Boulder County, CO

311 public highway bridges

Boulder County Bridge Snapshot

Boulder County, Colorado contains 311 public highway bridges in the FHWA National Bridge Inventory. Roughly 33.4% are rated “Good,” 60.5% “Fair,” 2.3% “Poor,” and 2.3% are classified as structurally deficient — the federal designation for spans whose deck, superstructure, or substructure has been rated 4 or below on the 0–9 NBI scale. Structurally deficient does not mean unsafe to cross; it means the bridge is on the priority list for repair or replacement.

Inspections in CO are conducted by certified engineers from the state Department of Transportation on a 24-month cycle, and results are reported back to the FHWA each spring. The list below shows every NBI-tracked bridge in the county, sorted by inventory load rating. Use the “Sort by” controls to surface the lowest-rated spans first, and click any row for full inspection history, traffic counts, and condition trends.

Source: FHWA National Bridge Inventory. See methodology for full definitions.

311
Total Bridges
33.4%
Good
2.3%
Poor
2.3%
Structurally Deficient

Condition Distribution

Good
33.4% (104)
Fair
60.5% (188)
Poor
2.3% (7)
SD
2.3% (7)

All Bridges (311)

NFSR 112.0

Good

Over: SOUTH ST VRAIN CREEK

W. SIDE OF BRAINARD LAKE, Boulder, CO

Built 2011 ADT: 200

S. Pratt Parkway

Good

Over: St Vrain Creek

250 Ft S of Boston Ave, Boulder, CO

Built 2019 Load: 21.1 t ADT: 12,909

US 287 ML

Good

Over: COAL CREEK

IN BOULDER COUNTY, Boulder, CO

Built 1996 Load: 23.1 t ADT: 32,000

SH 7 ML

Good

Over: COAL CREEK

2.3 MI E OF JCT US 287, Boulder, CO

Built 1990 Load: 23.7 t ADT: 17,000

Second Avenue

Good

Over: St. Vrain Creek

0.15 Mi S of Hwy 36, Boulder, CO

Built 2021 Load: 23.7 t ADT: 946

US 287 ML

Good

Over: ST VRAIN CREEK

IN LONGMONT, Boulder, CO

Built 2016 Load: 25.9 t ADT: 24,000

N 63rd St (CR39)

Good

Over: Lefthand Creek

0.4 Mi N of Niwot Rd, Boulder, CO

Built 2011 Load: 26.9 t ADT: 2,610

Mountain Dr.

Good

Over: Clover Basin Ditch

200 ft S. of Four Leaf Dr, Boulder, CO

Built 2018 Load: 29.2 t ADT: 1,399

County Road 1

Good

Over: ST VRAIN CREEK

.5 mi south of SH119, Boulder, CO

Built 2014 Load: 29.5 t ADT: 9,344

30th Street

Good

Over: Boulder, Lefthand Ditch

400 Ft So of Pearl St, Boulder, CO

Built 2011 Load: 29.6 t ADT: 20,225

Airport Road

Good

Over: St. Vrain River

600 Ft. S of 9th Ave., Boulder, CO

Built 2006 Load: 30.9 t ADT: 13,131

Co Rd 3 / 119th S

Good

Over: Dry Creek No 2

0.9 Mi S of SH119, Boulder, CO

Built 2013 Load: 31.4 t ADT: 2,541

US 287 ML

Good

Over: DRAW

0.9 MI S OF JCT SH 52, Boulder, CO

Built 1990 Load: 32.3 t ADT: 23,000

Broadway

Good

Over: Four Mile Creek/Bike Pth

At Rosewood Avenue, Boulder, CO

Built 1994 Load: 32.4 t ADT: 11,874

Lefthand Canyon Dr

Good

Over: Lefthand Creek

0.75 Mi W of Lee Hill Dr, Boulder, CO

Built 2019 Load: 32.7 t ADT: 1,078

Monarch Road

Good

Over: Dry Creek

800 ft S of N 79th St, Boulder, CO

Built 2019 Load: 32.7 t ADT: 349

Co Rd 39 (65th St)

Good

Over: LYKINS GULCH

0.8 Mi N of Nelson Rd, Boulder, CO

Built 2012 Load: 32.7 t ADT: 741

Fairways Drive

Good

Over: Local Drainage

.4 Mi S of Neva Rd, Boulder, CO

Built 2005 Load: 32.7 t ADT: 622

Golf Club Drive

Good

Over: Local Drainage

0.1 Mi So of Hogan Ct, Boulder, CO

Built 2005 Load: 32.7 t ADT: 644

Golf Club Drive

Good

Over: Local Drainage

0.4 Mi So of Hogan Ct, Boulder, CO

Built 2005 Load: 32.7 t ADT: 318

Wildwood Road

Good

Over: Bear Canyon Creek

150 Ft W of Bear Mtn. Rd, Boulder, CO

Built 1970 Load: 32.7 t ADT: 242

48th CT

Good

Over: S. Goose Creek

30 Ft N of Pearl Parkway, Boulder, CO

Built 1986 Load: 32.7 t ADT: 641

Mohawk Drive

Good

Over: Bear Crk and Bike Path

0.25 Mi No of Baseline Rd, Boulder, CO

Built 1996 Load: 32.7 t ADT: 1,707

Aurora Avenue

Good

Over: Gregory Creek

15 Ft. W of 6th Street, Boulder, CO

Built 1980 Load: 32.7 t ADT: 226

27th Street

Good

Over: Goose Creek

50 ft N of Mapleton Ave, Boulder, CO

Built 2001 Load: 32.7 t ADT: 201

34th Street

Good

Over: Wonderland Creek

40 ft S. of Iris Ave, Boulder, CO

Built 2018 Load: 32.7 t ADT: 1,200

Gilpin Drive

Good

Over: Bear Canyon Creek

350 ft S of Evans Dr, Boulder, CO

Built 1997 Load: 32.7 t ADT: 281

Valmont Road

Good

Over: Elmers Twomile Creek

400 ft W of 28th, Boulder, CO

Built 2010 Load: 32.7 t ADT: 10,720

48th Street

Good

Over: Goose Creek

Just N. of Pearl St, Boulder, CO

Built 1980 Load: 32.7 t ADT: 664

Harvard Street

Good

Over: Oligarchy Ditch

50 Ft So. of N. Shore Dr., Boulder, CO

Built 1998 Load: 32.7 t ADT: 2,509

Sunset Street

Good

Over: Saint Vrain Creek

0.1 S Boston Ave, Boulder, CO

Built 2016 Load: 32.7 t ADT: 7,282

96th Street

Good

Over: BNSF RR

250 Ft. N of CR 19, Boulder, CO

Built 2006 Load: 32.7 t ADT: 15,821

Kalmia Avenue

Good

Over: Dry Creek

350 Ft East of US 36, Boulder, CO

Built 2017 Load: 33.0 t ADT: 2,621

US 36 ML

Good

Over: NORTH ST VRAIN CREEK

IN LYONS, Boulder, CO

Built 2007 Load: 33.0 t ADT: 9,000

Niwot Road CR34

Good

Over: Boulder Feeder Ditch

100 Ft. E of N. 55th St, Boulder, CO

Built 2010 Load: 33.2 t ADT: 2,084

Grandview Meadow D

Good

Over: Dry Creek

0.4 Mi So of Nelson Rd, Boulder, CO

Built 2004 Load: 33.2 t ADT: 3,692

N. 95th St (CR19)

Good

Over: Left Hand Creek

.4 Mi S of SH 119, Boulder, CO

Built 2009 Load: 33.6 t ADT: 11,067

N. 95th St (CR10)

Good

Over: Highland Ditch

0.5 Mi N of Woodland, Boulder, CO

Built 1989 Load: 33.7 t ADT: 1,968

US 36 ML

Good

Over: Ped Underpath / Creek

28TH ST/WINDING TRAIL DR., Boulder, CO

Built 2015 Load: 33.7 t ADT: 16,000

Marshall Rd(Cr 51)

Good

Over: South Boulder Creek

0.5 Mi N of St Hwy 170, Boulder, CO

Built 1988 Load: 33.8 t ADT: 318

83rd St (CO Rd 23)

Good

Over: Little Thompson River

1.8 Mi N of Woodland, Boulder, CO

Built 2017 Load: 34.3 t ADT: 2,443

Marshall Road

Good

Over: Coal Creek

0.07 Mi N of Creek View, Boulder, CO

Built 2022 Load: 34.3 t ADT: 1,867

US 36 ML

Good

Over: RAMP B & BIKEPATH

1.5 MI E. OF SUPERIOR, Boulder, CO

Built 2001 Load: 34.7 t ADT: 68,000

County Road 94

Good

Over: Lefthand Creek

0.1 Mi N of Olde Stage Rd, Boulder, CO

Built 2019 Load: 35.3 t ADT: 1,441

US 36 ML

Good

Over: LEFT HAND CREEK

6.2 MI SO OF JCT SH 66, Boulder, CO

Built 2019 Load: 35.6 t ADT: 13,000

McConnell Dr.

Good

Over: Saint Vrain Creek Ovrflw

300 ft S of US36 / SH66, Boulder, CO

Built 2018 Load: 35.6 t ADT: 2,031

Iris Avenue/34 St

Good

Over: Wonderland Creek

Iris Ave and 34th St., Boulder, CO

Built 2017 Load: 36.3 t ADT: 1,937

US 36 ML

Good

Over: DAVIDSON DITCH

2.2 MI SE OF JCT SH 157, Boulder, CO

Built 2015 Load: 36.6 t ADT: 77,000

N 49th St (Cr 51)

Good

Over: Left Hand Creek

0.5 Mi N of Co Rd 34, Boulder, CO

Built 1993 Load: 36.9 t ADT: 191

County Road 103

Good

Over: Middle St. Vrain Creek

200 Ft S of Raymond Store, Boulder, CO

Built 1993 Load: 37.4 t ADT: 112

Read our methodology — how this data is sourced, computed, and verified.

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Data sourced from official U.S. government datasets. See our methodology for details. Retrieved and formatted by PlainBridges Editorial