County profile · official public datasets

Middlesex County, MA

818 public highway bridges tracked in the FHWA National Bridge Inventory: 20.7% rated Good, 68.2% Fair, 11.1% Poor.

818
Public bridges
20.7%
Good condition
11.1%
Poor condition

The verdict

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

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

11th
of 13 on Poor share
11.1%
Poor-condition share
818
public highway bridges
1958
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.

Middlesex County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Middlesex County ranks #11 of 13 Massachusetts counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 11.1%). Middlesex County, Massachusetts contains 818 public highway bridges. Roughly 20.7% are rated “Good,” 68.2% “Fair,” and 11.1% “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

818

Public highway bridges in Middlesex County

Good condition

20.7%

169 of 818 rated 7-9

Fair condition

68.2%

558 of 818 rated 5-6

Poor condition

11.1%

91 of 818 rated 4 or below

In-state Poor-share rank

#11 of 13

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

Condition distribution

Share of 818 NBI-tracked bridges by lowest applicable component rating.

Good
20.7% (169)
Fair
68.2% (558)
Poor
11.1% (91)

Middlesex County's Poor-condition bridges carry 3,395,813 vehicle crossings a day

That is 12.7% of the county's reported daily bridge traffic on 11.1% of its bridges: Poor-condition structures carry more traffic than their share of the inventory. Each Poor bridge averages 37,317 crossings a day against 21,585 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 818 of 818 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

70.5% of Middlesex County's bridges have passed the 50-year mark

577 of the 818 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 20.7% 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 5.9% of the county's Poor-condition bridge traffic

I 93 over I 95 /ST128, built 1957, carries 200,824 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 91-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 3,395,813 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

When Middlesex County's bridges were built

818 bridges with a recorded construction year, grouped by decade

bridges

What this shows Construction peaked in the 1950s, when 179 of the county's bridges still in the inventory were built, which is 21.9% of those with a recorded year. That cohort is now 65 to 74 years old in the 2024 inventory. Its average build year (1958) matches the Massachusetts average (1961).

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

How Middlesex County compares with Massachusetts's closest counties by inventory size

The 5 Massachusetts counties nearest Middlesex County in number of bridges, with their condition splits. Its 11.1% Poor share is the 5th-lowest of these 6. Its average build year of 1958 against a peer-group mean of 1961 is in line with the group.

Showing the 5 closest of 12 Massachusetts counties eligible for comparison.

Bridge inventory size and condition shares for Middlesex County and the 5 Massachusetts counties closest to it in inventory size
County Bridges Poor
Worcester County 1,014 7.6%
Middlesex County (this page) 818 11.1%
Suffolk County 489 9.6%
Berkshire County 450 7.8%
Hampden County 428 7.5%
Essex County 395 17.2%

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

Similar inventory size

Nearest county inventories outside MA (818 bridges here).

Similar average build year

Nearest mean year-built outside MA (1958 here).

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

All 818 Good 169 Fair 558 Poor 91

All bridges (818)

ST 2 A/MARRETT RD

Poor

Over: I 95 /ST128

RT 2A AT RT 128, Middlesex, MA

Built 1961 Load: 24.0 t ADT: 23,310

I 495 NB

Poor

Over: WATER ASSABET RIVER

MM 65.4, Middlesex, MA

Built 1963 Load: 24.1 t ADT: 55,989

ST 3 A/GORHAM ST

Poor

Over: I 495

1.25 MI W RT495/RT3, Middlesex, MA

Built 1962 Load: 24.3 t ADT: 84,000

HWY BRIDGE ST

Poor

Over: WATER EASTERN CANAL

0.4 KM S RTE 110 & 38, Middlesex, MA

Built 1937 Load: 24.8 t ADT: 25,862

ST119 MAIN ST

Poor

Over: WATER PEARL HILL BROOK

2.6 MI W OF ST-13, Middlesex, MA

Built 1907 Load: 24.9 t ADT: 8,358

ST 62 MAIN ST

Poor

Over: WATER ASSABET RIVER

0.25 MI SW RT 27 & MAIN, Middlesex, MA

Built 1922 Load: 25.6 t ADT: 8,000

I 95 SB/ST128 SB

Poor

Over: ST 3 A/CAMBRIDGE ST

AT JUNC. OF I 95 & ST 3A, Middlesex, MA

Built 1950 Load: 25.8 t ADT: 93,600

HWY SUFFOLK ST

Poor

Over: WATER NORTHERN CANAL

FRENCH ST EXT, Middlesex, MA

Built 1848 Load: 26.0 t ADT: 3,000

I 95 SB/ST128 SB

Poor

Over: HWY S BEDFORD ST

0.5 MI SW RT 95 & RT 3A, Middlesex, MA

Built 1950 Load: 26.5 t ADT: 92,706

HWY BOYLSTON ST

Poor

Over: I 495

1.3 KM SOUTH RT 38, Middlesex, MA

Built 1961 Load: 26.7 t ADT: 12,000

HWY TRAPELO RD

Poor

Over: I 95 /ST128

1.4 KM SLY RT 2, Middlesex, MA

Built 1960 Load: 26.7 t ADT: 24,727

ST129 LOWELL ST

Poor

Over: I 93

RT 129 AT RT 93, Middlesex, MA

Built 1957 Load: 26.8 t ADT: 25,500

HWY NORTH ST

Poor

Over: I 495

0.6 MI SWLY RT 133, Middlesex, MA

Built 1961 Load: 27.1 t ADT: 11,767

HWY MISHAWUM RD

Poor

Over: I 95 /ST128

1 MI NE RTE 38, Middlesex, MA

Built 1961 Load: 27.5 t ADT: 13,700

I 495 NB

Poor

Over: ST133 ANDOVER ST

RT 495 AT RT 133, Middlesex, MA

Built 1961 Load: 28.1 t ADT: 60,988

I 495 SB

Poor

Over: ST133 ANDOVER ST

RT 495 AT RT 133, Middlesex, MA

Built 1961 Load: 28.1 t ADT: 60,884

ST 9 BOYLSTON ST

Poor

Over: TR GREEN LINE D

2.3 KM ELY RT 128, Middlesex, MA

Built 1905 Load: 28.3 t ADT: 96,206

HWY FRUIT ST

Poor

Over: COMB MBTA/CSX & SUDBURY

.7 MI EAST OF I - 495, Middlesex, MA

Built 1936 Load: 28.8 t ADT: 4,238

ST117 MAIN ST

Poor

Over: I 95 /ST128

0.5 MI NLY RT 20, Middlesex, MA

Built 1962 Load: 28.8 t ADT: 18,600

HWY NB LOWLL CON

Poor

Over: I 495

1 MI E OF ST-110, Middlesex, MA

Built 1959 Load: 28.9 t ADT: 14,200

HWY SPEEN ST

Poor

Over: RR MBTA/CSX

0.1 MI NORTH OF RT 135, Middlesex, MA

Built 1900 Load: 29.5 t ADT: 13,000

I 495 SB

Poor

Over: ST 38 MAIN ST

RT 495 AT RT 38, Middlesex, MA

Built 1961 Load: 29.7 t ADT: 63,530

ST 2 EB

Poor

Over: HWY PLEASANT ST

2.25 MI SE RT 2 & RT 128, Middlesex, MA

Built 1965 Load: 29.8 t ADT: 86,300

ST126 CONCORD RD

Poor

Over: RR MBTA/BMRR

1 MI N RT 117 & RT 126, Middlesex, MA

Built 1950 Load: 30.0 t ADT: 6,853

ST 2 WB

Poor

Over: HWY PLEASANT ST

2.25 MI SE RT 2 & RT 128, Middlesex, MA

Built 1965 Load: 30.5 t ADT: 76,500

RANGE RD

Poor

Over: PONAKIN BROOK TRIBUTARY

BTW LUNEBURG & SHOEFELT, Middlesex, MA

Built 2011 Load: 30.8 t ADT: 6

ST 38 MAIN ST

Poor

Over: RR MBTA/BMRR

1.1 KM SELY RT 129, Middlesex, MA

Built 1928 Load: 31.0 t ADT: 24,600

HWY PARK AVE

Poor

Over: ST 2

1.6 KM NW RT 60, Middlesex, MA

Built 1967 Load: 31.3 t ADT: 19,500

I 495 NB

Poor

Over: I 90

MM 106.4, Middlesex, MA

Built 1965 Load: 31.3 t ADT: 45,046

I 495 SB

Poor

Over: WATER ASSABET RIVER

0.25 MI NW RT 290, Middlesex, MA

Built 1963 Load: 31.3 t ADT: 56,081

I 495 SB

Poor

Over: RR PAN AM

0.25 MI S OF ST-38, Middlesex, MA

Built 1961 Load: 31.4 t ADT: 62,395

ST111 MASS AVE

Poor

Over: I 495

MM 74.6, Middlesex, MA

Built 1963 Load: 31.5 t ADT: 4,605

I 93 NB OFFRAMP

Poor

Over: ST 38 NB/MYSTIC AVE

3.2 KM N OF JCT I93&US1, Middlesex, MA

Built 1973 Load: 31.6 t ADT: 19,300

I 495 NB

Poor

Over: RR PAN AM

0.25 MI S OF ST-38, Middlesex, MA

Built 1961 Load: 32.2 t ADT: 64,233

I 90 RAMPS A & B

Poor

Over: WATER CHARLES RIVER

AT INT 14 L50, Middlesex, MA

Built 1957 Load: 32.2 t ADT: 80,100

I 495 NB

Poor

Over: ST110 CHELMSFORD ST

RT 495 AT RT 110, Middlesex, MA

Built 1960 Load: 32.5 t ADT: 55,955

I 495 SB

Poor

Over: I 90

2.2 MI N OF ST-135, Middlesex, MA

Built 1965 Load: 32.5 t ADT: 42,619

HWY SB LOWLL CON

Poor

Over: I 495

1 MI E OF ST-110, Middlesex, MA

Built 1959 Load: 33.3 t ADT: 11,576

HWY LWLL CN B-10

Poor

Over: HWY LOWEL CON RAMP B8

RAMP B-10/RAMP B-8, Middlesex, MA

Built 1959 Load: 33.3 t ADT: 8,500

ST 16 WB/WSHGTN ST

Poor

Over: COMB I 90 & CSX/MBTA

AT INT 16 S16, Middlesex, MA

Built 1964 Load: 33.7 t ADT: 18,491

I 495 NB

Poor

Over: HWY TADMUCK RD

0.4 MI N OF RT 110, Middlesex, MA

Built 1961 Load: 33.7 t ADT: 97,289

ST119 /ST2 A

Poor

Over: WATER NASHOBA BROOK

0.25 MI S OF 27 & 2A, Middlesex, MA

Built 1940 Load: 33.9 t ADT: 12,463

I 495 NB

Poor

Over: HWY W MAIN ST

1.1 MI S OF ST-135, Middlesex, MA

Built 1966 Load: 33.9 t ADT: 48,152

I 95 /ST128

Poor

Over: RR MBTA/BMRR

1.6 KM W OF I-93 & I-95, Middlesex, MA

Built 1950 Load: 34.1 t ADT: 192,672

I 495 SB

Poor

Over: HWY W MAIN ST

MM 54.6, Middlesex, MA

Built 1966 Load: 34.3 t ADT: 42,766

HWY LWL CON B-11

Poor

Over: I 495

0.4 KM E RT 495 & RT 3, Middlesex, MA

Built 1959 Load: 35.0 t ADT: 8,952

I 93

Poor

Over: ST 16 MYST VAL PKY

1 MI S OF JCT I93 & SR60, Middlesex, MA

Built 1960 Load: 35.6 t ADT: 182,420

I 90 EX 111 IN 12

Poor

Over: ST 9 WORCESTER RD

OUTSIDE INT 12 L12, Middlesex, MA

Built 1957 Load: 36.5 t ADT: 25,868

I 495 NB

Poor

Over: HWY BOSTON RD

EXIT 83/N OF 110, Middlesex, MA

Built 1959 Load: 37.4 t ADT: 53,253

I 495 SB

Poor

Over: HWY BOSTON RD

0.2 MI N OF ST-110, Middlesex, MA

Built 1959 Load: 37.4 t ADT: 55,292

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.