US Bridges

Nh 31 over Blood Brook

Fair

Hillsborough County, New Hampshire · 0.2 MI from JCT RTE 101 · Structure no. 027701020009500

Built
1937
88 years old
Condition
Fair
inspected April 2024
Type
Frame
Concrete
Length
46 ft
1 main span
Daily traffic
4,387
2023 count
Owner
State
State Highway Agency

About this bridge

Nh 31 over Blood Brook is a concrete frame carrying Nh 31 over Blood Brook in Hillsborough County, New Hampshire. It was built in 1937, so it is 88 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 4,387 vehicles a day, roughly 4% of them trucks, projected to reach 6,492 by 2043. The structure is 46 ft (14 m) long and 30 ft wide. If it were closed, the detour would be 11.2 mi (18 km).

Location

Open in Google Maps
CarriesNh 31
CrossesBlood Brook
Location0.2 MI from JCT RTE 101
RouteState Highway 31
CountyHillsborough County
StateNew Hampshire
Coordinates42.82208, -71.76703
Functional classUrban Collector

Condition and inspection

Fair

The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.

ComponentRatingMeaning
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure7 GoodSome minor problems.
Channel and channel protection7 GoodSome minor problems.
Last inspectionApril 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation6: Equal to present minimum criteria
Deck geometry3: Basically intolerable, requiring high priority of corrective action
Waterway adequacy7: Better than present minimum criteria
Approach roadway alignment7: Better than present minimum criteria
Operating rating61.4 US tons
Inventory rating27.7 US tons

Structure

Structure typeFrame
MaterialConcrete
DeckConcrete, cast-in-place
Main spans1
Design loadH 15
Structure length46 ft (14 m)
Longest span40 ft (12.2 m)
Deck width30 ft (9.1 m)
Roadway width26 ft (7.9 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic4,387 (2023)
Projected traffic6,492 by 2043
Trucks4%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed11.2 mi (18 km)
TollOn a free road
National Highway SystemNo

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)
NavigationNo navigation control on waterway

Frequently asked questions

When was Nh 31 over Blood Brook built?

It was built in 1937, making it 88 years old in 2025.

What condition is Nh 31 over Blood 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 April 2024.

How much traffic does Nh 31 over Blood Brook carry?

About 4,387 vehicles per day (2023 count), of which roughly 4% are trucks.

How long is Nh 31 over Blood Brook?

The structure is 46 ft (14 m) long with a longest span of 40 ft (12.2 m) and a deck 30 ft wide.

Who owns Nh 31 over Blood Brook?

It is owned by the State Highway Agency.