US Bridges

Old Redwood HWY over Laguna De Santa Rosa

Poor

Sonoma County, California · Commerce Blvd · Structure no. 20C0067

Built
1956
69 years old
Condition
Poor
inspected June 2023
Type
Culvert
Concrete Continuous
Length
24 ft
2 main spans
Daily traffic
9,800
2015 count
Owner
City
City or Municipal Highway Agency

About this bridge

Old Redwood HWY over Laguna De Santa Rosa is a concrete continuous culvert carrying Old Redwood HWY over Laguna De Santa Rosa in Sonoma County, California. It was built in 1956, so it is 69 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 9,800 vehicles a day, roughly 2% of them trucks, projected to reach 13,085 by 2045. The structure is 24 ft (7.3 m) long and 37 ft wide. If it were closed, the detour would be 1.9 mi (3 km).

Location

Open in Google Maps
CarriesOld Redwood HWY
CrossesLaguna De Santa Rosa
LocationCommerce Blvd
RouteCity Street 0
CountySonoma County
StateCalifornia
Coordinates38.33578, -122.71225
Functional classUrban 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
Channel and channel protection8 Very GoodNo problems noted.
Culvert4 PoorAdvanced section loss, deterioration, spalling or scour.
Last inspectionJune 2023
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 geometry2: Basically intolerable, requiring high priority of replacement
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment6: Equal to present minimum criteria
Operating rating59.6 US tons
Inventory rating35.7 US tons

Structure

Structure typeCulvert
MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans2
Design loadUnknown
Structure length24 ft (7.3 m)
Longest span11 ft (3.4 m)
Deck width37 ft (11.4 m)
Roadway width27 ft (8.2 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic9,800 (2015)
Projected traffic13,085 by 2045
Trucks2%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed1.9 mi (3 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 proposedReplacement because of substandard load-carrying capacity or roadway geometry
Estimated improvement cost$328,000 (2024 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was Old Redwood HWY over Laguna De Santa Rosa built?

It was built in 1956, making it 69 years old in 2025.

What condition is Old Redwood HWY over Laguna De Santa Rosa 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 June 2023.

How much traffic does Old Redwood HWY over Laguna De Santa Rosa carry?

About 9,800 vehicles per day (2015 count), of which roughly 2% are trucks.

How long is Old Redwood HWY over Laguna De Santa Rosa?

The structure is 24 ft (7.3 m) long with a longest span of 11 ft (3.4 m) and a deck 37 ft wide.

Who owns Old Redwood HWY over Laguna De Santa Rosa?

It is owned by the City or Municipal Highway Agency.