County profile · official public datasets

Allegheny County, PA

1,294 public highway bridges tracked in the FHWA National Bridge Inventory: 29.6% rated Good, 61.5% Fair, 8.9% Poor.

1,294
Public bridges: 29.6%
Good condition: 8.9%
Poor condition

The verdict

According to the Federal Highway Administration's 2024 National Bridge Inventory.

Allegheny County posts a better-than-median Poor-condition share among rated counties in the state across large county bridge inventory.

Top 28%
lowest Poor share in state: 8.9%
Poor-condition share: 1,294
public highway bridges: 1967
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.

Allegheny County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Allegheny County ranks #19 of 67 Pennsylvania counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 8.9%). Allegheny County, Pennsylvania contains 1,294 public highway bridges. Roughly 29.6% are rated “Good,” 61.5% “Fair,” and 8.9% “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.

Total bridges

1,294

Public highway bridges in Allegheny County

Good condition

29.6%

383 of 1,294 rated 7-9

Fair condition

61.5%

796 of 1,294 rated 5-6

Poor condition

8.9%

115 of 1,294 rated 4 or below

In-state Poor-share rank

#19 of 67

Among Pennsylvania counties with 5+ bridges, lower share ranks better

Condition distribution

Share of 1,294 NBI-tracked bridges by lowest applicable component rating.

Good

29.6% (383)

Fair

61.5% (796)

Poor

8.9% (115)

Allegheny County's Poor-condition bridges carry 715,632 vehicle crossings a day

That is 4.4% of the county's reported daily bridge traffic on 8.7% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 6,390 crossings a day against 11,003 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 1,290 of 1,294 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

60.3% of Allegheny County's bridges have passed the 50-year mark

780 of the 1,294 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 29.6% 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 7.3% of the county's Poor-condition bridge traffic

PARKWAY EAST over OLD WM PENN HWY LEAK RUN, built 1962, carries 52,457 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 115-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 715,632 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

pre-1900

21
1900s

34
1910s

32
1920s

75
1930s

105
1940s

61
1950s

176
1960s

163
1970s

156
1980s

151
1990s

86
2000s

85
2010s

125
2020s

24

What this shows Construction peaked in the 1950s, when 176 of the county's bridges still in the inventory were built, which is 13.6% of those with a recorded year. That cohort is now 65 to 74 years old in the 2024 inventory. Its average build year (1967) matches the Pennsylvania average (1970).

How Allegheny County compares with Pennsylvania's closest counties by inventory size

The 5 Pennsylvania counties nearest Allegheny County in number of bridges, with their condition splits. Its 8.9% Poor share is the 1st-lowest of these 6. Its average build year of 1967 against a peer-group mean of 1965 is in line with the group.

Showing the 5 closest of 66 Pennsylvania counties eligible for comparison.

Bridge inventory size and condition shares for Allegheny County and the 5 Pennsylvania counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
Allegheny County (this page)	1,294	29.6%	61.5%	8.9%	1967
Montgomery County	828	32%	56.5%	11.5%	1968
Lancaster County	801	30.6%	58.2%	11.2%	1973
Bucks County	699	24.3%	60.2%	15.5%	1958
Chester County	680	25%	61.3%	13.7%	1963
Berks County	667	21.4%	63.6%	15%	1962

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 Allegheny 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 Allegheny County, both outside Pennsylvania so the neighborhoods are not the same-state size table above.

Similar inventory size

Nearest county inventories outside PA (1,294 bridges here).

Sedgwick County, KS · 1,333 bridges
King County, WA · 1,238 bridges
Oklahoma County, OK · 1,216 bridges
Williamson County, TX · 1,170 bridges

Similar average build year

Nearest mean year-built outside PA (1967 here).

Los Angeles County, CA · avg 1967 · 3,547 bridges
Sonoma County, CA · avg 1967 · 609 bridges
Merced County, CA · avg 1967 · 528 bridges
Shasta County, CA · avg 1967 · 492 bridges

Source: FHWA National Bridge Inventory, 2024 release. Peers floor at 10 bridges so stub inventories cannot own the match.

All 1,294 Good 383 Fair 796 Poor 115

All bridges (1,294)

Sort:

Allegheny County Bridge Snapshot

Condition distribution

Allegheny County's Poor-condition bridges carry 715,632 vehicle crossings a day

60.3% of Allegheny County's bridges have passed the 50-year mark

One structure carries 7.3% of the county's Poor-condition bridge traffic

How Allegheny County compares with Pennsylvania's closest counties by inventory size

Nationwide counties with similar inventory size or average build year

Similar inventory size

Similar average build year

All bridges (1,294)

Douglas Run Rd

GLASS RUN ROAD

SR 837 SB

SAXONBURG BLVD

WB-433

S 28th Street

SCRUBGRASS ROAD

BUNOLA RIVER RD

SR 0910

SR 0279 NB SB

WIBLE RUN RD

BL OF THE ALLIES

GULF LAB ROAD

GRUBBS RD

CURRY HOLLOW RD

WEST SMITHFIELD ST

S 27th Street

PA TPK (I-76)

RAMP D

GIBSONIA RD

SAXONBURG BLVD

G. BUENA VISTA RD

SR 0028 SB

BIG SEWICKLEY C RD

SR 28 SB

BULL CREEK RD

Dambach Ave

Bg Swkly Crk Rd

RAMP B

Mill Hill Rd

SR 0030 EB WB

LINCOLN HWY(US 30)

SHALER STREET

WALTON ROAD

PA TPK (TOLL 43)

PA TPK (I-576)

PA TPK (I-576)

Lincoln Hwy

MILL ST

SAXONBURG BL

BABCOCK BL

Lebanon Rd.

SOUTH BEND LANE

Brodhead Rd

Lesnett Road

PA TPK (I-76)

RAYMOND SHAFER HW

MCKNIGHT RD

PA TURNPIKE RAMP F

10TH ST BYPASS

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