US Bridges

Rock Road over Swan Creek Trib.

Fair

Hunterdon County, New Jersey · 300SO.ROCKTOWN-LAMB Rd. · Structure no. 1000057

Built
1925
100 years old, rebuilt 2009
Condition
Fair
inspected April 2023
Type
Stringer/Multi-beam or Girder
Steel
Length
34 ft
1 main span
Daily traffic
128
2023 count
Owner
County
County Highway Agency

About this bridge

Rock Road over Swan Creek Trib. is a steel stringer/multi-beam or girder carrying Rock Road over Swan Creek Trib. in Hunterdon County, New Jersey. It was built in 1925 and reconstructed in 2009, so it is 100 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 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 128 vehicles a day, roughly 1% of them trucks, projected to reach 155 by 2043. The structure is 34 ft (10.4 m) long and 19 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

Open in Google Maps
CarriesRock Road
CrossesSwan Creek Trib.
Location300SO.ROCKTOWN-LAMB Rd.
RouteCity Street 0
CountyHunterdon County
StateNew Jersey
Coordinates40.36741, -74.93587
Functional classUrban 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.
Superstructure8 Very GoodNo problems noted.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection5 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
ScourCountermeasures installed to correct a previously existing problem
Structural evaluation6: Equal to present minimum criteria
Deck geometry3: Basically intolerable, requiring high priority of corrective action
Waterway adequacy9: Superior to present desirable criteria
Approach roadway alignment4: Meets minimum tolerable limits to be left in place as is
Operating rating80.4 US tons
Inventory rating62.2 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckCorrugated steel
Main spans1
Design loadHL 93
Structure length34 ft (10.4 m)
Longest span33 ft (10.1 m)
Deck width19 ft (5.8 m)
Roadway width18 ft (5.6 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic128 (2023)
Projected traffic155 by 2043
Trucks1%
Lanes on structure1
Traffic directionOne-lane bridge for two-way traffic
CarriesHighway
CrossesWaterway
Detour if closed1.2 mi (2 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerCounty Highway Agency
Maintained byCounty Highway Agency
Historic statusNot eligible for the National Register of Historic Places
Work proposedWidening of existing bridge without deck rehabilitation
Estimated improvement cost$231,000 (2023 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was Rock Road over Swan Creek Trib. built?

It was built in 1925, making it 100 years old in 2025. It was reconstructed in 2009.

What condition is Rock Road over Swan Creek Trib. 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 Rock Road over Swan Creek Trib. carry?

About 128 vehicles per day (2023 count), of which roughly 1% are trucks.

How long is Rock Road over Swan Creek Trib.?

The structure is 34 ft (10.4 m) long with a longest span of 33 ft (10.1 m) and a deck 19 ft wide.

Who owns Rock Road over Swan Creek Trib.?

It is owned by the County Highway Agency.