I-89 SB
Carrying I-89 SB over TURKEY POND
1.5 MI NW JCT RT 13, Merrimack, New Hampshire
Data updated May 2026
FHWA NBI record, refreshed with each annual release.
Bridge Snapshot: I-89 SB
The I-89 SB bridge in Merrimack, New Hampshire carries I-89 SB over TURKEY POND. It was built in 1959, making it 67 years old today. It was last reconstructed in 1992, extending its service life. The structure is built primarily of steel and spans 3 sections, stretching 73.2 meters (240 feet) end to end. Daily traffic averages 19,873 vehicles, placing it in the heavily-trafficked tier of New Hampshire bridges. It is owned and maintained by State Highway Agency.
The latest FHWA inspection records show a deck rating of 7/9, superstructure at 7/9, substructure at 4/9. The weakest component sits in poor condition. A component scored 4 or below, placing this bridge in the federal Poor condition category rather than declaring it unsafe or closed. Its NBI inventory load rating is 47.4 metric tons.
Sourced from the FHWA National Bridge Inventory. See our methodology for refresh cadence and NBI release vintage.
How I-89 SB compares
Live comparison across New Hampshire.
Historical Sufficiency Rating
PlainBridge-computedFHWA discontinued this calculated item; it does not determine current condition, funding eligibility, posting, or closure. How the historical reference is calculated.
Condition Ratings
Full 0–9 scale + sufficiency-rating breakdown: how condition ratings work.
Structural Details
- Year Built
- 1959
- Last Reconstructed
- 1992
- Material
- Steel
- Number of Spans
- 3
- Structure Length
- 73.2 m (240 ft)
- Deck Width
- 17.4 m (57 ft)
- Owner
- State Highway Agency
- Avg Daily Traffic
- 19,873 vehicles/day
- Structure Number
- 005201650002900
Location
Data Source
FHWA National Bridge Inventory (NBI).
FHWA NBI Program ↗Condition Analysis
- • At 7/9, the deck (driving surface) is in good shape and shows no significant wear.
- • At 7/9, the superstructure (beams and supports above the deck) is in good shape and shows no significant wear.
- • At 4/9, the substructure (piers and abutments) is in poor shape, with advanced wear flagged for priority repair.
How to read this record
I-89 SB is in the federal Poor condition category. That is a component-based result, not a closure order.
- NBI condition ratings reflect the latest record in this annual dataset, not a live status. Current routine inspection intervals are risk-based.
- Understand what Poor condition does and does not mean before drawing conclusions. Poor condition explained
- Compare I-89 SB against other structures in Merrimack and across New Hampshire. New Hampshire bridges
- Noticed visible damage or a safety concern? Report it to the agency that owns the bridge, or call 911 in an emergency. How to report a bridge
Condition codes come straight from the FHWA National Bridge Inventory and are not a real-time safety judgment. Only the owning agency, a state DOT, county, or other owner, can post, restrict, or close a bridge.
Frequently Asked Questions
What do the condition ratings mean for I-89 SB?
I-89 SB in Merrimack, New Hampshire has a deck rating of 7/9, superstructure rating of 7/9, and substructure rating of 4/9 on the FHWA's 0–9 scale.
How often is I-89 SB inspected?
I-89 SB's responsible agency sets its routine interval under FHWA's risk-based inspection rules; this page does not expose the scheduled interval. It carries about 19,873 vehicles per day.
What does “structurally deficient” mean in older bridge reports?
FHWA retired that reported status beginning with the 2018 archive. I-89 SB is currently shown as Poor condition from its component ratings; that category is not a live closure or safety decision.
What is the inventory load rating for I-89 SB?
I-89 SB has an NBI inventory load rating of 47.4 metric tons.
Who is responsible for maintaining I-89 SB?
I-89 SB is owned and maintained by State Highway Agency.
How old is I-89 SB and does age affect safety?
I-89 SB was built in 1959, making it 67 years old and last reconstructed in 1992.
Disclaimer: Bridge condition data is from the FHWA NBI and reflects the last reported inspection. A Poor condition rating is not a live declaration that a bridge is closed or unsafe for travel. For current closure, posting, or safety information, contact the responsible transportation agency.
Every figure on PlainBridge is rendered directly from federal source data, no number is typed in by an editor. This page draws directly on federal source data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.