Nj 31 over Willoughby Brook

Hunterdon County, New Jersey · rated Fair in the 2025 National Bridge Inventory

United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled August 20, 2026

• Nj 31 over Willoughby Brook in Hunterdon County, New Jersey, is rated in fair condition in the 2025 National Bridge Inventory (as of August 20, 2026).
• Its lowest-rated component is the superstructure, rated 6 (satisfactory condition) on the 0-9 scale.
• It was built in 1930, making it 95 years old at the 2025 inventory.
• It carries about 24,297 vehicles a day (traffic count year 2023).
• Its listed owner is the state highway agency.
• It is one of 272 of the 373 inventoried bridges in Hunterdon County rated fair (72.9%); 26 (7.0%) are rated poor.
• Its traffic status in the 2025 inventory is open, no restriction (NBI item 41).
• Its condition class and component ratings are unchanged from the 2024 inventory.
• Its most recent inspection on record is dated March 2023, on a 24-month routine inspection cycle.
• It is coded scour critical (NBI item 113 = 3): scour critical: foundations unstable for the assessed or calculated scour.
• A fair rating means the lowest-rated major component scores 5 or 6 on FHWA's 0-9 scale: some deterioration or minor section loss, but the structure is sound. It is the middle class, not a warning.

View this bridge on a map → (40.67162, -74.91513)

Component ratings

Bridge details

Source: FHWA National Bridge Inventory, 2025 data as reported by the New Jersey department of transportation.

Busiest bridges in Hunterdon County

All bridges nearby: Hunterdon County, NJ bridge conditions · every bridge in Hunterdon County · New Jersey bridges.

Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.