Route 4
Carrying Route 4 over Ajayan River
8.7mi S of RTE4 n RTE4A, Unknown County, Guam
Inventory: FHWA NBI 2024 · last ETL August 2026
FHWA NBI record, refreshed with each annual release.
Route 4 in Unknown County, Guam sits above 4% of rated Guam bridges on inventory load rating (13 t), while its 1968 build year is earlier than 81% of Unknown County's recorded-year cohort (47 bridges).
Route 4 in Unknown County, Guam is rated Poor in the FHWA's 2024 National Bridge Inventory. Built in 1968, it carries 3 rated components on the inspecting agency's 0-9 scale, and its weakest reported component scores 3. The lowest applicable rating sets the federal condition category, so this Poor result describes the weakest reported component rather than the structure as a whole. No NBI category is a closure decision or a live crossing-safety verdict.
NBI record plate
Structure GU:66181000040G011
INTERSTATE-ERA · CONCRETE · SINGLE-SPAN · SUB-LED · ARTERIAL-ADT · LIGHT-LOAD · CAT-POOR
- INTERSTATE-ERA 1950–1979
- CONCRETE Concrete
- SINGLE-SPAN Single span
- SUB-LED Substructure-led
- ARTERIAL-ADT Arterial ADT
- LIGHT-LOAD Light load
- CAT-POOR Poor
Inspection-sheet codes from this record’s year, material family, spans, controlling component, ADT, inventory load, and NBI category, not a live closure verdict.
Bridge Snapshot: Route 4
The Route 4 bridge in Unknown County, Guam carries Route 4 over Ajayan River. It was built in 1968, making it 58 years old today. The structure is built primarily of concrete and spans 1 section, stretching 23.2 meters (76 feet) end to end. Daily traffic averages 3,000 vehicles, placing it in the moderately-trafficked tier of Guam bridges. It is owned and maintained by State Highway Agency.
The latest FHWA inspection records show a deck rating of 5/9, superstructure at 4/9, substructure at 3/9. The weakest component sits in poor condition. At least one major component here scores 4 or below, which produces a Poor condition classification under FHWA's current reporting rules.
How Route 4 compares
Age against the county: built in 1968, earlier than 38 of Unknown County's 47 bridges with a recorded construction year (81%), against a county median build year of 1982. Age is not a defect on its own, but it is the population from which future Poor ratings are drawn.
Live comparison across Guam bridges with a recorded inventory load rating (45 of 47 rated).
Route 4 vs every rated Guam bridge
Inventory load rating (metric tons), FHWA NBI, this state
13 Top 96% higher than 4% of 45 bridges
rated Guam bridges, bucketed by value
Each bar is a band; taller bars hold more bridges. The dashed line + filled bar mark this entry. Hover or tap any bar for its full count and share, and where it sits relative to this entry.
Source FHWA National Bridge Inventory · August 2026
Condition Ratings
Full 0–9 scale + sufficiency-rating breakdown: how condition ratings work.
Reported 0–9 component ratings from the FHWA NBI. The highlighted component is the lowest reported input to this record’s current condition category; it is not a closure or live crossing-safety decision.
Unknown County inventory by recorded NBI category
Exclusive Good/Fair/Poor bands across all 47 bridges in this county. Orthogonal to this structure's component profile above: a county catalog share, not a live crossing-safety verdict.
Structural Details
- Year Built
- 1968
- Material
- Concrete
- Number of Spans
- 1
- Structure Length
- 23.2 m (76 ft)
- Deck Width
- 9.1 m (30 ft)
- Owner
- State Highway Agency
- Avg Daily Traffic
- 3,000 vehicles/day
- Structure Number
- 66181000040G011
Condition Analysis
- • The deck (driving surface) is in fair condition (5/9), with minor deterioration that may require routine maintenance.
- • The superstructure (beams and supports above the deck) rates poor at 4/9, with advanced deterioration recorded on the latest inspection.
- • The substructure (piers and abutments) is in poor condition (3/9), showing advanced deterioration on the inspecting agency's 0-9 scale.
Location
Data Source
FHWA National Bridge Inventory (NBI).
FHWA NBI Program ↗How to read this record
Route 4 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 Route 4 against other structures in Unknown County and across Guam. Guam 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 Route 4?
Route 4 in Unknown County, Guam has a deck rating of 5/9, superstructure rating of 4/9, and substructure rating of 3/9 on the FHWA's 0–9 scale.
How often is Route 4 inspected?
Route 4'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 3,000 vehicles per day.
What does “structurally deficient” mean in older bridge reports?
FHWA retired that reported status beginning with the 2018 archive. Route 4 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 Route 4?
Route 4 has an NBI inventory load rating of 12.6 metric tons.
Who is responsible for maintaining Route 4?
Route 4 is owned and maintained by State Highway Agency.
How old is Route 4 and does age affect safety?
Route 4 was built in 1968, making it 58 years old.
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.
Share this inspection record
Send this source-bounded record or download its data card. An NBI condition category is not a closure or live crossing-safety verdict.
Every figure on PlainBridges is rendered directly from federal source data, no number is typed in by an editor. Component ratings, ADT, and condition category on this page are copied from the NBI record for this structure; no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of 2024 NBI release. NBI condition categories reflect the latest reported inventory record, not a live safety, closure, or travel decision.