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.

pre-1900

68
1900s

45
1910s

21
1920s

23
1930s

39
1940s

25
1950s

179
1960s

161
1970s

33
1980s

29
1990s

45
2000s

90
2010s

44
2020s

16

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).

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	Good	Fair	Poor	Avg. built
Worcester County	1,014	25.5%	66.9%	7.6%	1963
Middlesex County (this page)	818	20.7%	68.2%	11.1%	1958
Suffolk County	489	22.7%	67.7%	9.6%	1967
Berkshire County	450	34.7%	57.6%	7.8%	1961
Hampden County	428	17.1%	75.5%	7.5%	1956
Essex County	395	15.9%	66.8%	17.2%	1957

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).

Montgomery County, PA · 828 bridges
Duval County, FL · 831 bridges
Davidson County, TN · 832 bridges
Lancaster County, PA · 801 bridges

Similar average build year

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

Bucks County, PA · avg 1958 · 699 bridges
Butte County, CA · avg 1958 · 437 bridges
Cowley County, KS · avg 1958 · 337 bridges
Marin County, CA · avg 1958 · 207 bridges

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

Poor-condition bridges (91)

Sort:

Middlesex County Bridge Snapshot

Condition distribution

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

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

One structure carries 5.9% of the county's Poor-condition bridge traffic

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

Nationwide counties with similar inventory size or average build year

Similar inventory size

Similar average build year

Poor-condition bridges (91)

HWY PARK AVE

I 495 NB

I 495 SB

I 495 SB

ST111 MASS AVE

I 93 NB OFFRAMP

I 495 NB

I 90 RAMPS A & B

I 495 NB

I 495 SB

HWY SB LOWLL CON

HWY LWLL CN B-10

ST 16 WB/WSHGTN ST

I 495 NB

ST119 /ST2 A

I 495 NB

I 95 /ST128

I 495 SB

HWY LWL CON B-11

I 93

I 90 EX 111 IN 12

I 495 NB

I 495 SB

ST 16 EB/WSHGTN ST

ST 28 FELLSWAY W

HWY SPEEN ST SB

ST110 SB SMTH RTY

ST 38 NB SMITH RTY

ST113 MAIN ST

HWY AUBURN ST

US 3 NB

HWY WATERTOWN ST

HWY BOX MILL RD

I 90 WB RAMP OFF

HWY SPEEN ST NB

I 90 RAMP G

ST 60 PLEASANT ST

ST 2 CONCORD TPK

HWY CHESTNUT ST

ST119 STATE RD

HWY PLEASANT ST

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