County profile · official public datasets

Montgomery County, MD

515 public highway bridges tracked in the FHWA National Bridge Inventory: 38.8% rated Good, 56.3% Fair, 4.9% Poor.

515
Public bridges
38.8%
Good condition
4.9%
Poor condition

The verdict

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

Montgomery County pairs a higher-than-median Poor-condition share among rated counties in the state with a newer average build year than the state inventory.

14th
of 24 on Poor share
4.9%
Poor-condition share
515
public highway bridges
1978
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.

Montgomery County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Montgomery County ranks #14 of 24 Maryland counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 4.9%). Montgomery County, Maryland contains 515 public highway bridges. Roughly 38.8% are rated “Good,” 56.3% “Fair,” and 4.9% “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

515

Public highway bridges in Montgomery County

Good condition

38.8%

200 of 515 rated 7-9

Fair condition

56.3%

290 of 515 rated 5-6

Poor condition

4.9%

25 of 515 rated 4 or below

In-state Poor-share rank

#14 of 24

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

Condition distribution

Share of 515 NBI-tracked bridges by lowest applicable component rating.

Good
38.8% (200)
Fair
56.3% (290)
Poor
4.9% (25)

Montgomery County's Poor-condition bridges carry 242,194 vehicle crossings a day

That is 1.7% of the county's reported daily bridge traffic on 4.9% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 9,688 crossings a day against 21,166 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 513 of 515 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

44.9% of Montgomery County's bridges have passed the 50-year mark

231 of the 515 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 38.8% 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 16.5% of the county's Poor-condition bridge traffic

CLARA BARTON PARKW over CLARA BARTON PARKWAY (SB, built 1959, carries 40,057 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 25-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 242,194 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

When Montgomery County's bridges were built

515 bridges with a recorded construction year, grouped by decade

bridges

What this shows Construction peaked in the 1960s, when 84 of the county's bridges still in the inventory were built, which is 16.3% of those with a recorded year. That cohort is now 55 to 64 years old in the 2024 inventory. Its average build year is 1978, 6 years newer than the Maryland average of 1972.

Source FHWA National Bridge Inventory (year built) As of 2024 NBI release

How Montgomery County compares with Maryland's closest counties by inventory size

The 5 Maryland counties nearest Montgomery County in number of bridges, with their condition splits. Its 4.9% Poor share is the 4th-lowest of these 6. Its average build year of 1978 against a peer-group mean of 1974 is in line with the group.

Showing the 5 closest of 23 Maryland counties eligible for comparison.

Bridge inventory size and condition shares for Montgomery County and the 5 Maryland counties closest to it in inventory size
County Bridges Poor
Prince George's County 576 3.1%
Montgomery County (this page) 515 4.9%
Frederick County 486 2.7%
Anne Arundel County 389 1.5%
Baltimore city County 374 8.6%
Howard County 309 5.8%

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

Similar inventory size

Nearest county inventories outside MD (515 bridges here).

Similar average build year

Nearest mean year-built outside MD (1978 here).

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

All 515 Good 200 Fair 290 Poor 25

Fair-condition bridges (290)

MACARTHUR BLVD.

Fair

Over: CABIN JOHN CREEK

1.5 MI. E. OF I-495, Montgomery, MD

Built 1863 Load: 11.7 t ADT: 6,000

GLEN ROAD

Fair

Over: KILGOUR BRANCH

1.5 MI WEST OF MD 189, Montgomery, MD

Built 1942 Load: 13.6 t ADT: 5,880

GRIFFITH ROAD

Fair

Over: HAWLINGS RIVER

1 MI W OF JCT SR 650, Montgomery, MD

Built 1920 Load: 17.2 t ADT: 282

East Montgomery Ro

Fair

Over: Rockville Center Multipl

0.5 Miles West of Md. 355, Montgomery, MD

Built 1998 Load: 18.1 t ADT: 500

MD 28

Fair

Over: BR OF DRY SENECA CREEK

0.98 MILE WEST OF MD 117, Montgomery, MD

Built 1954 Load: 19.0 t ADT: 5,420

CARDEROCK ACCESS C

Fair

Over: CLARA BARTON PARKWAY

0.7 MILES WEST OF MACARTH, Montgomery, MD

Built 1962 Load: 19.0 t ADT: 2,000

SOUTH PALMER ROAD

Fair

Over: PARKING GARAGE

1 KM W OF RT. 185, Montgomery, MD

Built 1980 Load: 19.3 t ADT: 200

MD 355 SB

Fair

Over: IS 495 IL

1.31 MILES S OF MD 547, Montgomery, MD

Built 1959 Load: 20.0 t ADT: 55,020

CLARA BARTON PARKW

Fair

Over: CABIN JOHN CREEK & CABIN

1.6 MILES SOUTH OF I-495., Montgomery, MD

Built 1963 Load: 20.0 t ADT: 16,120

STOKES ROAD

Fair

Over: STONEY CREEK

50M EAST OF E PALMER RD, Montgomery, MD

Built 1950 Load: 20.8 t ADT: 2,000

IS 495

Fair

Over: STONEY BROOK DR ROCK CR

0.97 MILE EAST OF MD 185, Montgomery, MD

Built 1964 Load: 20.9 t ADT: 242,821

FALSTONE AVENUE

Fair

Over: LITTLE FALLS BRANCH

0.1 MI E OF WARWICK AVE, Montgomery, MD

Built 1965 Load: 20.9 t ADT: 50

PARKLAWN ENTRANCE

Fair

Over: ROCK CREEK

RT 28 SOUTH OF ROCKVILLE, Montgomery, MD

Built 1950 Load: 22.7 t ADT: 27

IS 495 NW RAMP

Fair

Over: MACARTHUR BOULEVARD

0.58 MI E OF VA LINE, Montgomery, MD

Built 1963 Load: 23.1 t ADT: 1,475

EDWARDS FERRY ROAD

Fair

Over: BROAD RUN

1 MI N OF WESTERLY ROAD, Montgomery, MD

Built 1982 Load: 24.0 t ADT: 312

EAST DEER PARK DRI

Fair

Over: CSXT RAILROAD

0.6 MILES EAST OF MD 355, Montgomery, MD

Built 1945 Load: 24.9 t ADT: 7,121

RIVER ROAD

Fair

Over: BROAD RUN

0.3 MI E OF ELMER SCHOOL, Montgomery, MD

Built 1911 Load: 25.4 t ADT: 444

US 29

Fair

Over: SLIGO CREEK

0.14 M S OF FRANKLIN AVE, Montgomery, MD

Built 1936 Load: 26.3 t ADT: 55,302

MD 396

Fair

Over: LITTLE FALLS BRANCH

0.69 MILE WEST OF WASH DC, Montgomery, MD

Built 1931 Load: 26.3 t ADT: 15,581

MD 97

Fair

Over: REDDY BRANCH

2.89 MILES S OF MD 650, Montgomery, MD

Built 1927 Load: 27.7 t ADT: 10,740

GAME PRESERVE ROAD

Fair

Over: WHETSTONE RUN

0.2 MI NORTH OF MD 355, Montgomery, MD

Built 1990 Load: 27.7 t ADT: 2,086

US 29

Fair

Over: PATUXENT RIVER

ON HOWARD CO LINE, Montgomery, MD

Built 1954 Load: 28.6 t ADT: 49,203

MD 119

Fair

Over: LONG DRAUGHT BRANCH

1.66 MILE NORTH OF MD 124, Montgomery, MD

Built 1990 Load: 29.0 t ADT: 10,766

BARNESVILLE ROAD

Fair

Over: LITTLE MONOCACY RIVER

0.6 MI E OF MT EPHRAIM RD, Montgomery, MD

Built 1940 Load: 29.0 t ADT: 918

PALMER ROAD SOUTH

Fair

Over: STONE LAKE RD/PARKING LT

600M E OF WOOD RD, Montgomery, MD

Built 1981 Load: 29.3 t ADT: 2,750

MD 355 SB

Fair

Over: IS 495 OL

0.07 MILE NORTH OF IS 495, Montgomery, MD

Built 1959 Load: 29.5 t ADT: 55,020

MD 97

Fair

Over: HAWLINGS RIVER

0.88 MILE SOUTH OF MD 650, Montgomery, MD

Built 1930 Load: 30.8 t ADT: 10,740

MD 189

Fair

Over: IS 270 & C-D ROADS

0.96 MILE SOUTH OF MD 28, Montgomery, MD

Built 1988 Load: 31.3 t ADT: 9,304

MD 190

Fair

Over: IS 495

1.19 MILES WEST OF MD 188, Montgomery, MD

Built 1962 Load: 31.3 t ADT: 22,022

FAIRLAND ROAD

Fair

Over: PAINT BRANCH

1.5 MI WEST OF US 29, Montgomery, MD

Built 1965 Load: 31.7 t ADT: 17,033

PERSIMMON TREE RD

Fair

Over: IS 495

0.06 MI S OF MD 996, Montgomery, MD

Built 1962 Load: 32.2 t ADT: 2,910

E. RIXEY ROAD

Fair

Over: STONEY CREEK

10M W STONE LAKE RD, Montgomery, MD

Built 1975 Load: 32.7 t ADT: 500

MD 28 & RAMP 6

Fair

Over: WATTS BRANCH

0.18 MILE WEST OF IS 270, Montgomery, MD

Built 1955 Load: 32.7 t ADT: 47,601

US 29

Fair

Over: NORTHWEST BRANCH

0.27 M S OF LOCKWOOD DR, Montgomery, MD

Built 1920 Load: 32.7 t ADT: 67,927

MD 107

Fair

Over: DRY SENECA CREEK

1.4 MILES WEST OF MD 28, Montgomery, MD

Built 1992 Load: 32.7 t ADT: 5,862

MD 115

Fair

Over: ROCK CREEK

0.34 M E OF OLDE MILL RUN, Montgomery, MD

Built 1970 Load: 32.7 t ADT: 16,981

MD 124

Fair

Over: GREAT SENECA CREEK

0.23 MI S OF WATKINS RD, Montgomery, MD

Built 1989 Load: 32.7 t ADT: 11,881

MD 182

Fair

Over: BEL PRE CREEK

1.15 MILE NORTH OF MD 97, Montgomery, MD

Built 1991 Load: 32.7 t ADT: 21,002

MD 190

Fair

Over: BOOZE CREEK

0.56 MILE EAST OF IS 495, Montgomery, MD

Built 1962 Load: 32.7 t ADT: 44,290

MD 193

Fair

Over: SLIGO CREEK

1.26 MILES EAST OF MD 97, Montgomery, MD

Built 1932 Load: 32.7 t ADT: 28,580

MD 185

Fair

Over: BR OF ROCK CREEK

0.14 MILE SOUTH OF MD 586, Montgomery, MD

Built 1963 Load: 32.7 t ADT: 38,552

MD 124

Fair

Over: GOSHEN BRANCH

0.6 MI N OF BRINK RD, Montgomery, MD

Built 1989 Load: 32.7 t ADT: 11,560

MD 586

Fair

Over: TURKEY BRANCH

0.98 MILE WEST OF MD 185, Montgomery, MD

Built 1955 Load: 32.7 t ADT: 47,792

IS 495X

Fair

Over: BOOZE CREEK

0.48 MILE SOUTH OF IS 495, Montgomery, MD

Built 1964 Load: 32.7 t ADT: 19,820

MD 185

Fair

Over: TURKEY BRANCH

0.99 MILE SOUTH OF MD 97, Montgomery, MD

Built 1969 Load: 32.7 t ADT: 36,532

CLARA BARTON PKWY

Fair

Over: ROCK RUN

W OF INTERCHANGE, Montgomery, MD

Built 1963 Load: 32.7 t ADT: 13,090

MD 927 & RAMP D

Fair

Over: IS 270 RAMP I

0.13 M E OF BR NO 1506800, Montgomery, MD

Built 1988 Load: 32.7 t ADT: 57,252

HAVILAND MILL ROAD

Fair

Over: HAWLINGS RIVER

0.8 MI EAST OF MD 650, Montgomery, MD

Built 1926 Load: 32.7 t ADT: 1,000

RANNOCH ROAD

Fair

Over: MINNEHAHA BRANCH

0.05 MILES WEST OF MD 614, Montgomery, MD

Built 1920 Load: 32.7 t ADT: 897

BALTIMORE ROAD

Fair

Over: ROCK CREEK

0.5 MI S OF JCT SR 28, Montgomery, MD

Built 1911 Load: 32.7 t ADT: 7,482

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

Related

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Data sourced from official public datasets. See our methodology for details. Retrieved and formatted by PlainBridges

Every figure on PlainBridges is rendered directly from federal source data, no number is typed in by an editor. This page draws directly on federal source data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. NBI condition categories reflect the latest reported inventory record, not a live safety, closure, or travel decision.