US Bridges

Root Hill Road over Mill Brook

FairPosted for load

Sullivan County, New Hampshire · 1.3 MI Nh 120 · Structure no. 005500810009500

Built
1883
142 years old
Condition
Fair
inspected September 2023
Type
Truss - Thru
Wood or Timber
Length
78 ft
1 main span
Daily traffic
92
2023 count
Owner
City
City or Municipal Highway Agency

About this bridge

Root Hill Road over Mill Brook is a wood or timber truss - thru carrying Root Hill Road over Mill Brook in Sullivan County, New Hampshire. It was built in 1883, so it is 142 years old, older than the New Hampshire average of 56.9 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. Its operating status is: posted for load restriction.

It carries about 92 vehicles a day, roughly 4% of them trucks, projected to reach 136 by 2043. The structure is 78 ft (23.8 m) long and 16 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

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CarriesRoot Hill Road
CrossesMill Brook
Location1.3 MI Nh 120
CountySullivan County
StateNew Hampshire
Coordinates43.4644, -72.36928
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
Deck6 SatisfactoryStructural elements show some minor deterioration.
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 protection7 GoodSome minor problems.
Last inspectionSeptember 2023
Inspection intervalevery 24 months
Operating statusPosted for load restriction
ScourFoundations stable; scour above top of footing
Structural evaluation2: Basically intolerable, requiring high priority of replacement
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 rating6 US tons
Inventory rating4 US tons

Structure

Structure typeTruss - Thru
MaterialWood or Timber
DeckWood or timber
Main spans1
Design loadUnknown
Structure length78 ft (23.8 m)
Longest span62 ft (18.9 m)
Deck width16 ft (4.9 m)
Roadway width13 ft (3.9 m)
Vertical clearance over deck8 ft (2.3 m)

Traffic and service

Average daily traffic92 (2023)
Projected traffic136 by 2043
Trucks4%
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

OwnerCity or Municipal Highway Agency
Maintained byCity or Municipal Highway Agency
Historic statusListed on the National Register of Historic Places
Work proposedReplacement because of substandard load-carrying capacity or roadway geometry
Estimated improvement cost$314,000 (2025 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was Root Hill Road over Mill Brook built?

It was built in 1883, making it 142 years old in 2025.

What condition is Root Hill Road 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 September 2023.

How much traffic does Root Hill Road over Mill Brook carry?

About 92 vehicles per day (2023 count), of which roughly 4% are trucks.

How long is Root Hill Road over Mill Brook?

The structure is 78 ft (23.8 m) long with a longest span of 62 ft (18.9 m) and a deck 16 ft wide.

Who owns Root Hill Road over Mill Brook?

It is owned by the City or Municipal Highway Agency.