171ST ST
Carrying 171ST ST over MIDLOTHIAN CREEK
0.03 MI. W 80TH AV, Cook, Illinois
Inventory: FHWA NBI 2024 · last ETL August 2026
FHWA NBI record, refreshed with each annual release.
171ST ST in Cook, Illinois sits above 14% of rated Illinois bridges on inventory load rating (26 t), while its 1951 build year is earlier than 80% of Cook's recorded-year cohort (1,721 bridges).
171ST ST in Cook, Illinois is rated Fair in the FHWA's 2024 National Bridge Inventory. Built in 1951, it carries 1 rated component on the inspecting agency's 0-9 scale, and its weakest reported component scores 5. The lowest applicable rating sets the federal condition category, so this Fair 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 IL:016326700000000
INTERSTATE-ERA · CONCRETE · MULTI-SPAN · CULVERT-LED · HEAVY-ADT · STANDARD-LOAD · CAT-FAIR
- INTERSTATE-ERA 1950–1979
- CONCRETE Concrete
- MULTI-SPAN 2 spans
- CULVERT-LED Culvert-led
- HEAVY-ADT Heavy ADT
- STANDARD-LOAD Standard load
- CAT-FAIR Fair
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: 171ST ST
The 171ST ST bridge in Cook, Illinois carries 171ST ST over MIDLOTHIAN CREEK. It was built in 1951, making it 75 years old today. It was last reconstructed in 1991, extending its service life. The structure is built primarily of concrete continuous and spans 2 sections, stretching 6.9 meters (23 feet) end to end. Daily traffic averages 16,400 vehicles, placing it in the heavily-trafficked tier of Illinois bridges. It is owned and maintained by County Highway Agency.
The latest FHWA inspection records show culvert at 5/9. The weakest component sits in fair condition. None of this bridge's reported major components fall into the Poor condition range.
How 171ST ST compares
Age against the county: built in 1951, earlier than 1,374 of Cook's 1,721 bridges with a recorded construction year (80%), against a county median build year of 1962. Age is not a defect on its own, but it is the population from which future Poor ratings are drawn.
Live comparison across Illinois bridges with a recorded inventory load rating (26,904 of 26,928 rated).
171ST ST vs every rated Illinois bridge
Inventory load rating (metric tons), FHWA NBI, this state
26 Top 86% higher than 14% of 26,904 bridges
rated Illinois 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.
Cook inventory by recorded NBI category
Exclusive Good/Fair/Poor bands across all 1,721 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
- 1951
- Last Reconstructed
- 1991
- Material
- Concrete Continuous
- Number of Spans
- 2
- Structure Length
- 6.9 m (23 ft) 0
- Owner
- County Highway Agency
- Avg Daily Traffic
- 16,400 vehicles/day
- Structure Number
- 016326700000000
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 171ST ST 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 171ST ST against other structures in Cook and across Illinois. Illinois 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 171ST ST?
171ST ST in Cook, Illinois on the FHWA's 0–9 scale.
How often is 171ST ST inspected?
171ST ST'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 16,400 vehicles per day.
What does “structurally deficient” mean in older bridge reports?
FHWA retired that reported status beginning with the 2018 archive. 171ST ST 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 171ST ST?
171ST ST has an NBI inventory load rating of 25.9 metric tons.
Who is responsible for maintaining 171ST ST?
171ST ST is owned and maintained by County Highway Agency.
How old is 171ST ST and does age affect safety?
171ST ST was built in 1951, making it 75 years old and last reconstructed in 1991.
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.