County profile · official public datasets

Ketchikan Gateway County, AK

100 public highway bridges tracked in the FHWA National Bridge Inventory: 43% rated Good, 45% Fair, 12% Poor.

100
Public bridges: 43%
Good condition: 12%
Poor condition

The verdict

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

Ketchikan Gateway County posts a higher-than-median Poor-condition share among rated counties in the state across mid-size county bridge inventory.

22nd
of 27 on Poor share: 12%
Poor-condition share: 100
public highway bridges: 1993
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.

Ketchikan Gateway County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Ketchikan Gateway County ranks #22 of 27 Alaska counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 12%). Ketchikan Gateway County, Alaska contains 100 public highway bridges. Roughly 43% are rated “Good,” 45% “Fair,” and 12% “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

100

Public highway bridges in Ketchikan Gateway County

Good condition

43%

43 of 100 rated 7-9

Fair condition

45%

45 of 100 rated 5-6

Poor condition

12%

12 of 100 rated 4 or below

In-state Poor-share rank

#22 of 27

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

Condition distribution

Share of 100 NBI-tracked bridges by lowest applicable component rating.

Good

43% (43)

Fair

45% (45)

Poor

12% (12)

Ketchikan Gateway County's Poor-condition bridges carry 33,940 vehicle crossings a day

That is 31.5% of the county's reported daily bridge traffic on 11.6% of its bridges: Poor-condition structures carry more traffic than their share of the inventory. Each Poor bridge averages 3,394 crossings a day against 318 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 86 of 100 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

22% of Ketchikan Gateway County's bridges have passed the 50-year mark

22 of the 100 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 43% 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 41.4% of the county's Poor-condition bridge traffic

SOUTH TONGASS HWY over WATER ST VIADUCT, built 1955, carries 14,046 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 12-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 33,940 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

1930s

1
1940s

1
1950s

6
1960s

10
1970s

7
1980s

15
1990s

14
2000s

16
2010s

28
2020s

2

What this shows Construction peaked in the 2010s, when 28 of the county's bridges still in the inventory were built, which is 28% of those with a recorded year. That cohort is now 5 to 14 years old in the 2024 inventory. Its average build year (1993) matches the Alaska average (1989).

How Ketchikan Gateway County compares with Alaska's closest counties by inventory size

The 5 Alaska counties nearest Ketchikan Gateway County in number of bridges, with their condition splits. Its 12% Poor share is the 4th-lowest of these 6. Its average build year of 1993 against a peer-group mean of 1988 is 5 years newer.

Showing the 5 closest of 26 Alaska counties eligible for comparison.

Bridge inventory size and condition shares for Ketchikan Gateway County and the 5 Alaska counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
Hoonah-Angoon County	125	49.6%	35.2%	15.2%	1994
Matanuska-Susitna County	120	50.8%	43.3%	5.8%	1993
Fairbanks North Star County	111	50.5%	42.3%	7.2%	1988
Kenai Peninsula County	103	35.9%	50.5%	13.6%	1988
Ketchikan Gateway County (this page)	100	43%	45%	12%	1993
Yukon-Koyukuk County	94	41.5%	50%	8.5%	1978

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 Ketchikan Gateway 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 Ketchikan Gateway County, both outside Alaska so the neighborhoods are not the same-state size table above.

Similar inventory size

Nearest county inventories outside AK (100 bridges here).

Gunnison County, CO · 100 bridges
Monroe County, FL · 100 bridges
Fayette County, IN · 100 bridges
LaGrange County, IN · 100 bridges

Similar average build year

Nearest mean year-built outside AK (1993 here).

Salt Lake County, UT · avg 1993 · 659 bridges
Marshall County, MS · avg 1993 · 255 bridges
Rowan County, NC · avg 1993 · 245 bridges
Cabarrus County, NC · avg 1993 · 236 bridges

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

All 100 Good 43 Fair 45 Poor 12

All bridges (100)

Sort:

Ketchikan Gateway County Bridge Snapshot

Condition distribution

Ketchikan Gateway County's Poor-condition bridges carry 33,940 vehicle crossings a day

22% of Ketchikan Gateway County's bridges have passed the 50-year mark

One structure carries 41.4% of the county's Poor-condition bridge traffic

How Ketchikan Gateway County compares with Alaska'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 (100)

8000000

YOUNG ST/SAYLES ST

HOPKINS ALLEY

NO DATA ENTERED

8000000-21.711

8040000

8340000

THOMAS STREET

8040000

8340000

GRANT STREET

NO DATA ENTERED

SOUTH TONGASS HWY

NORTH TONGASS HWY

MARINE HWY ROUTE

VALLEY FORGE DR

NORTH TONGASS HWY

FERRY SHUTTLE RTE

TIDAL OP STL SPAN

SOUTH TONGASS HWY

SOUTH TONGASS HWY

SOUTH TONGASS HWY

BOSTWICK LAKE ROAD

SOUTH TONGASS HWY

NO DATA ENTERED

FERRY SHUTTLE RTE

INTER ISLAND RTE

8400000

8400000

NO DATA ENTERED

NO DATA ENTERED

NO DATA ENTERED

FAIR STREET

PARK STREET

PARK STREET

NORTH TONGASS HWY

BOSTWICK LAKE ROAD

BOSTWICK LAKE ROAD

BOSTWICK LAKE ROAD

8430000

8400600-0.59

MARGARET

BOSTWICK LAKE ROAD

BOSTWICK LAKE ROAD

8400600-0.70

NO DATA ENTERED

SOUTH TONGASS HWY

NO DATA ENTERED

NO DATA ENTERED

GRAVINA ISLAND

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