SR 77 over Zapata Wash

Fair

Pinal County, Arizona · 15.6 MI S JCT SR 177 · Structure no. 00634

Built: 1961; 64 years old
Condition: Fair; inspected January 2025
Type: Slab; Concrete Continuous
Length: 166 ft; 5 main spans
Daily traffic: 2,421; 2025 count
Owner: State; State Highway Agency

About this bridge

SR 77 over Zapata Wash is a concrete continuous slab carrying SR 77 over Zapata Wash in Pinal County, Arizona. It was built in 1961, so it is 64 years old, older than the Arizona average of 47.8 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 2,421 vehicles a day, roughly 17% of them trucks, projected to reach 2,431 by 2042. The structure is 166 ft (50.6 m) long and 35 ft wide. If it were closed, the detour would be 24.2 mi (39 km).

Location

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CarriesSR 77

CrossesZapata Wash

Location15.6 MI S JCT SR 177

RouteState Highway 77

CountyPinal County

StateArizona

Coordinates32.7869, -110.6701

Functional classRural Minor Arterial

Condition and inspection

Fair

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

Component	Rating	Meaning
Deck	6 Satisfactory	Structural elements show some minor deterioration.
Superstructure	6 Satisfactory	Structural elements show some minor deterioration.
Substructure	7 Good	Some minor problems.
Channel and channel protection	7 Good	Some minor problems.

Last inspectionJanuary 2025

Inspection intervalevery 24 months

Operating statusOpen, no restriction

ScourScour critical; foundations unstable for calculated scour conditions

Structural evaluation6: Equal to present minimum criteria

Deck geometry4: Meets minimum tolerable limits to be left in place as is

Waterway adequacy7: Better than present minimum criteria

Approach roadway alignment8: Equal to present desirable criteria

Operating rating49.1 US tons

Inventory rating29 US tons

Structure

Structure typeSlab

MaterialConcrete Continuous

DeckConcrete, cast-in-place

Main spans5

Design loadHS 20

Structure length166 ft (50.6 m)

Longest span35 ft (10.7 m)

Deck width35 ft (10.7 m)

Roadway width32 ft (9.8 m)

Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic2,421 (2025)

Projected traffic2,431 by 2042

Trucks17%

Lanes on structure2

Traffic directionTwo-way traffic

CarriesHighway

CrossesWaterway

Detour if closed24.2 mi (39 km)

TollOn a free road

National Highway SystemNo

Ownership and planned work

OwnerState Highway Agency

Maintained byState Highway Agency

Historic statusNot eligible for the National Register of Historic Places

Work proposedNone recorded

Estimated improvement cost—

NavigationNo navigation control on waterway

Frequently asked questions

When was SR 77 over Zapata Wash built?

It was built in 1961, making it 64 years old in 2025.

What condition is SR 77 over Zapata Wash 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 January 2025.

How much traffic does SR 77 over Zapata Wash carry?

About 2,421 vehicles per day (2025 count), of which roughly 17% are trucks.

How long is SR 77 over Zapata Wash?

The structure is 166 ft (50.6 m) long with a longest span of 35 ft (10.7 m) and a deck 35 ft wide.

Who owns SR 77 over Zapata Wash?

It is owned by the State Highway Agency.