US Bridges

I-393 US 4 US202 over Merrimack River

Fair

Merrimack County, New Hampshire · 0.6 MI East of JCT I-93 · Structure no. 005201540012300

Built
1978
47 years old, rebuilt 2003
Condition
Fair
inspected August 2023
Type
Stringer/Multi-beam or Girder
Steel Continuous
Length
525 ft
3 main spans
Daily traffic
40,527
2023 count
Owner
State
State Highway Agency

About this bridge

I-393 US 4 US202 over Merrimack River is a steel continuous stringer/multi-beam or girder carrying I-393 US 4 US202 over Merrimack River in Merrimack County, New Hampshire. It was built in 1978 and reconstructed in 2003, so it is 47 years old, younger 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 40,527 vehicles a day, roughly 6% of them trucks, projected to reach 59,979 by 2043. The structure is 525 ft (160 m) long and 92 ft wide. If it were closed, the detour would be 3.1 mi (5 km).

Location

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CarriesI-393 US 4 US202
CrossesMerrimack River
Location0.6 MI East of JCT I-93
RouteInterstate 393
CountyMerrimack County
StateNew Hampshire
Coordinates43.2195, -71.52335
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
Deck7 GoodSome minor problems.
Superstructure7 GoodSome minor problems.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection7 GoodSome minor problems.
Last inspectionAugust 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation6: Equal to present minimum criteria
Deck geometry7: Better than present minimum criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating78.2 US tons
Inventory rating46.6 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel Continuous
DeckConcrete, precast panels
Main spans3
Design loadHS 20 + Mod
Structure length525 ft (160 m)
Longest span200 ft (61 m)
Deck width92 ft (28 m)
Roadway width84 ft (25.6 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic40,527 (2023)
Projected traffic59,979 by 2043
Trucks6%
Lanes on structure5
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed3.1 mi (5 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-393 US 4 US202 over Merrimack River built?

It was built in 1978, making it 47 years old in 2025. It was reconstructed in 2003.

What condition is I-393 US 4 US202 over Merrimack 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 August 2023.

How much traffic does I-393 US 4 US202 over Merrimack River carry?

About 40,527 vehicles per day (2023 count), of which roughly 6% are trucks.

How long is I-393 US 4 US202 over Merrimack River?

The structure is 525 ft (160 m) long with a longest span of 200 ft (61 m) and a deck 92 ft wide.

Who owns I-393 US 4 US202 over Merrimack River?

It is owned by the State Highway Agency.