US Bridges

Mountainside Drive over Mill Brook

Fair

Morris County, New Jersey · 0.05 Mile N. Grist Mill · Structure no. 1400773

Built
1929
96 years old, rebuilt 1989
Condition
Fair
inspected July 2023
Type
Stringer/Multi-beam or Girder
Steel
Length
27 ft
1 main span
Daily traffic
1,116
2023 count
Owner
County
County Highway Agency

About this bridge

Mountainside Drive over Mill Brook is a steel stringer/multi-beam or girder carrying Mountainside Drive over Mill Brook in Morris County, New Jersey. It was built in 1929 and reconstructed in 1989, so it is 96 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 1,116 vehicles a day, roughly 1% of them trucks, projected to reach 1,362 by 2043. The structure is 27 ft (8.2 m) long and 31 ft wide. If it were closed, the detour would be 1.9 mi (3 km).

Location

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CarriesMountainside Drive
CrossesMill Brook
Location0.05 Mile N. Grist Mill
RouteCity Street 0
CountyMorris County
StateNew Jersey
Coordinates40.86753, -74.54478
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.
Superstructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
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 inspectionJuly 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourCountermeasures installed to correct a previously existing problem
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Waterway adequacy7: Better than present minimum criteria
Approach roadway alignment5: Somewhat better than minimum adequacy to tolerate being left in place as is
Operating rating110.1 US tons
Inventory rating91.1 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckCorrugated steel
Main spans1
Design loadUnknown
Structure length27 ft (8.2 m)
Longest span26 ft (7.9 m)
Deck width31 ft (9.3 m)
Roadway width29 ft (8.9 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic1,116 (2023)
Projected traffic1,362 by 2043
Trucks1%
Lanes on structure2
Traffic directionTwo-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 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 Mountainside Drive over Mill Brook built?

It was built in 1929, making it 96 years old in 2025. It was reconstructed in 1989.

What condition is Mountainside Drive over Mill 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 July 2023.

How much traffic does Mountainside Drive over Mill Brook carry?

About 1,116 vehicles per day (2023 count), of which roughly 1% are trucks.

How long is Mountainside Drive over Mill Brook?

The structure is 27 ft (8.2 m) long with a longest span of 26 ft (7.9 m) and a deck 31 ft wide.

Who owns Mountainside Drive over Mill Brook?

It is owned by the County Highway Agency.