ST135 UNION ST
Carrying ST135 UNION ST over WATER SUDBURY RIVER
2.5 MI W OF 126 & 135, Middlesex, Massachusetts
Data updated May 2026
FHWA NBI record, refreshed with each annual release.
Bridge Snapshot: ST135 UNION ST
The ST135 UNION ST bridge in Middlesex, Massachusetts carries ST135 UNION ST over WATER SUDBURY RIVER. It was built in 1900, making it 126 years old today. It was last reconstructed in 1955, extending its service life. The structure is built primarily of steel and spans 1 section, stretching 28.0 meters (92 feet) end to end. Daily traffic averages 11,481 vehicles, placing it in the heavily-trafficked tier of Massachusetts bridges. It is owned and maintained by State Highway Agency.
The latest FHWA inspection records show a deck rating of 5/9, superstructure at 6/9, substructure at 6/9. The weakest component sits in fair condition. All reported major components score above the Poor range. Its NBI inventory load rating is 24.8 metric tons.
Sourced from the FHWA National Bridge Inventory. See our methodology for refresh cadence and NBI release vintage.
How ST135 UNION ST compares
Live comparison across Massachusetts.
Historical Sufficiency Rating
PlainBridge-computedFHWA discontinued this calculated item; it does not determine current condition, funding eligibility, posting, or closure. How the historical reference is calculated.
Condition Ratings
Full 0–9 scale + sufficiency-rating breakdown: how condition ratings work.
Structural Details
- Year Built
- 1900
- Last Reconstructed
- 1955
- Material
- Steel
- Number of Spans
- 1
- Structure Length
- 28.0 m (92 ft)
- Deck Width
- 14.6 m (48 ft)
- Owner
- State Highway Agency
- Avg Daily Traffic
- 11,481 vehicles/day
- Structure Number
- A1400128ADOTNBI
Location
Data Source
FHWA National Bridge Inventory (NBI).
FHWA NBI Program ↗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 fair at 6/9, minor deterioration that routine maintenance should address.
- • The substructure (piers and abutments) rates fair at 6/9, minor deterioration that routine maintenance should address.
How to read this record
This page shows what the last federal inspection recorded, not whether ST135 UNION 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 ST135 UNION ST against other structures in Middlesex and across Massachusetts. Massachusetts 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 ST135 UNION ST?
ST135 UNION ST in Middlesex, Massachusetts has a deck rating of 5/9, superstructure rating of 6/9, and substructure rating of 6/9 on the FHWA's 0–9 scale.
How often is ST135 UNION ST inspected?
ST135 UNION 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 11,481 vehicles per day.
What does “structurally deficient” mean in older bridge reports?
FHWA retired that reported status beginning with the 2018 archive. ST135 UNION 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 ST135 UNION ST?
ST135 UNION ST has an NBI inventory load rating of 24.8 metric tons.
Who is responsible for maintaining ST135 UNION ST?
ST135 UNION ST is owned and maintained by State Highway Agency.
How old is ST135 UNION ST and does age affect safety?
ST135 UNION ST was built in 1900, making it 126 years old and last reconstructed in 1955.
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.
Every figure on PlainBridge is rendered directly from federal source data, no number is typed in by an editor. This page draws directly on federal source data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.