ST IGNACE RD FH84
Carrying ST IGNACE RD FH84 over NUNS CREEK
4.0 MI E OF M-134, Mackinac, Michigan
Inventory: FHWA NBI 2024 · last ETL August 2026
FHWA NBI record, refreshed with each annual release.
ST IGNACE RD FH84 in Mackinac, Michigan sits above 44% of rated Michigan bridges on inventory load rating (37 t), while its 1985 build year is earlier than 17% of Mackinac's recorded-year cohort (63 bridges).
ST IGNACE RD FH84 in Mackinac, Michigan is rated Good in the FHWA's 2024 National Bridge Inventory. Built in 1985, it carries 3 rated components on the inspecting agency's 0-9 scale, and its weakest reported component scores 7. The lowest applicable rating sets the federal condition category, so this Good 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 MI:000000000005978
LATE-CENTURY · PRESTRESS · SINGLE-SPAN · TIED-CTRL · LOCAL-ADT · STANDARD-LOAD · CAT-GOOD
- LATE-CENTURY 1980–1999
- PRESTRESS Prestressed concrete
- SINGLE-SPAN Single span
- TIED-CTRL Tied control
- LOCAL-ADT Local ADT
- STANDARD-LOAD Standard load
- CAT-GOOD Good
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: ST IGNACE RD FH84
The ST IGNACE RD FH84 bridge in Mackinac, Michigan carries ST IGNACE RD FH84 over NUNS CREEK. It was built in 1985, making it 41 years old today. The structure is built primarily of prestressed concrete and spans 1 section, stretching 15.8 meters (52 feet) end to end. Daily traffic averages 220 vehicles, placing it in the lower-traffic tier of Michigan bridges. It is owned and maintained by County Highway Agency.
The latest FHWA inspection records show a deck rating of 7/9, superstructure at 7/9, substructure at 8/9. The weakest component sits in good condition. All reported major components score above the Poor range.
How ST IGNACE RD FH84 compares
Age against the county: built in 1985, earlier than 11 of Mackinac's 63 bridges with a recorded construction year (17%), against a county median build year of 1963. This is one of the newer structures in its county.
Live comparison across Michigan bridges with a recorded inventory load rating (11,366 of 11,371 rated).
ST IGNACE RD FH84 vs every rated Michigan bridge
Inventory load rating (metric tons), FHWA NBI, this state
37 Top 56% higher than 44% of 11,366 bridges
rated Michigan 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.
Mackinac inventory by recorded NBI category
Exclusive Good/Fair/Poor bands across all 63 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
- 1985
- Material
- Prestressed Concrete
- Number of Spans
- 1
- Structure Length
- 15.8 m (52 ft)
- Deck Width
- 9.6 m (31 ft)
- Owner
- County Highway Agency
- Avg Daily Traffic
- 220 vehicles/day
- Structure Number
- 000000000005978
Condition Analysis
- • At 7/9, the deck (driving surface) is in good shape and shows no significant wear.
- • The superstructure (beams and supports above the deck) is in good condition (7/9), showing no significant deterioration.
- • At 8/9, the substructure (piers and abutments) is in good shape and shows no significant wear.
Location
Data Source
FHWA National Bridge Inventory (NBI).
FHWA NBI Program ↗How to read this record
This page shows what the last federal inspection recorded, not whether ST IGNACE RD FH84 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 ST IGNACE RD FH84 against other structures in Mackinac and across Michigan. Michigan 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 ST IGNACE RD FH84?
ST IGNACE RD FH84 in Mackinac, Michigan has a deck rating of 7/9, superstructure rating of 7/9, and substructure rating of 8/9 on the FHWA's 0–9 scale.
How often is ST IGNACE RD FH84 inspected?
ST IGNACE RD FH84'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 220 vehicles per day.
What does “structurally deficient” mean in older bridge reports?
FHWA retired that reported status beginning with the 2018 archive. ST IGNACE RD FH84 is currently shown as Good condition from its component ratings; that category is not a live closure or safety decision.
What is the inventory load rating for ST IGNACE RD FH84?
ST IGNACE RD FH84 has an NBI inventory load rating of 37.3 metric tons.
Who is responsible for maintaining ST IGNACE RD FH84?
ST IGNACE RD FH84 is owned and maintained by County Highway Agency.
How old is ST IGNACE RD FH84 and does age affect safety?
ST IGNACE RD FH84 was built in 1985, making it 41 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.