US Bridges

SR 77 over San Pedro River

Fair

Pinal County, Arizona · 6.6 MI N JCT SR 76 · Structure no. 00664

Built
1961
64 years old
Condition
Fair
inspected July 2023
Type
Stringer/Multi-beam or Girder
Steel Continuous
Length
349 ft
4 main spans
Daily traffic
2,411
2021 count
Owner
State
State Highway Agency

About this bridge

SR 77 over San Pedro River is a steel continuous stringer/multi-beam or girder carrying SR 77 over San Pedro River 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 2,411 vehicles a day, roughly 17% of them trucks, projected to reach 2,421 by 2041. The structure is 349 ft (106.4 m) long and 35 ft wide. If it were closed, the detour would be 62.1 mi (100 km).

Location

Open in Google Maps
CarriesSR 77
CrossesSan Pedro River
Location6.6 MI N JCT SR 76
RouteState Highway 77
CountyPinal County
StateArizona
Coordinates32.7421, -110.6482
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.

ComponentRatingMeaning
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure7 GoodSome minor problems.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection7 GoodSome minor problems.
Last inspectionJuly 2023
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 alignment7: Better than present minimum criteria
Operating rating53 US tons
Inventory rating31 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel Continuous
DeckConcrete, cast-in-place
Main spans4
Design loadHS 20
Structure length349 ft (106.4 m)
Longest span96 ft (29.3 m)
Deck width35 ft (10.8 m)
Roadway width31 ft (9.6 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic2,411 (2021)
Projected traffic2,421 by 2041
Trucks17%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed62.1 mi (100 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 proposedReplacement because of substandard load-carrying capacity or roadway geometry
Estimated improvement cost$2,000 (2023 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was SR 77 over San Pedro River built?

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

What condition is SR 77 over San Pedro River 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 July 2023.

How much traffic does SR 77 over San Pedro River carry?

About 2,411 vehicles per day (2021 count), of which roughly 17% are trucks.

How long is SR 77 over San Pedro River?

The structure is 349 ft (106.4 m) long with a longest span of 96 ft (29.3 m) and a deck 35 ft wide.

Who owns SR 77 over San Pedro River?

It is owned by the State Highway Agency.