US Bridges

NH101 over Thorntons Ferry Road

Fair

Hillsborough County, New Hampshire · 2.3 MI Milford Tl · Structure no. 000701460011000

Built
1971
54 years old
Condition
Fair
inspected June 2023
Type
Stringer/Multi-beam or Girder
Steel
Length
84 ft
1 main span
Daily traffic
11,884
2023 count
Owner
State
State Highway Agency

About this bridge

NH101 over Thorntons Ferry Road is a steel stringer/multi-beam or girder carrying NH101 over Thorntons Ferry Road in Hillsborough County, New Hampshire. It was built in 1971, so it is 54 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 5 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 11,884 vehicles a day, roughly 7% of them trucks, projected to reach 17,588 by 2043. The structure is 84 ft (25.6 m) long and 47 ft wide. If it were closed, the detour would be 1.9 mi (3 km).

Location

Open in Google Maps
CarriesNH101
CrossesThorntons Ferry Road
Location2.3 MI Milford Tl
RouteState Highway 101
CountyHillsborough County
StateNew Hampshire
Coordinates42.8581, -71.61152
Functional classUrban Other Principal Arterial

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.
Superstructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Substructure7 GoodSome minor problems.
Last inspectionJune 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Approach roadway alignment8: Equal to present desirable criteria
Operating rating44.3 US tons
Inventory rating26.5 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckConcrete, cast-in-place
Main spans1
Design loadHS 20 + Mod
Structure length84 ft (25.6 m)
Longest span80 ft (24.4 m)
Deck width47 ft (14.3 m)
Roadway width43 ft (13.1 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic11,884 (2023)
Projected traffic17,588 by 2043
Trucks7%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesHighway
Detour if closed1.9 mi (3 km)
TollOn a free road
National Highway SystemYes

Ownership and planned work

OwnerState Highway Agency
Maintained byState Highway Agency
Historic statusPossibly eligible for the National Register; requires further investigation
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 NH101 over Thorntons Ferry Road built?

It was built in 1971, making it 54 years old in 2025.

What condition is NH101 over Thorntons Ferry Road 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 NH101 over Thorntons Ferry Road carry?

About 11,884 vehicles per day (2023 count), of which roughly 7% are trucks.

How long is NH101 over Thorntons Ferry Road?

The structure is 84 ft (25.6 m) long with a longest span of 80 ft (24.4 m) and a deck 47 ft wide.

Who owns NH101 over Thorntons Ferry Road?

It is owned by the State Highway Agency.