US Bridges

Knoll Road over Rockaway River

Fair

Morris County, New Jersey · 1.5MI SE of I-287 Exit 45 · Structure no. 1400265

Built
1900
125 years old, rebuilt 1965
Condition
Fair
inspected July 2023
Type
Stringer/Multi-beam or Girder
Steel
Length
95 ft
2 main spans
Daily traffic
8,583
2023 count
Owner
County
County Highway Agency

About this bridge

Knoll Road over Rockaway River is a steel stringer/multi-beam or girder carrying Knoll Road over Rockaway River in Morris County, New Jersey. It was built in 1900 and reconstructed in 1965, so it is 125 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 8,583 vehicles a day, roughly 4% of them trucks, projected to reach 10,472 by 2043. The structure is 95 ft (29 m) long and 52 ft wide. If it were closed, the detour would be 3.7 mi (6 km).

Location

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CarriesKnoll Road
CrossesRockaway River
Location1.5MI SE of I-287 Exit 45
RouteCity Street 0
CountyMorris County
StateNew Jersey
Coordinates40.89192, -74.3753
Functional classUrban Minor 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
Deck5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Superstructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
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 inspectionJuly 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourScour critical; foundations unstable for calculated scour conditions
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry9: Superior to present desirable criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment6: Equal to present minimum criteria
Operating rating52 US tons
Inventory rating31 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckCorrugated steel
Main spans2
Design loadUnknown
Structure length95 ft (29 m)
Longest span45 ft (13.7 m)
Deck width52 ft (15.8 m)
Roadway width48 ft (14.6 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic8,583 (2023)
Projected traffic10,472 by 2043
Trucks4%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed3.7 mi (6 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 proposedOther structural work, including hydraulic replacements
Estimated improvement cost$304,000 (2023 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was Knoll Road over Rockaway River built?

It was built in 1900, making it 125 years old in 2025. It was reconstructed in 1965.

What condition is Knoll Road over Rockaway 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 July 2023.

How much traffic does Knoll Road over Rockaway River carry?

About 8,583 vehicles per day (2023 count), of which roughly 4% are trucks.

How long is Knoll Road over Rockaway River?

The structure is 95 ft (29 m) long with a longest span of 45 ft (13.7 m) and a deck 52 ft wide.

Who owns Knoll Road over Rockaway River?

It is owned by the County Highway Agency.