County profile · official public datasets

Lyon County, KS

492 public highway bridges tracked in the FHWA National Bridge Inventory: 65.7% rated Good, 33.3% Fair, 1% Poor.

492
Public bridges: 65.7%
Good condition: 1%
Poor condition

The verdict

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

Lyon County posts a top-quartile lowest Poor-condition share among rated counties in the state across mid-size county bridge inventory.

Top 18%
lowest Poor share in state: 1%
Poor-condition share: 492
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.

Lyon County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Lyon County ranks #19 of 104 Kansas counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 1%). Lyon County, Kansas contains 492 public highway bridges. Roughly 65.7% are rated “Good,” 33.3% “Fair,” and 1% “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

492

Public highway bridges in Lyon County

Good condition

65.7%

323 of 492 rated 7-9

Fair condition

33.3%

164 of 492 rated 5-6

Poor condition

5 of 492 rated 4 or below

In-state Poor-share rank

#19 of 104

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

Condition distribution

Share of 492 NBI-tracked bridges by lowest applicable component rating.

Good

65.7% (323)

Fair

33.3% (164)

Poor

1% (5)

Lyon County's Poor-condition bridges carry 225 vehicle crossings a day

That is 0% of the county's reported daily bridge traffic on 1% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 45 crossings a day against 1,414 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 492 of 492 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

50.2% of Lyon County's bridges have passed the 50-year mark

247 of the 492 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 65.7% 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 35.6% of the county's Poor-condition bridge traffic

RD H 939.0-544.1 over MOON BRANCH CREEK, built 1928, carries 80 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 5-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 225 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

1900s

1
1910s

2
1920s

25
1930s

48
1940s

34
1950s

89
1960s

34
1970s

46
1980s

51
1990s

56
2000s

58
2010s

42
2020s

6

What this shows Construction peaked in the 1950s, when 89 of the county's bridges still in the inventory were built, which is 18.1% of those with a recorded year. That cohort is now 65 to 74 years old in the 2024 inventory. Its average build year (1972) matches the Kansas average (1972).

How Lyon County compares with Kansas's closest counties by inventory size

The 5 Kansas counties nearest Lyon County in number of bridges, with their condition splits. Its 1% Poor share is the 3rd-lowest of these 6. Its average build year of 1972 against a peer-group mean of 1975 is in line with the group.

Showing the 5 closest of 103 Kansas counties eligible for comparison.

Bridge inventory size and condition shares for Lyon County and the 5 Kansas counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
McPherson County	586	66.6%	32.8%	0.7%	1979
Reno County	573	51.8%	42.1%	6.1%	1980
Shawnee County	563	62.9%	34.1%	3%	1981
Lyon County (this page)	492	65.7%	33.3%	1%	1972
Barton County	449	50.1%	49.7%	0.2%	1959
Marshall County	402	49.8%	39.6%	10.7%	1974

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

Similar inventory size

Nearest county inventories outside KS (492 bridges here).

Shasta County, CA · 492 bridges
Greene County, MO · 493 bridges
Canadian County, OK · 493 bridges
Vermilion County, IL · 494 bridges

Similar average build year

Nearest mean year-built outside KS (1972 here).

Santa Clara County, CA · avg 1972 · 964 bridges
Madison County, AL · avg 1972 · 710 bridges
Kern County, CA · avg 1972 · 668 bridges
York County, PA · avg 1972 · 569 bridges

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

All 492 Good 323 Fair 164 Poor 5

Good-condition bridges (323)

Sort:

Lyon County Bridge Snapshot

Condition distribution

Lyon County's Poor-condition bridges carry 225 vehicle crossings a day

50.2% of Lyon County's bridges have passed the 50-year mark

One structure carries 35.6% of the county's Poor-condition bridge traffic

How Lyon County compares with Kansas's closest counties by inventory size

Nationwide counties with similar inventory size or average build year

Similar inventory size

Similar average build year

Good-condition bridges (323)

I-35 HWY SB

I-35 HWY NB

I-35 HWY NB

I-35 HWY SB

K99 HWY

I-35 HWY NB

I-35 HWY SB

RP TO & FROM KTA

RS 1078 H.6-26.0

RS 2139 L.0-25.1

K99 HWY

K99 HWY

IBP ACCESS RD.

RS 1507 R.7-130

RD 255 (G.3-225)

I-35 HWY NB

RD 300 (G.5-300)

RD. 310 (S.5-310)

I-35 HWY SB

I-35 HWY NB

RS 415 (K.0-11.1)

RD. P

K99 HWY

RD. U (U-370)

RD. B 927-532.3

RS 1507 I.0-24.5

RD 250 (M.3-250)

I-35 RAMP (KTA)

K99 HWY

RD 310 (G.8-310)

RD V 961.5-540.6

RD X5 965.5-538.7

I-35 HWY NB (KTA)

FAU 1101

RD Z (Z.0-345)

RD. E 933.0-549.8

RD. A (A.0-26.7)

I-35 HWY (KTA)

K-99 HIGHWAY

K99 HWY

K99 HWY

RD. U (U-300)

RS 2066 T.2-175

RD. 360 (Y.3-360)

RS 2066 T.0-175

COUNTY RD. 390

I-35 HWY (KTA)

RD 260 (M.0-258)

OLD HWY 50 T.0-170

US-50 HWY

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