US Bridges

I-89 NB over Heater Road

Fair

Grafton County, New Hampshire · 0.6 MI from Hardy Hill RD · Structure no. 014401410012300

Built
1966
59 years old
Condition
Fair
inspected June 2023
Type
Stringer/Multi-beam or Girder
Steel
Length
186 ft
3 main spans
Daily traffic
16,261
2023 count
Owner
State
State Highway Agency

About this bridge

I-89 NB over Heater Road is a steel stringer/multi-beam or girder carrying I-89 NB over Heater Road in Grafton County, New Hampshire. It was built in 1966, so it is 59 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 16,261 vehicles a day, roughly 9% of them trucks, projected to reach 24,066 by 2043. The structure is 186 ft (56.7 m) long and 42 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

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CarriesI-89 NB
CrossesHeater Road
Location0.6 MI from Hardy Hill RD
RouteInterstate 89
CountyGrafton County
StateNew Hampshire
Coordinates43.64556, -72.23397
Functional classUrban Principal Arterial - Interstate

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.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Last inspectionJune 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry6: Equal to present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating58 US tons
Inventory rating34.7 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20 + Mod
Structure length186 ft (56.7 m)
Longest span83 ft (25.3 m)
Deck width42 ft (12.9 m)
Roadway width38 ft (11.6 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic16,261 (2023)
Projected traffic24,066 by 2043
Trucks9%
Lanes on structure2
Traffic directionOne-way traffic
CarriesHighway
CrossesHighway
Detour if closed1.2 mi (2 km)
TollOn a free road
National Highway SystemYes
Strategic Highway NetworkInterstate STRAHNET route

Ownership and planned work

OwnerState Highway Agency
Maintained byState Highway Agency
Historic statusNot eligible for the National Register of Historic Places
Work proposedReplacement because of substandard load-carrying capacity or roadway geometry
Estimated improvement cost$314,000 (2025 estimate)
NavigationNot applicable (no waterway)

Frequently asked questions

When was I-89 NB over Heater Road built?

It was built in 1966, making it 59 years old in 2025.

What condition is I-89 NB over Heater Road 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 June 2023.

How much traffic does I-89 NB over Heater Road carry?

About 16,261 vehicles per day (2023 count), of which roughly 9% are trucks.

How long is I-89 NB over Heater Road?

The structure is 186 ft (56.7 m) long with a longest span of 83 ft (25.3 m) and a deck 42 ft wide.

Who owns I-89 NB over Heater Road?

It is owned by the State Highway Agency.