US Bridges

Highland Terrace over Hillside

Fair

Sonoma County, California · At Mesa Wy · Structure no. 20C0476

Built
1983
42 years old
Condition
Fair
inspected March 2024
Type
Stringer/Multi-beam or Girder
Steel Continuous
Length
96 ft
5 main spans
Daily traffic
100
2011 count
Owner
County
County Highway Agency

About this bridge

Highland Terrace over Hillside is a steel continuous stringer/multi-beam or girder carrying Highland Terrace over Hillside in Sonoma County, California. It was built in 1983, so it is 42 years old, younger 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 100 vehicles a day, projected to reach 109 by 2042. The structure is 96 ft (29.3 m) long and 14 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

Open in Google Maps
CarriesHighland Terrace
CrossesHillside
LocationAt Mesa Wy
RouteCounty Highway 0
CountySonoma County
StateCalifornia
Coordinates38.46495, -123.01584
Functional classRural 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
Deck7 GoodSome minor problems.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionMarch 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation6: Equal to present minimum criteria
Deck geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Approach roadway alignment3: Basically intolerable, requiring high priority of corrective action
Operating rating64.3 US tons
Inventory rating38.6 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel Continuous
DeckCorrugated steel
Main spans5
Design loadHS 20
Structure length96 ft (29.3 m)
Longest span19 ft (5.8 m)
Deck width14 ft (4.3 m)
Roadway width13 ft (4.1 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic100 (2011)
Projected traffic109 by 2042
Trucks—
Lanes on structure1
Traffic directionOne-lane bridge for two-way traffic
CarriesHighway
CrossesOther
Detour if closed1.2 mi (2 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 Highland Terrace over Hillside built?

It was built in 1983, making it 42 years old in 2025.

What condition is Highland Terrace over Hillside 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 March 2024.

How much traffic does Highland Terrace over Hillside carry?

About 100 vehicles per day (2011 count).

How long is Highland Terrace over Hillside?

The structure is 96 ft (29.3 m) long with a longest span of 19 ft (5.8 m) and a deck 14 ft wide.

Who owns Highland Terrace over Hillside?

It is owned by the County Highway Agency.