US 4 over Smith River
PoorMerrimack County, New Hampshire · 4.6 MI from Wilmot Tl · Structure no. 005801380009400
- Built
- 1929
- 96 years old, rebuilt 1991
- Condition
- Poor
- inspected November 2024
- Type
- Girder and Floorbeam System
- Steel
- Length
- 70 ft
- 1 main span
- Daily traffic
- 2,087
- 2023 count
- Owner
- State
- State Highway Agency
About this bridge
US 4 over Smith River is a steel girder and floorbeam system carrying US 4 over Smith River in Merrimack County, New Hampshire. It was built in 1929 and reconstructed in 1991, so it is 96 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 4 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 2,087 vehicles a day, roughly 4% of them trucks, projected to reach 3,088 by 2043. The structure is 70 ft (21.3 m) long and 27 ft wide. If it were closed, the detour would be 1.2 mi (2 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 | 6 Satisfactory | Structural elements show some minor deterioration. |
| Superstructure | 4 Poor | Advanced section loss, deterioration, spalling or scour. |
| Substructure | 4 Poor | Advanced section loss, deterioration, spalling or scour. |
| Channel and channel protection | 5 Fair | All primary structural elements are sound but may have minor section loss, cracking, spalling or scour. |
Structure
Traffic and service
Ownership and planned work
Frequently asked questions
When was US 4 over Smith River built?
It was built in 1929, making it 96 years old in 2025. It was reconstructed in 1991.
What condition is US 4 over Smith 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 Smith River carry?
About 2,087 vehicles per day (2023 count), of which roughly 4% are trucks.
How long is US 4 over Smith River?
The structure is 70 ft (21.3 m) long with a longest span of 63 ft (19.2 m) and a deck 27 ft wide.
Who owns US 4 over Smith River?
It is owned by the State Highway Agency.