PORTER ROAD
Carrying PORTER ROAD over WILD AMMONOOSUC RIVER
340 FEET FR NH 112, Grafton, New Hampshire
Data updated May 2026
FHWA NBI record, refreshed with each annual release.
Bridge Snapshot: PORTER ROAD
The PORTER ROAD bridge in Grafton, New Hampshire carries PORTER ROAD over WILD AMMONOOSUC RIVER. It was built in 1849, making it 177 years old today. It was last reconstructed in 1999, extending its service life. The structure is built primarily of wood or timber and spans 2 sections, stretching 48.8 meters (160 feet) end to end. Daily traffic averages 618 vehicles, placing it in the lower-traffic tier of New Hampshire bridges. It is owned and maintained by City/Municipal Highway Agency.
The latest FHWA inspection records show a deck rating of 6/9, superstructure at 5/9, substructure at 6/9. The weakest component sits in fair condition. None of this bridge's reported major components fall into the Poor condition range. Its NBI inventory load rating is 7.3 metric tons.
Sourced from the FHWA National Bridge Inventory. See our methodology for refresh cadence and NBI release vintage.
How PORTER ROAD 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 How the historical reference is calculated.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
- 1849
- Last Reconstructed
- 1999
- Material
- Wood or Timber
- Number of Spans
- 2
- Structure Length
- 48.8 m (160 ft)
- Deck Width
- 5.2 m (17 ft)
- Owner
- City/Municipal Highway Agency
- Avg Daily Traffic
- 618 vehicles/day
- Structure Number
- 001801630005300
Location
Data Source
FHWA National Bridge Inventory (NBI).
FHWA NBI Program ↗Condition Analysis
- • At 6/9, the deck (driving surface) shows fair condition, with minor wear flagged for upkeep.
- • The superstructure (beams and supports above the deck) is in fair condition (5/9), with minor deterioration that may require routine maintenance.
- • The substructure (piers and abutments) is in fair condition (6/9), with minor deterioration that may require routine maintenance.
How to read this record
This page shows what the last federal inspection recorded, not whether PORTER ROAD is safe to cross today. Here is how to use it.
- NBI condition ratings reflect the latest record in this annual dataset, not a live status. Current routine inspection intervals are risk-based.
- Learn how the 0–9 condition scale and Good/Fair/Poor categories are defined. How condition ratings work
- Compare PORTER ROAD against other structures in Grafton 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 PORTER ROAD?
PORTER ROAD in Grafton, New Hampshire has a deck rating of 6/9, superstructure rating of 5/9, and substructure rating of 6/9 on the FHWA's 0–9 scale.
How often is PORTER ROAD inspected?
PORTER ROAD'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 618 vehicles per day.
What does “structurally deficient” mean in older bridge reports?
FHWA retired that reported status beginning with the 2018 archive. PORTER ROAD is currently shown as Fair condition from its component ratings; that category is not a live closure or safety decision.
What is the inventory load rating for PORTER ROAD?
PORTER ROAD has an NBI inventory load rating of 7.3 metric tons.
Who is responsible for maintaining PORTER ROAD?
PORTER ROAD is owned and maintained by City/Municipal Highway Agency.
How old is PORTER ROAD and does age affect safety?
PORTER ROAD was built in 1849, making it 177 years old and last reconstructed in 1999.
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.