
StateNew Jersey
Coordinates40.49028, -74.93868
Functional classRural Local

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.
Superstructure7 GoodSome minor problems.
Substructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionApril 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry2: Basically intolerable, requiring high priority of replacement
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment6: Equal to present minimum criteria
Operating rating72 US tons
Inventory rating43 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckCorrugated steel
Main spans1
Design loadUnknown
Structure length30 ft (9.1 m)
Longest span28 ft (8.5 m)
Deck width16 ft (4.8 m)
Roadway width15 ft (4.7 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic133 (2023)
Projected traffic160 by 2043
Trucks3%
Lanes on structure1
Traffic directionOne-lane bridge for two-way traffic
CarriesHighway
CrossesWaterway
Detour if closed1.9 mi (3 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerCounty Highway Agency
Maintained byCounty Highway Agency
Historic statusEligible for the National Register of Historic Places
Work proposedReplacement because of substandard load-carrying capacity or roadway geometry
Estimated improvement cost$500,000 (2023 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was Stone Sign Post RD over Plum Brook built?

It was built in 1903, making it 122 years old in 2025. It was reconstructed in 2003.

What condition is Stone Sign Post RD over Plum Brook 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 Stone Sign Post RD over Plum Brook carry?

About 133 vehicles per day (2023 count), of which roughly 3% are trucks.

How long is Stone Sign Post RD over Plum Brook?

The structure is 30 ft (9.1 m) long with a longest span of 28 ft (8.5 m) and a deck 16 ft wide.

Who owns Stone Sign Post RD over Plum Brook?

It is owned by the County Highway Agency.