US Bridges

I-93 SB over Nh 18 NH135

Fair

Grafton County, New Hampshire · At JCT Nh 18 and Nh 135 · Structure no. 015301170011000

Built
1983
42 years old
Condition
Fair
inspected April 2023
Type
Stringer/Multi-beam or Girder
Steel
Length
99 ft
1 main span
Daily traffic
3,544
2023 count
Owner
State
State Highway Agency

About this bridge

I-93 SB over Nh 18 NH135 is a steel stringer/multi-beam or girder carrying I-93 SB over Nh 18 NH135 in Grafton County, New Hampshire. It was built in 1983, so it is 42 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 3,544 vehicles a day, roughly 9% of them trucks, projected to reach 5,245 by 2043. The structure is 99 ft (30.2 m) long and 45 ft wide.

Location

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CarriesI-93 SB
CrossesNh 18 NH135
LocationAt JCT Nh 18 and Nh 135
RouteInterstate 93
CountyGrafton County
StateNew Hampshire
Coordinates44.32908, -71.87448
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.
Last inspectionApril 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation6: Equal to present minimum criteria
Deck geometry7: Better than present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating65 US tons
Inventory rating39 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckConcrete, cast-in-place
Main spans1
Design loadHS 20 + Mod
Structure length99 ft (30.2 m)
Longest span94 ft (28.7 m)
Deck width45 ft (13.6 m)
Roadway width40 ft (12.3 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic3,544 (2023)
Projected traffic5,245 by 2043
Trucks9%
Lanes on structure2
Traffic directionOne-way traffic
CarriesHighway
CrossesHighway
Detour if closed—
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 SB over Nh 18 NH135 built?

It was built in 1983, making it 42 years old in 2025.

What condition is I-93 SB over Nh 18 NH135 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 April 2023.

How much traffic does I-93 SB over Nh 18 NH135 carry?

About 3,544 vehicles per day (2023 count), of which roughly 9% are trucks.

How long is I-93 SB over Nh 18 NH135?

The structure is 99 ft (30.2 m) long with a longest span of 94 ft (28.7 m) and a deck 45 ft wide.

Who owns I-93 SB over Nh 18 NH135?

It is owned by the State Highway Agency.