US Bridges

State Route 1 over Tunitas Creek

Fair

San Mateo County, California · 04-SM-001-20.82 · Structure no. 35 0031

Built
1962
63 years old
Condition
Fair
inspected October 2024
Type
Stringer/Multi-beam or Girder
Prestressed Concrete
Length
421 ft
6 main spans
Daily traffic
6,000
2009 count
Owner
State
State Highway Agency

About this bridge

State Route 1 over Tunitas Creek is a prestressed concrete stringer/multi-beam or girder carrying State Route 1 over Tunitas Creek in San Mateo County, California. It was built in 1962, so it is 63 years old, older 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 6 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 6,000 vehicles a day, roughly 8% of them trucks, projected to reach 10,129 by 2046. The structure is 421 ft (128.2 m) long and 34 ft wide. If it were closed, the detour would be 28 mi (45 km).

Location

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CarriesState Route 1
CrossesTunitas Creek
Location04-SM-001-20.82
RouteState Highway 1
CountySan Mateo County
StateCalifornia
Coordinates37.35671, -122.39694
Functional classRural Minor Arterial

Condition and inspection

Fair

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

ComponentRatingMeaning
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure8 Very GoodNo problems noted.
Substructure8 Very GoodNo problems noted.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionOctober 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation7: Better than present minimum criteria
Deck geometry4: Meets minimum tolerable limits to be left in place as is
Waterway adequacy9: Superior to present desirable criteria
Approach roadway alignment6: Equal to present minimum criteria
Operating rating58.2 US tons
Inventory rating33.2 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans6
Design loadHS 20 + Mod
Structure length421 ft (128.2 m)
Longest span75 ft (22.9 m)
Deck width34 ft (10.4 m)
Roadway width28 ft (8.5 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic6,000 (2009)
Projected traffic10,129 by 2046
Trucks8%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed28 mi (45 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 proposedNone recorded
Estimated improvement cost—
NavigationNo navigation control on waterway

Frequently asked questions

When was State Route 1 over Tunitas Creek built?

It was built in 1962, making it 63 years old in 2025.

What condition is State Route 1 over Tunitas Creek 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 October 2024.

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

About 6,000 vehicles per day (2009 count), of which roughly 8% are trucks.

How long is State Route 1 over Tunitas Creek?

The structure is 421 ft (128.2 m) long with a longest span of 75 ft (22.9 m) and a deck 34 ft wide.

Who owns State Route 1 over Tunitas Creek?

It is owned by the State Highway Agency.