US Bridges

Grizzly Island RD over Montezuma Slough

Fair

Solano County, California · 5.5 MI S SR 12 · Structure no. 23C0030

Built
1958
67 years old
Condition
Fair
inspected August 2024
Type
Stringer/Multi-beam or Girder
Steel
Length
927 ft
1 main span
Daily traffic
606
2008 count
Owner
County
County Highway Agency

About this bridge

Grizzly Island RD over Montezuma Slough is a steel stringer/multi-beam or girder carrying Grizzly Island RD over Montezuma Slough in Solano County, California. It was built in 1958, so it is 67 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 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 606 vehicles a day, roughly 3% of them trucks, projected to reach 708 by 2044. The structure is 927 ft (282.5 m) long and 27 ft wide. If it were closed, the detour would be 123.7 mi (199 km).

Location

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CarriesGrizzly Island RD
CrossesMontezuma Slough
Location5.5 MI S SR 12
RouteCounty Highway 0
CountySolano County
StateCalifornia
Coordinates38.18575, -121.97689
Functional classRural Minor 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.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection7 GoodSome minor problems.
Last inspectionAugust 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation6: Equal to present minimum criteria
Deck geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Waterway adequacy9: Superior to present desirable criteria
Approach roadway alignment5: Somewhat better than minimum adequacy to tolerate being left in place as is
Operating rating32.5 US tons
Inventory rating25 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckConcrete, cast-in-place
Main spans1 (+34 approach)
Design loadHS 20
Structure length927 ft (282.5 m)
Longest span53 ft (16.2 m)
Deck width27 ft (8.1 m)
Roadway width26 ft (7.9 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic606 (2008)
Projected traffic708 by 2044
Trucks3%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed123.7 mi (199 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerCounty Highway Agency
Maintained byCounty Highway Agency
Historic statusNot eligible 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 Grizzly Island RD over Montezuma Slough built?

It was built in 1958, making it 67 years old in 2025.

What condition is Grizzly Island RD over Montezuma 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 August 2024.

How much traffic does Grizzly Island RD over Montezuma Slough carry?

About 606 vehicles per day (2008 count), of which roughly 3% are trucks.

How long is Grizzly Island RD over Montezuma Slough?

The structure is 927 ft (282.5 m) long with a longest span of 53 ft (16.2 m) and a deck 27 ft wide.

Who owns Grizzly Island RD over Montezuma Slough?

It is owned by the County Highway Agency.