US Bridges

I-93 US 4 NB over Sewalls Falls Road

Good

Merrimack County, New Hampshire · 1.4 Mi. S. Jct. Rt 3 Byp. · Structure no. 005200680012200

Built
1959
66 years old
Condition
Good
inspected May 2023
Type
Frame
Concrete
Length
41 ft
1 main span
Daily traffic
23,491
2023 count
Owner
State
State Highway Agency

About this bridge

I-93 US 4 NB over Sewalls Falls Road is a concrete frame carrying I-93 US 4 NB over Sewalls Falls Road in Merrimack County, New Hampshire. It was built in 1959, 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 good condition with a lowest component rating of 7 out of 9. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

It carries about 23,491 vehicles a day, roughly 6% of them trucks, projected to reach 34,766 by 2043. The structure is 41 ft (12.5 m) long and 46 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

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CarriesI-93 US 4 NB
CrossesSewalls Falls Road
Location1.4 Mi. S. Jct. Rt 3 Byp.
RouteInterstate 93
CountyMerrimack County
StateNew Hampshire
Coordinates43.27381, -71.56105
Functional classUrban Principal Arterial - Interstate

Condition and inspection

Good

All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

ComponentRatingMeaning
Deck7 GoodSome minor problems.
Superstructure7 GoodSome minor problems.
Substructure7 GoodSome minor problems.
Last inspectionMay 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation7: Better than present minimum criteria
Deck geometry6: Equal to present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating79 US tons
Inventory rating47 US tons

Structure

Structure typeFrame
MaterialConcrete
DeckConcrete, cast-in-place
Main spans1
Design loadHS 20 + Mod
Structure length41 ft (12.5 m)
Longest span35 ft (10.7 m)
Deck width46 ft (14 m)
Roadway width38 ft (11.6 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic23,491 (2023)
Projected traffic34,766 by 2043
Trucks6%
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-93 US 4 NB over Sewalls Falls Road built?

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

What condition is I-93 US 4 NB over Sewalls Falls Road in?

The National Bridge Inventory rates it in good condition. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted. The last reported inspection was in May 2023.

How much traffic does I-93 US 4 NB over Sewalls Falls Road carry?

About 23,491 vehicles per day (2023 count), of which roughly 6% are trucks.

How long is I-93 US 4 NB over Sewalls Falls Road?

The structure is 41 ft (12.5 m) long with a longest span of 35 ft (10.7 m) and a deck 46 ft wide.

Who owns I-93 US 4 NB over Sewalls Falls Road?

It is owned by the State Highway Agency.