US Bridges

I-89 SB over Contoocook River

Fair

Merrimack County, New Hampshire · 1.2 MI N.W. JCT Rt 127 · Structure no. 012900920013800

Built
1959
66 years old, rebuilt 1991
Condition
Fair
inspected May 2024
Type
Stringer/Multi-beam or Girder
Steel Continuous
Length
242 ft
3 main spans
Daily traffic
11,574
2023 count
Owner
State
State Highway Agency

About this bridge

I-89 SB over Contoocook River is a steel continuous stringer/multi-beam or girder carrying I-89 SB over Contoocook River in Merrimack County, New Hampshire. It was built in 1959 and reconstructed in 1991, so it is 66 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 6 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 11,574 vehicles a day, roughly 9% of them trucks, projected to reach 17,129 by 2043. The structure is 242 ft (73.8 m) long and 48 ft wide. If it were closed, the detour would be 6.2 mi (10 km).

Location

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CarriesI-89 SB
CrossesContoocook River
Location1.2 MI N.W. JCT Rt 127
RouteInterstate 89
CountyMerrimack County
StateNew Hampshire
Coordinates43.21745, -71.72242
Functional classRural 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
Deck7 GoodSome minor problems.
Superstructure7 GoodSome minor problems.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection7 GoodSome minor problems.
Last inspectionMay 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation6: Equal to present minimum criteria
Deck geometry9: Superior to present desirable criteria
Waterway adequacy9: Superior to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating85.6 US tons
Inventory rating51.3 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel Continuous
DeckConcrete, cast-in-place
Main spans3
Design loadHS 25 or greater
Structure length242 ft (73.8 m)
Longest span90 ft (27.4 m)
Deck width48 ft (14.6 m)
Roadway width44 ft (13.4 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic11,574 (2023)
Projected traffic17,129 by 2043
Trucks9%
Lanes on structure2
Traffic directionOne-way traffic
CarriesHighway
CrossesWaterway
Detour if closed6.2 mi (10 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)
NavigationNo navigation control on waterway

Frequently asked questions

When was I-89 SB over Contoocook River built?

It was built in 1959, making it 66 years old in 2025. It was reconstructed in 1991.

What condition is I-89 SB over Contoocook 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 May 2024.

How much traffic does I-89 SB over Contoocook River carry?

About 11,574 vehicles per day (2023 count), of which roughly 9% are trucks.

How long is I-89 SB over Contoocook River?

The structure is 242 ft (73.8 m) long with a longest span of 90 ft (27.4 m) and a deck 48 ft wide.

Who owns I-89 SB over Contoocook River?

It is owned by the State Highway Agency.