US Bridges

Lassen ST over Susan River

Fair

Lassen County, California · 0.3 MI S of S.H. 36 · Structure no. 07C0016

Built
1965
60 years old
Condition
Fair
inspected August 2023
Type
Box Beam or Girders - Multiple
Concrete
Length
79 ft
1 main span
Daily traffic
400
1980 count
Owner
City
City or Municipal Highway Agency

About this bridge

Lassen ST over Susan River is a concrete box beam or girders - multiple carrying Lassen ST over Susan River in Lassen County, California. It was built in 1965, so it is 60 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 400 vehicles a day, roughly 1% of them trucks, projected to reach 875 by 2042. The structure is 79 ft (24.1 m) long and 27 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

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CarriesLassen ST
CrossesSusan River
Location0.3 MI S of S.H. 36
RouteCity Street 0
CountyLassen County
StateCalifornia
Coordinates40.41378, -120.66406
Functional classUrban 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
Deck5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Superstructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Substructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Channel and channel protection7 GoodSome minor problems.
Last inspectionAugust 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 geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Waterway adequacy5: Somewhat better than minimum adequacy to tolerate being left in place as is
Approach roadway alignment6: Equal to present minimum criteria
Operating rating54.2 US tons
Inventory rating41.8 US tons

Structure

Structure typeBox Beam or Girders - Multiple
MaterialConcrete
DeckConcrete, cast-in-place
Main spans1
Design loadHS 20
Structure length79 ft (24.1 m)
Longest span77 ft (23.5 m)
Deck width27 ft (8.1 m)
Roadway width26 ft (7.9 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic400 (1980)
Projected traffic875 by 2042
Trucks1%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed1.2 mi (2 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerCity or Municipal Highway Agency
Maintained byCity or Municipal 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 Lassen ST over Susan River built?

It was built in 1965, making it 60 years old in 2025.

What condition is Lassen ST over Susan 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 August 2023.

How much traffic does Lassen ST over Susan River carry?

About 400 vehicles per day (1980 count), of which roughly 1% are trucks.

How long is Lassen ST over Susan River?

The structure is 79 ft (24.1 m) long with a longest span of 77 ft (23.5 m) and a deck 27 ft wide.

Who owns Lassen ST over Susan River?

It is owned by the City or Municipal Highway Agency.