US Bridges

FM 521 over Mcfadden Slough

Fair

Brazoria County, Texas · 1.60 MI N of SH 332 · Structure no. 120200084703011

Built
1956
69 years old, rebuilt 2004
Condition
Fair
inspected November 2024
Type
Stringer/Multi-beam or Girder
Concrete
Length
92 ft
3 main spans
Daily traffic
4,943
2023 count
Owner
State
State Highway Agency

About this bridge

FM 521 over Mcfadden Slough is a concrete stringer/multi-beam or girder carrying FM 521 over Mcfadden Slough in Brazoria County, Texas. It was built in 1956 and reconstructed in 2004, so it is 69 years old, older than the Texas average of 44.4 years.

The most recent inspection reported to the Federal Highway Administration rates it in fair condition with a lowest component rating of 6 out of 9. The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.

It carries about 4,943 vehicles a day, roughly 7% of them trucks, projected to reach 4,690 by 2033. The structure is 92 ft (28.1 m) long and 46 ft wide. If it were closed, the detour would be 8.7 mi (14 km).

Location

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CarriesFM 521
CrossesMcfadden Slough
Location1.60 MI N of SH 332
RouteState Highway 521
CountyBrazoria County
StateTexas
Coordinates29.0771, -95.554
Functional classRural Major Collector

Condition and inspection

Fair

The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.

ComponentRatingMeaning
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure7 GoodSome minor problems.
Substructure7 GoodSome minor problems.
Channel and channel protection7 GoodSome minor problems.
Last inspectionNovember 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation7: Better than present minimum criteria
Deck geometry7: Better than present minimum criteria
Waterway adequacy6: Equal to present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating75 US tons
Inventory rating45 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialConcrete
DeckConcrete, cast-in-place
Main spans3
Design loadOther
Structure length92 ft (28.1 m)
Longest span30 ft (9.2 m)
Deck width46 ft (14.1 m)
Roadway width44 ft (13.4 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic4,943 (2023)
Projected traffic4,690 by 2033
Trucks7%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed8.7 mi (14 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerState Highway Agency
Maintained byState Highway Agency
Historic statusPossibly eligible for the National Register; requires further investigation
Work proposedOther structural work, including hydraulic replacements
Estimated improvement cost$6,000
NavigationNo navigation control on waterway

Frequently asked questions

When was FM 521 over Mcfadden Slough built?

It was built in 1956, making it 69 years old in 2025. It was reconstructed in 2004.

What condition is FM 521 over Mcfadden Slough in?

The National Bridge Inventory rates it in fair condition. The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound. The last reported inspection was in November 2024.

How much traffic does FM 521 over Mcfadden Slough carry?

About 4,943 vehicles per day (2023 count), of which roughly 7% are trucks.

How long is FM 521 over Mcfadden Slough?

The structure is 92 ft (28.1 m) long with a longest span of 30 ft (9.2 m) and a deck 46 ft wide.

Who owns FM 521 over Mcfadden Slough?

It is owned by the State Highway Agency.