US Bridges

Irwin Way over San Lorenzo River

Fair

Santa Cruz County, California · 0.2 MI E Highway 9 · Structure no. 36C0083

Built
1955
70 years old
Condition
Fair
inspected November 2024
Type
Stringer/Multi-beam or Girder
Steel
Length
108 ft
3 main spans
Daily traffic
1,500
2015 count
Owner
County
County Highway Agency

About this bridge

Irwin Way over San Lorenzo River is a steel stringer/multi-beam or girder carrying Irwin Way over San Lorenzo River in Santa Cruz County, California. It was built in 1955, so it is 70 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 1,500 vehicles a day, roughly 10% of them trucks, projected to reach 2,081 by 2046. The structure is 108 ft (32.9 m) long and 16 ft wide. If it were closed, the detour would be 1.9 mi (3 km).

Location

Open in Google Maps
CarriesIrwin Way
CrossesSan Lorenzo River
Location0.2 MI E Highway 9
RouteCounty Highway 0
CountySanta Cruz County
StateCalifornia
Coordinates37.11306, -122.1122
Functional classUrban Local

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.
Superstructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Substructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Channel and channel protection7 GoodSome minor problems.
Last inspectionNovember 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry2: Basically intolerable, requiring high priority of replacement
Waterway adequacy7: Better than present minimum criteria
Approach roadway alignment3: Basically intolerable, requiring high priority of corrective action
Operating rating60.4 US tons
Inventory rating36 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckConcrete, cast-in-place
Main spans3
Design loadUnknown
Structure length108 ft (32.9 m)
Longest span60 ft (18.2 m)
Deck width16 ft (4.9 m)
Roadway width12 ft (3.7 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic1,500 (2015)
Projected traffic2,081 by 2046
Trucks10%
Lanes on structure1
Traffic directionOne-lane bridge for two-way traffic
CarriesHighway
CrossesWaterway
Detour if closed1.9 mi (3 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 proposedNone recorded
Estimated improvement cost—
NavigationNo navigation control on waterway

Frequently asked questions

When was Irwin Way over San Lorenzo River built?

It was built in 1955, making it 70 years old in 2025.

What condition is Irwin Way over San Lorenzo River 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 November 2024.

How much traffic does Irwin Way over San Lorenzo River carry?

About 1,500 vehicles per day (2015 count), of which roughly 10% are trucks.

How long is Irwin Way over San Lorenzo River?

The structure is 108 ft (32.9 m) long with a longest span of 60 ft (18.2 m) and a deck 16 ft wide.

Who owns Irwin Way over San Lorenzo River?

It is owned by the County Highway Agency.