US Bridges

State Route 1 over Redwood Creek

Poor

Marin County, California · 04-MRN-001-6.02 · Structure no. 27 0019

Built
1926
99 years old, rebuilt 1970
Condition
Poor
inspected May 2024
Type
Culvert
Concrete Continuous
Length
40 ft
3 main spans
Daily traffic
3,800
2021 count
Owner
State
State Highway Agency

About this bridge

State Route 1 over Redwood Creek is a concrete continuous culvert carrying State Route 1 over Redwood Creek in Marin County, California. It was built in 1926 and reconstructed in 1970, so it is 99 years old, older 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.

It carries about 3,800 vehicles a day, projected to reach 5,116 by 2042. The structure is 40 ft (12.2 m) long and 29 ft wide. If it were closed, the detour would be 16.2 mi (26 km).

Location

Open in Google Maps
CarriesState Route 1
CrossesRedwood Creek
Location04-MRN-001-6.02
RouteState Highway 1
CountyMarin County
StateCalifornia
Coordinates37.86629, -122.57845
Functional classRural Minor Arterial

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
Channel and channel protection8 Very GoodNo problems noted.
Culvert4 PoorAdvanced section loss, deterioration, spalling or scour.
Last inspectionMay 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation4: Meets minimum tolerable limits to be left in place as is
Deck geometry3: Basically intolerable, requiring high priority of corrective action
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment6: Equal to present minimum criteria
Operating rating30 US tons
Inventory rating17.9 US tons

Structure

Structure typeCulvert
MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans3
Design loadH 15
Structure length40 ft (12.2 m)
Longest span12 ft (3.7 m)
Deck width29 ft (8.8 m)
Roadway width27 ft (8.2 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic3,800 (2021)
Projected traffic5,116 by 2042
Trucks0%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed16.2 mi (26 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerState Highway Agency
Maintained byState 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$417,000 (2017 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was State Route 1 over Redwood Creek built?

It was built in 1926, making it 99 years old in 2025. It was reconstructed in 1970.

What condition is State Route 1 over Redwood Creek 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 May 2024.

How much traffic does State Route 1 over Redwood Creek carry?

About 3,800 vehicles per day (2021 count).

How long is State Route 1 over Redwood Creek?

The structure is 40 ft (12.2 m) long with a longest span of 12 ft (3.7 m) and a deck 29 ft wide.

Who owns State Route 1 over Redwood Creek?

It is owned by the State Highway Agency.