US Bridges

CR 305 (mapes Rd) over Whitehead Slough

PoorPosted for load

Lassen County, California · 0.6 MI S/O RD 306 · Structure no. 07C0041

Built
1978
47 years old
Condition
Poor
inspected August 2024
Type
Stringer/Multi-beam or Girder
Wood or Timber
Length
60 ft
3 main spans
Daily traffic
162
2009 count
Owner
County
County Highway Agency

About this bridge

CR 305 (mapes Rd) over Whitehead Slough is a wood or timber stringer/multi-beam or girder carrying CR 305 (mapes Rd) over Whitehead 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 poor condition with a lowest component rating of 4 out of 9. The lowest-rated primary component is rated 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions. Its operating status is: posted for load restriction.

It carries about 162 vehicles a day, roughly 8% of them trucks, projected to reach 199 by 2043. The structure is 60 ft (18.3 m) long and 24 ft wide. If it were closed, the detour would be 5 mi (8 km).

Location

Open in Google Maps
CarriesCR 305 (mapes Rd)
CrossesWhitehead Slough
Location0.6 MI S/O RD 306
RouteCounty Highway 0
CountyLassen County
StateCalifornia
Coordinates40.32902, -120.34202
Functional classRural Minor Collector

Condition and inspection

Poor

The lowest-rated primary component is rated 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions.

ComponentRatingMeaning
Deck7 GoodSome minor problems.
Superstructure4 PoorAdvanced section loss, deterioration, 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 12 months
Operating statusPosted for load restriction
ScourUnknown foundation; not evaluated for scour
Structural evaluation2: Basically intolerable, requiring high priority of replacement
Deck geometry4: Meets minimum tolerable limits to be left in place as is
Waterway adequacy7: Better than present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating11 US tons
Inventory rating8.3 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialWood or Timber
DeckWood or timber
Main spans3
Design loadUnknown
Structure length60 ft (18.3 m)
Longest span20 ft (6.1 m)
Deck width24 ft (7.3 m)
Roadway width23 ft (7.1 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic162 (2009)
Projected traffic199 by 2043
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 proposedReplacement because of substandard load-carrying capacity or roadway geometry
Estimated improvement cost$510,000 (2017 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was CR 305 (mapes Rd) over Whitehead Slough built?

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

What condition is CR 305 (mapes Rd) over Whitehead Slough in?

The National Bridge Inventory rates it in poor condition. The lowest-rated primary component is rated 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions. The last reported inspection was in August 2024.

How much traffic does CR 305 (mapes Rd) over Whitehead Slough carry?

About 162 vehicles per day (2009 count), of which roughly 8% are trucks.

How long is CR 305 (mapes Rd) over Whitehead Slough?

The structure is 60 ft (18.3 m) long with a longest span of 20 ft (6.1 m) and a deck 24 ft wide.

Who owns CR 305 (mapes Rd) over Whitehead Slough?

It is owned by the County Highway Agency.