US Bridges

Greenhill Road over Isinglass River

Fair

Strafford County, New Hampshire · 3.1 MI FR Dover Tl · Structure no. 001501090016200

Built
1955
70 years old
Condition
Fair
inspected September 2023
Type
Stringer/Multi-beam or Girder
Steel
Length
66 ft
1 main span
Daily traffic
2,078
2023 count
Owner
City
City or Municipal Highway Agency

About this bridge

Greenhill Road over Isinglass River is a steel stringer/multi-beam or girder carrying Greenhill Road over Isinglass River in Strafford County, New Hampshire. It was built in 1955, so it is 70 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.

It carries about 2,078 vehicles a day, roughly 4% of them trucks, projected to reach 3,075 by 2043. The structure is 66 ft (20.1 m) long and 20 ft wide. If it were closed, the detour would be 1.9 mi (3 km).

Location

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CarriesGreenhill Road
CrossesIsinglass River
Location3.1 MI FR Dover Tl
CountyStrafford County
StateNew Hampshire
Coordinates43.2462, -71.00377
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
Deck5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Superstructure7 GoodSome minor problems.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection7 GoodSome minor problems.
Last inspectionSeptember 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation6: Equal to present minimum criteria
Deck geometry2: Basically intolerable, requiring high priority of replacement
Waterway adequacy9: Superior to present desirable criteria
Approach roadway alignment6: Equal to present minimum criteria
Operating rating38 US tons
Inventory rating26 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckConcrete, cast-in-place
Main spans1
Design loadHS 15
Structure length66 ft (20.1 m)
Longest span62 ft (18.9 m)
Deck width20 ft (6 m)
Roadway width18 ft (5.5 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic2,078 (2023)
Projected traffic3,075 by 2043
Trucks4%
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

OwnerCity or Municipal Highway Agency
Maintained byCity or Municipal Highway Agency
Historic statusPossibly eligible for the National Register; requires further investigation
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 Greenhill Road over Isinglass River built?

It was built in 1955, making it 70 years old in 2025.

What condition is Greenhill Road over Isinglass 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 September 2023.

How much traffic does Greenhill Road over Isinglass River carry?

About 2,078 vehicles per day (2023 count), of which roughly 4% are trucks.

How long is Greenhill Road over Isinglass River?

The structure is 66 ft (20.1 m) long with a longest span of 62 ft (18.9 m) and a deck 20 ft wide.

Who owns Greenhill Road over Isinglass River?

It is owned by the City or Municipal Highway Agency.