SH 170 ML
Carrying SH 170 ML over DAVIDSON DITCH
1.5 MI W OF JCT SH 93, Boulder, Colorado
Inventory: FHWA NBI 2024 · last ETL August 2026
FHWA NBI record, refreshed with each annual release.
SH 170 ML in Boulder, Colorado sits above 20% of rated Colorado bridges on inventory load rating (25 t), while its 1952 build year is earlier than 92% of Boulder's recorded-year cohort (311 bridges).
SH 170 ML in Boulder, Colorado is rated Fair in the FHWA's 2024 National Bridge Inventory. Built in 1952, it carries 1 rated component on the inspecting agency's 0-9 scale, and its weakest reported component scores 6. 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 CO:E-15-AB
INTERSTATE-ERA · CONCRETE · SINGLE-SPAN · CULVERT-LED · ARTERIAL-ADT · STANDARD-LOAD · CAT-FAIR
- INTERSTATE-ERA 1950–1979
- CONCRETE Concrete
- SINGLE-SPAN Single span
- CULVERT-LED Culvert-led
- ARTERIAL-ADT Arterial 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: SH 170 ML
The SH 170 ML bridge in Boulder, Colorado carries SH 170 ML over DAVIDSON DITCH. It was built in 1952, making it 74 years old today. The structure is built primarily of concrete and spans 1 section, stretching 7.3 meters (24 feet) end to end. Daily traffic averages 1,200 vehicles, placing it in the moderately-trafficked tier of Colorado bridges. It is owned and maintained by State Highway Agency.
The latest FHWA inspection records show culvert at 6/9. The weakest component sits in fair condition. None of this bridge's reported major components fall into the Poor condition range.
How SH 170 ML compares
Age against the county: built in 1952, earlier than 285 of Boulder's 311 bridges with a recorded construction year (92%), against a county median build year of 1990. Age is not a defect on its own, but it is the population from which future Poor ratings are drawn.
Live comparison across Colorado bridges with a recorded inventory load rating (8,962 of 8,965 rated).
SH 170 ML vs every rated Colorado bridge
Inventory load rating (metric tons), FHWA NBI, this state
25 Top 80% higher than 20% of 8,962 bridges
rated Colorado 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.
Boulder inventory by recorded NBI category
Exclusive Good/Fair/Poor bands across all 311 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
- 1952
- Material
- Concrete
- Number of Spans
- 1
- Structure Length
- 7.3 m (24 ft)
- Deck Width
- 14.0 m (46 ft)
- Owner
- State Highway Agency
- Avg Daily Traffic
- 1,200 vehicles/day
- Structure Number
- E-15-AB
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 SH 170 ML 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 SH 170 ML against other structures in Boulder and across Colorado. Colorado 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 SH 170 ML?
SH 170 ML in Boulder, Colorado on the FHWA's 0–9 scale.
How often is SH 170 ML inspected?
SH 170 ML'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 1,200 vehicles per day.
What does “structurally deficient” mean in older bridge reports?
FHWA retired that reported status beginning with the 2018 archive. SH 170 ML 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 SH 170 ML?
SH 170 ML has an NBI inventory load rating of 25.4 metric tons.
Who is responsible for maintaining SH 170 ML?
SH 170 ML is owned and maintained by State Highway Agency.
How old is SH 170 ML and does age affect safety?
SH 170 ML was built in 1952, making it 74 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.