Total bridges
449
Public highway bridges in Dauphin County
County profile · official public datasets
Dauphin County, PA
449 public highway bridges tracked in the FHWA National Bridge Inventory: 22% rated Good, 69.5% Fair, 8.5% Poor.
- 449
- Public bridges
- 22%
- Good condition
- 8.5%
- Poor condition
The verdict
According to the Federal Highway Administration's 2024 National Bridge Inventory.
Dauphin County posts a top-quartile lowest Poor-condition share among rated counties in the state across mid-size county bridge inventory.
- Top 25%
- lowest Poor share in state
- 8.5%
- Poor-condition share
- 449
- public highway bridges
- 1972
- avg year built
Poor is an FHWA condition category from the lowest applicable component rating (4 or below), not a live crossing-safety or closure decision. Rankings cover counties with at least five public highway bridges.
Dauphin County Bridge Snapshot
According to the Federal Highway Administration's 2024 National Bridge Inventory, Dauphin County ranks #17 of 67 Pennsylvania counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 8.5%). Dauphin County, Pennsylvania contains 449 public highway bridges. Roughly 22% are rated “Good,” 69.5% “Fair,” and 8.5% “Poor.” Poor means the lowest applicable deck, superstructure, substructure, or culvert rating is 4 or below on the 0–9 NBI scale. It is a condition category, not a live safety or closure decision.
Responsible agencies inspect covered bridges on risk-based intervals under current NBIS rules and submit inventory data to FHWA annually. The list below shows every NBI-tracked bridge in the county. Use the “Sort by” controls to change the ordering, and click any row for its reported inspection date, traffic count, and condition fields.
Source: FHWA National Bridge Inventory. See methodology for full definitions.
Good condition
22%
99 of 449 rated 7-9
Fair condition
69.5%
312 of 449 rated 5-6
Poor condition
8.5%
38 of 449 rated 4 or below
In-state Poor-share rank
#17 of 67
Among Pennsylvania counties with 5+ bridges, lower share ranks better
Condition distribution
Share of 449 NBI-tracked bridges by lowest applicable component rating.
Good 22% (99)
Fair 69.5% (312)
Poor 8.5% (38)
Dauphin County's Poor-condition bridges carry 282,999 vehicle crossings a day
That is 5.1% of the county's reported daily bridge traffic on 8.3% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 7,649 crossings a day against 11,791 for a Good-condition one. A Poor rating is a condition category, not a closure or a live safety judgement; it means the lowest applicable component rating is 4 or below.
Computed over the 446 of 449 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.
56.6% of Dauphin County's bridges have passed the 50-year mark
254 of the 449 bridges with a recorded construction year were built in 1974 or earlier. Age alone is not a defect: a well-maintained older bridge can rate Good, and 22% of this county's inventory does. Even so, this older cohort is the population from which future Poor ratings are drawn, which is why the age profile below matters alongside the condition split above.
Cutoff derives from the 2024 release year minus a 50-year design life. Source: FHWA National Bridge Inventory, 2024 release.
One structure carries 30.1% of the county's Poor-condition bridge traffic
SR 0083; I-83 over SUSQ.RIVER;R.R.LOWTHER S, built 1960, carries 85,221 vehicles a day, the most of any Poor-rated structure here. The county's Poor-condition exposure is concentrated rather than evenly spread, so the 38-bridge count understates how much of the daily burden sits on a single crossing.
Share is of the 282,999 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.
When Dauphin County's bridges were built
449 bridges with a recorded construction year, grouped by decade
- pre-1900 2
Built before 1900
2 bridges
- 1900s 5
1900–1909
5 bridges
- 1910s 7
1910–1919
7 bridges
- 1920s 16
1920–1929
16 bridges
- 1930s 17
1930–1939
17 bridges
- 1940s 28
1940–1949
28 bridges
- 1950s 26
1950–1959
26 bridges
- 1960s
1960–1969
84 bridges
- 1970s
1970–1979
109 bridges
- 1980s
1980–1989
48 bridges
- 1990s
1990–1999
46 bridges
- 2000s 18
2000–2009
18 bridges
- 2010s 30
2010–2019
30 bridges
- 2020s 13
2020–2029
13 bridges
What this shows Construction peaked in the 1970s, when 109 of the county's bridges still in the inventory were built, which is 24.3% of those with a recorded year. That cohort is now 45 to 54 years old in the 2024 inventory. Its average build year (1972) matches the Pennsylvania average (1970).
How Dauphin County compares with Pennsylvania's closest counties by inventory size
The 5 Pennsylvania counties nearest Dauphin County in number of bridges, with their condition splits. Its 8.5% Poor share is the 2nd-lowest of these 6. Its average build year of 1972 against a peer-group mean of 1973 is in line with the group.
Showing the 5 closest of 66 Pennsylvania counties eligible for comparison.
| County | Bridges | Good | Fair | Poor | Avg. built |
|---|---|---|---|---|---|
| Luzerne County | 457 | 28.9% | 45.5% | 25.6% | 1972 |
| Somerset County | 454 | 33% | 52.6% | 14.3% | 1969 |
| Dauphin County (this page) | 449 | 22% | 69.5% | 8.5% | 1972 |
| Erie County | 442 | 37.8% | 52.7% | 9.5% | 1976 |
| Mercer County | 438 | 39.3% | 45.2% | 15.5% | 1972 |
| Tioga County | 429 | 49.4% | 47.3% | 3.3% | 1977 |
Each share is of that county's own total tracked bridges; peers are the counties with 5 or more bridges whose inventory size is closest to Dauphin County's. Source: FHWA National Bridge Inventory, 2024 release.
Nationwide counties with similar inventory size or average build year
Two NBI-derived peer sets for Dauphin County, both outside Pennsylvania so the neighborhoods are not the same-state size table above.
Similar inventory size
Nearest county inventories outside PA (449 bridges here).
- Washington County, AR · 449 bridges
- Sioux County, IA · 449 bridges
- Barton County, KS · 449 bridges
- Grady County, OK · 449 bridges
Similar average build year
Nearest mean year-built outside PA (1972 here).
- Santa Clara County, CA · avg 1972 · 964 bridges
- Madison County, AL · avg 1972 · 710 bridges
- Kern County, CA · avg 1972 · 668 bridges
- Middlesex County, NJ · avg 1972 · 563 bridges
Source: FHWA National Bridge Inventory, 2024 release. Peers floor at 10 bridges so stub inventories cannot own the match.
Fair-condition bridges (312)
SR 8003; RAMP A
FairOver: I-81; SR 0081
INTER OF I81 & US22, Dauphin, PA
Built 1977 Load: 66.2 t ADT: 2,859
US 422; SR 0422
FairOver: US 322; SR 0322
1 MI. E. HUMMELSTOWN, Dauphin, PA
Built 1953 Load: 67.1 t ADT: 22,263
US 11 & 15 SR 0011
FairOver: US 22 & 322 SR 0022
2 MI N OF CLARKS FERRY, Dauphin, PA
Built 1959 Load: 68.0 t ADT: 14,715
PA 441; SR 0441
FairOver: SWATARA CREEK
ROYALTON BORO, Dauphin, PA
Built 1959 Load: 68.0 t ADT: 3,793
WATER COMPANY RD
FairOver: TRIB TO WICONISCO CREEK
WATER COMPANY ROAD BRIDGE, Dauphin, PA
Built 1985 Load: 74.4 t ADT: 75
GRANGE HALL RDT460
FairOver: LITTLE WICONISCO CREEK
3.2NE MILLBRG/L.WICONISCO, Dauphin, PA
Built 1982 Load: 78.0 t ADT: 50
PA 443; SR 0443
FairOver: MANADA CREEK
2 MI. N. SHELLSVILLE, Dauphin, PA
Built 1940 Load: 86.2 t ADT: 1,212
PA TPK (I-76)
FairOver: LAUREL RUN
HIGHSPIRE BORO, Dauphin, PA
Built 1949 Load: 89.7 t ADT: 29,356
PA TPK (I-76)
FairOver: IRON RUN
LONDONDERRY TWP, Dauphin, PA
Built 1949 Load: 89.7 t ADT: 24,423
PA TPK (I-76)
FairOver: HOFFERS CREEK
CONEWAGO TWP, Dauphin, PA
Built 1949 Load: 89.7 t ADT: 24,423
SR 1023
FairOver: CONLEY CREEK
2 MI N.W. CARSONVILLE, Dauphin, PA
Built 1941 Load: 95.3 t ADT: 195
US 22/322; SR 0022
FairOver: PRIVATE DRIVE;FISHING CR
0.1 MI S OF PA 443 INTER, Dauphin, PA
Built 1977 Load: 99.8 t ADT: 37,718
Read our methodology - how this data is sourced, computed, and verified.
Related
Data sourced from official public datasets. See our methodology for details. Retrieved and formatted by PlainBridges
Every figure on PlainBridges 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. NBI condition categories reflect the latest reported inventory record, not a live safety, closure, or travel decision.