US Bridges

Novato Blvd over Bowman Canyon

Poor

Marin County, California · 1 Mile N Intxn Sutro Ave. · Structure no. 27C0037

Built
1948
77 years old
Condition
Poor
inspected July 2024
Type
Tee Beam
Concrete
Length
23 ft
1 main span
Daily traffic
3,056
2023 count
Owner
County
County Highway Agency

About this bridge

Novato Blvd over Bowman Canyon is a concrete tee beam carrying Novato Blvd over Bowman Canyon in Marin County, California. It was built in 1948, so it is 77 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 2 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 3,056 vehicles a day, roughly 15% of them trucks, projected to reach 3,946 by 2046. The structure is 23 ft (7 m) long and 27 ft wide. If it were closed, the detour would be 21.7 mi (35 km).

Location

Open in Google Maps
CarriesNovato Blvd
CrossesBowman Canyon
Location1 Mile N Intxn Sutro Ave.
RouteCounty Highway 0
CountyMarin County
StateCalifornia
Coordinates38.12309, -122.6256
Functional classRural Major 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.
Superstructure7 GoodSome minor problems.
Substructure2 CriticalAdvanced deterioration of primary structural elements. Bridge may be closed until corrective action is taken.
Channel and channel protection4 PoorAdvanced section loss, deterioration, spalling or scour.
Last inspectionJuly 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourScour critical; extensive scour has occurred
Structural evaluation2: Basically intolerable, requiring high priority of replacement
Deck geometry2: Basically intolerable, requiring high priority of replacement
Waterway adequacy5: Somewhat better than minimum adequacy to tolerate being left in place as is
Approach roadway alignment6: Equal to present minimum criteria
Operating rating68.6 US tons
Inventory rating41.1 US tons

Structure

Structure typeTee Beam
MaterialConcrete
DeckConcrete, cast-in-place
Main spans1
Design loadHS 20
Structure length23 ft (7 m)
Longest span22 ft (6.7 m)
Deck width27 ft (8.1 m)
Roadway width24 ft (7.3 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic3,056 (2023)
Projected traffic3,946 by 2046
Trucks15%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed21.7 mi (35 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$208,000 (2017 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was Novato Blvd over Bowman Canyon built?

It was built in 1948, making it 77 years old in 2025.

What condition is Novato Blvd over Bowman Canyon 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 July 2024.

How much traffic does Novato Blvd over Bowman Canyon carry?

About 3,056 vehicles per day (2023 count), of which roughly 15% are trucks.

How long is Novato Blvd over Bowman Canyon?

The structure is 23 ft (7 m) long with a longest span of 22 ft (6.7 m) and a deck 27 ft wide.

Who owns Novato Blvd over Bowman Canyon?

It is owned by the County Highway Agency.