US Bridges

State Route 1 over Castro Canyon

Fair

Monterey County, California · 05-MON-001-43.12 · Structure no. 44 0035

Built
1937
88 years old
Condition
Fair
inspected February 2025
Type
Stringer/Multi-beam or Girder
Steel
Length
239 ft
5 main spans
Daily traffic
3,150
2009 count
Owner
State
State Highway Agency

About this bridge

State Route 1 over Castro Canyon is a steel stringer/multi-beam or girder carrying State Route 1 over Castro Canyon in Monterey County, California. It was built in 1937, so it is 88 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 5 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 3,150 vehicles a day, roughly 1% of them trucks, projected to reach 2,882 by 2045. The structure is 239 ft (72.8 m) long and 30 ft wide. If it were closed, the detour would be 123.7 mi (199 km).

Location

Open in Google Maps
CarriesState Route 1
CrossesCastro Canyon
Location05-MON-001-43.12
RouteState Highway 1
CountyMonterey County
StateCalifornia
Coordinates36.21686, -121.75008
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
Deck5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Superstructure7 GoodSome minor problems.
Substructure7 GoodSome minor problems.
Channel and channel protection7 GoodSome minor problems.
Last inspectionFebruary 2025
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
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 rating48.9 US tons
Inventory rating29.3 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckConcrete, cast-in-place
Main spans5
Design loadH 15
Structure length239 ft (72.8 m)
Longest span51 ft (15.5 m)
Deck width30 ft (9.2 m)
Roadway width27 ft (8.3 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic3,150 (2009)
Projected traffic2,882 by 2045
Trucks1%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed123.7 mi (199 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 Castro Canyon built?

It was built in 1937, making it 88 years old in 2025.

What condition is State Route 1 over Castro Canyon 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 February 2025.

How much traffic does State Route 1 over Castro Canyon carry?

About 3,150 vehicles per day (2009 count), of which roughly 1% are trucks.

How long is State Route 1 over Castro Canyon?

The structure is 239 ft (72.8 m) long with a longest span of 51 ft (15.5 m) and a deck 30 ft wide.

Who owns State Route 1 over Castro Canyon?

It is owned by the State Highway Agency.