US Bridges

State Route 1 over San Gregorio Creek

Fair

San Mateo County, California · 04-SM-001-17.90 · Structure no. 35 0030

Built
1941
84 years old
Condition
Fair
inspected October 2024
Type
Tee Beam
Concrete Continuous
Length
265 ft
5 main spans
Daily traffic
6,100
2009 count
Owner
State
State Highway Agency

About this bridge

State Route 1 over San Gregorio Creek is a concrete continuous tee beam carrying State Route 1 over San Gregorio Creek in San Mateo County, California. It was built in 1941, so it is 84 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 6,100 vehicles a day, roughly 5% of them trucks, projected to reach 9,189 by 2046. The structure is 265 ft (80.8 m) long and 32 ft wide. If it were closed, the detour would be 9.9 mi (16 km).

Location

Open in Google Maps
CarriesState Route 1
CrossesSan Gregorio Creek
Location04-SM-001-17.90
RouteState Highway 1
CountySan Mateo County
StateCalifornia
Coordinates37.32065, -122.40202
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
Deck7 GoodSome minor problems.
Superstructure7 GoodSome minor problems.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionOctober 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation6: Equal to present minimum criteria
Deck geometry3: Basically intolerable, requiring high priority of corrective action
Waterway adequacy9: Superior to present desirable criteria
Approach roadway alignment6: Equal to present minimum criteria
Operating rating44.3 US tons
Inventory rating31.1 US tons

Structure

Structure typeTee Beam
MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans5
Design loadH 20
Structure length265 ft (80.8 m)
Longest span59 ft (18 m)
Deck width32 ft (9.7 m)
Roadway width26 ft (7.9 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic6,100 (2009)
Projected traffic9,189 by 2046
Trucks5%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed9.9 mi (16 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 San Gregorio Creek built?

It was built in 1941, making it 84 years old in 2025.

What condition is State Route 1 over San Gregorio 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 San Gregorio Creek carry?

About 6,100 vehicles per day (2009 count), of which roughly 5% are trucks.

How long is State Route 1 over San Gregorio Creek?

The structure is 265 ft (80.8 m) long with a longest span of 59 ft (18 m) and a deck 32 ft wide.

Who owns State Route 1 over San Gregorio Creek?

It is owned by the State Highway Agency.