US Bridges

U. S. Highway 101 over 2nd 3rd 4th 5th Mssn

Fair

Marin County, California · 04-MRN-101-10.72-SRF · Structure no. 27 0035R

Built
1941
84 years old, rebuilt 1971
Condition
Fair
inspected May 2024
Type
Tee Beam
Concrete Continuous
Length
2,210 ft
37 main spans
Daily traffic
64,500
2009 count
Owner
State
State Highway Agency

About this bridge

U. S. Highway 101 over 2nd 3rd 4th 5th Mssn is a concrete continuous tee beam carrying U. S. Highway 101 over 2nd 3rd 4th 5th Mssn in Marin County, California. It was built in 1941 and reconstructed in 1971, so it is 84 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 64,500 vehicles a day, projected to reach 92,093 by 2046. The structure is 2,210 ft (673.6 m) long and 54 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

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CarriesU. S. Highway 101
Crosses2nd 3rd 4th 5th Mssn
Location04-MRN-101-10.72-SRF
RouteU.S. Route 101
CountyMarin County
StateCalifornia
Coordinates37.96876, -122.52061
Functional classUrban Principal Arterial - Other Freeway or Expressway

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.
Substructure7 GoodSome minor problems.
Channel and channel protection9 ExcellentNo problems noted.
Last inspectionMay 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 alignment7: Better than present minimum criteria
Operating rating49.6 US tons
Inventory rating30 US tons

Structure

Structure typeTee Beam
MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans37 (+30 approach)
Design loadUnknown
Structure length2,210 ft (673.6 m)
Longest span58 ft (17.7 m)
Deck width54 ft (16.4 m)
Roadway width51 ft (15.5 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic64,500 (2009)
Projected traffic92,093 by 2046
Trucks0%
Lanes on structure3
Traffic directionOne-way traffic
CarriesHighway
CrossesHighway and waterway
Detour if closed1.2 mi (2 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 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 U. S. Highway 101 over 2nd 3rd 4th 5th Mssn built?

It was built in 1941, making it 84 years old in 2025. It was reconstructed in 1971.

What condition is U. S. Highway 101 over 2nd 3rd 4th 5th Mssn 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 May 2024.

How much traffic does U. S. Highway 101 over 2nd 3rd 4th 5th Mssn carry?

About 64,500 vehicles per day (2009 count).

How long is U. S. Highway 101 over 2nd 3rd 4th 5th Mssn?

The structure is 2,210 ft (673.6 m) long with a longest span of 58 ft (17.7 m) and a deck 54 ft wide.

Who owns U. S. Highway 101 over 2nd 3rd 4th 5th Mssn?

It is owned by the State Highway Agency.