County profile · official public datasets

Summit County, UT

138 public highway bridges tracked in the FHWA National Bridge Inventory: 14.5% rated Good, 81.2% Fair, 4.3% Poor.

138
Public bridges: 14.5%
Good condition: 4.3%
Poor condition

The verdict

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

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

23rd
of 29 on Poor share: 4.3%
Poor-condition share: 138
public highway bridges: 1982
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.

Summit County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Summit County ranks #23 of 29 Utah counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 4.3%). Summit County, Utah contains 138 public highway bridges. Roughly 14.5% are rated “Good,” 81.2% “Fair,” and 4.3% “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

138

Public highway bridges in Summit County

Good condition

14.5%

20 of 138 rated 7-9

Fair condition

81.2%

112 of 138 rated 5-6

Poor condition

4.3%

6 of 138 rated 4 or below

In-state Poor-share rank

#23 of 29

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

Condition distribution

Share of 138 NBI-tracked bridges by lowest applicable component rating.

Good

14.5% (20)

Fair

81.2% (112)

Poor

4.3% (6)

Summit County's Poor-condition bridges carry 3,887 vehicle crossings a day

That is 0.3% of the county's reported daily bridge traffic on 4.4% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 648 crossings a day against 7,691 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 137 of 138 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

43.5% of Summit County's bridges have passed the 50-year mark

60 of the 138 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 14.5% 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 49.2% of the county's Poor-condition bridge traffic

SR-32 over WEBER RIVER, built 1955, carries 1,914 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 6-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 3,887 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

1920s

1
1930s

1
1940s

6
1950s

18
1960s

22
1970s

16
1980s

17
1990s

14
2000s

25
2010s

17
2020s

1

What this shows Construction peaked in the 2000s, when 25 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 15 to 24 years old in the 2024 inventory. Its average build year (1982) matches the Utah average (1984).

How Summit County compares with Utah's closest counties by inventory size

The 5 Utah counties nearest Summit County in number of bridges, with their condition splits. Its 4.3% Poor share is the 5th-lowest of these 6. Its average build year of 1982 against a peer-group mean of 1982 is in line with the group.

Showing the 5 closest of 28 Utah counties eligible for comparison.

Bridge inventory size and condition shares for Summit County and the 5 Utah counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
Sevier County	157	19.1%	80.3%	0.6%	1983
Davis County	139	28.8%	70.5%	0.7%	1996
Summit County (this page)	138	14.5%	81.2%	4.3%	1982
Weber County	129	14.7%	80.6%	4.7%	1979
Emery County	126	18.3%	81%	0.8%	1979
Grand County	121	18.2%	81.8%	0%	1973

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

Similar inventory size

Nearest county inventories outside UT (138 bridges here).

Santa Cruz County, AZ · 138 bridges
Hancock County, IA · 138 bridges
Boone County, KY · 138 bridges
Ralls County, MO · 138 bridges

Similar average build year

Nearest mean year-built outside UT (1982 here).

Oklahoma County, OK · avg 1982 · 1,216 bridges
Jackson County, MO · avg 1982 · 930 bridges
Milwaukee County, WI · avg 1982 · 893 bridges
Champaign County, IL · avg 1982 · 727 bridges

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

All 138 Good 20 Fair 112 Poor 6

All bridges (138)

Sort:

Summit County Bridge Snapshot

Condition distribution

Summit County's Poor-condition bridges carry 3,887 vehicle crossings a day

43.5% of Summit County's bridges have passed the 50-year mark

One structure carries 49.2% of the county's Poor-condition bridge traffic

How Summit County compares with Utah'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 (138)

I-80 (SR-80)EB&amp

TOWN STREET

ROAD BRIDGE

100 NORTH STREET

COUNTY ROAD

COUNTY ROAD

ROAD 80037

SR-32

COUNTY ROAD

DEER VALLEY DRIVE

MILLRACE RD.OAKLEY

Ramp I-80E to I-84

200 WEST STREET

I-80 (SR-80) EBL

I-80 (SR-80) WBL

COUNTY ROAD

COUNTY ROAD

SR-224

I-84 (SR-84)

COUNTY ROAD

COUNTY ROAD

SR-35

I-84 (SR-84) EBL

COUNTY ROAD

COUNTY ROAD

COUNTY ROAD

I-80 (SR-80) EBL

I-84 (SR-84) WBL

COUNTY ROAD

I-80 (SR-80) WBL

COUNTY ROAD

I-80 (SR-80) WBL

COUNTY ROAD

CENTER STREET

SOUTH FORK ROAD

SR-224 INT.X-RD.

SR-32

I-80 (SR-80)EB&amp

CO.RD. INT. X-ROAD

SR-150

COUNTY ROAD

SR-150

I-80 (SR-80) EBL

TOLL CYN.INT.X-RD

SR-65

SR-35

SR-150

I-84 (SR-84) EBL

INT.X-RD.to I-80EB

COUNTY ROAD

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