US Bridges

SR-312 WB over Matanzas River

Good

St. Johns County, Florida · SR-312 WB over Matanzas R · Structure no. 780100

Built
1999
26 years old
Condition
Good
inspected August 2023
Type
Stringer/Multi-beam or Girder
Prestressed Concrete Continuous
Length
3,575 ft
3 main spans
Daily traffic
19,000
2022 count
Owner
State
State Highway Agency

About this bridge

SR-312 WB over Matanzas River is a prestressed concrete continuous stringer/multi-beam or girder carrying SR-312 WB over Matanzas River in St. Johns County, Florida. It was built in 1999, so it is 26 years old, younger than the Florida average of 41.3 years.

The most recent inspection reported to the Federal Highway Administration rates it in good condition with a lowest component rating of 7 out of 9. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

It carries about 19,000 vehicles a day, roughly 2% of them trucks, projected to reach 32,965 by 2044. The structure is 3,575 ft (1,089.7 m) long and 43 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

Open in Google Maps
CarriesSR-312 WB
CrossesMatanzas River
LocationSR-312 WB over Matanzas R
RouteState Highway 312
CountySt. Johns County
StateFlorida
Coordinates29.86722, -81.3075
Functional classUrban Minor Arterial

Condition and inspection

Good

All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

ComponentRatingMeaning
Deck7 GoodSome minor problems.
Superstructure7 GoodSome minor problems.
Substructure7 GoodSome minor problems.
Channel and channel protection7 GoodSome minor problems.
Last inspectionAugust 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation7: Better than present minimum criteria
Deck geometry7: Better than present minimum criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating83 US tons
Inventory rating63.1 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete Continuous
DeckConcrete, cast-in-place
Main spans3 (+21 approach)
Design loadHS 20 + Mod
Structure length3,575 ft (1,089.7 m)
Longest span250 ft (76.2 m)
Deck width43 ft (13 m)
Roadway width40 ft (12.1 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic19,000 (2022)
Projected traffic32,965 by 2044
Trucks2%
Lanes on structure2
Traffic directionOne-way traffic
CarriesHighway
CrossesWaterway
Detour if closed1.2 mi (2 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 proposedRehabilitation because of general structure deterioration or inadequate strength
Estimated improvement cost$350,000
NavigationNavigation control on waterway (bridge permit required)

Frequently asked questions

When was SR-312 WB over Matanzas River built?

It was built in 1999, making it 26 years old in 2025.

What condition is SR-312 WB over Matanzas River in?

The National Bridge Inventory rates it in good condition. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted. The last reported inspection was in August 2023.

How much traffic does SR-312 WB over Matanzas River carry?

About 19,000 vehicles per day (2022 count), of which roughly 2% are trucks.

How long is SR-312 WB over Matanzas River?

The structure is 3,575 ft (1,089.7 m) long with a longest span of 250 ft (76.2 m) and a deck 43 ft wide.

Who owns SR-312 WB over Matanzas River?

It is owned by the State Highway Agency.