T-420
Carrying T-420 over KISH. CREEK
500FT E INTER LR29&T-420, Mifflin, Pennsylvania
Inventory: FHWA NBI 2024 · last ETL August 2026
FHWA NBI record, refreshed with each annual release.
T-420 in Mifflin, Pennsylvania sits above 1% of rated Pennsylvania bridges on inventory load rating (0 t), while its 1909 build year is earlier than 98% of Mifflin's recorded-year cohort (196 bridges).
T-420 in Mifflin, Pennsylvania is rated Poor in the FHWA's 2024 National Bridge Inventory. Built in 1909, it carries 2 rated components on the inspecting agency's 0-9 scale, and its weakest reported component scores 0. 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 PA:000000000026631
PRE-1950 · CONCRETE · MULTI-SPAN · SUPER-LED · ADT-UNK · TRACE-LOAD · CAT-POOR
- PRE-1950 Pre-1950
- CONCRETE Concrete
- MULTI-SPAN 3 spans
- SUPER-LED Superstructure-led
- ADT-UNK ADT unknown
- TRACE-LOAD Trace 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: T-420
The T-420 bridge in Mifflin, Pennsylvania carries T-420 over KISH. CREEK. It was built in 1909, making it 117 years old today. The structure is built primarily of concrete and spans 3 sections, stretching 60.0 meters (197 feet) end to end. Average daily traffic is not reported for this structure. It is owned and maintained by County Highway Agency.
The latest FHWA inspection records show superstructure at 0/9, substructure at 4/9. The weakest component sits in critical condition. A component scored 4 or below, placing this bridge in the federal Poor condition category rather than declaring it unsafe or closed.
How T-420 compares
Age against the county: built in 1909, earlier than 193 of Mifflin's 196 bridges with a recorded construction year (98%), against a county median build year of 1975. Age is not a defect on its own, but it is the population from which future Poor ratings are drawn.
Live comparison across Pennsylvania bridges with a recorded inventory load rating (23,297 of 23,299 rated).
T-420 vs every rated Pennsylvania bridge
Inventory load rating (metric tons), FHWA NBI, this state
0 Top 99% higher than 1% of 23,297 bridges
rated Pennsylvania 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.
Mifflin inventory by recorded NBI category
Exclusive Good/Fair/Poor bands across all 196 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
- 1909
- Material
- Concrete
- Number of Spans
- 3
- Structure Length
- 60.0 m (197 ft)
- Deck Width
- 5.0 m (16 ft)
- Owner
- County Highway Agency
- Structure Number
- 000000000026631
Condition Analysis
- • At 0/9, the superstructure (beams and supports above the deck) is in critical shape, with severe wear recorded for this vintage.
- • At 4/9, the substructure (piers and abutments) is in poor shape, with advanced wear on file for this vintage.
Location
Data Source
FHWA National Bridge Inventory (NBI).
FHWA NBI Program ↗How to read this record
T-420 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 T-420 against other structures in Mifflin and across Pennsylvania. Pennsylvania 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 T-420?
T-420 in Mifflin, Pennsylvania, superstructure rating of 0/9, and substructure rating of 4/9 on the FHWA's 0–9 scale.
How often is T-420 inspected?
T-420's responsible agency sets its routine interval under FHWA's risk-based inspection rules; this page does not expose the scheduled interval.
What does “structurally deficient” mean in older bridge reports?
FHWA retired that reported status beginning with the 2018 archive. T-420 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 T-420?
T-420 has an NBI inventory load rating of 0.0 metric tons.
Who is responsible for maintaining T-420?
T-420 is owned and maintained by County Highway Agency.
How old is T-420 and does age affect safety?
T-420 was built in 1909, making it 117 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.