US Bridges

State Route 4 over Middle River

Fair

San Joaquin County, California · 10-SJ-004-4.42 · Structure no. 29 0049

Built
1915
110 years old
Condition
Fair
inspected April 2023
Type
Truss - Thru
Steel
Length
545 ft
2 main spans
Daily traffic
7,200
2009 count
Owner
State
State Highway Agency

About this bridge

State Route 4 over Middle River is a steel truss - thru carrying State Route 4 over Middle River in San Joaquin County, California. It was built in 1915, so it is 110 years old, older than the California average of 54.8 years.

The most recent inspection reported to the Federal Highway Administration rates it in fair condition with a lowest component rating of 5 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 7,200 vehicles a day, roughly 11% of them trucks, projected to reach 23,542 by 2045. The structure is 545 ft (166.1 m) long and 22 ft wide. If it were closed, the detour would be 28 mi (45 km).

Location

Open in Google Maps
CarriesState Route 4
CrossesMiddle River
Location10-SJ-004-4.42
RouteState Highway 4
CountySan Joaquin County
StateCalifornia
Coordinates37.89119, -121.49004
Functional classRural Principal Arterial - Interstate

Condition and inspection

Fair

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

ComponentRatingMeaning
Deck5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Superstructure7 GoodSome minor problems.
Substructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionApril 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry2: Basically intolerable, requiring high priority of replacement
Waterway adequacy7: Better than present minimum criteria
Approach roadway alignment3: Basically intolerable, requiring high priority of corrective action
Operating rating48.2 US tons
Inventory rating28.9 US tons

Structure

Structure typeTruss - Thru
MaterialSteel
DeckConcrete, cast-in-place
Main spans2 (+3 approach)
Design loadH 15
Structure length545 ft (166.1 m)
Longest span129 ft (39.2 m)
Deck width22 ft (6.6 m)
Roadway width20 ft (6 m)
Vertical clearance over deck20 ft (6 m)

Traffic and service

Average daily traffic7,200 (2009)
Projected traffic23,542 by 2045
Trucks11%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed28 mi (45 km)
TollOn a free road
National Highway SystemYes
Strategic Highway NetworkInterstate STRAHNET route

Ownership and planned work

OwnerState Highway Agency
Maintained byState Highway Agency
Historic statusEligible for the National Register of Historic Places
Work proposedNone recorded
Estimated improvement cost—
NavigationNavigation control on waterway (bridge permit required)

Frequently asked questions

When was State Route 4 over Middle River built?

It was built in 1915, making it 110 years old in 2025.

What condition is State Route 4 over Middle 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 April 2023.

How much traffic does State Route 4 over Middle River carry?

About 7,200 vehicles per day (2009 count), of which roughly 11% are trucks.

How long is State Route 4 over Middle River?

The structure is 545 ft (166.1 m) long with a longest span of 129 ft (39.2 m) and a deck 22 ft wide.

Who owns State Route 4 over Middle River?

It is owned by the State Highway Agency.