US Bridges

I-93 over Williams Brook

Fair

Merrimack County, New Hampshire · 4.19MI Canterbury Tl · Structure no. 019600990013100

Built
1960
65 years old
Condition
Fair
inspected June 2023
Type
Culvert
Concrete Continuous
Length
23 ft
2 main spans
Daily traffic
30,961
2023 count
Owner
State
State Highway Agency

About this bridge

I-93 over Williams Brook is a concrete continuous culvert carrying I-93 over Williams Brook in Merrimack County, New Hampshire. It was built in 1960, so it is 65 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 30,961 vehicles a day, roughly 9% of them trucks, projected to reach 45,822 by 2043. The structure is 23 ft (7 m) long. If it were closed, the detour would be 1.2 mi (2 km).

Location

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CarriesI-93
CrossesWilliams Brook
Location4.19MI Canterbury Tl
RouteInterstate 93
CountyMerrimack County
StateNew Hampshire
Coordinates43.43084, -71.58813
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
Channel and channel protection7 GoodSome minor problems.
Culvert6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionJune 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation6: Equal to present minimum criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating99 US tons
Inventory rating99 US tons

Structure

Structure typeCulvert
MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans2
Design loadHS 20 + Mod
Structure length23 ft (7 m)
Longest span10 ft (3 m)
Deck width0 ft (0 m)
Roadway width0 ft (0 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic30,961 (2023)
Projected traffic45,822 by 2043
Trucks9%
Lanes on structure4
Traffic directionOne-way traffic
CarriesHighway
CrossesWaterway
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)
NavigationNo navigation control on waterway

Frequently asked questions

When was I-93 over Williams Brook built?

It was built in 1960, making it 65 years old in 2025.

What condition is I-93 over Williams 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 June 2023.

How much traffic does I-93 over Williams Brook carry?

About 30,961 vehicles per day (2023 count), of which roughly 9% are trucks.

How long is I-93 over Williams Brook?

The structure is 23 ft (7 m) long with a longest span of 10 ft (3 m).

Who owns I-93 over Williams Brook?

It is owned by the State Highway Agency.