US Bridges

RD 304 over Hartson Slough

Fair

Lassen County, California · 0.7 MI E/O RD 302 · Structure no. 07C0053

Built
1978
47 years old
Condition
Fair
inspected August 2024
Type
Stringer/Multi-beam or Girder
Wood or Timber
Length
28 ft
2 main spans
Daily traffic
100
1979 count
Owner
County
County Highway Agency

About this bridge

RD 304 over Hartson Slough is a wood or timber stringer/multi-beam or girder carrying RD 304 over Hartson Slough in Lassen County, California. It was built in 1978, so it is 47 years old, younger 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 100 vehicles a day, roughly 8% of them trucks, projected to reach 135 by 2046. The structure is 28 ft (8.4 m) long and 28 ft wide. If it were closed, the detour would be 5 mi (8 km).

Location

Open in Google Maps
CarriesRD 304
CrossesHartson Slough
Location0.7 MI E/O RD 302
RouteCounty Highway 0
CountyLassen County
StateCalifornia
Coordinates40.35102, -120.38644
Functional classRural Local

Condition and inspection

Fair

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

ComponentRatingMeaning
Deck7 GoodSome minor problems.
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 protection6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionAugust 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourUnknown foundation; not evaluated for scour
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry6: Equal to present minimum criteria
Waterway adequacy6: Equal to present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating41.1 US tons
Inventory rating28.9 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialWood or Timber
DeckCorrugated steel
Main spans2
Design loadUnknown
Structure length28 ft (8.4 m)
Longest span13 ft (4 m)
Deck width28 ft (8.5 m)
Roadway width28 ft (8.4 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic100 (1979)
Projected traffic135 by 2046
Trucks8%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed5 mi (8 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—
NavigationNo navigation control on waterway

Frequently asked questions

When was RD 304 over Hartson Slough built?

It was built in 1978, making it 47 years old in 2025.

What condition is RD 304 over Hartson 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 RD 304 over Hartson Slough carry?

About 100 vehicles per day (1979 count), of which roughly 8% are trucks.

How long is RD 304 over Hartson Slough?

The structure is 28 ft (8.4 m) long with a longest span of 13 ft (4 m) and a deck 28 ft wide.

Who owns RD 304 over Hartson Slough?

It is owned by the County Highway Agency.