US 4 over Blackwater River
PoorMerrimack County, New Hampshire · 0.3 MI from Salisbury Tl · Structure no. 000801430007700
- Built
- 1933
- 92 years old
- Condition
- Poor
- inspected November 2024
- Type
- Girder and Floorbeam System
- Steel
- Length
- 75 ft
- 1 main span
- Daily traffic
- 2,652
- 2023 count
- Owner
- State
- State Highway Agency
About this bridge
US 4 over Blackwater River is a steel girder and floorbeam system carrying US 4 over Blackwater River in Merrimack County, New Hampshire. It was built in 1933, so it is 92 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 poor condition with a lowest component rating of 3 out of 9. The lowest-rated primary component is rated 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions.
It carries about 2,652 vehicles a day, roughly 4% of them trucks, projected to reach 3,924 by 2043. The structure is 75 ft (22.9 m) long and 27 ft wide. If it were closed, the detour would be 16.2 mi (26 km).
Location
Open in Google MapsCondition and inspection
The lowest-rated primary component is rated 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions.
| Component | Rating | Meaning |
|---|---|---|
| Deck | 4 Poor | Advanced section loss, deterioration, spalling or scour. |
| Superstructure | 3 Serious | Loss of section, deterioration, spalling or scour have seriously affected primary structural components. |
| Substructure | 5 Fair | All primary structural elements are sound but may have minor section loss, cracking, spalling or scour. |
| Channel and channel protection | 7 Good | Some minor problems. |
Structure
Traffic and service
Ownership and planned work
Frequently asked questions
When was US 4 over Blackwater River built?
It was built in 1933, making it 92 years old in 2025.
What condition is US 4 over Blackwater River in?
The National Bridge Inventory rates it in poor condition. The lowest-rated primary component is rated 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions. The last reported inspection was in November 2024.
How much traffic does US 4 over Blackwater River carry?
About 2,652 vehicles per day (2023 count), of which roughly 4% are trucks.
How long is US 4 over Blackwater River?
The structure is 75 ft (22.9 m) long with a longest span of 67 ft (20.4 m) and a deck 27 ft wide.
Who owns US 4 over Blackwater River?
It is owned by the State Highway Agency.