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)

IS 270

Fair

Over: GR SENECA CR & GAME PRE

1.17 MILES N OF MD 124, Montgomery, MD

Built 1954 Load: 40.4 t ADT: 154,247

FERNWOOD RD

Fair

Over: IS 495

@ IS 495, Montgomery, MD

Built 1962 Load: 40.4 t ADT: 16,350

RIVER ROAD

Fair

Over: SENECA CREEK

0.5 MI W OF SENECA ROAD, Montgomery, MD

Built 1959 Load: 40.4 t ADT: 3,284

GREENTREE RD

Fair

Over: IS 495

@ IS 495, Montgomery, MD

Built 1962 Load: 40.8 t ADT: 8,600

GLEN MILL ROAD

Fair

Over: PINEY BRANCH

0.6 MI N OF GLEN RD., Montgomery, MD

Built 1960 Load: 40.8 t ADT: 4,190

MOUTH OF MONOCACY

Fair

Over: CSXT RAILROAD

0.9 MILES WEST OF MD 28, Montgomery, MD

Built 2007 Load: 40.8 t ADT: 300

RIFFLE FORD ROAD

Fair

Over: GREAT SENECA CREEK

1.8 MILES EAST OF MD 118, Montgomery, MD

Built 1952 Load: 40.8 t ADT: 4,131

REDLAND ROAD

Fair

Over: CSXT RR & WMATA METRO

0.2 MI E OF MD RTE 355, Montgomery, MD

Built 1980 Load: 41.3 t ADT: 20,246

CHANDLEE MILL ROAD

Fair

Over: JAMES CREEK

0.4 MI S OF GOLD MINE RD, Montgomery, MD

Built 1972 Load: 41.7 t ADT: 302

MD 355

Fair

Over: CSX TRANS MU 681 MU 77

0.19 M S OF BROOKS AVENUE, Montgomery, MD

Built 1987 Load: 42.2 t ADT: 34,970

US 29

Fair

Over: MD 650

0.35 M S OF STEWART LANE, Montgomery, MD

Built 1957 Load: 42.2 t ADT: 61,922

KENT STREET

Fair

Over: SILVER CREEK

0.1 MI E KENSINGTON PKWY, Montgomery, MD

Built 1940 Load: 42.5 t ADT: 3,407

IS 270 RAMP C

Fair

Over: IS 270Y RAMPS B & B3

0.85 MILE NORTH OF MD 187, Montgomery, MD

Built 1958 Load: 42.6 t ADT: 130,450

AIRPARK ROAD

Fair

Over: TRIBUTARY TO ROCK CREEK

0.6 MI NE OF JCT MD 115, Montgomery, MD

Built 1994 Load: 42.6 t ADT: 41,097

KENDALE ROAD

Fair

Over: KEN BRANCH

0.4 MI NORTH OF MD 191, Montgomery, MD

Built 2002 Load: 42.6 t ADT: 571

MD 185

Fair

Over: PROPOSED ROADWAY

0.92 MILE SOUTH OF MD 97, Montgomery, MD

Built 1968 Load: 43.1 t ADT: 36,532

MD 117

Fair

Over: GREAT SENECA CREEK

1.82 MILES EAST OF MD 118, Montgomery, MD

Built 1951 Load: 43.1 t ADT: 18,752

PARTNERSHIP RD

Fair

Over: RUSSELL BRANCH

1.2 MI S OF JCT SR 107, Montgomery, MD

Built 1920 Load: 43.1 t ADT: 2,174

SCOTT DRIVE

Fair

Over: WATTS BRANCH

0.1 MI W OF WOOTTON PKWY, Montgomery, MD

Built 1990 Load: 43.1 t ADT: 3,921

MD 191

Fair

Over: CABIN JOHN CREEK

0.96 MILE SOUTH OF IS 495, Montgomery, MD

Built 1991 Load: 43.5 t ADT: 8,530

IS 270

Fair

Over: MIDDLEBROOK ROAD

0.77 MILE SOUTH OF MD 118, Montgomery, MD

Built 1990 Load: 43.5 t ADT: 133,720

IS 495

Fair

Over: POTOMAC RIVER

ON VIRGINIA LINE, Montgomery, MD

Built 1963 Load: 43.5 t ADT: 239,022

AMBLESIDE DRIVE

Fair

Over: WATTS BRANCH

0.6 MI NORTH OF GLEN ROAD, Montgomery, MD

Built 1970 Load: 43.5 t ADT: 2,418

US 29 NB

Fair

Over: PAINT BRANCH

0.87 MILE NORTH OF MD 650, Montgomery, MD

Built 1957 Load: 44.4 t ADT: 66,948

US 29 SB

Fair

Over: PAINT BRANCH

0.87 MILE NORTH OF MD 650, Montgomery, MD

Built 1957 Load: 44.4 t ADT: 66,948

IS 495 RAMP F(1)

Fair

Over: IS 495

2.19 MILE NORTH OF MD 193, Montgomery, MD

Built 1964 Load: 44.4 t ADT: 5,541

IS 495

Fair

Over: MACARTHUR BLVD CB PKWY

0.52 MILE EAST OF VA LINE, Montgomery, MD

Built 1963 Load: 44.9 t ADT: 214,005

IS 270 RAMP C(5)

Fair

Over: IS 270; C-D RDS & RP F/1

AT I-270, Montgomery, MD

Built 1990 Load: 44.9 t ADT: 15,251

DEER RIDGE ROAD

Fair

Over: MD 119

1.39 M N OF MD 124, Montgomery, MD

Built 1989 Load: 44.9 t ADT: 21,111

RANDOLPH ROAD (EB)

Fair

Over: ROCK CREEK

1.5 MILES EAST OF MD 355, Montgomery, MD

Built 1953 Load: 44.9 t ADT: 23,434

SEVEN LOCKS ROAD

Fair

Over: CABIN JOHN CREEK

0.1 MI S OF JCT SR MD 190, Montgomery, MD

Built 1980 Load: 44.9 t ADT: 9,414

IS 495

Fair

Over: SEVEN LOCKS RD

0.59 MILE EAST OF MD 190, Montgomery, MD

Built 1962 Load: 45.4 t ADT: 214,005

MD 191

Fair

Over: IS 495 & THOMAS BRANCH

1.9 MILES NORTH OF MD 190, Montgomery, MD

Built 1962 Load: 45.4 t ADT: 10,370

SHADY GROVE ROAD

Fair

Over: MILL CREEK

1.1 MI SOUTH OF MD 115, Montgomery, MD

Built 1975 Load: 45.4 t ADT: 67,323

DECOVERLY DRIVE

Fair

Over: TRIBUTARY TO MUDDY BRANC

0.7 MILES NORTH OF MD 28, Montgomery, MD

Built 2006 Load: 45.4 t ADT: 5,804

MONROE STREET

Fair

Over: TRUCK STREET

0.16 MI NORTH OF MD 28, Montgomery, MD

Built 1996 Load: 45.4 t ADT: 3,663

MD 185

Fair

Over: CSX TRANS.

0.10 MILE NORTH OF MD 547, Montgomery, MD

Built 1957 Load: 45.8 t ADT: 42,252

IS 495

Fair

Over: SLIGO CREEK PARKWAY

0.604 MILE EAST OF MD 97, Montgomery, MD

Built 1959 Load: 45.8 t ADT: 232,010

IS 495

Fair

Over: MD 650

0.28 MI W OF PG CO, Montgomery, MD

Built 1963 Load: 45.8 t ADT: 242,500

WESTLAKE TERRACE-F

Fair

Over: I-270

1 MI N OF DEMOCRACY BLVD, Montgomery, MD

Built 1994 Load: 45.8 t ADT: 13,584

CASHELL ROAD

Fair

Over: WILLIAMSBURG RUN

0.9 MI S OF BOWIE MILL RD, Montgomery, MD

Built 1972 Load: 46.3 t ADT: 6,159

MD 320

Fair

Over: SLIGO CREEK

0.69 MILE SOUTH OF MD 193, Montgomery, MD

Built 1920 Load: 46.7 t ADT: 19,392

LITTLE FALLS PARKW

Fair

Over: WILLET BRANCH

0.1 MI N DORSET AVE, Montgomery, MD

Built 1963 Load: 46.7 t ADT: 17,283

MD 119

Fair

Over: SHADY BRANCH

0.3 M S OF SAM EIG HWY, Montgomery, MD

Built 1988 Load: 47.2 t ADT: 19,551

IS 495X NB

Fair

Over: CABIN JOHN CREEK

0.11 MILE NORTH OF GV 6, Montgomery, MD

Built 1963 Load: 47.6 t ADT: 19,820

IS 495 RAMP E

Fair

Over: KENSINGTON PKWY

0.19 MI E OF MD 185, Montgomery, MD

Built 1964 Load: 47.6 t ADT: 3,685

IS 270

Fair

Over: IS 370 AND RAMP B

1.53 MILE SOUTH OF MD 117, Montgomery, MD

Built 1990 Load: 47.6 t ADT: 216,270

MD 28

Fair

Over: CSXT WMATA RAMP

0.19 MILE WEST OF MD 911, Montgomery, MD

Built 1981 Load: 48.1 t ADT: 27,020

IS 270 NBR

Fair

Over: BR OF LITTLE BENNETT CRK

0.32 MILE SOUTH OF MD 109, Montgomery, MD

Built 1952 Load: 48.1 t ADT: 94,940

BROOKVILLE ROAD

Fair

Over: CSXT RAILROAD

0.4 MI SW OF MD 192, Montgomery, MD

Built 1976 Load: 48.1 t ADT: 19,611

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.