US Bridges

Blackwellsmills RD over Millstone River

Fair

Somerset County, New Jersey · At River RD Intersection · Structure no. 18G0404

Built
1994
31 years old
Condition
Fair
inspected October 2023
Type
Stringer/Multi-beam or Girder
Steel Continuous
Length
109 ft
2 main spans
Daily traffic
4,542
2023 count
Owner
County
County Highway Agency

About this bridge

Blackwellsmills RD over Millstone River is a steel continuous stringer/multi-beam or girder carrying Blackwellsmills RD over Millstone River in Somerset County, New Jersey. It was built in 1994, so it is 31 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 4,542 vehicles a day, roughly 1% of them trucks, projected to reach 5,450 by 2043. The structure is 109 ft (33.2 m) long and 38 ft wide. If it were closed, the detour would be 6.8 mi (11 km).

Location

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CarriesBlackwellsmills RD
CrossesMillstone River
LocationAt River RD Intersection
RouteCity Street 0
CountySomerset County
StateNew Jersey
Coordinates40.47472, -74.57617
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
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure8 Very GoodNo problems noted.
Substructure7 GoodSome minor problems.
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionOctober 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation7: Better than present minimum criteria
Deck geometry4: Meets minimum tolerable limits to be left in place as is
Waterway adequacy5: Somewhat better than minimum adequacy to tolerate being left in place as is
Approach roadway alignment7: Better than present minimum criteria
Operating rating110.1 US tons
Inventory rating66 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel Continuous
DeckConcrete, cast-in-place
Main spans2
Design loadHS 20 + Mod
Structure length109 ft (33.2 m)
Longest span53 ft (16.2 m)
Deck width38 ft (11.6 m)
Roadway width30 ft (9.2 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic4,542 (2023)
Projected traffic5,450 by 2043
Trucks1%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway and pedestrian
CrossesWaterway
Detour if closed6.8 mi (11 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 proposedNone recorded
Estimated improvement cost—
NavigationNo navigation control on waterway

Frequently asked questions

When was Blackwellsmills RD over Millstone River built?

It was built in 1994, making it 31 years old in 2025.

What condition is Blackwellsmills RD over Millstone River 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 October 2023.

How much traffic does Blackwellsmills RD over Millstone River carry?

About 4,542 vehicles per day (2023 count), of which roughly 1% are trucks.

How long is Blackwellsmills RD over Millstone River?

The structure is 109 ft (33.2 m) long with a longest span of 53 ft (16.2 m) and a deck 38 ft wide.

Who owns Blackwellsmills RD over Millstone River?

It is owned by the County Highway Agency.